Developmental and Epileptic Encephalopathy with Spike-Wave Activation in Sleep

Complex MONDO:0800501 Pathograph 12 Show in embeddings browser Epilepsy Neurological Disease

A childhood epilepsy syndrome whose defining lesion is not a seizure type but a sleep state. Epileptiform discharge that is sparse or absent while the child is awake becomes near-continuous once non-rapid-eye-movement sleep begins, and the child loses skills already acquired: language, attention, behaviour, or general cognition depending on which cortex is involved. Seizures are often mild and are not what does the damage. The syndrome is developmentally gated, appearing in mid-childhood and remitting spontaneously around adolescence whether or not it is treated, while the cognitive losses may not recover. Causes are heterogeneous, split roughly between genetic variants and early structural injury to the thalamus. The ILAE splits the syndrome by baseline development: DEE-SWAS in children already developmentally delayed, EE-SWAS in children whose development was normal until the regression.

Ask OpenScientist

Ask a research question about Developmental and Epileptic Encephalopathy with Spike-Wave Activation in Sleep. OpenScientist will conduct autonomous deep research using the Disorder Mechanisms Knowledge Base and PubMed literature (typically 10-30 minutes).

Submitting...

Do not include personal health information in your question. Questions and results are cached in your browser's local storage.

1
Mappings
3
Inheritance
9
Pathophys.
9
Phenotypes
4
Gaps
12
Pathograph
2
Genes
3
Medical Actions
2
Subtypes
3
Differentials
3
References
1
Deep Research
🔗

Mappings

MONDO
MONDO:0800501 developmental and/or epileptic encephalopathy with spike-wave activation in sleep
skos:exactMatch MONDO
MONDO:0800501 is the current concept for the syndrome the ILAE renamed from continuous spike-and-wave during sleep, and covers both the DEE-SWAS and EE-SWAS arms this entry models together.
👪

Inheritance

3
Heterogeneous, mostly de novo genetic or non-genetic HP:0003745
There is no single inheritance pattern. A genetic cause is found in about a third of patients, spread across many genes rather than concentrated in one, with channelopathies and transcriptional regulators prominent. A comparable share have an acquired structural cause, chiefly perinatal thalamic injury, which is not heritable at all. Counselling therefore depends entirely on which arm a given child falls into, and in over half of cases no cause is identified.
Sporadic
Show evidence (2 references)
PMID:39096015 SUPPORT Human Clinical
"A genetic etiology was identified in 31/91 (34%)."
Quantifies the genetic share, and by implication the majority in which a Mendelian inheritance pattern cannot be offered.
PMID:39096015 SUPPORT Human Clinical
"DEE-SWAS and EE-SWAS have highly heterogeneous genetic and structural etiologies."
States the etiological heterogeneity that makes a single inheritance statement impossible for this syndrome.
Autosomal dominant, usually de novo HP:0000006
Most of the identified genetic causes are autosomal genes in which a single variant is sufficient, and the variants are typically de novo rather than inherited, which is why the family history is usually blank. The counselling consequence is that recurrence risk for siblings is low but not zero, because parental gonadal mosaicism cannot be excluded.
Autosomal dominant inheritance
Show evidence (1 reference)
PMID:39096015 SUPPORT Human Clinical
"We identified 10 novel D/EE-SWAS genes with a range of functions: ATP1A2, CACNA1A, FOXP1, GRIN1, KCNMA1, KCNQ3, PPFIA3, PUF60, SETD1B, and ZBTB18, and 2 novel copy number variants, 17p11.2 duplication and 5q22 deletion."
The named genes are autosomal and are established dominant developmental-disorder genes, which is the basis for curating an autosomal dominant block. Marked PARTIAL because the cited abstract lists the genes without stating the inheritance mode for each, so the mode is inferred from the genes rather than quoted.
X-linked HP:0001417
A minority of cases arise from X-linked genes, which matters disproportionately for counselling because the recurrence risk and the pattern of who is affected differ completely from the autosomal forms. CNKSR2 is the best-known example in this syndrome.
X-linked inheritance
Show evidence (1 reference)
PMID:39096015 SUPPORT Human Clinical
"DEE-SWAS and EE-SWAS have highly heterogeneous genetic and structural etiologies."
Supports genetic heterogeneity broad enough to include X-linked causes. Marked PARTIAL because the abstract does not name an X-linked gene, so this block records the counselling-relevant possibility rather than quoting a demonstration of it, and the X-linked genes named in the wider literature are not asserted here without verifiable snippets.
◆

Subtypes

2
Developmental and epileptic encephalopathy with spike-wave activation in sleep
The arm in which development was already impaired before the spike-wave activation began, so the child has both a developmental encephalopathy and an epileptic one. It behaves differently from its sibling arm in two ways that a mere difference in starting point does not obviously predict: an etiology is found roughly two thirds of the time, more than twice as often as in EE-SWAS, and the epilepsy runs longer with a poorer intellectual outcome. Whether that makes it a distinct entity is an open question curated in the discussions block.
Show evidence (2 references)
PMID:39096015 SUPPORT Human Clinical
"We identified the etiology in 42/91 (46%) patients in our Core cohort, including 29/44 (66%) with DEE-SWAS and 13/47 (28%) with EE-SWAS."
Quantifies the etiological yield in this arm and the contrast with the other, which is the strongest evidence that the split tracks something real.
PMID:39096015 SUPPORT Human Clinical
"Although developmental regression patterns were similar in both syndromes, DEE-SWAS was associated with a longer duration of epilepsy and poorer intellectual outcome than EE-SWAS."
Documents the worse course of this arm alongside the shared regression process.
Epileptic encephalopathy with spike-wave activation in sleep
The arm in which development was normal until the regression, so the encephalopathy is purely epileptic in the sense that the child had nothing wrong before it started. An etiology is found in only about a quarter of these children, and the intellectual outcome is better than in DEE-SWAS. Landau-Kleffner syndrome is the best-known presentation within this arm, distinguished by the activation sitting over perisylvian language cortex so that the regression is specifically an acquired auditory agnosia. This is the arm the randomized treatment evidence was generated in.
Show evidence (2 references)
PMID:39096015 SUPPORT Human Clinical
"We identified the etiology in 42/91 (46%) patients in our Core cohort, including 29/44 (66%) with DEE-SWAS and 13/47 (28%) with EE-SWAS."
Quantifies the much lower etiological yield in this arm, which is what makes the label practically useful when deciding how hard to investigate.
PMID:38081201 SUPPORT Human Clinical
"Epileptic encephalopathy with spike-wave activation in sleep (EE-SWAS) is a rare syndrome associated with cognitive and behavioural regression."
Confirms that the randomized treatment evidence in this entry was generated specifically in this arm, which is a limit on generalizing it to DEE-SWAS.
?

Discussions and Knowledge Gaps

4
Does the sleep-activated epileptiform discharge actually cause the developmental regression, or are the discharge and the regression parallel consequences of the same underlying lesion, and what would distinguish the two?
CONTROVERSY UNDER DISCUSSION dee_swas_does_the_eeg_cause_the_regression
Attached to
pathophysiology#Sleep-Potentiated Spike-Wave Activation pathophysiology#Disruption of Sleep-Dependent Synaptic Plasticity pathophysiology#Developmental Regression and Cognitive-Behavioural Encephalopathy
The syndrome's name embeds the causal claim, and there is a coherent mechanism for it: slow-wave sleep is when synaptic strengths are rescaled and cortical maps consolidate during critical periods, so filling that window with continuous discharge should damage exactly what it appears to damage. The topographic correlation supports it too, since the domain lost tracks which cortex carries the activation rather than tracking seizure burden. The strongest evidence is therapeutic: in the only randomized trial, children given corticosteroids were substantially more likely to gain intelligence quotient points than children given clobazam, which is hard to explain if the discharge were a bystander. But the case is not closed. The trial stopped early without its target sample, and its two co-primary cognitive measures disagreed, with the sum score showing no difference at all. The alternative reading is that a single lesion, whether a thalamic injury or a gene, produces both an abnormally excitable cortex and a cortex that develops badly, and that suppressing the discharge treats a marker. Two observations sit awkwardly for the strong causal reading. The electrographic pattern remits spontaneously at adolescence in essentially everyone, yet cognitive recovery is variable and often incomplete, which is at least consistent with the deficit having been set by the lesion rather than accumulated by the discharge. And regression patterns are similar in DEE-SWAS and EE-SWAS despite those groups differing substantially in underlying etiology and in eventual outcome. The stake is concrete: if the discharge is causal, aggressive early suppression is worth its steroid toxicity, and normalizing the sleep record is a legitimate treatment target. If it is a marker, both of those are wrong.
Proposed experiments
Mediation analysis of discharge burden between etiology and cognitive outcome
exp_dee_swas_discharge_burden_mediation
A prospective cohort with etiology characterized at entry, quantified spike-wave index measured serially through the active period, and standardized cognitive testing at fixed intervals, analysed to test whether discharge burden mediates the relationship between etiology and cognitive trajectory, or whether etiology predicts outcome independently of how much discharge occurred.
Decision criterion
If cumulative discharge burden mediates the etiology-outcome relationship and predicts cognitive decline after adjustment for etiology, the causal reading is supported and suppression is a legitimate target. If etiology predicts outcome with no independent contribution from discharge burden, the discharge is a marker and treatment should be judged on cognition alone.
Dissociation of electrographic and cognitive response to treatment
exp_dee_swas_eeg_response_versus_cognitive_response
Within treated cohorts, classify children by whether the sleep record normalized and separately by whether cognition improved, and quantify the agreement between the two. Cases of electrographic response without cognitive response, and the reverse, are the informative cells.
Decision criterion
Tight concordance would support the causal chain. A substantial number of children whose record normalizes without cognitive benefit would show that suppressing the discharge is not sufficient, and would undermine normalization of the electroencephalogram as a treatment endpoint.
Show evidence (5 references)
PMID:25160535 SUPPORT Other
"Over the last 20 years, a variety of basic science findings suggest how spike-wave activity during sleep can cause the observed clinical outcomes."
States the mechanistic case for the causal reading, and states it as suggestion rather than demonstration, which is the epistemic situation this discussion records.
PMID:38081201 SUPPORT Human Clinical
"Our findings strengthen those from previous uncontrolled studies that support the early use of corticosteroids for children with EE-SWAS."
The randomized evidence that a treatment aimed at the discharge improves cognition, which is the strongest argument for the causal reading.
PMID:38081201 SUPPORT Human Clinical
"Our data indicated an improvement in IQ outcomes with corticosteroids compared with clobazam treatment, but no difference was seen in cognitive sum score."
The disagreement between the two co-primary measures, which is why the trial supports rather than settles the causal reading.
+ 2 more references
Is the ILAE split between DEE-SWAS and EE-SWAS, which rests entirely on whether development was already impaired before the spike-wave activation began, a real boundary or a description of the starting point?
CONTROVERSY OPEN dee_swas_one_syndrome_or_two
Attached to
pathophysiology#Developmental Regression and Cognitive-Behavioural Encephalopathy pathophysiology#Heterogeneous Genetic Etiology
The two labels differ only in baseline development, which is a statement about the child before the process started rather than about the process. The mechanism modeled in this entry is the same for both, which is why they are curated together. Evidence for the split being real is that the arms behave differently in ways a mere baseline difference does not obviously predict: an etiology is found in about two thirds of DEE-SWAS but only about a quarter of EE-SWAS, and DEE-SWAS carries a longer duration of epilepsy and a poorer intellectual outcome. Evidence against is that the regression itself looks the same in both, which is what one expects if a common process is acting on two different starting points. There is also a measurement problem underneath the boundary: mild pre-existing delay is hard to establish retrospectively once a child has regressed, and families reconstruct the before-picture through the after-picture, so some children are probably assigned to the wrong arm. The practical consequence of getting this right is diagnostic effort, because the etiological yield difference between the arms is large enough that the label changes how hard it is worth looking for a cause.
Proposed experiments
Prospectively measured baseline development before regression
exp_dee_swas_prospective_baseline_phenotyping
Use cohorts in which developmental assessment was performed before the onset of spike-wave activation, such as children under surveillance for another reason or those with an early structural lesion followed from infancy, to assign the arms on prospectively measured rather than retrospectively recalled baselines, then compare etiological yield and outcome.
Decision criterion
If the etiological yield and outcome differences survive prospective baseline assignment, the split is a real boundary. If they shrink toward each other, much of the apparent difference was misclassification driven by retrospective assessment.
Show evidence (3 references)
PMID:39096015 SUPPORT Human Clinical
"We identified the etiology in 42/91 (46%) patients in our Core cohort, including 29/44 (66%) with DEE-SWAS and 13/47 (28%) with EE-SWAS."
Quantifies the large etiological yield difference between the arms, the strongest argument that the split tracks something real.
PMID:39096015 SUPPORT Human Clinical
"Although developmental regression patterns were similar in both syndromes, DEE-SWAS was associated with a longer duration of epilepsy and poorer intellectual outcome than EE-SWAS."
Cuts both ways, which is why it is PARTIAL: the shared regression pattern argues for one process, the outcome difference argues for two entities.
PMID:35503717 SUPPORT Other
"Based on the 2017 Classification of Seizures and Epilepsies, some syndrome names have been updated using terms directly describing the seizure semiology."
Records that the current names are a recent nosological revision rather than a long-settled biological distinction, which is the context in which this question is live.
Corticosteroids outperform a benzodiazepine on cognitive outcome in this syndrome, but no immune or inflammatory mechanism has been established for it. What are steroids actually doing, and would knowing let us keep the benefit without the toxicity?
KNOWLEDGE GAP OPEN dee_swas_why_do_steroids_work
Attached to
pathophysiology#Sleep-Potentiated Spike-Wave Activation pathophysiology#Disruption of Sleep-Dependent Synaptic Plasticity
This is an uncomfortable gap because the treatment recommendation is relatively firm while the reason for it is not. Corticosteroids are used across several developmental and epileptic encephalopathies with a similar pattern of empirical success and mechanistic silence, and in this syndrome the randomized comparison showed them beating clobazam on intelligence quotient gain. Several accounts are available and none is established. The neuroinflammatory account holds that there is an immune contribution to the cortical hyperexcitability that steroids suppress, but no confirmed inflammatory mechanism has been demonstrated in this syndrome, and the corollary prediction, that other immunotherapies should work comparably, has not been tested head to head. A second account is genomic and has nothing to do with immunity: glucocorticoid receptors are abundant in cortex and hippocampus and steroids alter expression of genes governing excitability and synaptic scaling, which would act directly on the plasticity mechanism this entry models. A third possibility is that the effect is on sleep architecture itself, since steroids measurably alter slow-wave sleep, which would withdraw the very drive that potentiates the discharge. These make different predictions and are separable. The practical stake is real: steroid toxicity is the main reason treatment is delayed or truncated, and weight gain was the commonest adverse event in the trial. A mechanism would tell us which better-tolerated drug to reach for instead.
Proposed experiments
Inflammatory and sleep-architecture markers across steroid response
exp_dee_swas_steroid_mechanism_biomarker_panel
In children starting corticosteroids, measure cerebrospinal fluid and serum inflammatory markers, quantified slow-wave sleep parameters, and spike-wave burden before and during treatment, and relate each to cognitive response. Responders and non-responders provide the contrast.
Decision criterion
If response tracks a fall in inflammatory markers, the immune account is supported and other immunotherapies become rational comparators. If response tracks a change in slow-wave sleep parameters with inflammatory markers unchanged, the mechanism is architectural and sleep-directed treatments become the better-tolerated alternative to chase.
Show evidence (2 references)
PMID:38081201 SUPPORT Human Clinical
"Our findings strengthen those from previous uncontrolled studies that support the early use of corticosteroids for children with EE-SWAS."
Establishes that the effect this gap is about is real enough to drive a treatment recommendation, which is what makes the missing mechanism worth curating rather than merely noting.
PMID:38081201 SUPPORT Human Clinical
"Adverse events occurred in ten (45%) of 22 children who received corticosteroids, most frequently weight gain, and in 11 (52%) of 21 children who received clobazam, most often fatigue and behavioural disturbances."
Quantifies the toxicity that makes finding the mechanism practically worthwhile rather than academic.
Why does this syndrome switch on in mid-childhood and switch itself off at adolescence, in a child whose causal lesion, whether a thalamic injury or a germline variant, was present all along and does not go away?
KNOWLEDGE GAP OPEN dee_swas_developmental_gating
Attached to
pathophysiology#Sleep-Potentiated Spike-Wave Activation pathophysiology#Age-Dependent Remission of the Electrographic Pattern
Both ends of the course are developmentally regulated, and neither is explained. A perinatal thalamic lesion is present from birth, yet the sleep activation does not appear for years and then disappears on its own, regardless of treatment, while the lesion remains. Whatever gates it is a property of the developing cortex rather than of the cause. Candidate explanations exist but have not been discriminated: the closure of a critical period, so that the augmenting-response plasticity the syndrome exploits is simply no longer available; maturational change in the sleep architecture itself, since slow-wave sleep declines steeply across adolescence and would withdraw the drive; developmental change in inhibitory circuit maturation; or myelination altering the conduction properties of the surviving thalamocortical projections. Distinguishing them matters for practice in a specific way: if remission comes from withdrawal of the slow-wave drive, then interventions targeting sleep architecture become rational, and the treatment window is defined by the child's developmental stage rather than by the duration of therapy.
Proposed experiments
Longitudinal sleep architecture through onset and remission
exp_dee_swas_sleep_architecture_trajectory
Serial whole-night polysomnography with quantified slow-wave activity and spindle density in the same children from before onset through to spontaneous remission, testing whether the appearance and disappearance of the activation track measurable changes in the sleep parameters that are proposed to drive it.
Decision criterion
If onset and remission coincide with the rise and fall of the specific sleep parameters that supply the drive, sleep maturation explains the gating and becomes a therapeutic target. If the activation appears and disappears with sleep architecture unchanged, the gate is in cortical plasticity rather than in the drive.
Show evidence (2 references)
PMID:25160535 SUPPORT Other
"These disorders, of which continuous spike-wave in slow-wave sleep and Landau-Kleffner are the most common, are characterized by continuous spike-wave activity during slow-wave sleep, developmentally regulated onset and termination of abnormal electrical activity, and loss of previously acquired skills."
Names the developmentally regulated onset and termination as a defining feature of the syndrome class, which is what makes its lack of explanation a genuine gap rather than an incidental observation.
PMID:29133062 SUPPORT Human Clinical
"Early neonatal thalamic lesions account for about 14% of continuous spike-wave of sleep (CSWS) syndrome, representing the most common etiology in this epileptic encephalopathy in children"
Establishes that the commonest identifiable cause is present from birth, which is what makes the years-long delay before onset require an explanation.
⚙

Pathophysiology

9
Heterogeneous Genetic Etiology
About a third of patients have an identifiable genetic cause, but it is spread thinly: no single gene dominates, and the genes implicated cluster functionally rather than positionally, into ion channels and transcriptional regulators that are highly co-expressed in brain. GRIN2A is the longest-associated, and a recent cohort added ten more with functions ranging from sodium-potassium pump subunits to chromatin modifiers. The practical consequence is that gene identity predicts less here than the converging network output does.
GRIN2A hgnc:4585 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves GRIN2A (hgnc:4585). hgnc:4585 is a gene from the HUGO Gene Nomenclature Committee.
regulation of postsynaptic membrane potential GO:0060078 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal regulation of postsynaptic membrane potential (GO:0060078). GO:0060078 is a biological process from the Gene Ontology. ⚠ ABNORMAL
Downstream
Abnormal Frequency-Dependent Cortical Excitability
Show evidence (2 references)
PMID:39096015 SUPPORT Human Clinical
"D/EE-SWAS genes were highly co-expressed in brain, highlighting the importance of channelopathies and transcriptional regulators."
Establishes the functional convergence of an otherwise scattered gene list, which is why this node is modeled as one etiological class rather than as many.
PMID:39096015 SUPPORT Human Clinical
"We identified 10 novel D/EE-SWAS genes with a range of functions: ATP1A2, CACNA1A, FOXP1, GRIN1, KCNMA1, KCNQ3, PPFIA3, PUF60, SETD1B, and ZBTB18, and 2 novel copy number variants, 17p11.2 duplication and 5q22 deletion."
Enumerates the breadth of the genetic contribution and shows it is still expanding, which is the reason no single gene is named as the cause.
Early Thalamic Injury
The best-characterized route into this syndrome is not genetic at all. A perinatal thalamic lesion, typically unilateral, accounts for roughly one in seven cases and is the single commonest identifiable cause. The damage is concentrated in medial and dorsal nuclei and spares the ventral thalamus, a distribution that matters because it disconnects association cortex while leaving the machinery that generates sleep spindles intact. The child is often neurologically unremarkable for years before the electroencephalogram changes.
dorsal plus ventral thalamus UBERON:0001897 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in dorsal plus ventral thalamus (UBERON:0001897). UBERON:0001897 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Selective Thalamocortical Disconnection
Show evidence (2 references)
PMID:29133062 SUPPORT Human Clinical
"Early neonatal thalamic lesions account for about 14% of continuous spike-wave of sleep (CSWS) syndrome, representing the most common etiology in this epileptic encephalopathy in children"
Establishes the frequency and the standing of this etiology, which is why it is modeled as a root node rather than as a rare variant.
PMID:29133062 SUPPORT Human Clinical
"Thalamic volume loss ranged from 19% to 94%, predominantly on medial and dorsal nuclei and sparing the ventral thalamus."
Documents the nuclear distribution of the damage asserted by this node.
Selective Thalamocortical Disconnection
What the thalamic lesion produces is not a general loss of thalamic function but a selective severing of thalamic-cortical fibres on one side, with ipsilateral white matter loss. The selectivity is the point. Sleep spindles are preserved and the waking electroencephalogram is only mildly affected, so the rhythmic drive that normally organizes non-rapid-eye-movement sleep still arrives at a cortex that has lost its normal thalamic regulation. The continuous sleep spiking then appears on the side of the lesion, which is the observation tying the anatomy to the electrophysiology.
cerebral cortex UBERON:0000956 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in cerebral cortex (UBERON:0000956). UBERON:0000956 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Abnormal Frequency-Dependent Cortical Excitability
Show evidence (3 references)
PMID:29133062 SUPPORT Human Clinical
"Unilateral selective thalamic-cortical disconnection is a common feature in our patients and is associated with both a focal pattern of CSWS and a pathological type of frequency-dependent excitability (peak: 10-20Hz)."
States the disconnection and links it to both the electrographic pattern and the excitability abnormality downstream.
PMID:29133062 SUPPORT Human Clinical
"Impact on EEG rhythms was mild, with a volume-loss-related decrease in alpha power and preservation of sleep spindles."
Documents the preserved spindle machinery, which is what makes the selectivity of the disconnection mechanistically load-bearing.
PMID:29133062 SUPPORT Human Clinical
"The sleep continuous spiking was lateralized to the hemisphere with the lesion."
Ties the electrographic abnormality to the side of the anatomical lesion, which is the strongest available evidence that this edge is causal.
Abnormal Frequency-Dependent Cortical Excitability
Cortex that has lost thalamic regulation acquires an abnormal response to being driven at particular rates. Probing visual cortex in patients with posterior spiking reveals excitability that peaks when stimulation is delivered at ten to twenty hertz on the side of the lesion. This is the augmenting response, a form of synaptic potentiation that is absent from cortico-cortical interactions in intact animals and emerges after the thalamus is ablated. It is a state of latent, frequency-tuned potentiation rather than continuous overexcitation, which is why the child can look electrically normal while awake.
pyramidal neuron CL:0000598 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves pyramidal neuron (CL:0000598). CL:0000598 is a cell type from the Cell Ontology.
regulation of synaptic plasticity GO:0048167 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal regulation of synaptic plasticity (GO:0048167). GO:0048167 is a biological process from the Gene Ontology. ⚠ ABNORMAL
Downstream
Sleep-Potentiated Spike-Wave Activation
Show evidence (2 references)
PMID:29133062 SUPPORT Human Clinical
"Visual cortex stimulation in five patients with posterior cortex spiking revealed an abnormal frequency-dependent excitability at 10-20Hz on the side of the lesion."
The direct human measurement of the abnormal excitability this node asserts, with lateralization to the lesion as an internal control.
PMID:29133062 SUPPORT Human Clinical
"We propose that this excitability represents an abnormal synaptic plasticity previously described as the augmenting response."
Names the mechanism. Framed as a proposal by the authors, which is why this node describes a well-measured phenomenon with a proposed identity rather than an established one.
Sleep-Potentiated Spike-Wave Activation
Two things coincide in non-rapid-eye-movement sleep and neither is sufficient alone: brainstem activation falls away, which is the condition under which the augmenting response is strongest, and sleep spindles supply rhythmic drive in precisely the frequency band the cortex has become abnormally responsive to. The result is that discharge which was intermittent or absent in wakefulness becomes near-continuous once the child falls asleep. This state-dependence is the defining feature of the syndrome and the reason a routine waking electroencephalogram can be reported as normal.
sleep GO:0030431 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves sleep (GO:0030431). GO:0030431 is a biological process from the Gene Ontology.
Downstream
Disruption of Sleep-Dependent Synaptic Plasticity
Focal and Atypical Absence Seizures
Age-Dependent Remission of the Electrographic Pattern
Show evidence (2 references)
PMID:29133062 SUPPORT Human Clinical
"Because this response is potentiated by sleep states of reduced brainstem activation and by appropriate stimulating rhythms, such as sleep spindles, the simultaneous occurrence of these two factors in nonrapid-eye-movement sleep is proposed as an explanation for CSWS in our patients."
States the two-factor account of state-dependence that this node encodes, explicitly as a proposal.
PMID:25160535 SUPPORT Other
"These disorders, of which continuous spike-wave in slow-wave sleep and Landau-Kleffner are the most common, are characterized by continuous spike-wave activity during slow-wave sleep, developmentally regulated onset and termination of abnormal electrical activity, and loss of previously acquired skills."
Establishes the three features this node and its two downstream nodes model: the sleep-locked activity, its developmental gating, and the skill loss.
Disruption of Sleep-Dependent Synaptic Plasticity
Slow-wave sleep is not passive for a developing cortex. It is when synaptic strengths are rescaled and the day's experience is consolidated into developing cortical maps, and it does this during critical periods when those maps are still plastic. Occupying that window with continuous epileptiform discharge is the proposed mechanism by which an electroencephalographic abnormality becomes a cognitive one, and it explains why the deficit tracks which cortex is involved rather than seizure burden: perisylvian activation costs language, frontal activation costs attention and behaviour.
pyramidal neuron CL:0000598 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves pyramidal neuron (CL:0000598). CL:0000598 is a cell type from the Cell Ontology.
regulation of synaptic plasticity GO:0048167 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal regulation of synaptic plasticity (GO:0048167). GO:0048167 is a biological process from the Gene Ontology. ⚠ ABNORMAL
Downstream
Developmental Regression and Cognitive-Behavioural Encephalopathy
Show evidence (2 references)
PMID:25160535 SUPPORT Other
"The role of slow-wave sleep in normal cortical plasticity during developmental critical periods, how disruption of slow-wave sleep by electrographic seizures could affect cortical maps and development, and the organization and functional connectivity of the thalamic structures that when damaged..."
States the plasticity-disruption account this node encodes, and the critical-period framing that makes the developmental gating expected rather than puzzling.
PMID:25160535 SUPPORT Other
"Over the last 20 years, a variety of basic science findings suggest how spike-wave activity during sleep can cause the observed clinical outcomes."
Supports the causal direction from discharge to cognitive outcome. Marked PARTIAL because the source says basic science findings suggest how this could work, which is a mechanism sketch rather than a demonstration in patients, and that gap is the subject of a discussion in this entry.
Focal and Atypical Absence Seizures
Clinical seizures do occur, typically focal seizures often arising from sleep and atypical absences, but they are frequently mild, sometimes absent entirely, and they are not what causes the regression. This is the feature that most distinguishes the syndrome from other developmental and epileptic encephalopathies, where seizure burden and cognitive outcome move together. A child can have this syndrome, and lose skills to it, with barely any seizures at all.
Show evidence (1 reference)
PMID:38081201 SUPPORT Human Clinical
"Epileptic encephalopathy with spike-wave activation in sleep (EE-SWAS) is a rare syndrome associated with cognitive and behavioural regression."
Frames the syndrome by its cognitive rather than its seizure burden, which is the claim this node is qualifying. The trial's primary outcome was cognitive, not seizure control, for the same reason.
Age-Dependent Remission of the Electrographic Pattern
The sleep activation switches itself off, usually around adolescence, and it does so whether or not treatment worked. That spontaneous termination is as developmentally regulated as the onset, and it is the single most important thing to understand about prognosis: the electroencephalogram will normalize on its own, but the cognitive ground lost while it was active may not be recovered. It is also why treatment is judged on cognition rather than on the eventual disappearance of the pattern, which would have happened anyway.
Show evidence (1 reference)
PMID:25160535 SUPPORT Other
"These disorders, of which continuous spike-wave in slow-wave sleep and Landau-Kleffner are the most common, are characterized by continuous spike-wave activity during slow-wave sleep, developmentally regulated onset and termination of abnormal electrical activity, and loss of previously acquired skills."
States the developmentally regulated termination that this node models, alongside the persisting skill loss that makes it a poor measure of treatment success.
Developmental Regression and Cognitive-Behavioural Encephalopathy
The clinical endpoint and the reason the syndrome matters: loss of skills the child already had. Which skills depends on which cortex carries the activation, giving language regression, attentional and behavioural collapse, or global cognitive decline. Regression patterns are similar whether the child was developmentally normal beforehand or already delayed, but the eventual intellectual outcome is worse in the delayed group, which also has a longer duration of epilepsy.
Show evidence (1 reference)
PMID:39096015 SUPPORT Human Clinical
"Although developmental regression patterns were similar in both syndromes, DEE-SWAS was associated with a longer duration of epilepsy and poorer intellectual outcome than EE-SWAS."
Documents both the shared regression process and the outcome difference between the two arms, which is what this node asserts and what the nosology discussion turns on.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Developmental and Epileptic Encephalopathy with Spike-Wave Activation in Sleep Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
●

Phenotypes

9
Nervous System 8
Developmental regression HP:0002376 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Developmental regression (HP:0002376). HP:0002376 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:38081201 SUPPORT Human Clinical
"Epileptic encephalopathy with spike-wave activation in sleep (EE-SWAS) is a rare syndrome associated with cognitive and behavioural regression."
States the regression that defines the syndrome and that the trial's primary outcome was designed to capture.
Intellectual disability HP:0001249 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Intellectual disability (HP:0001249). HP:0001249 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:39096015 SUPPORT Human Clinical
"Although developmental regression patterns were similar in both syndromes, DEE-SWAS was associated with a longer duration of epilepsy and poorer intellectual outcome than EE-SWAS."
Documents the intellectual outcome and its difference between the two arms.
Language regression Aphasia HP:0002381 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Aphasia (HP:0002381). HP:0002381 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:25160535 SUPPORT Other
"Several pediatric seizure disorders have common electrophysiological features during slow-wave sleep that produce different syndromes based on which part of the developing brain is involved."
States the topographic principle that makes language the affected domain when perisylvian cortex carries the activation.
Behavioural disturbance and attentional impairment Atypical behavior HP:0000708 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Atypical behavior (HP:0000708). HP:0000708 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:38081201 SUPPORT Human Clinical
"Epileptic encephalopathy with spike-wave activation in sleep (EE-SWAS) is a rare syndrome associated with cognitive and behavioural regression."
Names behavioural regression alongside the cognitive component.
Atypical absence seizure HP:0007270 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Atypical absence seizure (HP:0007270). HP:0007270 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:35503717 SUPPORT Other
"In this paper, we describe the childhood onset epilepsy syndromes, most of which have both mandatory seizure type(s) and interictal electroencephalographic (EEG) features."
Establishes that the ILAE defines these syndromes by mandatory seizure types. Marked PARTIAL because the abstract does not enumerate them for this syndrome, so the absence seizure type rests on the wider literature rather than on this quote.
Global developmental delay HP:0001263 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Global developmental delay (HP:0001263). HP:0001263 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:39096015 SUPPORT Human Clinical
"Although developmental regression patterns were similar in both syndromes, DEE-SWAS was associated with a longer duration of epilepsy and poorer intellectual outcome than EE-SWAS."
Documents the developmental impairment that distinguishes the DEE-SWAS arm and its worse outcome.
Attention deficit hyperactivity disorder HP:0007018 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Attention deficit hyperactivity disorder (HP:0007018). HP:0007018 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:38081201 SUPPORT Human Clinical
"Epileptic encephalopathy with spike-wave activation in sleep (EE-SWAS) is a rare syndrome associated with cognitive and behavioural regression."
Establishes behavioural regression as a defining component. Marked PARTIAL because the abstract does not name the attentional phenotype specifically, so the more specific term is curated on the strength of the behavioural regression it belongs to.
Focal-onset seizure HP:0007359 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Focal-onset seizure (HP:0007359). HP:0007359 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:35503717 SUPPORT Other
"In this paper, we describe the childhood onset epilepsy syndromes, most of which have both mandatory seizure type(s) and interictal electroencephalographic (EEG) features."
Establishes that the ILAE defines these syndromes by mandatory seizure types together with EEG features. Marked PARTIAL because the abstract does not enumerate the seizure types for this specific syndrome, so the seizure semiology here rests on the wider literature.
Other 1
Spike-wave activation in sleep Continuous spike and waves during slow sleep HP:0031491 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Continuous spike and waves during slow sleep (HP:0031491). HP:0031491 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:25160535 SUPPORT Other
"These disorders, of which continuous spike-wave in slow-wave sleep and Landau-Kleffner are the most common, are characterized by continuous spike-wave activity during slow-wave sleep, developmentally regulated onset and termination of abnormal electrical activity, and loss of previously acquired skills."
Establishes the sleep-locked continuous discharge as the defining feature.
🧬

Genetic Associations

2
GRIN2A (The longest-established gene for this syndrome, encoding an NMDA receptor subunit. It sits in the channelopathy group that the cohort analysis found to be functionally enriched, and it is the gene for which a mechanism-directed therapy is most plausible, since the direction of the functional change determines whether receptor blockade would help or harm.)
Gene: GRIN2A hgnc:4585 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is GRIN2A (hgnc:4585). hgnc:4585 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE
Show evidence (4 references)
PMID:30544257 SUPPORT In Vitro
"misTMD+Linker predominantly led to NMDAR gain-of-function, while misATD+LBD exclusively caused NMDAR loss-of-function"
Names this gene directly and establishes that the functional direction depends on which domain the variant hits, which is the fact that makes receptor-directed therapy conceivable and also potentially harmful in the wrong direction. Tagged IN_VITRO because this is receptor electrophysiology, with the null-variant arm measured in rodent cortical neurons, so the provenance of the entry's precision-therapy reasoning is bench data rather than a clinical observation.
PMID:30544257 SUPPORT Human Clinical
"pathogenic missense variants in transmembrane and linker domains (misTMD+Linker) were associated with severe developmental phenotypes, whereas missense variants within amino terminal or ligand-binding domains (misATD+LBD) and null variants led to less severe developmental phenotypes"
Establishes the genotype-phenotype relationship within this gene, which is why gene identity alone under-predicts severity here.
PMID:30544257 SUPPORT INDIRECT Human Clinical
"This new pathomechanistic model may ultimately help in predicting phenotype severity as well as eligibility for potential precision medicine approaches in GRIN2A-related disorders"
Records the precision-therapy prospect without asserting a drug. Marked INDIRECT because it states a possibility rather than a demonstrated treatment, which is the honest strength of this claim today.
+ 1 more reference
Expanding gene set identified by cohort sequencing (No single gene dominates. A recent cohort added ten genes at once, spanning ion channels, a sodium-potassium pump subunit, chromatin modifiers, and transcription factors, plus two recurrent copy number variants, and the genes cluster by brain co-expression rather than by pathway membership. GRIN1 is named as the representative because it appears in the quoted list and, like GRIN2A, encodes an NMDA receptor subunit, so it connects this set to the best-characterized arm of the syndrome's genetics. The gene list should be read as open rather than settled. X-linked causes exist and are counselling-relevant, but they are recorded in the inheritance block rather than given a gene record here, because no X-linked gene is named in a source cached for this entry.)
Gene: GRIN1 hgnc:4584 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is GRIN1 (hgnc:4584). hgnc:4584 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE
Show evidence (2 references)
PMID:39096015 SUPPORT Human Clinical
"We identified 10 novel D/EE-SWAS genes with a range of functions: ATP1A2, CACNA1A, FOXP1, GRIN1, KCNMA1, KCNQ3, PPFIA3, PUF60, SETD1B, and ZBTB18, and 2 novel copy number variants, 17p11.2 duplication and 5q22 deletion."
Enumerates the newly added genes and copy number variants, and shows the list is still growing, which is why this record is framed as a set rather than as a gene.
PMID:39096015 SUPPORT Human Clinical
"A genetic etiology was identified in 31/91 (34%)."
Quantifies how much of the syndrome this expanding gene set currently accounts for.
💊

Medical Actions

3
Corticosteroids
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: prednisolone CHEBI:8378 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses prednisolone (CHEBI:8378). CHEBI:8378 is a therapeutic agent from Chemical Entities of Biological Interest. methylprednisolone CHEBI:6888 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses methylprednisolone, annotated with 6alpha-methylprednisolone (CHEBI:6888). CHEBI:6888 is a therapeutic agent from Chemical Entities of Biological Interest.
The best-supported treatment, and unusually for this syndrome the support is randomized. In a head-to-head trial against clobazam, a quarter of children given corticosteroids gained at least eleven and a quarter intelligence quotient points at six months while none of the clobazam group did. The trial's other cognitive measure showed no difference, and it stopped early without reaching its target sample, so the result strengthens rather than settles the case for early steroid use. Either continuous oral prednisolone or pulsed intravenous methylprednisolone is used.
Mechanism Target:
INHIBITS Sleep-Potentiated Spike-Wave Activation
Show evidence (3 references)
PMID:38081201 SUPPORT Human Clinical
"Our findings strengthen those from previous uncontrolled studies that support the early use of corticosteroids for children with EE-SWAS."
The trial's own summary of what its result licenses, which is the strength of recommendation this record encodes.
PMID:38081201 SUPPORT Human Clinical
"Our data indicated an improvement in IQ outcomes with corticosteroids compared with clobazam treatment, but no difference was seen in cognitive sum score."
Records the split result across the two co-primary cognitive measures. Marked PARTIAL because one measure showed benefit and the other did not.
PMID:38081201 SUPPORT Human Clinical
"The trial was terminated prematurely, and the target sample size was not met, so our findings must be interpreted with caution."
Records the limitation the investigators attach to their own result, which is why this treatment is curated as best-supported rather than established.
Clobazam
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: clobazam CHEBI:31413 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses clobazam (CHEBI:31413). CHEBI:31413 is a therapeutic agent from Chemical Entities of Biological Interest.
A benzodiazepine long used for this syndrome on observational grounds. When finally compared head to head with corticosteroids it did not produce the intelligence quotient gains that steroids did, though the two were indistinguishable on the other cognitive measure and in adverse event rates. It remains in use, but the trial removes the basis for treating it as equivalent first-line.
Mechanism Target:
INHIBITS Sleep-Potentiated Spike-Wave Activation
Show evidence (2 references)
PMID:38081201 SUPPORT Human Clinical
"On the basis of mostly small observational and retrospective studies, corticosteroids and clobazam are often considered the most effective treatments for this syndrome."
Establishes clobazam's standing as a conventional treatment and the weak evidence base that standing rested on.
PMID:38081201 SUPPORT Human Clinical
"Adverse events occurred in ten (45%) of 22 children who received corticosteroids, most frequently weight gain, and in 11 (52%) of 21 children who received clobazam, most often fatigue and behavioural disturbances."
Documents the adverse event profile of both arms, which is the other half of the comparison and shows the two did not differ on tolerability.
Avoidance of sodium channel blocking antiseizure medications
Action: Supportive CareNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Supportive Care (NCIT:C15747). NCIT:C15747 is a clinical intervention from the NCI Thesaurus. NCIT:C15747
Carbamazepine, oxcarbazepine, phenytoin, and phenobarbital can induce or worsen the sleep activation, which makes stopping them the cheapest intervention available in this syndrome and one that costs nothing to try. The trap is structural rather than careless: these children often have focal seizures, focal seizures are a standard indication for carbamazepine, and the sleep activation that the drug then aggravates is invisible unless someone records a sleep electroencephalogram.
Show evidence (1 reference)
PMID:26415787 SUPPORT Human Clinical
"Cases of worsening or induction of ESES with phenytoin, carbamazepine and phenobarbital have been reported."
Names three of the four drugs directly, which converts this record from an argument by omission into a directly evidenced management claim.
🔬

Diagnosis

3
Sleep electroencephalography
The diagnostic test, and one that will be missed if only a waking recording is done. A sleep study, ideally whole-night, is required to demonstrate the activation, because the waking record can be normal or show only sparse discharge. Quantifying how much of non-rapid-eye-movement sleep is occupied is what turns the observation into a diagnosis. This entry deliberately does not assert a numeric spike-wave index threshold. Published thresholds differ, the ILAE definition cited here does not mandate one, and a curated number would give a false impression of consensus about who has this disease.
Electroencephalography NCIT:C38054 NCI Thesaurus (NCIT)
Results: Marked activation of epileptiform discharge in non-rapid-eye-movement sleep relative to wakefulness, often near-continuous, and lateralized to the side of any structural lesion.
Show evidence (2 references)
PMID:29133062 SUPPORT Human Clinical
"Longitudinal whole-night and high-density electroencephalograms (EEGs) were performed, as well as detailed imaging and clinical evaluation."
Documents whole-night recording as the method used to characterize the syndrome, which is the diagnostic standard this record describes.
PMID:29133062 SUPPORT Human Clinical
"The sleep continuous spiking was lateralized to the hemisphere with the lesion."
Supports the lateralization described in the results field, which is what links the electrographic finding to a structural cause when one exists.
Brain MRI for thalamic and structural lesions
Imaging is directed at the thalamus in particular, since perinatal thalamic injury is the commonest identifiable cause and the volume loss can be subtle. Structural causes account for roughly one in eight patients overall.
Magnetic Resonance Imaging NCIT:C16809 NCI Thesaurus (NCIT)
Results: Unilateral thalamic volume loss predominantly affecting medial and dorsal nuclei, with ipsilateral white matter loss and ventricular enlargement, or another structural lesion.
Show evidence (2 references)
PMID:39096015 SUPPORT Human Clinical
"Structural etiologies were found in 12/91 (13%) individuals."
Quantifies the yield of imaging for a structural cause in a systematically investigated cohort.
PMID:29133062 SUPPORT Human Clinical
"Lesions produced white matter loss and ventricle enlargement on the same hemisphere, which in four patients was associated with selective loss of thalamic-cortical fibers."
Describes the imaging findings reported in the results field.
Genetic testing
Worth doing, because a genetic cause is found in about a third of patients and the yield is much higher in the developmentally delayed arm than in the previously normal one. No single gene dominates, so panel or exome testing rather than targeted analysis is appropriate.
Genetic Testing NCIT:C15709 NCI Thesaurus (NCIT)
Results: A pathogenic variant in one of a broad set of channel and transcriptional regulator genes, or a copy number variant, in roughly a third of patients.
Show evidence (1 reference)
PMID:39096015 SUPPORT Human Clinical
"We identified the etiology in 42/91 (46%) patients in our Core cohort, including 29/44 (66%) with DEE-SWAS and 13/47 (28%) with EE-SWAS."
Quantifies the overall diagnostic yield and the large difference between the two arms, which is what makes baseline development a useful guide to how hard to look.
📈

Progression

2
Onset of sleep activation with regression
Age: Mid-childhood
The electroencephalographic activation appears in mid-childhood, often after a period in which seizures alone were present and unremarkable, and the loss of skills follows. Because a waking recording can be normal, the interval between the regression starting and the diagnosis being made is frequently long.
Show evidence (1 reference)
PMID:25160535 SUPPORT Other
"developmentally regulated onset and termination of abnormal electrical activity, and loss of previously acquired skills"
States the developmentally regulated onset and the associated skill loss that define this phase.
Spontaneous remission of the electrographic pattern with residual deficit
Age: Adolescence
The sleep activation resolves on its own around adolescence regardless of treatment. Cognitive recovery is variable and often incomplete, so the prognosis is set less by whether the pattern eventually stops, which it will, than by how long it ran and over which cortex.
Show evidence (1 reference)
PMID:25160535 SUPPORT Other
"developmentally regulated onset and termination of abnormal electrical activity, and loss of previously acquired skills"
Supports the developmentally regulated termination described in this phase.
📊

Prevalence

2
Children with epilepsy
Unknown Rare
No population-based prevalence estimate is available. The syndrome is described as rare in the randomized trial literature, and its ascertainment depends on whether a sleep electroencephalogram is performed, since a waking record can be normal. That dependence makes any published rate a lower bound on the true one.
Show evidence (1 reference)
PMID:38081201 SUPPORT Human Clinical
"Epileptic encephalopathy with spike-wave activation in sleep (EE-SWAS) is a rare syndrome associated with cognitive and behavioural regression."
Supports the qualitative rarity band. Marked PARTIAL because it is a descriptor rather than a measurement, which is why no rate is asserted.
Children with continuous spike-wave of sleep
Unknown Unknown
Within the syndrome, early neonatal thalamic lesions account for about 14 percent of cases, making them the commonest single identifiable cause. This is an etiological fraction rather than a population rate.
Show evidence (1 reference)
PMID:29133062 SUPPORT Human Clinical
"Early neonatal thalamic lesions account for about 14% of continuous spike-wave of sleep (CSWS) syndrome, representing the most common etiology in this epileptic encephalopathy in children"
Gives the etiological fraction reported in the notes.
🔀

Differential Diagnoses

3

Conditions with similar clinical presentations that must be differentiated from Developmental and Epileptic Encephalopathy with Spike-Wave Activation in Sleep:

Landau-Kleffner Syndrome MONDO:0009509
Overlapping Features The closest relative and arguably a variant rather than a separate disease. It shares the sleep-activated epileptiform activity and the developmentally regulated course, and differs mainly in that the activation sits over perisylvian language cortex, so the regression is specifically an acquired auditory agnosia.
Distinguishing Features
  • Regression is specifically of language comprehension, presenting as acquired auditory agnosia.
  • Epileptiform activity is centrotemporal and perisylvian rather than diffuse or frontal.
  • Non-language cognition and behaviour are relatively preserved at onset.
Show evidence (1 reference)
PMID:25160535 SUPPORT Other
"Several pediatric seizure disorders have common electrophysiological features during slow-wave sleep that produce different syndromes based on which part of the developing brain is involved."
States the shared mechanism and the topographic basis of the difference, which is precisely why these two are differentials of each other rather than unrelated conditions.
Lennox-Gastaut Syndrome MONDO:0016532
Overlapping Features Another childhood developmental and epileptic encephalopathy classified alongside this one by the ILAE, and confusable because both feature slow spike-wave and cognitive decline.
Distinguishing Features
  • Tonic seizures in sleep are mandatory and are not a feature of spike-wave activation in sleep.
  • Slow spike-wave is present in wakefulness rather than being sleep-activated.
  • Seizure burden is high and tracks the encephalopathy, whereas here seizures may be minimal.
  • No spontaneous remission of the electrographic pattern at adolescence.
Show evidence (1 reference)
PMID:35503717 SUPPORT Other
"developmental and/or epileptic encephalopathies, comprising five syndromes: epilepsy with myoclonic-atonic seizures, Lennox-Gastaut syndrome, developmental and/or epileptic encephalopathy with spike-and-wave activation in sleep, hemiconvulsion-hemiplegia-epilepsy syndrome, and febrile..."
Establishes that the ILAE treats these as distinct syndromes within the same category, which is what makes the differentiation necessary.
Self-Limited Epilepsy with Centrotemporal Spikes MONDO:0007295
Overlapping Features Shares sleep-activated centrotemporal discharge and an age-limited course, and sits at the benign end of what may be a continuum. The distinction matters because one needs treating and the other largely does not.
Distinguishing Features
  • Discharge activates in sleep but does not become near-continuous.
  • No regression; cognition is normal or only subtly affected.
  • Seizures are infrequent, nocturnal, and remit in adolescence without deficit.
Show evidence (1 reference)
PMID:35503717 SUPPORT Other
"self-limited focal epilepsies, comprising four syndromes: self-limited epilepsy with centrotemporal spikes, self-limited epilepsy with autonomic seizures, childhood occipital visual epilepsy, and photosensitive occipital lobe epilepsy"
Establishes that the ILAE places this syndrome in the self-limited focal category, separate from the encephalopathies, which is the classificatory basis of the distinction.
{ }

Source YAML

click to show 
name: Developmental and Epileptic Encephalopathy with Spike-Wave Activation in Sleep
creation_date: "2026-08-05T00:00:00Z"
category: Complex
description: >-
  A childhood epilepsy syndrome whose defining lesion is not a seizure type but a
  sleep state. Epileptiform discharge that is sparse or absent while the child is
  awake becomes near-continuous once non-rapid-eye-movement sleep begins, and the
  child loses skills already acquired: language, attention, behaviour, or general
  cognition depending on which cortex is involved. Seizures are often mild and
  are not what does the damage. The syndrome is developmentally gated, appearing
  in mid-childhood and remitting spontaneously around adolescence whether or not
  it is treated, while the cognitive losses may not recover. Causes are
  heterogeneous, split roughly between genetic variants and early structural
  injury to the thalamus. The ILAE splits the syndrome by baseline development:
  DEE-SWAS in children already developmentally delayed, EE-SWAS in children whose
  development was normal until the regression.
parents:
  - Epilepsy
  - Neurological Disease
synonyms:
  - DEE-SWAS
  - EE-SWAS
  - D/EE-SWAS
  - continuous spike-and-wave during sleep
  - CSWS
  - electrical status epilepticus in sleep
  - ESES
disease_term:
  preferred_term: developmental and/or epileptic encephalopathy with spike-wave activation in sleep
  term:
    id: MONDO:0800501
    label: developmental and/or epileptic encephalopathy with spike-wave activation in sleep
mappings:
  mondo_mappings:
    - term:
        id: MONDO:0800501
        label: developmental and/or epileptic encephalopathy with spike-wave activation in sleep
      mapping_predicate: skos:exactMatch
      mapping_source: MONDO
      mapping_justification: >-
        MONDO:0800501 is the current concept for the syndrome the ILAE renamed
        from continuous spike-and-wave during sleep, and covers both the DEE-SWAS
        and EE-SWAS arms this entry models together.
references:
  - reference: PMID:35503717
    title: >-
      International League Against Epilepsy classification and definition of
      epilepsy syndromes with onset in childhood: Position paper by the ILAE Task
      Force on Nosology and Definitions.
  - reference: PMID:39096015
    title: >-
      Solving the Etiology of Developmental and Epileptic Encephalopathy with
      Spike-Wave Activation in Sleep (D/EE-SWAS).
  - reference: PMID:38081201
    title: >-
      Corticosteroids versus clobazam for treatment of children with epileptic
      encephalopathy with spike-wave activation in sleep (RESCUE ESES): a
      multicentre randomised controlled trial.
notes: >-
  Scope note. This entry models DEE-SWAS and EE-SWAS as one mechanism with two
  clinical framings rather than as two diseases. The ILAE distinguishes them only
  by whether development was already impaired before the spike-wave activation
  began, which is a statement about the baseline rather than about the process,
  and the mechanism graph is identical for both. Whether that boundary is the
  right one is curated as an explicit discussion rather than settled here, since
  the two arms do differ in how often an etiology is found and in outcome. The
  older names, continuous spike-and-wave during sleep and electrical status
  epilepticus in sleep, are retained as synonyms because most of the mechanistic
  literature this entry cites uses them.

  On the central causal claim. The syndrome's name assumes the epileptiform
  activation causes the regression. This entry does model that edge, but treats
  it as contested rather than established, because the alternative reading, in
  which the sleep activation and the regression are parallel consequences of one
  lesion, has not been excluded and carries different treatment implications. The
  relevant randomized evidence is curated with its limitations attached.

  Sourcing note. The entry was drafted from the ILAE position paper, the
  etiological cohort, the thalamic-lesion physiology series, and the randomized
  trial, then cross-checked against a deep-research report generated with the
  claude_code provider and committed here as
  research/DEE_with_Spike-Wave_Activation_in_Sleep-deep-research-claude_code.md.
  The cross-check prompted the subtype split recorded above and the discussion on
  why corticosteroids work. One of its recommendations was deliberately declined:
  it supplied competing numeric spike-wave index thresholds from the literature,
  and rather than curate a number this entry states in the diagnosis record that
  no threshold is asserted, because the thresholds disagree and quoting one would
  imply a consensus that does not exist.

  Module conformance note. Two nodes conform to
  epilepsy_excitation_inhibition_imbalance. The graph joins the module at the
  hyperexcitability node rather than at its ion-channel trigger, because the
  most-studied route into this syndrome is a structural thalamic lesion rather
  than a channel defect, and because the state-dependence is the part the generic
  module does not capture at all: what is unusual here is not that cortex is
  excitable but that it is excitable only in a particular sleep stage.
has_subtypes:
  - name: DEE-SWAS
    display_name: Developmental and epileptic encephalopathy with spike-wave activation in sleep
    description: >-
      The arm in which development was already impaired before the spike-wave
      activation began, so the child has both a developmental encephalopathy and
      an epileptic one. It behaves differently from its sibling arm in two ways
      that a mere difference in starting point does not obviously predict: an
      etiology is found roughly two thirds of the time, more than twice as often
      as in EE-SWAS, and the epilepsy runs longer with a poorer intellectual
      outcome. Whether that makes it a distinct entity is an open question curated
      in the discussions block.
    evidence:
      - reference: PMID:39096015
        reference_title: >-
          Solving the Etiology of Developmental and Epileptic Encephalopathy with
          Spike-Wave Activation in Sleep (D/EE-SWAS).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          We identified the etiology in 42/91 (46%) patients in our Core cohort,
          including 29/44 (66%) with DEE-SWAS and 13/47 (28%) with EE-SWAS.
        explanation: >-
          Quantifies the etiological yield in this arm and the contrast with the
          other, which is the strongest evidence that the split tracks something
          real.
      - reference: PMID:39096015
        reference_title: >-
          Solving the Etiology of Developmental and Epileptic Encephalopathy with
          Spike-Wave Activation in Sleep (D/EE-SWAS).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Although developmental regression patterns were similar in both
          syndromes, DEE-SWAS was associated with a longer duration of epilepsy and
          poorer intellectual outcome than EE-SWAS.
        explanation: >-
          Documents the worse course of this arm alongside the shared regression
          process.
  - name: EE-SWAS
    display_name: Epileptic encephalopathy with spike-wave activation in sleep
    description: >-
      The arm in which development was normal until the regression, so the
      encephalopathy is purely epileptic in the sense that the child had nothing
      wrong before it started. An etiology is found in only about a quarter of
      these children, and the intellectual outcome is better than in DEE-SWAS.
      Landau-Kleffner syndrome is the best-known presentation within this arm,
      distinguished by the activation sitting over perisylvian language cortex so
      that the regression is specifically an acquired auditory agnosia. This is
      the arm the randomized treatment evidence was generated in.
    evidence:
      - reference: PMID:39096015
        reference_title: >-
          Solving the Etiology of Developmental and Epileptic Encephalopathy with
          Spike-Wave Activation in Sleep (D/EE-SWAS).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          We identified the etiology in 42/91 (46%) patients in our Core cohort,
          including 29/44 (66%) with DEE-SWAS and 13/47 (28%) with EE-SWAS.
        explanation: >-
          Quantifies the much lower etiological yield in this arm, which is what
          makes the label practically useful when deciding how hard to investigate.
      - reference: PMID:38081201
        reference_title: >-
          Corticosteroids versus clobazam for treatment of children with epileptic
          encephalopathy with spike-wave activation in sleep (RESCUE ESES): a
          multicentre randomised controlled trial.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Epileptic encephalopathy with spike-wave activation in sleep (EE-SWAS) is
          a rare syndrome associated with cognitive and behavioural regression.
        explanation: >-
          Confirms that the randomized treatment evidence in this entry was
          generated specifically in this arm, which is a limit on generalizing it
          to DEE-SWAS.
inheritance:
  - name: Heterogeneous, mostly de novo genetic or non-genetic
    description: >-
      There is no single inheritance pattern. A genetic cause is found in about a
      third of patients, spread across many genes rather than concentrated in one,
      with channelopathies and transcriptional regulators prominent. A comparable
      share have an acquired structural cause, chiefly perinatal thalamic injury,
      which is not heritable at all. Counselling therefore depends entirely on
      which arm a given child falls into, and in over half of cases no cause is
      identified.
    inheritance_term:
      preferred_term: Sporadic
      term:
        id: HP:0003745
        label: Sporadic
    evidence:
      - reference: PMID:39096015
        reference_title: >-
          Solving the Etiology of Developmental and Epileptic Encephalopathy with
          Spike-Wave Activation in Sleep (D/EE-SWAS).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          A genetic etiology was identified in 31/91 (34%).
        explanation: >-
          Quantifies the genetic share, and by implication the majority in which a
          Mendelian inheritance pattern cannot be offered.
      - reference: PMID:39096015
        reference_title: >-
          Solving the Etiology of Developmental and Epileptic Encephalopathy with
          Spike-Wave Activation in Sleep (D/EE-SWAS).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          DEE-SWAS and EE-SWAS have highly heterogeneous genetic and structural
          etiologies.
        explanation: >-
          States the etiological heterogeneity that makes a single inheritance
          statement impossible for this syndrome.
  - name: Autosomal dominant, usually de novo
    description: >-
      Most of the identified genetic causes are autosomal genes in which a single
      variant is sufficient, and the variants are typically de novo rather than
      inherited, which is why the family history is usually blank. The
      counselling consequence is that recurrence risk for siblings is low but not
      zero, because parental gonadal mosaicism cannot be excluded.
    inheritance_term:
      preferred_term: Autosomal dominant inheritance
      term:
        id: HP:0000006
        label: Autosomal dominant inheritance
    evidence:
      - reference: PMID:39096015
        reference_title: >-
          Solving the Etiology of Developmental and Epileptic Encephalopathy with
          Spike-Wave Activation in Sleep (D/EE-SWAS).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          We identified 10 novel D/EE-SWAS genes with a range of functions:
          ATP1A2, CACNA1A, FOXP1, GRIN1, KCNMA1, KCNQ3, PPFIA3, PUF60, SETD1B, and
          ZBTB18, and 2 novel copy number variants, 17p11.2 duplication and 5q22
          deletion.
        explanation: >-
          The named genes are autosomal and are established dominant
          developmental-disorder genes, which is the basis for curating an
          autosomal dominant block. Marked PARTIAL because the cited abstract lists
          the genes without stating the inheritance mode for each, so the mode is
          inferred from the genes rather than quoted.
  - name: X-linked
    description: >-
      A minority of cases arise from X-linked genes, which matters
      disproportionately for counselling because the recurrence risk and the
      pattern of who is affected differ completely from the autosomal forms. CNKSR2
      is the best-known example in this syndrome.
    inheritance_term:
      preferred_term: X-linked inheritance
      term:
        id: HP:0001417
        label: X-linked inheritance
    evidence:
      - reference: PMID:39096015
        reference_title: >-
          Solving the Etiology of Developmental and Epileptic Encephalopathy with
          Spike-Wave Activation in Sleep (D/EE-SWAS).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          DEE-SWAS and EE-SWAS have highly heterogeneous genetic and structural
          etiologies.
        explanation: >-
          Supports genetic heterogeneity broad enough to include X-linked causes.
          Marked PARTIAL because the abstract does not name an X-linked gene, so
          this block records the counselling-relevant possibility rather than
          quoting a demonstration of it, and the X-linked genes named in the wider
          literature are not asserted here without verifiable snippets.
genetic:
  - name: GRIN2A
    gene_term:
      preferred_term: GRIN2A
      term:
        id: hgnc:4585
        label: GRIN2A
    relationship_type: CAUSATIVE
    association: >-
      The longest-established gene for this syndrome, encoding an NMDA receptor
      subunit. It sits in the channelopathy group that the cohort analysis found
      to be functionally enriched, and it is the gene for which a
      mechanism-directed therapy is most plausible, since the direction of the
      functional change determines whether receptor blockade would help or harm.
    evidence:
      - reference: PMID:30544257
        reference_title: >-
          GRIN2A-related disorders: genotype and functional consequence predict
          phenotype.
        supports: SUPPORT
        evidence_source: IN_VITRO
        snippet: >-
          misTMD+Linker predominantly led to NMDAR gain-of-function, while
          misATD+LBD exclusively caused NMDAR loss-of-function
        explanation: >-
          Names this gene directly and establishes that the functional direction
          depends on which domain the variant hits, which is the fact that makes
          receptor-directed therapy conceivable and also potentially harmful in the
          wrong direction. Tagged IN_VITRO because this is receptor
          electrophysiology, with the null-variant arm measured in rodent cortical
          neurons, so the provenance of the entry's precision-therapy reasoning is
          bench data rather than a clinical observation.
      - reference: PMID:30544257
        reference_title: >-
          GRIN2A-related disorders: genotype and functional consequence predict
          phenotype.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          pathogenic missense variants in transmembrane and linker domains
          (misTMD+Linker) were associated with severe developmental phenotypes,
          whereas missense variants within amino terminal or ligand-binding domains
          (misATD+LBD) and null variants led to less severe developmental
          phenotypes
        explanation: >-
          Establishes the genotype-phenotype relationship within this gene, which
          is why gene identity alone under-predicts severity here.
      - reference: PMID:30544257
        reference_title: >-
          GRIN2A-related disorders: genotype and functional consequence predict
          phenotype.
        supports: SUPPORT
        directness: INDIRECT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          This new pathomechanistic model may ultimately help in predicting
          phenotype severity as well as eligibility for potential precision
          medicine approaches in GRIN2A-related disorders
        explanation: >-
          Records the precision-therapy prospect without asserting a drug. Marked
          INDIRECT because it states a possibility rather than a demonstrated
          treatment, which is the honest strength of this claim today.
      - reference: PMID:39096015
        reference_title: >-
          Solving the Etiology of Developmental and Epileptic Encephalopathy with
          Spike-Wave Activation in Sleep (D/EE-SWAS).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          D/EE-SWAS genes were highly co-expressed in brain, highlighting the
          importance of channelopathies and transcriptional regulators.
        explanation: >-
          Places the gene class this record belongs to at the centre of the
          syndrome's genetics. Marked PARTIAL because it does not name GRIN2A
          itself, so it supports the class rather than the gene.
  - name: Expanding gene set identified by cohort sequencing
    gene_term:
      preferred_term: GRIN1
      term:
        id: hgnc:4584
        label: GRIN1
    relationship_type: CAUSATIVE
    association: >-
      No single gene dominates. A recent cohort added ten genes at once, spanning
      ion channels, a sodium-potassium pump subunit, chromatin modifiers, and
      transcription factors, plus two recurrent copy number variants, and the
      genes cluster by brain co-expression rather than by pathway membership.
      GRIN1 is named as the representative because it appears in the quoted list
      and, like GRIN2A, encodes an NMDA receptor subunit, so it connects this set
      to the best-characterized arm of the syndrome's genetics. The gene list
      should be read as open rather than settled. X-linked causes exist and are
      counselling-relevant, but they are recorded in the inheritance block rather
      than given a gene record here, because no X-linked gene is named in a source
      cached for this entry.
    evidence:
      - reference: PMID:39096015
        reference_title: >-
          Solving the Etiology of Developmental and Epileptic Encephalopathy with
          Spike-Wave Activation in Sleep (D/EE-SWAS).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          We identified 10 novel D/EE-SWAS genes with a range of functions:
          ATP1A2, CACNA1A, FOXP1, GRIN1, KCNMA1, KCNQ3, PPFIA3, PUF60, SETD1B, and
          ZBTB18, and 2 novel copy number variants, 17p11.2 duplication and 5q22
          deletion.
        explanation: >-
          Enumerates the newly added genes and copy number variants, and shows the
          list is still growing, which is why this record is framed as a set rather
          than as a gene.
      - reference: PMID:39096015
        reference_title: >-
          Solving the Etiology of Developmental and Epileptic Encephalopathy with
          Spike-Wave Activation in Sleep (D/EE-SWAS).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          A genetic etiology was identified in 31/91 (34%).
        explanation: >-
          Quantifies how much of the syndrome this expanding gene set currently
          accounts for.
pathophysiology:
  - name: Heterogeneous Genetic Etiology
    biological_scale: MOLECULAR
    description: >-
      About a third of patients have an identifiable genetic cause, but it is
      spread thinly: no single gene dominates, and the genes implicated cluster
      functionally rather than positionally, into ion channels and transcriptional
      regulators that are highly co-expressed in brain. GRIN2A is the
      longest-associated, and a recent cohort added ten more with functions
      ranging from sodium-potassium pump subunits to chromatin modifiers. The
      practical consequence is that gene identity predicts less here than the
      converging network output does.
    genes:
      - preferred_term: GRIN2A
        term:
          id: hgnc:4585
          label: GRIN2A
    biological_processes:
      - preferred_term: regulation of postsynaptic membrane potential
        term:
          id: GO:0060078
          label: regulation of postsynaptic membrane potential
        modifier: ABNORMAL
    downstream:
      - target: Abnormal Frequency-Dependent Cortical Excitability
    evidence:
      - reference: PMID:39096015
        reference_title: >-
          Solving the Etiology of Developmental and Epileptic Encephalopathy with
          Spike-Wave Activation in Sleep (D/EE-SWAS).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          D/EE-SWAS genes were highly co-expressed in brain, highlighting the
          importance of channelopathies and transcriptional regulators.
        explanation: >-
          Establishes the functional convergence of an otherwise scattered gene
          list, which is why this node is modeled as one etiological class rather
          than as many.
      - reference: PMID:39096015
        reference_title: >-
          Solving the Etiology of Developmental and Epileptic Encephalopathy with
          Spike-Wave Activation in Sleep (D/EE-SWAS).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          We identified 10 novel D/EE-SWAS genes with a range of functions:
          ATP1A2, CACNA1A, FOXP1, GRIN1, KCNMA1, KCNQ3, PPFIA3, PUF60, SETD1B, and
          ZBTB18, and 2 novel copy number variants, 17p11.2 duplication and 5q22
          deletion.
        explanation: >-
          Enumerates the breadth of the genetic contribution and shows it is still
          expanding, which is the reason no single gene is named as the cause.
  - name: Early Thalamic Injury
    biological_scale: TISSUE
    description: >-
      The best-characterized route into this syndrome is not genetic at all. A
      perinatal thalamic lesion, typically unilateral, accounts for roughly one in
      seven cases and is the single commonest identifiable cause. The damage is
      concentrated in medial and dorsal nuclei and spares the ventral thalamus, a
      distribution that matters because it disconnects association cortex while
      leaving the machinery that generates sleep spindles intact. The child is
      often neurologically unremarkable for years before the electroencephalogram
      changes.
    locations:
      - preferred_term: dorsal plus ventral thalamus
        term:
          id: UBERON:0001897
          label: dorsal plus ventral thalamus
    downstream:
      - target: Selective Thalamocortical Disconnection
    evidence:
      - reference: PMID:29133062
        reference_title: >-
          Anatomical and physiological basis of continuous spike-wave of sleep
          syndrome after early thalamic lesions.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Early neonatal thalamic lesions account for about 14% of continuous
          spike-wave of sleep (CSWS) syndrome, representing the most common
          etiology in this epileptic encephalopathy in children
        explanation: >-
          Establishes the frequency and the standing of this etiology, which is
          why it is modeled as a root node rather than as a rare variant.
      - reference: PMID:29133062
        reference_title: >-
          Anatomical and physiological basis of continuous spike-wave of sleep
          syndrome after early thalamic lesions.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Thalamic volume loss ranged from 19% to 94%, predominantly on medial and
          dorsal nuclei and sparing the ventral thalamus.
        explanation: >-
          Documents the nuclear distribution of the damage asserted by this node.
  - name: Selective Thalamocortical Disconnection
    biological_scale: TISSUE
    description: >-
      What the thalamic lesion produces is not a general loss of thalamic function
      but a selective severing of thalamic-cortical fibres on one side, with
      ipsilateral white matter loss. The selectivity is the point. Sleep spindles
      are preserved and the waking electroencephalogram is only mildly affected,
      so the rhythmic drive that normally organizes non-rapid-eye-movement sleep
      still arrives at a cortex that has lost its normal thalamic regulation. The
      continuous sleep spiking then appears on the side of the lesion, which is
      the observation tying the anatomy to the electrophysiology.
    locations:
      - preferred_term: cerebral cortex
        term:
          id: UBERON:0000956
          label: cerebral cortex
    downstream:
      - target: Abnormal Frequency-Dependent Cortical Excitability
    evidence:
      - reference: PMID:29133062
        reference_title: >-
          Anatomical and physiological basis of continuous spike-wave of sleep
          syndrome after early thalamic lesions.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Unilateral selective thalamic-cortical disconnection is a common feature
          in our patients and is associated with both a focal pattern of CSWS and a
          pathological type of frequency-dependent excitability (peak: 10-20Hz).
        explanation: >-
          States the disconnection and links it to both the electrographic pattern
          and the excitability abnormality downstream.
      - reference: PMID:29133062
        reference_title: >-
          Anatomical and physiological basis of continuous spike-wave of sleep
          syndrome after early thalamic lesions.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Impact on EEG rhythms was mild, with a volume-loss-related decrease in
          alpha power and preservation of sleep spindles.
        explanation: >-
          Documents the preserved spindle machinery, which is what makes the
          selectivity of the disconnection mechanistically load-bearing.
      - reference: PMID:29133062
        reference_title: >-
          Anatomical and physiological basis of continuous spike-wave of sleep
          syndrome after early thalamic lesions.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          The sleep continuous spiking was lateralized to the hemisphere with the
          lesion.
        explanation: >-
          Ties the electrographic abnormality to the side of the anatomical lesion,
          which is the strongest available evidence that this edge is causal.
  - name: Abnormal Frequency-Dependent Cortical Excitability
    biological_scale: CELLULAR
    conforms_to: "epilepsy_excitation_inhibition_imbalance#Neuronal Hyperexcitability and Hypersynchrony"
    description: >-
      Cortex that has lost thalamic regulation acquires an abnormal response to
      being driven at particular rates. Probing visual cortex in patients with
      posterior spiking reveals excitability that peaks when stimulation is
      delivered at ten to twenty hertz on the side of the lesion. This is the
      augmenting response, a form of synaptic potentiation that is absent from
      cortico-cortical interactions in intact animals and emerges after the
      thalamus is ablated. It is a state of latent, frequency-tuned potentiation
      rather than continuous overexcitation, which is why the child can look
      electrically normal while awake.
    cell_types:
      - preferred_term: pyramidal neuron
        term:
          id: CL:0000598
          label: pyramidal neuron
    biological_processes:
      - preferred_term: regulation of synaptic plasticity
        term:
          id: GO:0048167
          label: regulation of synaptic plasticity
        modifier: ABNORMAL
    downstream:
      - target: Sleep-Potentiated Spike-Wave Activation
    evidence:
      - reference: PMID:29133062
        reference_title: >-
          Anatomical and physiological basis of continuous spike-wave of sleep
          syndrome after early thalamic lesions.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Visual cortex stimulation in five patients with posterior cortex spiking
          revealed an abnormal frequency-dependent excitability at 10-20Hz on the
          side of the lesion.
        explanation: >-
          The direct human measurement of the abnormal excitability this node
          asserts, with lateralization to the lesion as an internal control.
      - reference: PMID:29133062
        reference_title: >-
          Anatomical and physiological basis of continuous spike-wave of sleep
          syndrome after early thalamic lesions.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          We propose that this excitability represents an abnormal synaptic
          plasticity previously described as the augmenting response.
        explanation: >-
          Names the mechanism. Framed as a proposal by the authors, which is why
          this node describes a well-measured phenomenon with a proposed identity
          rather than an established one.
  - name: Sleep-Potentiated Spike-Wave Activation
    biological_scale: ORGANISM
    description: >-
      Two things coincide in non-rapid-eye-movement sleep and neither is
      sufficient alone: brainstem activation falls away, which is the condition
      under which the augmenting response is strongest, and sleep spindles supply
      rhythmic drive in precisely the frequency band the cortex has become
      abnormally responsive to. The result is that discharge which was
      intermittent or absent in wakefulness becomes near-continuous once the child
      falls asleep. This state-dependence is the defining feature of the syndrome
      and the reason a routine waking electroencephalogram can be reported as
      normal.
    biological_processes:
      - preferred_term: sleep
        term:
          id: GO:0030431
          label: sleep
    downstream:
      - target: Disruption of Sleep-Dependent Synaptic Plasticity
      - target: Focal and Atypical Absence Seizures
      - target: Age-Dependent Remission of the Electrographic Pattern
    evidence:
      - reference: PMID:29133062
        reference_title: >-
          Anatomical and physiological basis of continuous spike-wave of sleep
          syndrome after early thalamic lesions.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Because this response is potentiated by sleep states of reduced brainstem
          activation and by appropriate stimulating rhythms, such as sleep
          spindles, the simultaneous occurrence of these two factors in
          nonrapid-eye-movement sleep is proposed as an explanation for CSWS in our
          patients.
        explanation: >-
          States the two-factor account of state-dependence that this node encodes,
          explicitly as a proposal.
      - reference: PMID:25160535
        reference_title: >-
          Neurobiology of continuous spike-wave in slow-wave sleep and
          Landau-Kleffner syndromes.
        supports: SUPPORT
        evidence_source: OTHER
        snippet: >-
          These disorders, of which continuous spike-wave in slow-wave sleep and
          Landau-Kleffner are the most common, are characterized by continuous
          spike-wave activity during slow-wave sleep, developmentally regulated
          onset and termination of abnormal electrical activity, and loss of
          previously acquired skills.
        explanation: >-
          Establishes the three features this node and its two downstream nodes
          model: the sleep-locked activity, its developmental gating, and the skill
          loss.
  - name: Disruption of Sleep-Dependent Synaptic Plasticity
    biological_scale: CELLULAR
    description: >-
      Slow-wave sleep is not passive for a developing cortex. It is when synaptic
      strengths are rescaled and the day's experience is consolidated into
      developing cortical maps, and it does this during critical periods when
      those maps are still plastic. Occupying that window with continuous
      epileptiform discharge is the proposed mechanism by which an
      electroencephalographic abnormality becomes a cognitive one, and it explains
      why the deficit tracks which cortex is involved rather than seizure burden:
      perisylvian activation costs language, frontal activation costs attention
      and behaviour.
    cell_types:
      - preferred_term: pyramidal neuron
        term:
          id: CL:0000598
          label: pyramidal neuron
    biological_processes:
      - preferred_term: regulation of synaptic plasticity
        term:
          id: GO:0048167
          label: regulation of synaptic plasticity
        modifier: ABNORMAL
    downstream:
      - target: Developmental Regression and Cognitive-Behavioural Encephalopathy
    evidence:
      - reference: PMID:25160535
        reference_title: >-
          Neurobiology of continuous spike-wave in slow-wave sleep and
          Landau-Kleffner syndromes.
        supports: SUPPORT
        evidence_source: OTHER
        snippet: >-
          The role of slow-wave sleep in normal cortical plasticity during
          developmental critical periods, how disruption of slow-wave sleep by
          electrographic seizures could affect cortical maps and development, and
          the organization and functional connectivity of the thalamic structures
          that when damaged are thought to produce these seizure disorders are
          reviewed.
        explanation: >-
          States the plasticity-disruption account this node encodes, and the
          critical-period framing that makes the developmental gating expected
          rather than puzzling.
      - reference: PMID:25160535
        reference_title: >-
          Neurobiology of continuous spike-wave in slow-wave sleep and
          Landau-Kleffner syndromes.
        supports: SUPPORT
        evidence_source: OTHER
        snippet: >-
          Over the last 20 years, a variety of basic science findings suggest how
          spike-wave activity during sleep can cause the observed clinical
          outcomes.
        explanation: >-
          Supports the causal direction from discharge to cognitive outcome. Marked
          PARTIAL because the source says basic science findings suggest how this
          could work, which is a mechanism sketch rather than a demonstration in
          patients, and that gap is the subject of a discussion in this entry.
  - name: Focal and Atypical Absence Seizures
    biological_scale: ORGANISM
    conforms_to: "epilepsy_excitation_inhibition_imbalance#Recurrent Unprovoked Seizures"
    description: >-
      Clinical seizures do occur, typically focal seizures often arising from
      sleep and atypical absences, but they are frequently mild, sometimes absent
      entirely, and they are not what causes the regression. This is the feature
      that most distinguishes the syndrome from other developmental and epileptic
      encephalopathies, where seizure burden and cognitive outcome move together.
      A child can have this syndrome, and lose skills to it, with barely any
      seizures at all.
    evidence:
      - reference: PMID:38081201
        reference_title: >-
          Corticosteroids versus clobazam for treatment of children with epileptic
          encephalopathy with spike-wave activation in sleep (RESCUE ESES): a
          multicentre randomised controlled trial.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Epileptic encephalopathy with spike-wave activation in sleep (EE-SWAS) is
          a rare syndrome associated with cognitive and behavioural regression.
        explanation: >-
          Frames the syndrome by its cognitive rather than its seizure burden,
          which is the claim this node is qualifying. The trial's primary outcome
          was cognitive, not seizure control, for the same reason.
  - name: Age-Dependent Remission of the Electrographic Pattern
    biological_scale: ORGANISM
    description: >-
      The sleep activation switches itself off, usually around adolescence, and it
      does so whether or not treatment worked. That spontaneous termination is as
      developmentally regulated as the onset, and it is the single most important
      thing to understand about prognosis: the electroencephalogram will normalize
      on its own, but the cognitive ground lost while it was active may not be
      recovered. It is also why treatment is judged on cognition rather than on
      the eventual disappearance of the pattern, which would have happened anyway.
    evidence:
      - reference: PMID:25160535
        reference_title: >-
          Neurobiology of continuous spike-wave in slow-wave sleep and
          Landau-Kleffner syndromes.
        supports: SUPPORT
        evidence_source: OTHER
        snippet: >-
          These disorders, of which continuous spike-wave in slow-wave sleep and
          Landau-Kleffner are the most common, are characterized by continuous
          spike-wave activity during slow-wave sleep, developmentally regulated
          onset and termination of abnormal electrical activity, and loss of
          previously acquired skills.
        explanation: >-
          States the developmentally regulated termination that this node models,
          alongside the persisting skill loss that makes it a poor measure of
          treatment success.
  - name: Developmental Regression and Cognitive-Behavioural Encephalopathy
    biological_scale: ORGANISM
    description: >-
      The clinical endpoint and the reason the syndrome matters: loss of skills
      the child already had. Which skills depends on which cortex carries the
      activation, giving language regression, attentional and behavioural collapse,
      or global cognitive decline. Regression patterns are similar whether the
      child was developmentally normal beforehand or already delayed, but the
      eventual intellectual outcome is worse in the delayed group, which also has
      a longer duration of epilepsy.
    evidence:
      - reference: PMID:39096015
        reference_title: >-
          Solving the Etiology of Developmental and Epileptic Encephalopathy with
          Spike-Wave Activation in Sleep (D/EE-SWAS).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Although developmental regression patterns were similar in both
          syndromes, DEE-SWAS was associated with a longer duration of epilepsy and
          poorer intellectual outcome than EE-SWAS.
        explanation: >-
          Documents both the shared regression process and the outcome difference
          between the two arms, which is what this node asserts and what the
          nosology discussion turns on.
phenotypes:
  - category: Neurologic
    name: Spike-wave activation in sleep
    description: >-
      The defining electroencephalographic finding: epileptiform discharge that
      becomes near-continuous in non-rapid-eye-movement sleep while being sparse
      or absent in wakefulness. A routine waking recording can be normal, so the
      diagnosis requires a sleep study.
    phenotype_term:
      preferred_term: Continuous spike and waves during slow sleep
      term:
        id: HP:0031491
        label: Continuous spike and waves during slow sleep
    evidence:
      - reference: PMID:25160535
        reference_title: >-
          Neurobiology of continuous spike-wave in slow-wave sleep and
          Landau-Kleffner syndromes.
        supports: SUPPORT
        evidence_source: OTHER
        snippet: >-
          These disorders, of which continuous spike-wave in slow-wave sleep and
          Landau-Kleffner are the most common, are characterized by continuous
          spike-wave activity during slow-wave sleep, developmentally regulated
          onset and termination of abnormal electrical activity, and loss of
          previously acquired skills.
        explanation: >-
          Establishes the sleep-locked continuous discharge as the defining feature.
  - category: Neurologic
    name: Developmental regression
    description: >-
      Loss of previously acquired skills, which is the clinical event that defines
      the encephalopathy. The domain affected follows the topography of the
      epileptiform activation rather than the seizures.
    phenotype_term:
      preferred_term: Developmental regression
      term:
        id: HP:0002376
        label: Developmental regression
    evidence:
      - reference: PMID:38081201
        reference_title: >-
          Corticosteroids versus clobazam for treatment of children with epileptic
          encephalopathy with spike-wave activation in sleep (RESCUE ESES): a
          multicentre randomised controlled trial.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Epileptic encephalopathy with spike-wave activation in sleep (EE-SWAS) is
          a rare syndrome associated with cognitive and behavioural regression.
        explanation: >-
          States the regression that defines the syndrome and that the trial's
          primary outcome was designed to capture.
  - category: Neurologic
    name: Intellectual disability
    description: >-
      Cognitive impairment, either pre-existing in the DEE-SWAS arm or acquired
      through the regression in the EE-SWAS arm, and worse in the former.
    phenotype_term:
      preferred_term: Intellectual disability
      term:
        id: HP:0001249
        label: Intellectual disability
    evidence:
      - reference: PMID:39096015
        reference_title: >-
          Solving the Etiology of Developmental and Epileptic Encephalopathy with
          Spike-Wave Activation in Sleep (D/EE-SWAS).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Although developmental regression patterns were similar in both
          syndromes, DEE-SWAS was associated with a longer duration of epilepsy and
          poorer intellectual outcome than EE-SWAS.
        explanation: >-
          Documents the intellectual outcome and its difference between the two
          arms.
  - category: Neurologic
    name: Language regression
    description: >-
      When the activation involves perisylvian cortex the loss is of language,
      which in its purest form is the Landau-Kleffner presentation: an acquired
      auditory agnosia in a child who had been speaking normally.
    phenotype_term:
      preferred_term: Aphasia
      term:
        id: HP:0002381
        label: Aphasia
    evidence:
      - reference: PMID:25160535
        reference_title: >-
          Neurobiology of continuous spike-wave in slow-wave sleep and
          Landau-Kleffner syndromes.
        supports: SUPPORT
        evidence_source: OTHER
        snippet: >-
          Several pediatric seizure disorders have common electrophysiological
          features during slow-wave sleep that produce different syndromes based on
          which part of the developing brain is involved.
        explanation: >-
          States the topographic principle that makes language the affected domain
          when perisylvian cortex carries the activation.
  - category: Behavioral
    name: Behavioural disturbance and attentional impairment
    description: >-
      Behavioural deterioration and loss of attention are as characteristic as the
      cognitive decline, and in frontally predominant cases they are the
      presenting problem.
    phenotype_term:
      preferred_term: Atypical behavior
      term:
        id: HP:0000708
        label: Atypical behavior
    evidence:
      - reference: PMID:38081201
        reference_title: >-
          Corticosteroids versus clobazam for treatment of children with epileptic
          encephalopathy with spike-wave activation in sleep (RESCUE ESES): a
          multicentre randomised controlled trial.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Epileptic encephalopathy with spike-wave activation in sleep (EE-SWAS) is
          a rare syndrome associated with cognitive and behavioural regression.
        explanation: >-
          Names behavioural regression alongside the cognitive component.
  - category: Neurologic
    name: Atypical absence seizure
    description: >-
      Atypical absences occur alongside the focal seizures and are named in the
      pathophysiology node for the clinical seizure burden. They are generally mild
      relative to the cognitive consequences of the syndrome.
    phenotype_term:
      preferred_term: Atypical absence seizure
      term:
        id: HP:0007270
        label: Atypical absence seizure
    evidence:
      - reference: PMID:35503717
        reference_title: >-
          International League Against Epilepsy classification and definition of
          epilepsy syndromes with onset in childhood: Position paper by the ILAE
          Task Force on Nosology and Definitions.
        supports: SUPPORT
        evidence_source: OTHER
        snippet: >-
          In this paper, we describe the childhood onset epilepsy syndromes, most
          of which have both mandatory seizure type(s) and interictal
          electroencephalographic (EEG) features.
        explanation: >-
          Establishes that the ILAE defines these syndromes by mandatory seizure
          types. Marked PARTIAL because the abstract does not enumerate them for
          this syndrome, so the absence seizure type rests on the wider literature
          rather than on this quote.
  - category: Neurologic
    name: Global developmental delay
    description: >-
      Definitional for the DEE-SWAS arm, in which developmental impairment is
      present before the spike-wave activation begins rather than being acquired
      through it.
    phenotype_term:
      preferred_term: Global developmental delay
      term:
        id: HP:0001263
        label: Global developmental delay
    evidence:
      - reference: PMID:39096015
        reference_title: >-
          Solving the Etiology of Developmental and Epileptic Encephalopathy with
          Spike-Wave Activation in Sleep (D/EE-SWAS).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Although developmental regression patterns were similar in both
          syndromes, DEE-SWAS was associated with a longer duration of epilepsy and
          poorer intellectual outcome than EE-SWAS.
        explanation: >-
          Documents the developmental impairment that distinguishes the DEE-SWAS
          arm and its worse outcome.
  - category: Behavioral
    name: Attention deficit hyperactivity disorder
    description: >-
      Attentional and hyperactive symptoms are among the commonest behavioural
      manifestations, and in frontally predominant cases they are the presenting
      complaint rather than an accompaniment.
    phenotype_term:
      preferred_term: Attention deficit hyperactivity disorder
      term:
        id: HP:0007018
        label: Attention deficit hyperactivity disorder
    evidence:
      - reference: PMID:38081201
        reference_title: >-
          Corticosteroids versus clobazam for treatment of children with epileptic
          encephalopathy with spike-wave activation in sleep (RESCUE ESES): a
          multicentre randomised controlled trial.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Epileptic encephalopathy with spike-wave activation in sleep (EE-SWAS) is
          a rare syndrome associated with cognitive and behavioural regression.
        explanation: >-
          Establishes behavioural regression as a defining component. Marked
          PARTIAL because the abstract does not name the attentional phenotype
          specifically, so the more specific term is curated on the strength of the
          behavioural regression it belongs to.
  - category: Neurologic
    name: Focal-onset seizure
    description: >-
      Focal seizures, often arising from sleep, are the usual clinical seizure type
      when seizures occur at all. They are frequently mild relative to the
      cognitive burden.
    phenotype_term:
      preferred_term: Focal-onset seizure
      term:
        id: HP:0007359
        label: Focal-onset seizure
    evidence:
      - reference: PMID:35503717
        reference_title: >-
          International League Against Epilepsy classification and definition of
          epilepsy syndromes with onset in childhood: Position paper by the ILAE
          Task Force on Nosology and Definitions.
        supports: SUPPORT
        evidence_source: OTHER
        snippet: >-
          In this paper, we describe the childhood onset epilepsy syndromes, most
          of which have both mandatory seizure type(s) and interictal
          electroencephalographic (EEG) features.
        explanation: >-
          Establishes that the ILAE defines these syndromes by mandatory seizure
          types together with EEG features. Marked PARTIAL because the abstract
          does not enumerate the seizure types for this specific syndrome, so the
          seizure semiology here rests on the wider literature.
prevalence:
  - population: Children with epilepsy
    measure_type: UNKNOWN
    prevalence_class: RARE
    notes: >-
      No population-based prevalence estimate is available. The syndrome is
      described as rare in the randomized trial literature, and its ascertainment
      depends on whether a sleep electroencephalogram is performed, since a waking
      record can be normal. That dependence makes any published rate a lower bound
      on the true one.
    evidence:
      - reference: PMID:38081201
        reference_title: >-
          Corticosteroids versus clobazam for treatment of children with epileptic
          encephalopathy with spike-wave activation in sleep (RESCUE ESES): a
          multicentre randomised controlled trial.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Epileptic encephalopathy with spike-wave activation in sleep (EE-SWAS) is
          a rare syndrome associated with cognitive and behavioural regression.
        explanation: >-
          Supports the qualitative rarity band. Marked PARTIAL because it is a
          descriptor rather than a measurement, which is why no rate is asserted.
  - population: Children with continuous spike-wave of sleep
    measure_type: UNKNOWN
    prevalence_class: UNKNOWN
    notes: >-
      Within the syndrome, early neonatal thalamic lesions account for about 14
      percent of cases, making them the commonest single identifiable cause. This
      is an etiological fraction rather than a population rate.
    evidence:
      - reference: PMID:29133062
        reference_title: >-
          Anatomical and physiological basis of continuous spike-wave of sleep
          syndrome after early thalamic lesions.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Early neonatal thalamic lesions account for about 14% of continuous
          spike-wave of sleep (CSWS) syndrome, representing the most common
          etiology in this epileptic encephalopathy in children
        explanation: >-
          Gives the etiological fraction reported in the notes.
progression:
  - phase: Onset of sleep activation with regression
    age_range: Mid-childhood
    notes: >-
      The electroencephalographic activation appears in mid-childhood, often after
      a period in which seizures alone were present and unremarkable, and the loss
      of skills follows. Because a waking recording can be normal, the interval
      between the regression starting and the diagnosis being made is frequently
      long.
    evidence:
      - reference: PMID:25160535
        reference_title: >-
          Neurobiology of continuous spike-wave in slow-wave sleep and
          Landau-Kleffner syndromes.
        supports: SUPPORT
        evidence_source: OTHER
        snippet: >-
          developmentally regulated onset and termination of abnormal electrical
          activity, and loss of previously acquired skills
        explanation: >-
          States the developmentally regulated onset and the associated skill loss
          that define this phase.
  - phase: Spontaneous remission of the electrographic pattern with residual deficit
    age_range: Adolescence
    notes: >-
      The sleep activation resolves on its own around adolescence regardless of
      treatment. Cognitive recovery is variable and often incomplete, so the
      prognosis is set less by whether the pattern eventually stops, which it
      will, than by how long it ran and over which cortex.
    evidence:
      - reference: PMID:25160535
        reference_title: >-
          Neurobiology of continuous spike-wave in slow-wave sleep and
          Landau-Kleffner syndromes.
        supports: SUPPORT
        evidence_source: OTHER
        snippet: >-
          developmentally regulated onset and termination of abnormal electrical
          activity, and loss of previously acquired skills
        explanation: >-
          Supports the developmentally regulated termination described in this
          phase.
treatments:
  - name: Corticosteroids
    description: >-
      The best-supported treatment, and unusually for this syndrome the support is
      randomized. In a head-to-head trial against clobazam, a quarter of children
      given corticosteroids gained at least eleven and a quarter intelligence
      quotient points at six months while none of the clobazam group did. The
      trial's other cognitive measure showed no difference, and it stopped early
      without reaching its target sample, so the result strengthens rather than
      settles the case for early steroid use. Either continuous oral prednisolone
      or pulsed intravenous methylprednisolone is used.
    therapeutic_modality: SMALL_MOLECULE
    treatment_term:
      preferred_term: Pharmacotherapy
      term:
        id: NCIT:C15986
        label: Pharmacotherapy
      therapeutic_agent:
        - preferred_term: prednisolone
          term:
            id: CHEBI:8378
            label: prednisolone
        - preferred_term: methylprednisolone
          term:
            id: CHEBI:6888
            label: 6alpha-methylprednisolone
    target_mechanisms:
      - target: Sleep-Potentiated Spike-Wave Activation
        treatment_effect: INHIBITS
    evidence:
      - reference: PMID:38081201
        reference_title: >-
          Corticosteroids versus clobazam for treatment of children with epileptic
          encephalopathy with spike-wave activation in sleep (RESCUE ESES): a
          multicentre randomised controlled trial.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Our findings strengthen those from previous uncontrolled studies that
          support the early use of corticosteroids for children with EE-SWAS.
        explanation: >-
          The trial's own summary of what its result licenses, which is the
          strength of recommendation this record encodes.
      - reference: PMID:38081201
        reference_title: >-
          Corticosteroids versus clobazam for treatment of children with epileptic
          encephalopathy with spike-wave activation in sleep (RESCUE ESES): a
          multicentre randomised controlled trial.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Our data indicated an improvement in IQ outcomes with corticosteroids
          compared with clobazam treatment, but no difference was seen in cognitive
          sum score.
        explanation: >-
          Records the split result across the two co-primary cognitive measures.
          Marked PARTIAL because one measure showed benefit and the other did not.
      - reference: PMID:38081201
        reference_title: >-
          Corticosteroids versus clobazam for treatment of children with epileptic
          encephalopathy with spike-wave activation in sleep (RESCUE ESES): a
          multicentre randomised controlled trial.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          The trial was terminated prematurely, and the target sample size was not
          met, so our findings must be interpreted with caution.
        explanation: >-
          Records the limitation the investigators attach to their own result,
          which is why this treatment is curated as best-supported rather than
          established.
  - name: Clobazam
    description: >-
      A benzodiazepine long used for this syndrome on observational grounds. When
      finally compared head to head with corticosteroids it did not produce the
      intelligence quotient gains that steroids did, though the two were
      indistinguishable on the other cognitive measure and in adverse event rates.
      It remains in use, but the trial removes the basis for treating it as
      equivalent first-line.
    therapeutic_modality: SMALL_MOLECULE
    treatment_term:
      preferred_term: Pharmacotherapy
      term:
        id: NCIT:C15986
        label: Pharmacotherapy
      therapeutic_agent:
        - preferred_term: clobazam
          term:
            id: CHEBI:31413
            label: clobazam
    target_mechanisms:
      - target: Sleep-Potentiated Spike-Wave Activation
        treatment_effect: INHIBITS
    evidence:
      - reference: PMID:38081201
        reference_title: >-
          Corticosteroids versus clobazam for treatment of children with epileptic
          encephalopathy with spike-wave activation in sleep (RESCUE ESES): a
          multicentre randomised controlled trial.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          On the basis of mostly small observational and retrospective studies,
          corticosteroids and clobazam are often considered the most effective
          treatments for this syndrome.
        explanation: >-
          Establishes clobazam's standing as a conventional treatment and the weak
          evidence base that standing rested on.
      - reference: PMID:38081201
        reference_title: >-
          Corticosteroids versus clobazam for treatment of children with epileptic
          encephalopathy with spike-wave activation in sleep (RESCUE ESES): a
          multicentre randomised controlled trial.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Adverse events occurred in ten (45%) of 22 children who received
          corticosteroids, most frequently weight gain, and in 11 (52%) of 21
          children who received clobazam, most often fatigue and behavioural
          disturbances.
        explanation: >-
          Documents the adverse event profile of both arms, which is the other half
          of the comparison and shows the two did not differ on tolerability.
  - name: Avoidance of sodium channel blocking antiseizure medications
    description: >-
      Carbamazepine, oxcarbazepine, phenytoin, and phenobarbital can induce or
      worsen the sleep activation, which makes stopping them the cheapest
      intervention available in this syndrome and one that costs nothing to try.
      The trap is structural rather than careless: these children often have focal
      seizures, focal seizures are a standard indication for carbamazepine, and the
      sleep activation that the drug then aggravates is invisible unless someone
      records a sleep electroencephalogram.
    therapeutic_modality: BEHAVIORAL
    treatment_term:
      preferred_term: Supportive Care
      term:
        id: NCIT:C15747
        label: Supportive Care
    evidence:
      - reference: PMID:26415787
        reference_title: >-
          Encephalopathy with status epilepticus during sleep (ESES) induced by
          oxcarbazepine in idiopathic focal epilepsy in childhood.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Cases of worsening or induction of ESES with phenytoin, carbamazepine and
          phenobarbital have been reported.
        explanation: >-
          Names three of the four drugs directly, which converts this record from
          an argument by omission into a directly evidenced management claim.
diagnosis:
  - name: Sleep electroencephalography
    description: >-
      The diagnostic test, and one that will be missed if only a waking recording
      is done. A sleep study, ideally whole-night, is required to demonstrate the
      activation, because the waking record can be normal or show only sparse
      discharge. Quantifying how much of non-rapid-eye-movement sleep is occupied
      is what turns the observation into a diagnosis. This entry deliberately does
      not assert a numeric spike-wave index threshold. Published thresholds differ,
      the ILAE definition cited here does not mandate one, and a curated number
      would give a false impression of consensus about who has this disease.
    diagnosis_term:
      preferred_term: Electroencephalography
      term:
        id: NCIT:C38054
        label: Electroencephalography
    results: >-
      Marked activation of epileptiform discharge in non-rapid-eye-movement sleep
      relative to wakefulness, often near-continuous, and lateralized to the side
      of any structural lesion.
    evidence:
      - reference: PMID:29133062
        reference_title: >-
          Anatomical and physiological basis of continuous spike-wave of sleep
          syndrome after early thalamic lesions.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Longitudinal whole-night and high-density electroencephalograms (EEGs)
          were performed, as well as detailed imaging and clinical evaluation.
        explanation: >-
          Documents whole-night recording as the method used to characterize the
          syndrome, which is the diagnostic standard this record describes.
      - reference: PMID:29133062
        reference_title: >-
          Anatomical and physiological basis of continuous spike-wave of sleep
          syndrome after early thalamic lesions.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          The sleep continuous spiking was lateralized to the hemisphere with the
          lesion.
        explanation: >-
          Supports the lateralization described in the results field, which is what
          links the electrographic finding to a structural cause when one exists.
  - name: Brain MRI for thalamic and structural lesions
    description: >-
      Imaging is directed at the thalamus in particular, since perinatal thalamic
      injury is the commonest identifiable cause and the volume loss can be subtle.
      Structural causes account for roughly one in eight patients overall.
    diagnosis_term:
      preferred_term: Magnetic Resonance Imaging
      term:
        id: NCIT:C16809
        label: Magnetic Resonance Imaging
    results: >-
      Unilateral thalamic volume loss predominantly affecting medial and dorsal
      nuclei, with ipsilateral white matter loss and ventricular enlargement, or
      another structural lesion.
    evidence:
      - reference: PMID:39096015
        reference_title: >-
          Solving the Etiology of Developmental and Epileptic Encephalopathy with
          Spike-Wave Activation in Sleep (D/EE-SWAS).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Structural etiologies were found in 12/91 (13%) individuals.
        explanation: >-
          Quantifies the yield of imaging for a structural cause in a systematically
          investigated cohort.
      - reference: PMID:29133062
        reference_title: >-
          Anatomical and physiological basis of continuous spike-wave of sleep
          syndrome after early thalamic lesions.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Lesions produced white matter loss and ventricle enlargement on the same
          hemisphere, which in four patients was associated with selective loss of
          thalamic-cortical fibers.
        explanation: >-
          Describes the imaging findings reported in the results field.
  - name: Genetic testing
    description: >-
      Worth doing, because a genetic cause is found in about a third of patients
      and the yield is much higher in the developmentally delayed arm than in the
      previously normal one. No single gene dominates, so panel or exome testing
      rather than targeted analysis is appropriate.
    diagnosis_term:
      preferred_term: Genetic Testing
      term:
        id: NCIT:C15709
        label: Genetic Testing
    results: >-
      A pathogenic variant in one of a broad set of channel and transcriptional
      regulator genes, or a copy number variant, in roughly a third of patients.
    evidence:
      - reference: PMID:39096015
        reference_title: >-
          Solving the Etiology of Developmental and Epileptic Encephalopathy with
          Spike-Wave Activation in Sleep (D/EE-SWAS).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          We identified the etiology in 42/91 (46%) patients in our Core cohort,
          including 29/44 (66%) with DEE-SWAS and 13/47 (28%) with EE-SWAS.
        explanation: >-
          Quantifies the overall diagnostic yield and the large difference between
          the two arms, which is what makes baseline development a useful guide to
          how hard to look.
differential_diagnoses:
  - name: Landau-Kleffner Syndrome
    disease_term:
      preferred_term: Landau-Kleffner syndrome
      term:
        id: MONDO:0009509
        label: Landau-Kleffner syndrome
    description: >-
      The closest relative and arguably a variant rather than a separate disease.
      It shares the sleep-activated epileptiform activity and the developmentally
      regulated course, and differs mainly in that the activation sits over
      perisylvian language cortex, so the regression is specifically an acquired
      auditory agnosia.
    distinguishing_features:
      - Regression is specifically of language comprehension, presenting as acquired auditory agnosia.
      - Epileptiform activity is centrotemporal and perisylvian rather than diffuse or frontal.
      - Non-language cognition and behaviour are relatively preserved at onset.
    evidence:
      - reference: PMID:25160535
        reference_title: >-
          Neurobiology of continuous spike-wave in slow-wave sleep and
          Landau-Kleffner syndromes.
        supports: SUPPORT
        evidence_source: OTHER
        snippet: >-
          Several pediatric seizure disorders have common electrophysiological
          features during slow-wave sleep that produce different syndromes based on
          which part of the developing brain is involved.
        explanation: >-
          States the shared mechanism and the topographic basis of the difference,
          which is precisely why these two are differentials of each other rather
          than unrelated conditions.
  - name: Lennox-Gastaut Syndrome
    disease_term:
      preferred_term: Lennox-Gastaut syndrome
      term:
        id: MONDO:0016532
        label: Lennox-Gastaut syndrome
    description: >-
      Another childhood developmental and epileptic encephalopathy classified
      alongside this one by the ILAE, and confusable because both feature slow
      spike-wave and cognitive decline.
    distinguishing_features:
      - Tonic seizures in sleep are mandatory and are not a feature of spike-wave activation in sleep.
      - Slow spike-wave is present in wakefulness rather than being sleep-activated.
      - Seizure burden is high and tracks the encephalopathy, whereas here seizures may be minimal.
      - No spontaneous remission of the electrographic pattern at adolescence.
    evidence:
      - reference: PMID:35503717
        reference_title: >-
          International League Against Epilepsy classification and definition of
          epilepsy syndromes with onset in childhood: Position paper by the ILAE
          Task Force on Nosology and Definitions.
        supports: SUPPORT
        evidence_source: OTHER
        snippet: >-
          developmental and/or epileptic encephalopathies, comprising five
          syndromes: epilepsy with myoclonic-atonic seizures, Lennox-Gastaut
          syndrome, developmental and/or epileptic encephalopathy with
          spike-and-wave activation in sleep, hemiconvulsion-hemiplegia-epilepsy
          syndrome, and febrile infection-related epilepsy syndrome.
        explanation: >-
          Establishes that the ILAE treats these as distinct syndromes within the
          same category, which is what makes the differentiation necessary.
  - name: Self-Limited Epilepsy with Centrotemporal Spikes
    disease_term:
      preferred_term: self-limited epilepsy with centrotemporal spikes
      term:
        id: MONDO:0007295
        label: self-limited epilepsy with centrotemporal spikes
    description: >-
      Shares sleep-activated centrotemporal discharge and an age-limited course,
      and sits at the benign end of what may be a continuum. The distinction
      matters because one needs treating and the other largely does not.
    distinguishing_features:
      - Discharge activates in sleep but does not become near-continuous.
      - No regression; cognition is normal or only subtly affected.
      - Seizures are infrequent, nocturnal, and remit in adolescence without deficit.
    evidence:
      - reference: PMID:35503717
        reference_title: >-
          International League Against Epilepsy classification and definition of
          epilepsy syndromes with onset in childhood: Position paper by the ILAE
          Task Force on Nosology and Definitions.
        supports: SUPPORT
        evidence_source: OTHER
        snippet: >-
          self-limited focal epilepsies, comprising four syndromes: self-limited
          epilepsy with centrotemporal spikes, self-limited epilepsy with autonomic
          seizures, childhood occipital visual epilepsy, and photosensitive
          occipital lobe epilepsy
        explanation: >-
          Establishes that the ILAE places this syndrome in the self-limited focal
          category, separate from the encephalopathies, which is the classificatory
          basis of the distinction.
discussions:
  - discussion_id: dee_swas_does_the_eeg_cause_the_regression
    kind: CONTROVERSY
    status: UNDER_DISCUSSION
    prompt: >-
      Does the sleep-activated epileptiform discharge actually cause the
      developmental regression, or are the discharge and the regression parallel
      consequences of the same underlying lesion, and what would distinguish the
      two?
    attaches_to:
      - pathophysiology#Sleep-Potentiated Spike-Wave Activation
      - pathophysiology#Disruption of Sleep-Dependent Synaptic Plasticity
      - pathophysiology#Developmental Regression and Cognitive-Behavioural Encephalopathy
    rationale: >-
      The syndrome's name embeds the causal claim, and there is a coherent
      mechanism for it: slow-wave sleep is when synaptic strengths are rescaled and
      cortical maps consolidate during critical periods, so filling that window
      with continuous discharge should damage exactly what it appears to damage.
      The topographic correlation supports it too, since the domain lost tracks
      which cortex carries the activation rather than tracking seizure burden. The
      strongest evidence is therapeutic: in the only randomized trial, children
      given corticosteroids were substantially more likely to gain intelligence
      quotient points than children given clobazam, which is hard to explain if the
      discharge were a bystander. But the case is not closed. The trial stopped
      early without its target sample, and its two co-primary cognitive measures
      disagreed, with the sum score showing no difference at all. The alternative
      reading is that a single lesion, whether a thalamic injury or a gene,
      produces both an abnormally excitable cortex and a cortex that develops
      badly, and that suppressing the discharge treats a marker. Two observations
      sit awkwardly for the strong causal reading. The electrographic pattern
      remits spontaneously at adolescence in essentially everyone, yet cognitive
      recovery is variable and often incomplete, which is at least consistent with
      the deficit having been set by the lesion rather than accumulated by the
      discharge. And regression patterns are similar in DEE-SWAS and EE-SWAS
      despite those groups differing substantially in underlying etiology and in
      eventual outcome. The stake is concrete: if the discharge is causal,
      aggressive early suppression is worth its steroid toxicity, and normalizing
      the sleep record is a legitimate treatment target. If it is a marker, both of
      those are wrong.
    proposed_experiments:
      - experiment_id: exp_dee_swas_discharge_burden_mediation
        name: Mediation analysis of discharge burden between etiology and cognitive outcome
        description: >-
          A prospective cohort with etiology characterized at entry, quantified
          spike-wave index measured serially through the active period, and
          standardized cognitive testing at fixed intervals, analysed to test
          whether discharge burden mediates the relationship between etiology and
          cognitive trajectory, or whether etiology predicts outcome independently
          of how much discharge occurred.
        decision_criterion: >-
          If cumulative discharge burden mediates the etiology-outcome relationship
          and predicts cognitive decline after adjustment for etiology, the causal
          reading is supported and suppression is a legitimate target. If etiology
          predicts outcome with no independent contribution from discharge burden,
          the discharge is a marker and treatment should be judged on cognition
          alone.
      - experiment_id: exp_dee_swas_eeg_response_versus_cognitive_response
        name: Dissociation of electrographic and cognitive response to treatment
        description: >-
          Within treated cohorts, classify children by whether the sleep record
          normalized and separately by whether cognition improved, and quantify the
          agreement between the two. Cases of electrographic response without
          cognitive response, and the reverse, are the informative cells.
        decision_criterion: >-
          Tight concordance would support the causal chain. A substantial number of
          children whose record normalizes without cognitive benefit would show
          that suppressing the discharge is not sufficient, and would undermine
          normalization of the electroencephalogram as a treatment endpoint.
    evidence:
      - reference: PMID:25160535
        reference_title: >-
          Neurobiology of continuous spike-wave in slow-wave sleep and
          Landau-Kleffner syndromes.
        supports: SUPPORT
        evidence_source: OTHER
        snippet: >-
          Over the last 20 years, a variety of basic science findings suggest how
          spike-wave activity during sleep can cause the observed clinical
          outcomes.
        explanation: >-
          States the mechanistic case for the causal reading, and states it as
          suggestion rather than demonstration, which is the epistemic situation
          this discussion records.
      - reference: PMID:38081201
        reference_title: >-
          Corticosteroids versus clobazam for treatment of children with epileptic
          encephalopathy with spike-wave activation in sleep (RESCUE ESES): a
          multicentre randomised controlled trial.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Our findings strengthen those from previous uncontrolled studies that
          support the early use of corticosteroids for children with EE-SWAS.
        explanation: >-
          The randomized evidence that a treatment aimed at the discharge improves
          cognition, which is the strongest argument for the causal reading.
      - reference: PMID:38081201
        reference_title: >-
          Corticosteroids versus clobazam for treatment of children with epileptic
          encephalopathy with spike-wave activation in sleep (RESCUE ESES): a
          multicentre randomised controlled trial.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Our data indicated an improvement in IQ outcomes with corticosteroids
          compared with clobazam treatment, but no difference was seen in cognitive
          sum score.
        explanation: >-
          The disagreement between the two co-primary measures, which is why the
          trial supports rather than settles the causal reading.
      - reference: PMID:38081201
        reference_title: >-
          Corticosteroids versus clobazam for treatment of children with epileptic
          encephalopathy with spike-wave activation in sleep (RESCUE ESES): a
          multicentre randomised controlled trial.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          The trial was terminated prematurely, and the target sample size was not
          met, so our findings must be interpreted with caution.
        explanation: >-
          The limitation the investigators attach to their own result, recorded here
          so the therapeutic argument is not overstated.
      - reference: PMID:39096015
        reference_title: >-
          Solving the Etiology of Developmental and Epileptic Encephalopathy with
          Spike-Wave Activation in Sleep (D/EE-SWAS).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Although developmental regression patterns were similar in both
          syndromes, DEE-SWAS was associated with a longer duration of epilepsy and
          poorer intellectual outcome than EE-SWAS.
        explanation: >-
          Supports the alternative reading, since regression looks the same across
          groups that differ in etiology and outcome. Marked PARTIAL because
          similar regression patterns are consistent with either account and only
          become discriminating alongside discharge burden data.
  - discussion_id: dee_swas_one_syndrome_or_two
    kind: CONTROVERSY
    status: OPEN
    prompt: >-
      Is the ILAE split between DEE-SWAS and EE-SWAS, which rests entirely on
      whether development was already impaired before the spike-wave activation
      began, a real boundary or a description of the starting point?
    attaches_to:
      - pathophysiology#Developmental Regression and Cognitive-Behavioural Encephalopathy
      - pathophysiology#Heterogeneous Genetic Etiology
    rationale: >-
      The two labels differ only in baseline development, which is a statement
      about the child before the process started rather than about the process. The
      mechanism modeled in this entry is the same for both, which is why they are
      curated together. Evidence for the split being real is that the arms behave
      differently in ways a mere baseline difference does not obviously predict: an
      etiology is found in about two thirds of DEE-SWAS but only about a quarter of
      EE-SWAS, and DEE-SWAS carries a longer duration of epilepsy and a poorer
      intellectual outcome. Evidence against is that the regression itself looks
      the same in both, which is what one expects if a common process is acting on
      two different starting points. There is also a measurement problem underneath
      the boundary: mild pre-existing delay is hard to establish retrospectively
      once a child has regressed, and families reconstruct the before-picture
      through the after-picture, so some children are probably assigned to the
      wrong arm. The practical consequence of getting this right is diagnostic
      effort, because the etiological yield difference between the arms is large
      enough that the label changes how hard it is worth looking for a cause.
    proposed_experiments:
      - experiment_id: exp_dee_swas_prospective_baseline_phenotyping
        name: Prospectively measured baseline development before regression
        description: >-
          Use cohorts in which developmental assessment was performed before the
          onset of spike-wave activation, such as children under surveillance for
          another reason or those with an early structural lesion followed from
          infancy, to assign the arms on prospectively measured rather than
          retrospectively recalled baselines, then compare etiological yield and
          outcome.
        decision_criterion: >-
          If the etiological yield and outcome differences survive prospective
          baseline assignment, the split is a real boundary. If they shrink toward
          each other, much of the apparent difference was misclassification driven
          by retrospective assessment.
    evidence:
      - reference: PMID:39096015
        reference_title: >-
          Solving the Etiology of Developmental and Epileptic Encephalopathy with
          Spike-Wave Activation in Sleep (D/EE-SWAS).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          We identified the etiology in 42/91 (46%) patients in our Core cohort,
          including 29/44 (66%) with DEE-SWAS and 13/47 (28%) with EE-SWAS.
        explanation: >-
          Quantifies the large etiological yield difference between the arms, the
          strongest argument that the split tracks something real.
      - reference: PMID:39096015
        reference_title: >-
          Solving the Etiology of Developmental and Epileptic Encephalopathy with
          Spike-Wave Activation in Sleep (D/EE-SWAS).
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Although developmental regression patterns were similar in both
          syndromes, DEE-SWAS was associated with a longer duration of epilepsy and
          poorer intellectual outcome than EE-SWAS.
        explanation: >-
          Cuts both ways, which is why it is PARTIAL: the shared regression pattern
          argues for one process, the outcome difference argues for two entities.
      - reference: PMID:35503717
        reference_title: >-
          International League Against Epilepsy classification and definition of
          epilepsy syndromes with onset in childhood: Position paper by the ILAE
          Task Force on Nosology and Definitions.
        supports: SUPPORT
        evidence_source: OTHER
        snippet: >-
          Based on the 2017 Classification of Seizures and Epilepsies, some syndrome
          names have been updated using terms directly describing the seizure
          semiology.
        explanation: >-
          Records that the current names are a recent nosological revision rather
          than a long-settled biological distinction, which is the context in which
          this question is live.
  - discussion_id: dee_swas_why_do_steroids_work
    kind: KNOWLEDGE_GAP
    status: OPEN
    prompt: >-
      Corticosteroids outperform a benzodiazepine on cognitive outcome in this
      syndrome, but no immune or inflammatory mechanism has been established for
      it. What are steroids actually doing, and would knowing let us keep the
      benefit without the toxicity?
    attaches_to:
      - pathophysiology#Sleep-Potentiated Spike-Wave Activation
      - pathophysiology#Disruption of Sleep-Dependent Synaptic Plasticity
    rationale: >-
      This is an uncomfortable gap because the treatment recommendation is
      relatively firm while the reason for it is not. Corticosteroids are used
      across several developmental and epileptic encephalopathies with a similar
      pattern of empirical success and mechanistic silence, and in this syndrome
      the randomized comparison showed them beating clobazam on intelligence
      quotient gain. Several accounts are available and none is established. The
      neuroinflammatory account holds that there is an immune contribution to the
      cortical hyperexcitability that steroids suppress, but no confirmed
      inflammatory mechanism has been demonstrated in this syndrome, and the
      corollary prediction, that other immunotherapies should work comparably, has
      not been tested head to head. A second account is genomic and has nothing to
      do with immunity: glucocorticoid receptors are abundant in cortex and
      hippocampus and steroids alter expression of genes governing excitability
      and synaptic scaling, which would act directly on the plasticity mechanism
      this entry models. A third possibility is that the effect is on sleep
      architecture itself, since steroids measurably alter slow-wave sleep, which
      would withdraw the very drive that potentiates the discharge. These make
      different predictions and are separable. The practical stake is real:
      steroid toxicity is the main reason treatment is delayed or truncated, and
      weight gain was the commonest adverse event in the trial. A mechanism would
      tell us which better-tolerated drug to reach for instead.
    proposed_experiments:
      - experiment_id: exp_dee_swas_steroid_mechanism_biomarker_panel
        name: Inflammatory and sleep-architecture markers across steroid response
        description: >-
          In children starting corticosteroids, measure cerebrospinal fluid and
          serum inflammatory markers, quantified slow-wave sleep parameters, and
          spike-wave burden before and during treatment, and relate each to
          cognitive response. Responders and non-responders provide the contrast.
        decision_criterion: >-
          If response tracks a fall in inflammatory markers, the immune account is
          supported and other immunotherapies become rational comparators. If
          response tracks a change in slow-wave sleep parameters with inflammatory
          markers unchanged, the mechanism is architectural and sleep-directed
          treatments become the better-tolerated alternative to chase.
    evidence:
      - reference: PMID:38081201
        reference_title: >-
          Corticosteroids versus clobazam for treatment of children with epileptic
          encephalopathy with spike-wave activation in sleep (RESCUE ESES): a
          multicentre randomised controlled trial.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Our findings strengthen those from previous uncontrolled studies that
          support the early use of corticosteroids for children with EE-SWAS.
        explanation: >-
          Establishes that the effect this gap is about is real enough to drive a
          treatment recommendation, which is what makes the missing mechanism worth
          curating rather than merely noting.
      - reference: PMID:38081201
        reference_title: >-
          Corticosteroids versus clobazam for treatment of children with epileptic
          encephalopathy with spike-wave activation in sleep (RESCUE ESES): a
          multicentre randomised controlled trial.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Adverse events occurred in ten (45%) of 22 children who received
          corticosteroids, most frequently weight gain, and in 11 (52%) of 21
          children who received clobazam, most often fatigue and behavioural
          disturbances.
        explanation: >-
          Quantifies the toxicity that makes finding the mechanism practically
          worthwhile rather than academic.
  - discussion_id: dee_swas_developmental_gating
    kind: KNOWLEDGE_GAP
    status: OPEN
    prompt: >-
      Why does this syndrome switch on in mid-childhood and switch itself off at
      adolescence, in a child whose causal lesion, whether a thalamic injury or a
      germline variant, was present all along and does not go away?
    attaches_to:
      - pathophysiology#Sleep-Potentiated Spike-Wave Activation
      - pathophysiology#Age-Dependent Remission of the Electrographic Pattern
    rationale: >-
      Both ends of the course are developmentally regulated, and neither is
      explained. A perinatal thalamic lesion is present from birth, yet the sleep
      activation does not appear for years and then disappears on its own,
      regardless of treatment, while the lesion remains. Whatever gates it is a
      property of the developing cortex rather than of the cause. Candidate
      explanations exist but have not been discriminated: the closure of a
      critical period, so that the augmenting-response plasticity the syndrome
      exploits is simply no longer available; maturational change in the sleep
      architecture itself, since slow-wave sleep declines steeply across
      adolescence and would withdraw the drive; developmental change in inhibitory
      circuit maturation; or myelination altering the conduction properties of the
      surviving thalamocortical projections. Distinguishing them matters for
      practice in a specific way: if remission comes from withdrawal of the
      slow-wave drive, then interventions targeting sleep architecture become
      rational, and the treatment window is defined by the child's developmental
      stage rather than by the duration of therapy.
    proposed_experiments:
      - experiment_id: exp_dee_swas_sleep_architecture_trajectory
        name: Longitudinal sleep architecture through onset and remission
        description: >-
          Serial whole-night polysomnography with quantified slow-wave activity and
          spindle density in the same children from before onset through to
          spontaneous remission, testing whether the appearance and disappearance
          of the activation track measurable changes in the sleep parameters that
          are proposed to drive it.
        decision_criterion: >-
          If onset and remission coincide with the rise and fall of the specific
          sleep parameters that supply the drive, sleep maturation explains the
          gating and becomes a therapeutic target. If the activation appears and
          disappears with sleep architecture unchanged, the gate is in cortical
          plasticity rather than in the drive.
    evidence:
      - reference: PMID:25160535
        reference_title: >-
          Neurobiology of continuous spike-wave in slow-wave sleep and
          Landau-Kleffner syndromes.
        supports: SUPPORT
        evidence_source: OTHER
        snippet: >-
          These disorders, of which continuous spike-wave in slow-wave sleep and
          Landau-Kleffner are the most common, are characterized by continuous
          spike-wave activity during slow-wave sleep, developmentally regulated
          onset and termination of abnormal electrical activity, and loss of
          previously acquired skills.
        explanation: >-
          Names the developmentally regulated onset and termination as a defining
          feature of the syndrome class, which is what makes its lack of explanation
          a genuine gap rather than an incidental observation.
      - reference: PMID:29133062
        reference_title: >-
          Anatomical and physiological basis of continuous spike-wave of sleep
          syndrome after early thalamic lesions.
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: >-
          Early neonatal thalamic lesions account for about 14% of continuous
          spike-wave of sleep (CSWS) syndrome, representing the most common
          etiology in this epileptic encephalopathy in children
        explanation: >-
          Establishes that the commonest identifiable cause is present from birth,
          which is what makes the years-long delay before onset require an
          explanation.
📚

References & Deep Research

References

3
PMID:35503717
International League Against Epilepsy classification and definition of epilepsy syndromes with onset in childhood: Position paper by the ILAE Task Force on Nosology and Definitions.
No top-level findings curated for this source.
PMID:39096015
Solving the Etiology of Developmental and Epileptic Encephalopathy with Spike-Wave Activation in Sleep (D/EE-SWAS).
No top-level findings curated for this source.
PMID:38081201
Corticosteroids versus clobazam for treatment of children with epileptic encephalopathy with spike-wave activation in sleep (RESCUE ESES): a multicentre randomised controlled trial.
No top-level findings curated for this source.

Deep Research

1
Claude Code ▸
1. Disease Information
claude-haiku-4-5-20251001, claude-opus-5[1m] 27 citations 2026-08-05T13:56:11.237445

1. Disease Information

What it is

DEE-SWAS is one of those syndromes that's really a state the brain slides into rather than a single disease. A kid — usually somewhere between 2 and 12, peaking around 4–5 — starts having seizures, and then, a year or two later, starts losing ground: language, attention, behavior, sometimes motor skills. The tell is on the overnight EEG: during non-REM sleep, spike-and-wave discharges bloom until they occupy most of the tracing. Wakefulness looks comparatively tame. Sleep is where the damage happens.

The ILAE's 2022 nosology (Specchio et al., PMID:35503717) folded a whole graveyard of older names into this single umbrella. The formal definition: "a spectrum of conditions with varied degree of cognitive, language, behavioral, and motor regression associated with marked spike-wave activation in sleep" [reported — epilepsydiagnosis.org syndrome page].

The split between the two halves is purely developmental history: - EE-SWAS — development was normal before the regression. The epileptic activity is doing all the harm. - DEE-SWAS — there was pre-existing developmental impairment, and then regression on top. Two encephalopathies stacked.

Think of it like a fever in a healthy adult versus a fever in someone already immunosuppressed — same insult, very different baseline, very different ending.

Landau-Kleffner syndrome (LKS) was retained as a clinically distinct EE-SWAS subtype: the variant where the regression is essentially all language — acquired auditory verbal agnosia in a previously normal child, ages ~3–9.

Identifiers

Resource ID Notes
MONDO MONDO:0800501 developmental and/or epileptic encephalopathy with spike-wave activation in sleep — verified via local sqlite:obo:mondo. Parents: MONDO:0002254 (syndromic disease), MONDO:0800500 (childhood-onset epilepsy syndrome with DEE)
Orphanet ORPHA:725 "Developmental and epileptic encephalopathy with spike-wave activation in sleep"
GARD GARD:0027304 from MONDO xref
MedGen MEDGEN:1790601 from MONDO xref
UMLS UMLS:C5552731 from MONDO xref
ICD-11 8A62.Y "Other specified epileptic encephalopathies" (per Orphanet mapping) — no dedicated ICD-11 stem code exists
ICD-10 G40.8 (likely) ⚠️ not independently verified; check Orphanet before curating
MeSH D018887 Landau-Kleffner Syndrome (MeSH UID 68018887, verified via E-utilities). No dedicated MeSH descriptor exists for CSWS/DEE-SWAS itself
OMIM #245570 EPILEPSY, FOCAL, WITH SPEECH DISORDER AND WITH OR WITHOUT IMPAIRED INTELLECTUAL DEVELOPMENT (FESD) — the GRIN2A phenotype entry, which explicitly encompasses LKS, ECSWS/CSWSS, ADRESD and BECTS. There is no OMIM entry for the syndrome as an etiologically agnostic entity
OMIM (gene) GRIN2A = 138253

Synonyms (all from the MONDO synonym block, verified)

CSWS · CSWSS syndrome · DEE-SWAS · EE-SWAS · EESWAS · ESES · electrical status epilepticus of sleep · electrographic status epilepticus in sleep · continuous spike-wave in sleep · continuous spikes and waves during sleep · continuous spikes and waves during slow-wave sleep · continuous slow spike and wave of sleep · epileptic encephalopathy with continuous spike-and-wave during slow sleep (EE-CSWS) · epileptic encephalopathy with spike-and-wave activation in sleep · ESES with language regression · epileptic aphasia · Landau-Kleffner syndrome / LKS / LK syndrome. Also retired but still in the literature: atypical benign partial epilepsy (ABPE), pseudo-Lennox syndrome, Penelope syndrome.

Data provenance

Everything below is disease-level aggregated — case series, tertiary-center cohorts, systematic reviews, one small RCT. There is no EHR-derived phenotype library for this syndrome, and the OMOP/ICD coding is so coarse (8A62.Y "other specified") that EHR case-finding would be near-useless without EEG-report NLP. Worth flagging as a KNOWLEDGE_GAP if you're curating definitions.

2. Etiology

The big picture: heterogeneous as hell, and half of it stays unsolved

The best-powered modern etiology study is Viswanathan et al., Ann Neurol 2024 (PMID:39096015) — 91-patient Core cohort, all meeting ILAE D/EE-SWAS criteria.

"We identified the etiology in 42/91 (46%) patients in our Core cohort, including 29/44 (66%) with DEE-SWAS and 13/47 (28%) with EE-SWAS. A genetic etiology was identified in 31/91 (34%)." [verbatim-verified from references_cache/PMID_39096015.md]

"D/EE-SWAS genes were highly co-expressed in brain, highlighting the importance of channelopathies and transcriptional regulators. Structural etiologies were found in 12/91 (13%) individuals." [verbatim-verified]

That 66% vs 28% gap is the single most curation-relevant number in the whole literature: DEE-SWAS (pre-existing impairment) is more than twice as likely to have a findable cause as EE-SWAS. Makes intuitive sense — an already-abnormal brain usually got that way for a reason you can find.

Breakdown from the same cohort: - Genetic: 31/91 (34%) — 23 single-gene variants, 6 CNVs, 1 chromosomal abnormality [reported] - Structural: 12/91 (13%) — polymicrogyria ×5, thalamic lesions ×5, post-hemorrhagic hydrocephalus ×2 [reported] - Unsolved: 49/91 (54%)

Older tertiary-center series put the structural fraction much higher (~45–59%, with perinatal vascular lesions 21–78% and cortical malformations ~25%) [reported, PMC3929187] — the discrepancy is almost certainly ascertainment: an epilepsy-genetics research program enriches for undiagnosed kids, a general pediatric neurology clinic enriches for kids with obvious perinatal brain injury.

Causal factor classes

(a) Structural — early thalamic injury is the standout.

This one is mechanistically load-bearing, not just a bucket. From Sánchez Fernández / Leal et al., Epilepsy Behav 2018 (PMID:29133062):

"Early neonatal thalamic lesions account for about 14% of continuous spike-wave of sleep (CSWS) syndrome, representing the most common etiology in this epileptic encephalopathy in children, and promise useful insights into the pathophysiology of the disease." [verbatim-verified from cache]

Other structural causes: polymicrogyria (especially unilateral perisylvian), periventricular leukomalacia and other perinatal vascular insults, post-hemorrhagic hydrocephalus, porencephaly, hemimegalencephaly, cortical dysplasia, and — importantly — shunted hydrocephalus.

(b) Genetic. See §4 for the gene-by-gene detail. Headline: GRIN2A is the single most frequent gene; the two functional classes that dominate are ion channels/receptors and transcriptional regulators.

(c) Iatrogenic / drug-provoked — an under-appreciated and modifiable cause.

Sodium-channel-blocking and GABAergic ASMs can precipitate SWAS in a child with self-limited focal epilepsy who would otherwise have coasted to remission. Carbamazepine, oxcarbazepine, phenytoin and phenobarbital are all implicated (e.g. PMID:26415787, oxcarbazepine-induced ESES in idiopathic childhood focal epilepsy). Practically: "Carbamazepine is relatively contraindicated in ESES and should be discontinued" [reported, StatPearls NBK553167]. This deserves its own pathophysiology node — it's one of the few genuinely preventable routes into the syndrome.

(d) Unknown / presumed developmental. Over half. Age-dependency (onset window 2–12, remission around puberty) strongly implies the causal factor isn't the lesion or variant alone but its interaction with a developmental window — the same lesion in an adult brain doesn't do this.

Risk factors

Genetic risk: - Pathogenic/likely pathogenic variants in the genes in §4 (causal, not merely susceptibility, in solved cases) - Being a male carrier of an X-linked CNKSR2 variant (hemizygous males affected; most carrier mothers neurologically unremarkable [reported]) - Underlying self-limited epilepsy with centrotemporal spikes (SeLECTS) — sits on the same epilepsy-aphasia spectrum as DEE-SWAS; GRIN2A detection rate climbs from ~4.9% in BECTS/SeLECTS to ~17.6% in CSWS [reported, Lemke et al. Nat Genet 2013] - Incomplete penetrance and intrafamilial variability documented even for the same GRIN2A variant [reported, OMIM #245570]

Environmental / acquired risk: - Neonatal thalamic hemorrhage or infarction (often associated with neonatal sinovenous thrombosis) - Perinatal hypoxic-ischemic injury, prematurity, periventricular leukomalacia - Intraventricular hemorrhage → post-hemorrhagic hydrocephalus → shunt - Exposure to carbamazepine/oxcarbazepine/phenytoin/phenobarbital in a child with focal childhood epilepsy - Age 2–12 is itself the dominant risk factor — this is a developmental-window disease - Sex: mild male excess (~60:40) [reported, PMC3929187]; the Ann Neurol cohort was 53% male [reported]. Not a strong signal except in X-linked CNKSR2 families.

Protective factors: Honestly, nothing established. No protective allele, no dietary or lifestyle factor with evidence. The nearest thing to a protective factor is early recognition and early spike-suppressing treatment (see §12) plus avoiding the aggravating ASMs. Worth curating explicitly as absent rather than leaving the section blank.

Gene–environment interaction: The clearest one is pharmacogenetic-ish rather than classical GxE: a child with a GRIN2A variant and a SeLECTS phenotype who gets started on carbamazepine may be tipped into full SWAS. Also: a genetic background (e.g. channelopathy) plus a structural thalamic hit appears additive in some series. No formal GxE study exists — flag as a gap.

3. Phenotypes

The two-act structure

Act I (age ~2–7): seizures appear, often nocturnal, often unimpressive. Up to 80% of children present with seizures as the first symptom [reported], and about 80% have only one seizure type at onset [reported]. Roughly 20% present the other way round — cognitive/behavioral change first, seizures later or never prominent [reported].

Act II (~1–2 years later): SWAS establishes on the sleep EEG, seizure frequency often jumps (up to 70% have multiple daily seizures once ESES appears [reported]), and the regression begins. This is the encephalopathy proper.

Phenotype table with HPO suggestions

All HP IDs below verified against sqlite:obo:hp via OAK.

Phenotype HPO term Category Onset Course Frequency
Developmental regression (the defining feature) HP:0002376 Developmental regression Neurologic / behavioral ~1–2 yr after seizure onset; median 5–6 yr Subacute then plateau; partial recovery after SWAS remits Obligate (100% by definition)
Seizure HP:0001250 Seizure Neurologic 2–12 yr, peak 4–5 Episodic; remits at puberty ~80–90% (a minority are seizure-free)
Focal-onset seizure HP:0007359 Neurologic as above episodic Very frequent
Focal motor seizure (often unilateral clonic, nocturnal) HP:0011153 Neurologic as above episodic Frequent
Bilateral tonic-clonic seizure HP:0002069 Neurologic as above episodic Frequent
Generalized non-motor (absence) seizure — "atypical absence" HP:0002121 Neurologic after SWAS onset episodic, often many/day Frequent
Atonic seizure / epileptic negative myoclonus (drop attacks, head nods) HP:0010819 Neurologic after SWAS onset episodic Occasional–frequent
Myoclonic seizure HP:0032794 Neurologic variable episodic Occasional
Epileptic encephalopathy HP:0200134 Neurologic — — Obligate
EEG abnormality HP:0002353 Lab / electrophysiology at SWAS onset — Obligate
Interictal epileptiform activity HP:0011182 Lab — markedly sleep-activated Obligate
Multifocal epileptiform discharges HP:0010841 Lab — — Frequent
Intellectual disability HP:0001249 Cognitive after regression often persists DEE-SWAS 49% moderate-severe; EE-SWAS 8% [reported]
Global developmental delay HP:0001263 Cognitive pre-dates regression in DEE-SWAS — Defining for DEE-SWAS arm
Delayed speech and language development HP:0000750 Language — — Very frequent
Aphasia (acquired — the LKS core) HP:0002381 Language 3–9 yr in LKS subacute or fluctuating Obligate in LKS subtype
Receptive language delay / auditory verbal agnosia HP:0010863 Language 3–9 yr — Obligate in LKS
Poor speech / mutism HP:0002465 Language — may progress to complete mutism Frequent in LKS
ADHD HP:0007018 Behavioral with/before regression often persists Very frequent
Hyperactivity HP:0000752 Behavioral — — Very frequent
Autistic behavior HP:0000729 Behavioral may be the regression phenotype — Occasional
Autism HP:0000717 Behavioral — — Occasional
Specific learning disability HP:0001328 Cognitive — persists Frequent
Ataxia HP:0001251 Motor with SWAS improves with remission Occasional
Dysarthria HP:0001260 Motor speech — — Occasional
Hemiparesis HP:0001269 Motor pre-existing in structural cases static Occasional (structural etiologies)
Status epilepticus HP:0002133 Neurologic — — Occasional
Polymicrogyria HP:0002126 Structural (imaging) congenital static ~5/91 in solved structural cases
Hydrocephalus HP:0000238 Structural perinatal static ~2/91

⚠️ Frequency-band caution (per docs/frequency-evidence-guidelines.md): most of the percentages above are single-cohort tertiary-center figures, not pooled. I would only assign a frequency: enum to Developmental regression (definitional, obligate) and the EEG features. For the rest, omit the band rather than manufacture support.

The regression is not one thing

Worth splitting into nodes if you're curating carefully. Per the ILAE description, "All cognitive domains are affected including language and communication, temporo-spatial orientation, attention and social interaction" [reported]. The domain hit tracks the anatomy of the spike focus: - Perisylvian/temporal focus → LKS phenotype (auditory verbal agnosia, aphasia) - Frontal focus → CSWS phenotype (dysexecutive/frontal syndrome, behavioral disinhibition, global cognitive drop)

From Issa NP, Pediatr Neurol 2014 (PMID:25160535):

"Several pediatric seizure disorders have common electrophysiological features during slow-wave sleep that produce different syndromes based on which part of the developing brain is involved." [verbatim-verified from cache]

That sentence is a good anchor for a "topography determines phenotype" pathophysiology node.

Quality of life

No EQ-5D/PROMIS/SF-36 data specific to D/EE-SWAS that I could find — a genuine gap. Qualitatively: the burden is dominated by (1) permanent language/cognitive deficit rather than seizures, since seizures usually remit; (2) behavioral dysregulation and ADHD, which drive school placement and family stress; (3) in LKS, the profound communication loss — a child who could speak in sentences and now cannot understand speech at all. Caregiver burden is high across the active phase (typically 2–5+ years). Flag as KNOWLEDGE_GAP: no validated disease-specific QoL instrument.

4. Genetic / Molecular Information

Causal genes

The flagship: GRIN2A (HGNC:4585; OMIM 138253; 16p13.2; GluN2A subunit of the NMDA receptor).

  • Lemke et al., Nat Genet 2013: "Heterozygous mutations in GRIN2A were detected in 27 of 359 affected individuals from independent cohorts with IFE (7.5%), with mutation detection rates ranging from 4.9% in individuals with BECTS to 17.6% in individuals with CSWS." [reported]
  • In the Ann Neurol 2024 cohort, GRIN2A was the most common single gene (~23% of genetic cases) [reported]
  • GRIN2A accounts for ~9–20% of epilepsy-aphasia syndromes overall [reported]

Functional consequence predicts phenotype — this is the therapeutically actionable bit. Strehlow et al., Brain 2019 (PMID:30544257):

"Null variants and mis_ATD+LBD_ of GRIN2A share the same clinical spectrum (milder phenotypes), but also result in similar electrophysiological consequences (loss-of-function) opposing those of mis_TMD+Linker_ (severe phenotypes; predominantly gain-of-function)." [reported]

"Individuals with developmental and epileptic encephalopathy due to misTMD+Linker are prone to having an underlying gain of NMDAR function and represent promising candidates for treatment with NMDAR blockers, such as memantine." [reported]

So: null / ATD+LBD missense → loss of function → milder, epilepsy-aphasia-spectrum end; TMD+Linker missense → gain of function → severe DEE end. Domain-level annotation, not just "pathogenic," is what determines whether memantine (block) or a positive allosteric modulator is the rational move.

The other established genes. From the Ann Neurol 2024 cohort (previously known): CNKSR2, SCN2A, ARID1B, CUL4B, GRIN2B, KCNH5, MECP2, SCN1A [reported].

Ten novel D/EE-SWAS genes from the same study, verbatim from the abstract:

"We identified 10 novel D/EE-SWAS genes with a range of functions: ATP1A2, CACNA1A, FOXP1, GRIN1, KCNMA1, KCNQ3, PPFIA3, PUF60, SETD1B, and ZBTB18, and 2 novel copy number variants, 17p11.2 duplication and 5q22 deletion." [verbatim-verified from cache]

From the systematic review of genetic ESES etiologies (PMID:29976148) — 16 studies, 151 cases, 11 monogenic genes: GRIN2A (34 cases), SCN2A (6), KCNA2 (5), KCNB1 (5), KCNQ2 (2), CNKSR2 (2), SLC6A1 (2), SLC9A6/NHE6 (1), ATN1/DRPLA (1), SRPX2/neuroserpin (1), OPA3 (1) [reported]. Key conclusion: "The most common underlying pathway was channelopathy" (56 cases) [reported].

From the Seizure 2023 systematic review (PMID:37352690), 172 cases: variants in GRIN2A, ZEB2, CNKSR2, and 17q21.31 deletions; conclusion that "presentations occurring before age five warrant genetic investigation" [reported].

From the Turkish cohort (PMID:38388889), 24 patients, 7 solved (29%): novel variants in SLC12A5, DLG4, SLC9A6; also SCN8A and Smith-Magenis syndrome [reported].

CNKSR2 (Xp22.12; connector enhancer of KSR-2) deserves its own node — it's the X-linked epilepsy-aphasia gene:

"The disease is characterized by intellectual disability, attention deficit-hyperactivity and abrupt lifelong language loss following a brief early-childhood epilepsy with continuous spike-waves in sleep." [reported]

~50% de novo; carrier mothers usually unaffected [reported]. Predominance of loss-of-function variants (PMC8281706).

Consolidated gene table

Gene HGNC Locus Class Mechanism Inheritance
GRIN2A hgnc:4585 16p13.2 NMDAR subunit LoF or GoF, domain-dependent AD, incomplete penetrance
CNKSR2 hgnc:2570 Xp22.12 Postsynaptic scaffold LoF X-linked
GRIN2B hgnc:4586 12p13.1 NMDAR subunit LoF/GoF AD de novo
GRIN1 hgnc:4584 9q34.3 NMDAR subunit LoF/GoF AD de novo
SCN1A hgnc:10585 2q24.3 Nav1.1 LoF AD de novo
SCN2A hgnc:10588 2q24.3 Nav1.2 GoF (early) / LoF (late) AD de novo
SCN8A hgnc:10596 12q13.13 Nav1.6 GoF AD de novo
KCNQ2 hgnc:6296 20q13.33 Kv7.2 LoF / dominant-negative AD
KCNQ3 hgnc:6297 8q24.22 Kv7.3 LoF AD
KCNA2 hgnc:6220 1p13.3 Kv1.2 LoF/GoF AD de novo
KCNB1 hgnc:6231 20q13.13 Kv2.1 LoF/dominant-negative AD de novo
KCNH5 hgnc:6254 14q23.1 Kv10.2 GoF AD de novo
KCNMA1 hgnc:6284 10q22.3 BK channel LoF/GoF AD
CACNA1A hgnc:1388 19p13.13 Cav2.1 LoF/GoF AD
ATP1A2 hgnc:800 1q23.2 Na/K-ATPase α2 LoF AD
SLC6A1 hgnc:11042 3p25.3 GAT-1 GABA transporter LoF AD de novo
SLC12A5 hgnc:13818 20q13.12 KCC2 chloride extruder LoF AR/AD
SLC9A6 hgnc:11079 Xq26.3 NHE6 (Christianson) LoF X-linked
DLG4 hgnc:2903 17p13.1 PSD-95 LoF AD de novo
MECP2 hgnc:6990 Xq28 Transcriptional regulator LoF X-linked
FOXP1 hgnc:3823 3p13 TF LoF/haploinsufficiency AD de novo
ZBTB18 hgnc:13030 1q44 TF LoF AD de novo
SETD1B hgnc:29187 12q24.31 H3K4 methyltransferase LoF AD de novo
ARID1B hgnc:18040 6q25.3 BAF chromatin remodeler Haploinsufficiency AD de novo
PUF60 hgnc:17042 8q24.3 Splicing factor LoF AD de novo
CUL4B hgnc:2555 Xq24 E3 ligase LoF X-linked
ZEB2 hgnc:14881 2q22.3 TF (Mowat-Wilson) LoF AD de novo
PPFIA3 hgnc:9247 19q13.33 Liprin-α3, active zone LoF AD
SRPX2 hgnc:30668 Xq22.1 Secreted, synaptogenesis — X-linked (contested)
ATN1 hgnc:3033 12p13.31 DRPLA repeat expansion Toxic GoF AD, anticipation
OPA3 hgnc:8142 19q13.32 Mitochondrial (Costeff) LoF AR

⚠️ HGNC IDs above are from memory and are NOT OAK-verified. Run just validate-terms before committing any of them — the repo uses lowercase hgnc:.

Copy number variants and chromosomal abnormalities

Recurrent CNVs from the systematic review (89 CNVs total, 9 recurrent) [reported]: - 15q11.2–13.1 duplication — 15 cases (also relevant to your existing 15q11q13 microduplication entry — likely a comorbidity/grouping link) - 3q29 duplication — 11 cases - Xp22.12 deletion (removing CNKSR2) — 6 cases - 16p13 deletion (removing GRIN2A) — 4 cases - 17q21.31 deletion (Koolen-de Vries) [reported, Seizure 2023] - 17p11.2 duplication (Potocki-Lupski) — novel, Ann Neurol 2024 - 5q22 deletion — novel, Ann Neurol 2024 - 17p11.2 deletion (Smith-Magenis) [reported, Turkish cohort]

Allele frequency / somatic vs germline

All reported variants are germline (constitutional). Somatic mosaicism has not been established as a mechanism in D/EE-SWAS — though it's plausible in cases with focal cortical dysplasia. Pathogenic variants are absent or vanishingly rare in gnomAD; GRIN2A is strongly constrained (missense- and LoF-intolerant). ⚠️ Specific gnomAD constraint scores not retrieved — look them up if you want to cite pLI/o/e values.

Modifier genes

None validated. The obvious candidate class — genes affecting sleep spindle generation and thalamocortical rhythm — is theorized but not demonstrated. The intrafamilial variability of the same GRIN2A variant strongly implies modifiers exist. Gap.

Epigenetics

Indirect but suggestive: SETD1B (H3K4 methyltransferase), ARID1B (BAF chromatin remodeling), and MECP2 (methyl-CpG binding) all appear as causal genes, i.e. chromatin/transcriptional regulation is one of the two major functional clusters. Per the Ann Neurol brain co-expression analysis, the D/EE-SWAS genes partition into Cluster 1 (ion channels: GRIN2A, GRIN2B, KCNH5, KCNQ3, CACNA1A, SCN1A, SCN2A) and Cluster 2 (transcriptional regulators: FOXP1, PUF60, MECP2, ARID1B, ZBTB18), both co-expressed above chance [reported]. No DNA-methylation episignature has been published for D/EE-SWAS as a syndrome (though episignatures exist for some individual causal genes, e.g. ARID1B/Coffin-Siris). Gap.

5. Environmental Information

Thin section, and that's the honest answer.

  • Toxins / pollution / occupational / radiation: no established role. Nothing in CTD.
  • Lifestyle: no established role. Sleep deprivation may worsen seizures generically but is not a syndrome-specific factor.
  • Infectious agents: no causal pathogen. Post-encephalitic and post-meningitic acquired brain injury can be a structural substrate in individual cases, but this is generic acquired-lesion territory, not a specific infectious etiology. Notably, LKS was historically suspected to be inflammatory/autoimmune (hence steroid responsiveness), but no pathogen or autoantibody has been confirmed.
  • The one real "environmental" exposure is pharmacological — the carbamazepine/oxcarbazepine/phenytoin/phenobarbital aggravation described in §2. I'd model this as an environmental/iatrogenic trigger node rather than leaving §5 empty.
  • Perinatal events (hypoxia-ischemia, IVH, sinovenous thrombosis) are the most important non-genetic contributors, acting via structural injury — especially thalamic.

6. Mechanism / Pathophysiology

This is the interesting part. There are three distinct, partly complementary mechanistic models, and I'd curate them as competing/complementary mechanistic_hypotheses rather than blending them.

Model A — Thalamocortical disconnection and the "augmenting response" (CANONICAL for structural cases)

The thalamus is the metronome for non-REM sleep rhythms. Lesion it early and unilaterally, and the cortex on that side loses its normal pacing input — and, critically, gains an abnormal form of frequency-dependent synaptic potentiation.

From PMID:29133062 (nine patients with unilateral neonatal thalamic lesions):

"Thalamic volume loss ranged from 19% to 94%, predominantly on medial and dorsal nuclei and sparing the ventral thalamus. Lesions produced white matter loss and ventricle enlargement on the same hemisphere, which in four patients was associated with selective loss of thalamic-cortical fibers." [verbatim-verified from cache]

"Impact on EEG rhythms was mild, with a volume-loss-related decrease in alpha power and preservation of sleep spindles. The sleep continuous spiking was lateralized to the hemisphere with the lesion." [verbatim-verified]

"Unilateral selective thalamic-cortical disconnection is a common feature in our patients and is associated with both a focal pattern of CSWS and a pathological type of frequency-dependent excitability (peak: 10-20Hz). We propose that this excitability represents an abnormal synaptic plasticity previously described as the augmenting response. This synaptic plasticity has been described as absent in the corticocortical interactions in healthy experimental animals, emerging after ablation of the thalamus and producing a frequency-dependent potentiation with a peak at 10-20Hz. Because this response is potentiated by sleep states of reduced brainstem activation and by appropriate stimulating rhythms, such as sleep spindles, the simultaneous occurrence of these two factors in nonrapid-eye-movement sleep is proposed as an explanation for CSWS in our patients." [verbatim-verified — this is the money quote for the whole mechanism section]

The causal chain, node by node:

Early thalamic lesion (medial/dorsal nuclei)
  → selective loss of thalamocortical fibers (unilateral disconnection)
    → emergence of pathological corticocortical "augmenting response"
       (frequency-dependent potentiation peaking 10–20 Hz — absent in healthy cortex)
      → sleep spindles (10–16 Hz) + reduced brainstem arousal tone in NREM
 act as the ideal driving stimulus
→ runaway spike-wave activation confined to NREM sleep
  → [feeds Model B]

That's elegant: the spindle, a normal sleep rhythm, becomes the trigger pulse for a pathological potentiation the healthy brain doesn't have. Like a heart with a re-entrant circuit — the sinus beat isn't the problem, the abnormal pathway is; the normal rhythm just keeps lighting the fuse.

  • UBERON:0001903 thalamic reticular nucleus (verified)
  • UBERON:0001897 dorsal plus ventral thalamus (verified)
  • UBERON:0000956 cerebral cortex, UBERON:0001950 neocortex (verified)
  • GO:0021794 thalamus development (verified)
  • CL:0000617 GABAergic neuron (TRN neurons), CL:0000598 pyramidal neuron, CL:0000679 glutamatergic neuron (all verified)

Model B — Disruption of sleep-dependent synaptic homeostasis (CANONICAL for the encephalopathy)

Model A explains why the spikes happen in sleep. Model B explains why the spikes make the child worse.

Normal picture: you potentiate synapses all day (learning), and slow-wave sleep runs a global downscaling program that renormalizes synaptic weight, preserving signal-to-noise and consolidating what matters. It's a nightly pruning shift — like the lymphatic system clearing the interstitium overnight, except for synaptic weight instead of fluid.

In SWAS, that shift doesn't happen. Per the literature summarized around Bölsterli et al. (impaired slow-wave downscaling in ESES):

"The profound spike activation in sleep found in CSWS disrupts synaptic homeostasis—the balanced synaptic potentiation during daytime and synaptic downscaling in sleep—leading to an inefficient cerebral network." [reported]

"Alterations in synaptic strength are shown through changes in sleep slow-wave activity (SWA), but notably during CSWS there are no sleep SWA changes, which occur again after CSWS remission" [reported]

That last observation is the strongest causal evidence available in humans: the overnight slope of slow-wave activity — the electrophysiological fingerprint of downscaling — flattens during the active phase and returns when SWAS remits. State-dependent, reversible, and time-locked to the clinical course.

And from PMID:25160535 (Issa 2014):

"Over the last 20 years, a variety of basic science findings suggest how spike-wave activity during sleep can cause the observed clinical outcomes." [verbatim-verified]

"The role of slow-wave sleep in normal cortical plasticity during developmental critical periods, how disruption of slow-wave sleep by electrographic seizures could affect cortical maps and development, and the organization and functional connectivity of the thalamic structures that when damaged are thought to produce these seizure disorders are reviewed." [verbatim-verified]

Chain:

Near-continuous NREM spike-wave
  → failure of sleep-dependent synaptic downscaling (flat overnight SWA slope)
    → saturated, non-selective synaptic weights → poor signal-to-noise
      → failed overnight memory consolidation + corrupted cortical map refinement
→ domain-specific regression matching the spike topography
  → (spikes remit at puberty) partial recovery, but the critical-period
     window for that cortical map has closed → residual permanent deficit

The critical-period framing is what explains the syndrome's cruellest feature: seizures stop, EEG normalizes, and the child still doesn't fully get the language back. The scaffolding came down before the building was finished.

  • GO:0048167 regulation of synaptic plasticity (verified)
  • GO:0060291 long-term synaptic potentiation, GO:0060292 long-term synaptic depression (verified)
  • GO:0030431 sleep (verified)
  • GO:0050803 regulation of synapse structure or activity (verified)
  • GO:0050890 cognition, GO:0007613 memory (verified)

Model C — Molecular substrate: NMDAR/channel dysfunction and E/I imbalance

For the genetic cases, the proximate lesion is at the synapse.

GRIN2A encodes GluN2A, the subunit that dominates NMDA receptors in cortex from late infancy onward — exactly the developmental window of this syndrome. GluN2A-containing NMDARs have fast deactivation kinetics; alter them and you alter the temporal integration window for coincidence detection, i.e. the machinery of plasticity itself. Both directions break things: - GoF (TMD/linker missense): prolonged current, excess Ca²⁺ influx, excitotoxic/hyperexcitable phenotype → severe DEE - LoF (null, ATD/LBD missense): reduced NMDAR signalling — including on GABAergic interneurons, so net disinhibition → milder epilepsy-aphasia spectrum

The other genes converge on the same theme from different angles: Nav/Kv/Cav channelopathies (intrinsic excitability), SLC6A1/GAT-1 and SLC12A5/KCC2 (GABAergic inhibitory tone and chloride gradient), DLG4/PSD-95, CNKSR2, PPFIA3 (postsynaptic scaffolding and active zone). Plus the transcriptional-regulator cluster acting further upstream on the whole developmental program.

  • GO:0004972 NMDA glutamate receptor activity (verified)
  • GO:0035249 synaptic transmission, glutamatergic (verified)
  • GO:0060079 excitatory postsynaptic potential (verified)
  • GO:0098978 glutamatergic synapse (verified)
  • GO:0005248 voltage-gated sodium channel activity, GO:0005249 voltage-gated potassium channel activity (verified)
  • GO:0006357 regulation of transcription by RNA polymerase II (verified — for Cluster 2)
  • UniProt: GluN2A = Q12879; PDB structures of NMDAR GluN1/GluN2A heterotetramer available

Note for the KB: this maps cleanly onto your existing module epilepsy_excitation_inhibition_imbalance — #Excitation-Inhibition Imbalance is an obvious conforms_to target. Model B (sleep-dependent downscaling failure) is not covered by any existing module and might be worth one, since it also touches your glymphatic_dysfunction module's territory conceptually (both are "sleep does maintenance work; disease blocks the maintenance") without duplicating it — glymphatic is extracellular clearance, this is synaptic weight renormalization. Different plumbing, same night shift.

Network-level: functional imaging

FDG-PET and EEG-fMRI (De Tiège et al., Epilepsia 2009) show the syndrome is a network disease, not a focal one:

"Hypermetabolism in perisylvian regions bilaterally and hypometabolism in lateral and mesial prefrontal cortex, precuneus, posterior cingulate cortex and parahippocampal gyri characterized the acute phase of CSWS. Altered functional connectivity was found between hyper- and hypometabolic regions" [reported]

The hypometabolic set is essentially the default mode network (see "Default mode network hypometabolism in epileptic encephalopathies with CSWS," Epilepsy Res 2014). The mechanism proposed is remote inhibition — the hyperactive epileptic focus actively suppresses distant connected cortex. That explains how a perisylvian spike focus produces a frontal-executive clinical syndrome: the deficit is downstream of the focus, not at it.

  • UBERON:0000451 prefrontal cortex, UBERON:0016525 frontal lobe, UBERON:0001871 temporal lobe (verified)

Not involved

  • Metabolic changes: no primary metabolic derangement (excepting the rare OPA3/Costeff case). Regional cerebral glucose metabolism is altered (above), but that's a consequence.
  • Immune system: steroid responsiveness has long tempted people toward a neuroinflammatory hypothesis, and microglial (CL:0000129) / astrocytic (CL:0000127) contributions are plausible, but no autoantibody, no CSF inflammatory signature, no confirmed immune mechanism. Steroids may work via non-immune routes (direct effects on neuronal excitability, BBB, or neurosteroid pathways). Curate this as an explicit KNOWLEDGE_GAP — it's a real open question and the biggest unexplained therapeutic observation in the syndrome.
  • Tissue damage: no necrosis, no fibrosis, no gliotic signature attributable to the SWAS itself. The "damage" is functional/synaptic, which is precisely why partial recovery is possible.

Molecular profiling

Essentially absent for this syndrome specifically. The one systems-level result worth citing is the Ann Neurol brain-specific gene co-expression analysis showing the two functional clusters. No GEO dataset, no proteomics, no metabolomics, no single-cell or spatial data specific to D/EE-SWAS. Large gap, and a legitimate one to record.

7. Anatomical Structures Affected

Organ level - Primary: brain (UBERON:0000955), specifically cerebral cortex (UBERON:0000956) and thalamus (UBERON:0001897) (verified) - Body system: central nervous system only. No systemic organ involvement — this is a purely neurological syndrome unless the underlying genetic cause is syndromic (e.g. Mowat-Wilson, Smith-Magenis, Christianson, Costeff bring their own multi-organ features) - Secondary: none organ-wise; secondary consequences are behavioral/educational/psychosocial

Regional - Thalamus — medial and dorsal nuclei preferentially; ventral thalamus spared (verified from PMID:29133062). Thalamic reticular nucleus (UBERON:0001903) is the spindle generator and is the mechanistic linchpin - Perisylvian cortex — hypermetabolic in the acute phase; the LKS substrate (superior temporal / auditory association cortex) - Frontal cortex (UBERON:0016525) and prefrontal cortex (UBERON:0000451) — hypometabolic; the CSWS/dysexecutive substrate - Precuneus, posterior cingulate, parahippocampal gyrus — hypometabolic (DMN) - Centrotemporal / rolandic region — the SeLECTS-spectrum spike focus - Ipsilateral white matter and lateral ventricle — volume loss / enlargement in thalamic-lesion cases

Lateralization Genuinely variable and clinically informative: unilateral/focal SWAS in thalamic-lesion and other unilateral structural cases (spiking lateralizes to the lesioned hemisphere — verified in PMID:29133062); bilateral/diffuse SWAS in genetic and idiopathic cases. Bilateral secondary synchrony from a unilateral generator is common. Worth curating as a distinguishing feature.

Cell level - CL:0000598 pyramidal neuron (cortical, layer V — the augmenting-response substrate) - CL:0000679 glutamatergic neuron - CL:0000617 GABAergic neuron (TRN, cortical interneurons) - CL:0000099 interneuron - CL:0010012 cerebral cortex neuron - CL:0000127 astrocyte, CL:0000129 microglial cell — speculative, no direct evidence (all verified against sqlite:obo:cl)

Subcellular - GO:0045202 synapse; GO:0098978 glutamatergic synapse (verified) - Postsynaptic density (GO:0014069), dendritic spine (GO:0043197), plasma membrane, axon initial segment — ⚠️ these four IDs are from memory, verify with OAK - No mitochondrial, lysosomal, ER, or nuclear-envelope pathology (excepting rare OPA3)

8. Temporal Development

This syndrome has one of the tightest and most reproducible time courses in pediatric neurology, which makes it very curatable.

Onset - Seizure onset: 2–12 years, peak 4–5 years; medians in cohorts cluster at 3.3 yr (DEE-SWAS) / 4.4 yr (EE-SWAS) [reported, Ann Neurol 2024] and 4 years in the Turkish cohort [reported] - Regression onset: ~1–2 years after seizures, typically 5–6 years - LKS auditory verbal agnosia onset: 3–9 years - Pattern: insidious-to-subacute. Regression can be gradual over months or, disconcertingly, abrupt over weeks. Fluctuation (especially in LKS language) is characteristic and often misread as behavioral or psychiatric

Stages

Stage Age Features
Prodrome 2–5 yr Infrequent nocturnal focal seizures; development normal (EE-SWAS) or already delayed (DEE-SWAS); EEG shows focal spikes without SWAS
Active / encephalopathic 5–9 yr SWAS on sleep EEG; seizure frequency escalates (up to 70% with multiple daily seizures [reported]); regression; new seizure types appear (atypical absence, atonic/negative myoclonus)
Remission ~9–12 yr, near puberty SWAS resolves (~age 11 typically [reported]); seizures cease; some cognitive recovery
Residual adolescence–adult Persistent deficits in most; degree tracks how long the active phase lasted

Progression rate & course: stepwise/subacute during the active phase, then a spontaneous, age-dependent remission — one of the few epileptic encephalopathies that reliably self-terminates. But the neurodevelopmental damage does not fully reverse.

Duration: active phase typically 2–5 years. From the Ann Neurol cohort: DEE-SWAS median epilepsy duration 10.0 years vs EE-SWAS 5.2 years [reported], and:

"Although developmental regression patterns were similar in both syndromes, DEE-SWAS was associated with a longer duration of epilepsy and poorer intellectual outcome than EE-SWAS." [verbatim-verified from cache]

Remission patterns: both spontaneous (age-dependent, near-universal for the EEG pattern and seizures) and treatment-induced (steroids/benzodiazepines can abolish SWAS in weeks). Relapse after treatment-induced remission is common — the diazepam and steroid literature is full of it — which is why prolonged/pulsed courses are used.

Critical period — the whole therapeutic rationale: the vulnerable window is the intervention window. Because the deficit accrues from cumulative SWAS exposure during an active cortical-map-refinement period, duration of ESES is the main predictor of neurocognitive outcome [reported, PMC3929187]. Every month of unsuppressed SWAS is irreversible developmental opportunity cost. This is the argument for early aggressive treatment and for annual sleep EEG surveillance in at-risk children.

9. Inheritance and Population

Epidemiology - Prevalence among childhood epilepsies: "0.5% to 0.6% of all childhood epilepsy cases" at tertiary referral epilepsy centers [reported, PMC3929187]; other sources give a wider 0.2%–2% of epilepsies [reported] - Population prevalence: ⚠️ Not reliably published. Orphanet classes it as rare (< 1 in 2,000). Back-of-envelope from a childhood epilepsy prevalence of ~0.5–1% and a 0.5% share gives an order of magnitude around 2–5 per 100,000 children, but that's a derived estimate, not a cited figure — do not curate it as a sourced prevalence. Use prevalence_class: UNKNOWN or NOT_YET_DOCUMENTED with a notes field, or cite the ORPHA:725 epidemiology row directly via the structured Orphanet cache - Incidence: no published incidence figure found. Gap. - Sex ratio: ~60:40 male:female [reported, PMC3929187]; 53% male in the Ann Neurol cohort [reported]. ILAE states both sexes equally affected [reported]. Treat as "slight male predominance or none" — sources disagree - Age distribution: exclusively pediatric onset (2–12), remitting around puberty. Adults exist only as survivors with residual deficits

Inheritance (for the genetic subset — ~34% of cases) - Predominantly de novo autosomal dominant. Most single-gene cases are de novo heterozygous variants - X-linked for CNKSR2 (~50% de novo; carrier mothers usually unaffected [reported]), MECP2, CUL4B, SLC9A6 - Autosomal recessive rarely (OPA3/Costeff) - HPO inheritance terms: HP:0000006 (AD), HP:0001417 (X-linked), HP:0001423 (X-linked dominant), HP:0001419 (X-linked recessive), HP:0000007 (AR) — ⚠️ verify these IDs with OAK; I did not check them - Penetrance: incomplete, explicitly documented for GRIN2A — OMIM #245570 notes "incomplete penetrance and intrafamilial variability, even among family members who carry the same GRIN2A mutation" [reported]. Use penetrance: INCOMPLETE - Expressivity: highly variable — the same GRIN2A variant can produce anything from asymptomatic to severe DEE across one family. This is the single best-documented genotype-phenotype caveat in the syndrome - Anticipation: not a feature, except in the one ATN1/DRPLA repeat-expansion case - Germline mosaicism: not documented specifically; theoretically possible for any de novo dominant gene, and standard recurrence-risk counselling (~1%) applies - Founder effects: none reported - Consanguinity: no established role (the recessive fraction is tiny) - Carrier frequency: not applicable at syndrome level; not meaningfully estimable

Population demographics - Ethnic/geographic: no established variation. Cohorts published from Australia/NZ, UK, Netherlands, Italy, France, Germany, Spain, Denmark, Turkey, Serbia, Romania, Malaysia, Hong Kong, USA — the syndrome appears globally with no reported prevalence differences. Ascertainment is heavily skewed to high-income countries with routine overnight EEG access, which is itself worth noting: you cannot diagnose this without a sleep EEG, so under-diagnosis in low-resource settings is near-certain - Variant geography: no population-specific variants reported

10. Diagnostics

The single indispensable test

Overnight / sleep EEG. Nothing else diagnoses this. A routine awake EEG can be entirely normal or show only modest focal spikes; the syndrome hides in NREM sleep. If you take one thing from this section: a child with unexplained developmental regression needs a sleep EEG, not a waking one.

EEG features: - Bilateral (or, less often, unilateral) continuous or near-continuous slow spike-wave during NREM sleep - Frequency 1.5–3 Hz (often stated as 1–2 Hz) - Marked attenuation in REM sleep and wakefulness — the state-dependence is the diagnostic signature - SWI highest in the first sleep cycle, declining across the night - Localization typically frontotemporal or centrotemporal - HP:0011182 Interictal epileptiform activity; HP:0010841 Multifocal epileptiform discharges; HP:0002353 EEG abnormality (verified)

Spike-wave index (SWI) — and its controversy. SWI = (minutes containing spike-wave × 100) / total NREM minutes.

Thresholds are genuinely unsettled, and this matters for any computable phenotype: - Classic/strict: ≥85% of NREM ("typical ESES") - Commonly used pragmatic: ≥50% - SWI <85% sometimes labeled "atypical ESES" - Resolution often defined as SWI <50% - The ILAE 2022 criteria deliberately do NOT specify a minimum percentage — they require "marked activation" clinically judged, precisely because the thresholds were never validated against outcome

⚠️ This is a real curation trap. Do not write "SWI ≥85% is the ILAE criterion" — it isn't. Model it as an open methodological question (KNOWLEDGE_GAP) with the competing thresholds recorded. The systematic review noted ~67.6% of published genetic cases were diagnosed using a >50% threshold [reported] — i.e. the literature isn't even internally consistent about who has the disease.

Imaging

  • Brain MRI is mandatory. Looking for: thalamic lesion (often small, requires deliberate attention to medial/dorsal nuclei — easy to miss), polymicrogyria, periventricular leukomalacia, porencephaly, hydrocephalus/shunt, cortical dysplasia. Volumetric analysis may be needed for subtle thalamic volume loss (range in the published series: 19%–94%)
  • FDG-PET (research/selected): perisylvian hypermetabolism + prefrontal/precuneus/posterior cingulate hypometabolism in the active phase
  • SPECT: focal hyperperfusion with remote hypoperfusion
  • EEG-fMRI: research tool for mapping the generator and remote effects
  • Polysomnography with spindle quantification: emerging — sleep spindle density is both a biomarker and, per the rTMS work, a treatment-response correlate

Genetic testing

Given a 34% genetic yield, this is not optional. Recommended approach:

  1. Chromosomal microarray (CMA) first or in parallel — CNVs are ~19% of the genetic yield (6/31 in the Ann Neurol cohort), and several recurrent CNVs (15q11.2-13.1 dup, 3q29 dup, Xp22.12 del, 16p13 del, 17q21.31 del, 17p11.2 dup/del) are microarray-detectable
  2. Exome or genome sequencing — best single-test yield; genome adds CNV/structural resolution and non-coding coverage. The Seizure 2023 review concluded that "presentations occurring before age five warrant genetic investigation" [reported]
  3. Epilepsy gene panels — acceptable but will miss the syndromic and novel genes; must include GRIN2A, GRIN2B, GRIN1, CNKSR2, SCN1A, SCN2A, SCN8A, KCNQ2, KCNQ3, KCNA2, KCNB1, KCNH5, KCNMA1, CACNA1A, ATP1A2, SLC6A1, SLC12A5, SLC9A6, DLG4, MECP2, FOXP1, ZBTB18, SETD1B, ARID1B, PUF60, CUL4B, ZEB2, PPFIA3
  4. Single-gene GRIN2A — reasonable only when the phenotype is classic epilepsy-aphasia/LKS and cost is limiting
  5. Karyotype/FISH: low yield; reserve for suspected specific rearrangements
  6. Mitochondrial DNA testing: not indicated
  7. Repeat expansion testing: not indicated (except the DRPLA outlier if there's a suggestive family history)
  8. Variant classification per ACMG/AMP; interpret in ClinVar/ClinGen context. For GRIN2A, push for protein-domain annotation (ATD/LBD vs TMD/linker) because it changes the therapeutic hypothesis

Omics diagnostics: RNA-seq, proteomics, metabolomics, methylation episignature — none established for this syndrome. Metabolic workup is generally low-yield unless the phenotype suggests a specific IEM.

Clinical criteria

ILAE 2022 (Specchio et al., PMID:35503717) — DEE-SWAS/EE-SWAS, in substance: - Regression or plateauing in development affecting one or more of cognition, language, behavior, motor function - Marked spike-wave activation in NREM sleep, temporally related to the regression - Onset 2–12 years (peak 4–5) - Seizures usually present but not mandatory - EE-SWAS if development was normal before; DEE-SWAS if impaired before - LKS as a distinct EE-SWAS subtype defined by acquired auditory verbal agnosia

⚠️ I could not retrieve the position paper's formal mandatory / alerts / exclusionary tables — Epilepsia and the ILAE site both blocked automated fetch. Get the actual table from the PDF before curating definitions for this entry. The cached references_cache/PMID_35503717.md is abstract-only.

Differential diagnosis

Condition How to distinguish
SeLECTS (self-limited epilepsy with centrotemporal spikes) Same spectrum, but no marked sleep activation, no regression. Can evolve into DEE-SWAS — hence the surveillance argument
Lennox-Gastaut syndrome Slow (1.5–2.5 Hz) spike-wave in wakefulness, tonic seizures in sleep, generalized paroxysmal fast activity, no discrete regression event
Autism spectrum disorder with regression Regression typically <3 yr, no SWAS on sleep EEG. Overlaps genuinely — a sleep EEG is the discriminator
Acquired aphasia from stroke/tumor/encephalitis Focal lesion on MRI, no SWAS
Hearing loss / auditory processing disorder Normal audiometry and ABR distinguish LKS's auditory verbal agnosia from deafness — a classic misdiagnosis
Myoclonic-atonic epilepsy (Doose) Myoclonic-atonic seizures dominant, generalized 2–3 Hz spike-wave awake
Progressive neurodegenerative / metabolic disease Progressive and non-remitting; DEE-SWAS plateaus and improves at puberty
Rett syndrome / MECP2 Hand stereotypies, deceleration of head growth — but note MECP2 is also a D/EE-SWAS gene, so these can coexist
Psychiatric / selective mutism Sleep EEG

Screening

  • No newborn or population screening exists or is warranted
  • Targeted surveillance is the meaningful intervention: serial sleep EEG in children with (a) early thalamic lesion, (b) polymicrogyria, (c) shunted hydrocephalus, (d) SeLECTS with new cognitive/behavioral change, (e) known pathogenic variant in a D/EE-SWAS gene. There is no formal guideline endorsing an interval — I'd flag "annual, or on any cognitive change" as expert-practice, not evidence-based
  • Cascade testing where a familial variant is identified; be explicit about incomplete penetrance in counselling
  • Carrier screening: not applicable

11. Outcome / Prognosis

Mortality: Not a fatal syndrome. No excess mortality established, no survival statistics, no life-expectancy reduction attributable to D/EE-SWAS itself. SUDEP risk is presumably that of the underlying epilepsy generally, but has not been quantified for this syndrome. The RESCUE ESES trial explicitly recorded "No deaths were reported" [verbatim-verified]. This is a morbidity disease, not a mortality disease — curate disease-specific mortality: none established rather than leaving it blank.

Morbidity — the actual endpoint. Persistent intellectual disability, language impairment, ADHD, and learning disability in most patients. Educational placement and independent adult functioning are the outcomes that matter.

Concrete numbers from the Ann Neurol 2024 cohort [reported]:

DEE-SWAS EE-SWAS
Moderate–severe intellectual disability 49% 8%
Normal / mild ID 51% 92%
Median epilepsy duration 10.0 yr 5.2 yr

Plus, verbatim: "Phenotypic analysis highlights valuable clinical differences between DEE-SWAS and EE-SWAS which inform clinical care and prognostic counseling." [verbatim-verified]

From the older CSWS literature: "Most patients continue to demonstrate some degree of impairment" [reported], and "Duration of ESES seems to be the main predictor of neurocognitive function" [reported].

Recovery potential: Partial. Seizures and the EEG pattern remit near-universally around puberty. Cognition recovers partially — the earlier and more completely SWAS is suppressed, the more is recovered. Full return to premorbid function is uncommon, and in LKS specifically, complete language recovery is the exception; many are left with lasting receptive language impairment into adulthood.

Prognostic factors (best supported → weakest): 1. Duration of SWAS — the strongest predictor 2. Etiology — from the 50-child Serbian cohort: SeLECTS-background patients had "shorter symptom duration and superior prognosis, whereas those with structural etiologies experienced prolonged manifestations and reduced treatment efficacy" [reported, PMID:41076959] 3. DEE-SWAS vs EE-SWAS — pre-existing impairment predicts worse outcome (49% vs 8% moderate-severe ID) 4. Age at SWAS onset — earlier onset, worse (more of the critical period consumed) 5. Spike-wave index magnitude — higher SWI associated with more severe developmental disturbance [reported], though weaker/less consistent than duration 6. Time to effective treatment — the modifiable one

Prognostic biomarkers: SWI and its trajectory; sleep spindle density (emerging — the rTMS study found spindle increase correlated with IQ improvement, p=0.035 [reported]); overnight slow-wave-activity slope (research). No molecular/fluid biomarker exists.

Complications: educational failure, behavioral/psychiatric comorbidity, social exclusion; steroid-related complications from prolonged treatment (weight gain, hypertension, immunosuppression, bone effects) — treatment toxicity is a genuine part of the disease burden here.

12. Treatment

The uncomfortable headline: treatment for this syndrome rests on a single small, prematurely terminated RCT plus a lot of retrospective case series. Every decision below is made in an evidence twilight.

The one randomized trial: RESCUE ESES (PMID:38081201, Lancet Neurol 2024)

Corticosteroids vs clobazam, 8 tertiary centres, 7 European countries, children 2–12 diagnosed within 6 months, steroid- and clobazam-naive.

"At the 6-month assessment, an improvement of 11·25 IQ points or greater was reported for five (25%) of 20 children assigned corticosteroids versus zero (0%) of 18 assigned clobazam (risk ratio [RR] 10·0, 95% CI 1·2-1310·4; p=0·025)." [verbatim-verified from cache]

"An improvement of 0·75 points or more in the cognitive sum score was recorded for one (5%) of 22 children assigned corticosteroids versus one (5%) of 21 children assigned clobazam (RR 1·0, 95% CI 0·1-11·7, p=0·97)." [verbatim-verified]

"The trial was terminated prematurely, and the target sample size was not met, so our findings must be interpreted with caution. Our data indicated an improvement in IQ outcomes with corticosteroids compared with clobazam treatment, but no difference was seen in cognitive sum score. Our findings strengthen those from previous uncontrolled studies that support the early use of corticosteroids for children with EE-SWAS." [verbatim-verified]

Read that carefully before curating: the two co-primary outcomes disagreed. IQ favored steroids with a confidence interval you could drive a bus through (1.2 to 1310.4); the cognitive sum score showed literally nothing. 45 children enrolled against a target of 130 over eight years. This is suggestive evidence for steroids, not established efficacy — and it should be curated with that caveat intact, not laundered into "steroids are proven effective."

Regimens used: prednisolone 1–2 mg/kg/day oral continuous, or methylprednisolone 20 mg/kg/day IV ×3 days every 4 weeks (pulse). Clobazam 0.5–1.2 mg/kg/day.

Safety [verbatim-verified]: "Adverse events occurred in ten (45%) of 22 children who received corticosteroids, most frequently weight gain, and in 11 (52%) of 21 children who received clobazam, most often fatigue and behavioural disturbances."

Real-world effectiveness (PMID:41076959, Seizure 2025, n=50)

"corticosteroids (80.9%), clobazam (55.8%), levetiracetam (54.1%), and sulthiame (52.9%) were the most effective treatments." [reported]

Pooled historical data

A pooled analysis of 575 treated ESES cases found improvement in cognition or EEG most often with surgery (90%), steroids (81%), or benzodiazepines (68%), with standard ASMs least effective (49%) [reported]. Note the surgery figure is drowning in selection bias — only carefully chosen structural cases get operated.

Treatment table with NCIT/CHEBI annotations

Treatment Modality NCIT Agent (CHEBI) Evidence
Prednisolone / prednisone (continuous oral) SMALL_MOLECULE NCIT:C15986 Pharmacotherapy † CHEBI:8378 prednisolone ‡ / CHEBI:8382 prednisone ‡ RESCUE ESES RCT; drug class NCIT:C2322 Corticosteroid †
Methylprednisolone pulse (20 mg/kg/d ×3d, monthly) SMALL_MOLECULE NCIT:C15986 † CHEBI:6888 6alpha-methylprednisolone ‡ RESCUE ESES; 47% of European centres use pulse-only [reported, PMID:40301922]
ACTH PEPTIDE NCIT:C15986 † ⚠️ CHEBI unverified Case series only
Clobazam SMALL_MOLECULE NCIT:C15986 † CHEBI:31413 clobazam ‡ RCT comparator; 55.8% effective real-world
High-dose oral/rectal diazepam (nocturnal) SMALL_MOLECULE NCIT:C15986 † CHEBI:49575 diazepam ‡ Case series; rapid EEG effect, frequent relapse
Levetiracetam SMALL_MOLECULE NCIT:C15986 † CHEBI:6437 levetiracetam ‡ 54.1% effective real-world
Sulthiame SMALL_MOLECULE NCIT:C15986 † ⚠️ no CHEBI term found via OAK — use NCIT drug term or free-text 52.9% effective; European/Japanese use; case report of GRIN2A-variant EE-SWAS responding (PMC9996194)
Ethosuximide SMALL_MOLECULE NCIT:C15986 † CHEBI:4887 ethosuximide ‡ First-line historically; T-type Ca²⁺ block fits the thalamocortical model
Valproate SMALL_MOLECULE NCIT:C15986 † CHEBI:39867 valproic acid ‡ First-line historically
Acetazolamide SMALL_MOLECULE NCIT:C15986 † CHEBI:27690 acetazolamide ‡ Adjunct, case series
Ketogenic diet BEHAVIORAL NCIT:C15447 Dietary Intervention † n/a Weak: one 5-patient series (1 complete, 1 partial, 3 no response) [reported]
IVIG OTHER NCIT:C15986 † ⚠️ unverified Anecdotal; rests on the unproven immune hypothesis
Epilepsy surgery (resection, multiple subpial transection, hemispherotomy, corpus callosotomy) SURGERY NCIT:C15329 Surgical Procedure † n/a 90% improvement in pooled series (selection-biased); "should be considered in cases of drug-resistant D/EE-SWAS that have an underlying structural abnormality" [reported]
rTMS DEVICE ⚠️ no verified NCIT term n/a Open-label, n=9, PMID:40620003
tDCS DEVICE ⚠️ unverified n/a Case-level only
Speech and language therapy BEHAVIORAL NCIT:C159273 speech therapy † n/a Supportive; essential, especially LKS
Special education / neuropsych support BEHAVIORAL NCIT:C15747 Supportive Care † n/a Universal
Genetic counselling — NCIT:C15240 Genetic Counseling † n/a For solved genetic cases

† NCIT IDs taken from the verified list in CLAUDE.md. ‡ CHEBI IDs verified via sqlite:obo:chebi. Everything marked ⚠️ needs an OAK lookup before curating.

Contraindicated / to avoid

Carbamazepine (CHEBI:3387 ‡), oxcarbazepine, phenytoin, phenobarbital — can induce or worsen SWAS. "Carbamazepine is relatively contraindicated in ESES and should be discontinued" [reported]. This belongs in the entry as an explicit negative treatment recommendation — it's the cheapest intervention in the whole syndrome.

Precision medicine — the frontier

The rational-therapy story here is genuinely good, and it's the reason etiologic workup matters:

  • GRIN2A gain-of-function (TMD/linker missense) → memantine (CHEBI:64312 ‡), an NMDAR open-channel blocker. Per Strehlow et al.: these individuals "represent promising candidates for treatment with NMDAR blockers, such as memantine" [reported]
  • GRIN2A loss-of-function (null, ATD/LBD) → NMDAR positive allosteric modulators (investigational; L-serine has been tried for GRIN LoF)
  • Sodium-channel GoF (SCN2A early-onset, SCN8A) → high-dose sodium channel blockers — note this directly conflicts with the general "avoid carbamazepine" rule, which is exactly why genotype matters
  • Sodium-channel LoF (SCN1A, SCN2A late-onset) → avoid sodium channel blockers
  • SLC6A1/GAT-1 LoF → GABAergic strategies under investigation

From the Ann Neurol conclusion: "Our etiological findings pave the way for the development of precision therapies." [verbatim-verified]

Emerging: rTMS via sleep-spindle restoration

Small (n=9) open-label study, PMID:40620003, and mechanistically the most interesting thing in the treatment literature because it tests Model B directly. Low-frequency (0.3–1 Hz) rTMS over the central facial motor area or a PET-identified hypometabolic zone, 10 workdays, 1,000–1,500 pulses/day: - Sleep spindle density: 55 → 91 (3 mo) → 147 (6 mo), p=0.002 [reported] - Median SWI: 81% → 68% → 57% (p=0.045, p=0.035) [reported] - Median IQ 72 → 83, and "improvement correlated significantly with sleep spindle increase (p = 0.035)" [reported] - "The mean probability of the sleep spindle coupling in the slow wave 'up' state increased from 28% to 55%" [reported]

n=9, open-label, no control — nowhere near practice-changing. But it's the first study to move a mechanistic variable (spindle–slow-wave coupling) and show cognition follow it. If Model B is right, this is what right looks like.

Treatment strategy in practice

  1. Diagnose with sleep EEG; get MRI and genetics going in parallel
  2. Stop any carbamazepine/oxcarbazepine/phenytoin/phenobarbital
  3. First-line: corticosteroids (continuous or pulse) and/or high-dose benzodiazepine (clobazam/nocturnal diazepam) — early, because duration is the prognostic driver
  4. Adjunct/alternative ASMs: levetiracetam, sulthiame, ethosuximide, valproate
  5. Genotype-guided adjustment once results return
  6. Ketogenic diet or IVIG in refractory cases (weak evidence)
  7. Surgery if a resectable structural lesion is driving it
  8. Throughout: speech therapy, special education, neuropsychological monitoring, serial sleep EEG to track SWI

Note the guideline vacuum. Per the European steroid survey (PMID:40301922), 60 centres in 18 countries, 11 different published steroid regimens, only 7 used as published: "Steroids are part of the first line therapy of (D)EE-SWAS across Europe, but heterogeneity in formulations, dosages, and regimens persists due to limited guideline availability." [reported]. And per the Seizure 2023 review: "Uniformity concerning the new definition of EE/DEE-SWAS, guidelines for management and more frequent genetic screening will be needed to guide best practices." [reported]

Clinical trials: RESCUE ESES = Dutch Trial Register NL43510.041.13 / ISRCTN42686094 (note: ISRCTN, not an NCT — your clinical_trials block wants NCT IDs, so this one may not fit the standard pattern). No large active NCT-registered interventional trial specific to D/EE-SWAS was identified; GRIN-disorder trials (memantine, L-serine) exist but enroll by gene, not by this syndrome.

13. Prevention

Short section, honestly assessed.

Primary prevention: No means of preventing the syndrome. The genetic cases are overwhelmingly de novo. The one partial lever is preventing the perinatal brain injuries (neonatal thalamic hemorrhage/infarction, IVH, HIE) that constitute the commonest structural etiology — i.e. general perinatal and neonatal care quality, not anything syndrome-specific. No vaccine, no immunization strategy applies.

The genuine preventive intervention is avoiding iatrogenic precipitation: don't put a child with SeLECTS on carbamazepine/oxcarbazepine. Small, cheap, real.

Secondary prevention (early detection) — this is where the value is: - Sleep EEG surveillance in the at-risk groups listed in §10 - Low threshold for sleep EEG in any child with unexplained developmental regression, language loss, or new behavioral deterioration - Rationale is explicit: because outcome tracks SWAS duration, shortening the delay to diagnosis is itself the therapy. Median diagnostic delay is not well quantified — gap.

Tertiary prevention (limiting damage in diagnosed patients): - Early aggressive SWAS suppression - Serial sleep EEG to confirm suppression and catch relapse - Serial neuropsychological assessment - Speech/language therapy and educational support to compensate for what can't be prevented - Monitor for steroid toxicity during prolonged courses (BP, weight, glucose — 98%/93%/64% of European centres respectively [reported])

Genetic screening / counselling: - No newborn or population screening - Post-diagnosis genetic counselling for solved cases; recurrence risk usually low (de novo) but not zero (germline mosaicism ~1%) - X-linked CNKSR2 families need proper carrier counselling — 50% recurrence for sons of carrier mothers - Prenatal testing / PGT technically available for known familial variants but complicated by incomplete penetrance and extreme variable expressivity — a GRIN2A variant carrier may be asymptomatic. This is a genuine counselling difficulty and worth recording - NCIT:C15240 Genetic Counseling

Public health / environmental interventions: not applicable.

14. Other Species / Natural Disease

Naturally occurring animal disease: none. There is no reported spontaneous DEE-SWAS analog in companion animals, livestock, or wildlife. I checked OMIA-adjacent literature and found nothing — this is unsurprising, because the diagnosis depends on (a) a sleep EEG and (b) documented loss of language, neither of which transfers to veterinary medicine. Curate as explicitly not applicable rather than leaving blank.

  • Taxonomy: NCBITaxon:9606 Homo sapiens (only)
  • Breed (VBO): not applicable
  • Zoonotic potential / cross-species transmission: not applicable (non-infectious)

Comparative biology / evolutionary conservation: - The molecular substrate is deeply conserved: NMDA receptor subunits, voltage-gated Na⁺/K⁺/Ca²⁺ channels, and the thalamocortical circuit itself are conserved across mammals. Sleep spindles and slow-wave sleep are present in all mammals studied, and the synaptic homeostasis hypothesis was developed largely in rodents and Drosophila - Orthologs: Grin2a (mouse MGI, NCBI Gene 14811), Cnksr2 (mouse), Grin2a (rat, zebrafish grin2aa/grin2ab) - What does NOT conserve is the phenotype: the defining clinical feature is acquired aphasia / language regression, which has no animal correlate. This is a fundamental HUMAN_MODEL_MISMATCH and should be curated as one — models can reproduce the seizures, the sleep-EEG abnormality, and social/vocalization deficits, but never the syndrome's core clinical feature

15. Model Organisms

Mouse — the workhorse

Cnksr2 knockout mouse (PMID:34580165, J Neurosci 2021):

"Cnksr2 KO mice have increased seizures, impaired learning and memory, increased levels of anxiety, and loss of ultrasonic vocalizations (USV)." [reported]

Follow-up (eNeuro 2025, "The Epilepsy–Aphasia Syndrome Gene, Cnksr2, Plays a Critical Role in the Anterior Cingulate Cortex Mediating Vocal Communication") localized the USV deficit to excitatory neurons of the anterior cingulate cortex [reported].

This is the best available model, and the USV loss is the closest thing to a rodent "aphasia" readout that exists. But be careful how you phrase it: mouse ultrasonic vocalization is a social/affective signal, not language. It is analogous, not homologous, and that gap is exactly the HUMAN_MODEL_MISMATCH to record.

Grin2a mouse models — heterozygous and null lines exist. The Grin2a⁺/⁻ mouse shows changes in prefrontal cortex, insular cortex, superficial cortical layers, and thalamic reticular nucleus [reported], which is intriguing given the TRN's role in spindle generation. Caveat: most Grin2a mouse work is framed around schizophrenia, not epilepsy-aphasia, so the literature is oriented elsewhere and should be read with that in mind.

Thalamic lesion models: the "augmenting response" — the pathological frequency-dependent potentiation at the heart of Model A — was originally characterized in cats and rodents after experimental thalamic ablation (see PMID:29133062's discussion). These aren't disease models per se, but they're the physiological foundation of the leading mechanistic hypothesis. Worth curating as MODEL_ORGANISM evidence for the mechanism node even though they long predate the syndrome's molecular era.

Other genetic models available: Scn1a, Scn2a, Scn8a, Kcnq2, Kcnb1, Kcna2, Slc6a1, Mecp2, Arid1b, Foxp1, Zeb2 mouse lines all exist (MGI, IMPC/KOMP), constitutive and conditional. None were built as DEE-SWAS models; all are DEE models more broadly.

In vitro

  • Xenopus oocyte and HEK293 two-electrode/patch electrophysiology — the workhorse for GRIN2A variant functional classification (this is how Strehlow et al. established the LoF/GoF domain split). This is the assay that makes the precision-medicine claim actionable
  • Patient iPSC-derived neurons and cortical organoids — feasible and being pursued for GRIN and channelopathy genes; nothing published specific to D/EE-SWAS
  • Cellosaurus/ATCC: no disease-specific cell line

Model limitations — be explicit

  1. No rodent model reproduces the defining EEG pattern (near-continuous NREM spike-wave with sleep-state dependence) together with regression. This is the single biggest gap
  2. No language phenotype is possible — the clinical core of the syndrome is untestable in animals
  3. The age-dependent spontaneous remission at puberty — the syndrome's most distinctive natural-history feature — has no established animal correlate
  4. Mouse sleep architecture (polyphasic, much shorter cycles, different spindle characteristics) differs enough that translating slow-wave downscaling findings to a child's overnight EEG requires real caution
  5. Most single-gene models were made for a different indication and are studied under different phenotyping batteries

Research applications the models do support

  • Variant functional classification → therapeutic stratification (in vitro electrophysiology; strongest translational value)
  • Circuit dissection of thalamocortical/TRN contributions
  • Sleep-dependent synaptic homeostasis mechanisms
  • Preclinical testing of NMDAR blockers/PAMs
  • Vocalization/social-communication readouts as a partial language proxy (Cnksr2)

Resources

MGI (informatics.jax.org), IMPC, KOMP/EuMMCR, IMSR, RGD, ZFIN, Alliance of Genome Resources, Cellosaurus.

Curation notes for the dismech entry

A few things I'd flag before this goes into kb/disorders/:

  1. disease_term: MONDO:0800501 is verified and correct. It's a relatively new-ish MONDO term — per the repo's known gotcha, seed both cache/enums/diseaseterm_*.csv and cache/mondo/terms.csv from the local sqlite adapter, in the worktree and the primary checkout, or CI will fail with an OLS timeout dressed up as "term not found."

  2. Model this as two subtypes, not one blob: DEE-SWAS and EE-SWAS, with LKS as a sub-subtype or a distinguishing-feature block under EE-SWAS. The 66%/28% etiologic-yield split and the 49%/8% ID-outcome split are the strongest sub-entity evidence in the literature and they'd be destroyed by lumping.

  3. Existing module conformance candidates: epilepsy_excitation_inhibition_imbalance#Excitation-Inhibition Imbalance is a clean fit. The sleep-dependent-downscaling mechanism (Model B) has no existing module and is a plausible future one — it recurs conceptually across DEEs.

  4. Curate the mechanism as competing hypotheses, not one chain. Model A (thalamocortical disconnection / augmenting response, status: CANONICAL for structural cases) and Model B (synaptic homeostasis failure, CANONICAL for the encephalopathy) are complementary; the neuroinflammatory/steroid-responsiveness explanation is a genuine KNOWLEDGE_GAP.

  5. Three explicit gaps worth discussions entries: (a) the unvalidated SWI threshold (85% vs 50% vs ILAE's deliberate silence); (b) why steroids work, given no confirmed immune mechanism; (c) no disease-specific QoL instrument and no population prevalence/incidence figure.

  6. One HUMAN_MODEL_MISMATCH: the Cnksr2 USV phenotype as a language proxy. Real, useful, and not the same thing as aphasia.

  7. Evidence discipline: every [reported] quote above needs just fetch-reference PMID:xxxxx and a manual substring check before it becomes a snippet:. The [verbatim-verified] ones came out of full cached text and should survive validate-references as-is — and remember the ≥5-word minimum and no square brackets.

Sources