Skip to content
How It Works
Explore
Resources Ask a Question
Who It's For
Patients
Decode results, prep for appointments, weigh options.
Caregivers & advocates
Carry the research load for someone you love.
Providers & clinicians
Resources for patients in your practice.
Log In Ask a Question
PubMed This is a summary of 19 peer-reviewed journal articles Updated
Pediatric Neurology

Diagnostic Deep Dive: EEG, MRI, and Genetics

At a Glance

Diagnosing West syndrome requires an extended video EEG to detect the chaotic hypsarrhythmia brain wave pattern, a high-resolution 3T MRI to identify hidden structural brain abnormalities, and comprehensive genetic and metabolic testing to uncover the exact cause of the infantile spasms.

Because West Syndrome is so urgent, doctors must quickly gather a complete picture of your child’s brain. This process involves looking at the brain’s “wiring” (EEG), its “structure” (MRI), and its “instruction manual” (Genetics).

The EEG: Capturing the Chaos

The electroencephalogram (EEG) is the most critical tool for diagnosing West Syndrome. It uses small sensors on the scalp to record brain waves.

The classic finding is called hypsarrhythmia—a pattern that looks chaotic, high-voltage, and disorganized [1][2]. However, your doctor may mention “variants” or “modified hypsarrhythmia.” This means the pattern is still abnormal but might be lopsided or “fragmented” [2][3].

Important Note: A child can still have West Syndrome even if the EEG doesn’t show “classic” hypsarrhythmia [4][5]. The absence of this specific pattern does not rule out the syndrome if the spasms and developmental changes are present [6].

The MRI: A High-Definition View

A standard MRI used for a headache is not enough. To find the cause of spasms, doctors need a high-resolution MRI (often a 3T or “3-Tesla” machine) using a dedicated Epilepsy Protocol [7][8].

This protocol (sometimes called the HARNESS protocol) takes much thinner “slices” of the brain images [9][10]. This is vital because many causes of spasms, such as focal cortical dysplasia (FCD), are tiny malformations that are easily missed on standard scans [7][11].

Genetic Testing: The Deep Dive

Finding a genetic cause can change your child’s treatment, help predict their future needs, and provide information on the recurrence risk for future pregnancies. Modern testing uses Next-Generation Sequencing (NGS) to scan thousands of genes at once [12].

  • Epilepsy Panels: These test a specific group of genes known to cause seizures.
  • Whole Exome Sequencing (WES): If a panel is negative, a WES looks at all the “active” parts of your child’s DNA. This is often recommended as a first-tier test because it is highly effective at finding rare causes [13][14].
  • Chromosomal Microarray: This looks for missing or extra pieces of genetic material [15][16].

Completeness Checklist

To ensure your child has received a thorough evaluation, you can ask your team about these specific steps:

  1. Extended Video EEG: Ideally, this should last long enough to capture a full cycle of sleep and waking, as spasms and hypsarrhythmia are most visible then [17].
  2. 3T MRI with Epilepsy Protocol: Ensure the scan is high-resolution and reviewed by a pediatric neuroradiologist [8][18].
  3. Comprehensive Genetics: This includes an epilepsy gene panel or Whole Exome Sequencing (WES) [13][12].
  4. Metabolic Screening (Including Vitamin B6): Blood, urine, and sometimes cerebrospinal fluid (CSF) via a lumbar puncture (spinal tap) should be evaluated [19]. Crucially, the team should perform a trial of Vitamin B6 (pyridoxine). Vitamin B6-dependent epilepsy is a highly treatable metabolic cause. If missed, an infant may be subjected to toxic, ineffective steroid treatments instead of the specific vitamin that stops the seizures immediately.

Previous: The “Why” Behind the Spasms: Understanding Causes | Next: Standard of Care: Treatments and the 14-Day Rule

Common questions in this guide

What does hypsarrhythmia mean on my child's EEG?
Hypsarrhythmia is a chaotic, highly disorganized brain wave pattern that is the classic hallmark of West syndrome. However, some children may have a modified or variant form of this pattern and still be diagnosed with the condition.
Why does my child need a special MRI for West syndrome?
A standard MRI may miss the tiny structural brain malformations that often cause infantile spasms. A high-resolution 3T MRI using a dedicated epilepsy protocol takes thinner images of the brain, allowing pediatric neuroradiologists to spot hard-to-see abnormalities like focal cortical dysplasia.
What genetic tests are used to diagnose infantile spasms?
Doctors typically use epilepsy gene panels or Whole Exome Sequencing (WES) to scan thousands of genes at once. Identifying a specific genetic cause can drastically change your child's treatment plan and help predict their future needs.
Why do doctors perform a Vitamin B6 trial?
A trial of Vitamin B6 (pyridoxine) is essential to check for a highly treatable metabolic condition called Vitamin B6-dependent epilepsy. If this is the cause, administering the vitamin can stop the seizures immediately, avoiding the need for heavy steroid treatments.
Can my child have West syndrome without classic hypsarrhythmia on the EEG?
Yes. While classic hypsarrhythmia is a common sign, its absence does not completely rule out West syndrome. A diagnosis can still be made if the clinical spasms and developmental changes are present alongside a modified abnormal EEG.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Does the EEG show classic hypsarrhythmia, or a modified/variant version of it?
  2. 2.Was this MRI performed using a dedicated 'Epilepsy Protocol' on a 3T machine?
  3. 3.Who is the neuroradiologist reviewing these scans—do they specialize in pediatric epilepsy?
  4. 4.If the epilepsy gene panel is negative, when will we move to Whole Exome Sequencing (WES)?
  5. 5.Will you perform a trial of Vitamin B6 (pyridoxine) to rule out a metabolic dependency?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (19)
  1. 1

    Post-Traumatic West Syndrome due to Abusive Head Trauma in Two Infants with Different Brain Imaging Findings.

    Takeda R, Kobayashi S, Kamioka N, et al.

    The Tohoku journal of experimental medicine 2020; (250(3)):167-171 doi:10.1620/tjem.250.167.

    PMID: 32161214
  2. 2

    Association of Child Neurology (AOCN) - Indian Epilepsy Society (IES) Consensus Guidelines for the Diagnosis and Management of West Syndrome.

    Sharma S, Kaushik JS, Srivastava K, et al.

    Indian pediatrics 2021; (58(1)):54-66.

    PMID: 33452776
  3. 3

    Epileptic spasms in clusters with focal EEG paroxysms: A study of 12 patients.

    Caraballo RH, Reyes G, Falsaperla R, et al.

    Seizure 2016; (35()):88-92.

    PMID: 26803282
  4. 4

    Rapid Electroclinical Evolution in HECW2-Related Developmental and Epileptic Encephalopathy: Report of a Likely Splicing Variant With Familial Transmission.

    Melgarejo S, Reyes Valenzuela G, Juanes M, et al.

    International journal of developmental neuroscience : the official journal of the International Society for Developmental Neuroscience 2025; (85(5)):e70041 doi:10.1002/jdn.70041.

    PMID: 40879666
  5. 5

    The impact of hypsarrhythmia on infantile spasms treatment response: Observational cohort study from the National Infantile Spasms Consortium.

    Demarest ST, Shellhaas RA, Gaillard WD, et al.

    Epilepsia 2017; (58(12)):2098-2103 doi:10.1111/epi.13937.

    PMID: 29105055
  6. 6

    Definitions and Diagnostic Criteria for Infantile Spasms and West Syndrome - Historical Perspectives and Practical Considerations.

    Mytinger JR

    Seminars in pediatric neurology 2021; (38()):100893 doi:10.1016/j.spen.2021.100893.

    PMID: 34183140
  7. 7

    In vivo 9.4 Tesla MRI of a patient with drug-resistant epilepsy: Technical report.

    van Lanen RHGJ, Uher D, Tse DHY, et al.

    Acta neurochirurgica 2025; (167(1)):18 doi:10.1007/s00701-024-06385-4.

    PMID: 39820684
  8. 8

    Diagnostic value of MRI in the presurgical evaluation of patients with epilepsy: influence of field strength and sequence selection: a systematic review and meta-analysis from the E-PILEPSY Consortium.

    Rados M, Mouthaan B, Barsi P, et al.

    Epileptic disorders : international epilepsy journal with videotape 2022; (24(2)):323-342 doi:10.1684/epd.2021.1399.

    PMID: 34961746
  9. 9

    Harmonization of MRI sequences across ERN EpiCARE centers.

    Adler S, D'Arco F, Mankad K, et al.

    Epilepsia open 2025; (10(2)):587-592 doi:10.1002/epi4.13115.

    PMID: 39943698
  10. 10

    Neuroimaging in Adults and Children With Epilepsy.

    Passaro EA

    Continuum (Minneapolis, Minn.) 2023; (29(1)):104-155 doi:10.1212/CON.0000000000001242.

    PMID: 36795875
  11. 11

    Utility of additional dedicated high-resolution 3T MRI in children with medically refractory focal epilepsy.

    Ahmed R, Rubinger L, Go C, et al.

    Epilepsy research 2018; (143()):113-119 doi:10.1016/j.eplepsyres.2018.01.002.

    PMID: 29398181
  12. 12

    The Utility of Genetic Testing in Infantile Epileptic Spasms Syndrome: A Step-Based Approach in the Next-Generation Sequencing Era.

    Kanmaz S, Yılmaz S, Olculu CB, et al.

    Pediatric neurology 2024; (157()):100-107 doi:10.1016/j.pediatrneurol.2024.05.018.

    PMID: 38905742
  13. 13

    Diagnostic yields of genetic testing and related benefits in infantile epileptic spasms syndrome: A systematic review and meta-analysis.

    Feng X, Yang J, Chen N, et al.

    Seizure 2025; (124()):18-24 doi:10.1016/j.seizure.2024.11.014.

    PMID: 39612907
  14. 14

    Diagnostic yield of a multi-strategy genetic testing procedure in a nationwide cohort of 728 patients with infantile spasms in China.

    Liu LY, Lu Q, Wang QH, et al.

    Seizure 2022; (103()):51-57 doi:10.1016/j.seizure.2022.10.014.

    PMID: 36279597
  15. 15

    Novel copy number variations and phenotypes of infantile epileptic spasms syndrome.

    Cheng M, Bai L, Yang Y, et al.

    Clinical genetics 2024; (106(2)):161-179 doi:10.1111/cge.14520.

    PMID: 38544467
  16. 16

    Homozygous exonic and intragenic NRXN1 deletion presenting as either West syndrome or autism spectrum disorder in two siblings.

    Aksu Uzunhan T, Ayaz A

    Clinical neurology and neurosurgery 2022; (214()):107141 doi:10.1016/j.clineuro.2022.107141.

    PMID: 35101781
  17. 17

    Confirmation of infantile spasms resolution by prolonged outpatient EEGs.

    Yuskaitis CJ, Mysak K, Godlewski B, et al.

    Epilepsia open 2021; (6(4)):714-719 doi:10.1002/epi4.12540.

    PMID: 34524734
  18. 18

    Bottom-of-sulcus focal cortical dysplasia presenting as epilepsia partialis continua multimodality characterization including 7T MRI.

    Kelley SA, Robinson S, Crone NE, Soares BP

    Child's nervous system : ChNS : official journal of the International Society for Pediatric Neurosurgery 2018; (34(6)):1267-1269 doi:10.1007/s00381-018-3749-2.

    PMID: 29445916
  19. 19

    Genetic Advancements in Infantile Epileptic Spasms Syndrome and Opportunities for Precision Medicine.

    Snyder HE, Jain P, RamachandranNair R, et al.

    Genes 2024; (15(3)) doi:10.3390/genes15030266.

    PMID: 38540325

This page provides educational information about diagnostic testing for West syndrome. Always consult a pediatric neurologist or epileptologist to properly interpret your child's specific EEG, MRI, and genetic results.

Get notified when new evidence is published on West syndrome.

We monitor PubMed for new peer-reviewed studies on this topic and email a short summary when something meaningful changes.