Clinical Scenario: Episodes of abnormal flexion | Abnormal EEG
A 6-month-old infant is brought by his parents because of repeated episodes of sudden flexion of the head, trunk, and arms occurring in clusters, especially shortly after waking. The parents report that he has lost previously acquired developmental milestones over the last month.
Examination reveals:
- Poor eye contact
- Axial hypotonia
- Developmental regression
EEG shows:
- High-amplitude, chaotic, asynchronous slow waves
- Multifocal spikes and sharp waves
- No consistent background rhythm
Which of the following is the most likely diagnosis?
A. Childhood absence epilepsy
B. Infantile spasms (West syndrome)
C. Lennox–Gastaut syndrome
D. Benign epilepsy with centrotemporal spikes
E. Juvenile myoclonic epilepsy
Correct answer & Explanation:
Correct Answer:
B. Infantile spasms (West syndrome)
Explanation
This infant has West syndrome (infantile epileptic spasms syndrome), characterized by the classic triad:
- Infantile spasms
- Sudden brief contractions involving flexion, extension, or mixed movements
- Often occur in clusters, particularly after awakening
- Developmental regression or arrest
- Hypsarrhythmia on EEG
Hypsarrhythmia EEG pattern:
- Very high-voltage (>200 µV) slow waves
- Multifocal spikes and sharp waves
- Chaotic, disorganized background
- No normal sleep-wake organization
This EEG pattern reflects severe disruption of cortical electrical activity.
Why the other options are incorrect
A. Childhood absence epilepsy
- Usually occurs after 4 years of age
- Brief staring episodes
- EEG: regular 3-Hz generalized spike-wave
- No developmental regression
B. Infantile spasms (West syndrome) – Correct
- Age: usually 3–12 months
- Spasms in clusters
- Developmental regression
- Hypsarrhythmia EEG
C. Lennox–Gastaut syndrome
- Usually begins between 1–8 years
- Multiple seizure types including tonic and atonic seizures
- EEG: slow spike-wave (<3 Hz) and paroxysmal fast activity
D. Benign epilepsy with centrotemporal spikes
- Older children
- Focal seizures, often during sleep
- Normal development
E. Juvenile myoclonic epilepsy
- Adolescent onset
- Morning myoclonic jerks
- Generalized polyspike-wave EEG
Learning Point
West syndrome = Infantile spasms + developmental regression + hypsarrhythmia
First-line treatments:
- Hormonal therapy:
- ACTH or high-dose corticosteroids
- Vigabatrin
- Particularly first-line in children with tuberous sclerosis complex
Early treatment is important because persistent spasms and hypsarrhythmia are associated with poorer neurodevelopmental outcomes.
