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PubMed This is a summary of 22 peer-reviewed journal articles Updated
Pediatric Neurology · Developmental and Epileptic Encephalopathy With Spike-Wave Activation in Sleep

The Diagnostic Journey: Finding the Cause and Tracking Progress

At a Glance

DEE-SWAS is evaluated with a sleep EEG that captures NREM activity, together with a child's developmental history and repeated cognitive testing. MRI and genetic testing may help identify an underlying cause, but no single result determines diagnosis or progress.

Diagnosing D/EE-SWAS is a multi-step process that looks beyond the surface of a child’s symptoms. It requires “linking” the behavioral and cognitive changes you see at home with specific electrical patterns in the brain during sleep. The goal of the diagnostic workup is not just to name the condition, but to find its underlying cause and create a roadmap for treatment [1][2].

The Sleep EEG: Capturing the “Night Shift”

The most critical tool for diagnosis is the EEG (electroencephalogram). Because the electrical activity that defines this condition specifically activates during sleep, a standard 20-minute daytime EEG may not be enough [3].

  • Capturing NREM Sleep: Doctors must see the brain’s activity during NREM (Non-Rapid Eye Movement) sleep, which is when the “spike-wave” pattern typically emerges [3]. While an all-night EEG is often ideal, some centers use a daytime “nap” EEG if it captures an adequate sample of NREM sleep [4][5]. There is no universally accepted minimum sleep duration, and the choice between a nap and overnight study is individualized.
  • The Spike-Wave Index (SWI): This is a measurement of how “busy” the brain is during sleep. It is often calculated as the percentage of 1-second intervals during sleep that contain at least one electrical spike [6].
  • The “Threshold” Debate: Historically, definitions often referenced an SWI of >85%. However, many modern clinical frameworks now consider thresholds like >50% if the child is showing clear signs of developmental regression [7][8]. It is important to remember that the SWI is just one number, not a definitive diagnostic cutoff by itself; your child’s actual daily functioning and skills matter more than the exact percentage on a screen [9][10][11].

MRI: Looking for a Structural Cause

An MRI (Magnetic Resonance Imaging) scan is used to see if a physical difference in the brain is “triggering” the electrical activity. In certain selected research cohorts, the MRI has shown a structural abnormality in about 33% to 66% of cases [12][13].

  • What Doctors Look For: They specifically check for conditions like polymicrogyria (where the surface of the brain has too many small folds) or focal cortical dysplasia (where some brain cells didn’t develop correctly) [14][15].
  • The Thalamus Connection: Note that thalamic volume differences are currently group-level research observations rather than routine diagnostic findings [16][17]. Even if a visual review of the MRI looks “normal,” specialized analysis may find subtle changes [18].

Genetic Testing: The “Blueprint”

Because D/EE-SWAS can sometimes be caused by a “glitch” in the child’s genetic code, genetic testing is often considered, especially with developmental concerns [1].

  • Common Genes: The most frequently identified gene involved is GRIN2A, but several others like CNKSR2 or ZEB2 have also been linked to the condition [2][19].
  • Why it Matters: Testing can result in uncertain findings, but a genetic diagnosis can sometimes help inform the etiology, provide prognostic information, and guide genetic counseling, though it rarely provides an immediate change to precise treatment [1][20].

Serial Neuropsychological Testing

Because this condition directly impacts learning and behavior, a single IQ test is not enough. Experts recommend serial neuropsychological testing—repeated assessments every few months or years [1]. These tests measure several “domains,” including:

  • Language and speech
  • Attention and executive function (planning and focus)
  • Memory and visuospatial skills [21]

Tracking these scores over time is the best way to tell if a treatment is working. If the EEG gets “cleaner” but the child’s scores continue to drop, the medical team may need to adjust their approach [9][22]. No single test provides the whole answer; the diagnosis is built by looking at the EEG, the MRI, the genes, and your child’s daily progress together.

Common questions in this guide

Why does a child need a sleep EEG for DEE-SWAS?
The electrical pattern doctors look for in DEE-SWAS becomes more prominent during sleep, especially during NREM sleep. A short daytime EEG may not capture it, so an overnight study or a nap EEG with enough NREM sleep may be recommended.
What does the spike-wave index mean in DEE-SWAS?
The spike-wave index, or SWI, is the percentage of one-second intervals during sleep that contain at least one electrical spike. Older definitions often used a value above 85%, while some modern approaches consider values above 50% when developmental regression is clear; the SWI must be interpreted alongside the child's functioning rather than used alone.
Can an MRI show why a child has DEE-SWAS?
An MRI looks for structural differences in the brain that may contribute to abnormal electrical activity. Examples include polymicrogyria, in which the brain surface has extra small folds, and focal cortical dysplasia, in which some brain cells develop abnormally. A scan that looks normal on routine review may still contain subtle findings requiring specialized analysis.
Should genetic testing be considered for a child with DEE-SWAS?
Genetic testing is often considered when a child has developmental concerns. GRIN2A is the most frequently identified gene, and CNKSR2 or ZEB2 may also be involved; results can clarify the cause, inform prognosis, and support genetic counseling, but they do not usually produce an immediate, precise treatment change.
Why are neuropsychological tests repeated over time in DEE-SWAS?
Repeated testing measures changes in language, speech, attention, planning, memory, and visuospatial skills. Comparing results over time helps the care team judge whether development is improving or declining and whether the treatment approach needs adjustment, even if the EEG looks better.
What should caregivers track before a DEE-SWAS evaluation?
Keep a timeline of the first changes in skills, language, behavior, attention, or learning, and note whether they seem worse after poor sleep. Also share prior medical or developmental concerns and any daytime changes, and ask whether evaluation by a pediatric epilepsy specialist is appropriate.

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References

References (22)
  1. 1

    Developmental and/or Epileptic Encephalopathy with Spike-Wave Activation in Sleep: From Thalamocortical Mechanisms to Precision Therapy.

    Samanta D

    Children (Basel, Switzerland) 2026; (13(8)) doi:10.3390/children13080993.

    PMID: 42650333
  2. 2

    Pathophysiology of developmental and/or epileptic encephalopathy with spike-wave activation in sleep: A diagnostic framework.

    Rasheed A, Sekar S, Naqvi R, et al.

    Developmental medicine and child neurology 2026; doi:10.1111/dmcn.70462.

    PMID: 42623508
  3. 3

    How to Manage Electrical Status Epilepticus in Sleep.

    Veggiotti P, Pera MC, Olivotto S, De Giorgis V

    Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society 2016; (33(1)):3-9 doi:10.1097/WNP.0000000000000235.

    PMID: 26840869
  4. 4

    The First 100 Seconds of Sleep of rEEGs Can Be a Reliable Scoring Method for D/EE-SWAS.

    Kulkarni N, Klamer B, Drees M, Twanow JD

    Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society 2025; (42(2)):172-175 doi:10.1097/WNP.0000000000001089.

    PMID: 38857411
  5. 5

    The Spike-Wave Index of the First 100 Seconds of Sleep Can Be a Reliable Scoring Method for Electrographic Status Epilepticus in Sleep.

    Kulkarni N, Albert DVF, Klamer B, et al.

    Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society 2023; (40(6)):547-552 doi:10.1097/WNP.0000000000000918.

    PMID: 35025840
  6. 6

    EEG response to high dose nocturnal diazepam in children with developmental/epileptic encephalopathy with spike-and-wave activation in sleep (DEE/EE-SWAS).

    Kiani H, Whitney R, Go C, et al.

    Epilepsy & behavior : E&B 2025; (171()):110498 doi:10.1016/j.yebeh.2025.110498.

    PMID: 40412341
  7. 7

    Perinatal thalamic injury: MRI predictors of electrical status epilepticus in sleep and long-term neurodevelopment.

    van den Munckhof B, Zwart AF, Weeke LC, et al.

    NeuroImage. Clinical 2020; (26()):102227 doi:10.1016/j.nicl.2020.102227.

    PMID: 32182576
  8. 8

    Neurobehavioral deterioration associated with sleep-augmented epileptiform abnormalities: A steroid responsive state in children.

    Jauhari P, Madaan P, Sirolia V, et al.

    Epilepsy & behavior : E&B 2022; (129()):108505 doi:10.1016/j.yebeh.2021.108505.

    PMID: 35168122
  9. 9

    Effect of immunotherapy on seizure severity and spike-wave index in epileptic encephalopathy with spike-wave activation in sleep: The value of EEG spikes in monitoring treatment response.

    Topaloğlu P, Dörtkol O, Emekli S, et al.

    Epilepsy research 2026; (226()):107861 doi:10.1016/j.eplepsyres.2026.107861.

    PMID: 42407303
  10. 10

    Clinical and Molecular Genetic Characterization of Landau Kleffner Syndrome: An Observational Cohort and Experimental Study.

    Ngoh A, Clark M, Greenaway R, et al.

    Annals of neurology 2025; (98(5)):951-966 doi:10.1002/ana.27306.

    PMID: 40944498
  11. 11

    European experience of steroid therapy in children with developmental and epileptic encephalopathy with spike wave activation in sleep ((D)EE-SWAS).

    Canbay D, Jansen FE, Schönberger J, et al.

    Orphanet journal of rare diseases 2025; (20(1)):204 doi:10.1186/s13023-025-03725-0.

    PMID: 40301922
  12. 12

    Epileptic encephalopathy with electrical status epilepticus during slow sleep: evaluation of treatment response from a tertiary center.

    Kılıç B, Acar M, Topçu Y, Turanlı G

    The Turkish journal of pediatrics 2022; (64(2)):302-311.

    PMID: 35611419
  13. 13

    Expanding the clinical and genetic landscape of (developmental) epileptic encephalopathy with spike-and-wave activation in sleep: results from studies of a Turkish cohort.

    Türkyılmaz A, Sağer SG, Tekin E, et al.

    Neurogenetics 2024; (25(2)):119-130 doi:10.1007/s10048-024-00751-1.

    PMID: 38388889
  14. 14

    The syndrome of polymicrogyria, thalamic hypoplasia, and epilepsy with CSWS.

    Bartolini E, Falchi M, Zellini F, et al.

    Neurology 2016; (86(13)):1250-9 doi:10.1212/WNL.0000000000002526.

    PMID: 26944271
  15. 15

    Surgically Remediable Secondary Network Epileptic Encephalopathies With Continuous Spike Wave in Sleep: Lesions May Not Be Visible on Brain Magnetic Resonance Imaging (MRI).

    Alawadhi A, Appendino JP, Hader W, et al.

    Journal of child neurology 2022; (37(12-14)):992-1002 doi:10.1177/08830738221129919.

    PMID: 36184927
  16. 16

    Thalamic volumetric analysis in Developmental and/or Epileptic Encephalopathy with Spike Wave Activation in Sleep (D/EE-SWAS): A cross-sectional study.

    Kamila G, Jauhari P, Kumar A, et al.

    Seizure 2025; (127()):94-100 doi:10.1016/j.seizure.2025.03.006.

    PMID: 40120364
  17. 17

    Reduced thalamic volume in patients with Electrical Status Epilepticus in Sleep.

    Sánchez Fernández I, Peters JM, Akhondi-Asl A, et al.

    Epilepsy research 2017; (130()):74-80 doi:10.1016/j.eplepsyres.2017.01.010.

    PMID: 28160673
  18. 18

    Thalamic abnormalities in children with continuous spike-wave during slow-wave sleep: An F-18-fluorodeoxyglucose positron emission tomography perspective.

    Agarwal R, Kumar A, Tiwari VN, Chugani H

    Epilepsia 2016; (57(2)):263-71 doi:10.1111/epi.13278.

    PMID: 26697846
  19. 19

    The genetic landscape of developmental and epileptic encephalopathy with spike-and-wave activation in sleep.

    Freibauer AE, RamachandranNair R, Jain P, et al.

    Seizure 2023; (110()):119-125 doi:10.1016/j.seizure.2023.06.017.

    PMID: 37352690
  20. 20

    Primidone improves symptoms in TRPM3-linked developmental and epileptic encephalopathy with spike-and-wave activation in sleep.

    Becker LL, Horn D, Boschann F, et al.

    Epilepsia 2023; (64(5)):e61-e68 doi:10.1111/epi.17586.

    PMID: 36929095
  21. 21

    Paediatric-tailored modified IC-CoDE approach in non-lesional D/EE-SWAS.

    Andreoli L, Granocchio E, Caputo D, et al.

    Epilepsy & behavior : E&B 2025; (173()):110784 doi:10.1016/j.yebeh.2025.110784.

    PMID: 41161200
  22. 22

    Treatment of electrical status epilepticus in sleep: Clinical and EEG characteristics and response to 147 treatments in 47 patients.

    van den Munckhof B, Alderweireld C, Davelaar S, et al.

    European journal of paediatric neurology : EJPN : official journal of the European Paediatric Neurology Society 2018; (22(1)):64-71 doi:10.1016/j.ejpn.2017.08.006.

    PMID: 29128194

This page is for informational purposes only and does not replace medical advice. A pediatric neurologist or epilepsy team should interpret your child's EEG, MRI, genetic results, and developmental testing.

Guide contents Continuous spikes and waves during sleep
Research & Literature
02 Symptoms of D/EE-SWAS 04 Treatment Options