What is West Syndrome?

West Syndrome: A Catastrophic Epileptic Syndrome of Infancy

West Syndrome is a catastrophic epileptic syndrome in infancy characterized by a triad of infantile spasms, psychomotor deterioration, and a distinctive hypsarrhythmic EEG pattern, with poor long-term outcomes particularly in symptomatic cases. 1, 2

Clinical Presentation

Core Features

• Infantile spasms: Brief, sudden contractions of muscles of the neck, trunk, and extremities that typically occur in clusters
• Developmental regression or arrest: Often noticed around the time spasms begin
• Hypsarrhythmia on EEG: Chaotic, high-amplitude, disorganized pattern that is the hallmark EEG finding

Age of Onset

• Typically occurs in infants younger than 1 year
• Peak onset between 4-7 months of age 3
• Rarely seen in children older than 2 years 2

Etiology

West Syndrome can be classified based on underlying causes:

1. Symptomatic (80-85% of cases): Identifiable underlying cause

   • Hypoxic-ischemic encephalopathy (most common - ~70%) 1
   • Brain malformations/cortical development disorders
   • Chromosomal abnormalities (including Down syndrome)
   • Tuberous sclerosis
   • Sturge-Weber syndrome
   • Metabolic disorders

2. Cryptogenic (10-15%): Presumed organic cause but not identified

3. Idiopathic (rare, ~3%): No identifiable cause 1

Diagnosis

Diagnosis is based on the clinical triad:

1. Clinical observation of characteristic spasm patterns
2. EEG findings showing hypsarrhythmia (high-amplitude, chaotic, disorganized pattern)
3. Developmental assessment showing regression or arrest

Additional diagnostic workup:

• Brain MRI to identify structural abnormalities
• Genetic testing
• Metabolic screening
• Video-EEG monitoring to capture events

Treatment

Early diagnosis and prompt treatment are critical for improving outcomes. First-line treatments include:

1. ACTH (Adrenocorticotropic hormone):

   • Traditionally considered highly effective
   • Various dosing protocols exist, with evidence suggesting low doses may be as effective as high doses
   • Typically administered for 2 weeks followed by tapering 3
   • Potential serious side effects include hypertension, Cushing syndrome, and rarely death 1

2. Vigabatrin:

   • Particularly effective for tuberous sclerosis-related infantile spasms
   • Dosage: 50-150 mg/kg/day 3
   • Major concern is retinal toxicity (21-34% of infants), especially with treatment >6 months 3
   • Recommended as first-line therapy by many experts

3. Oral corticosteroids:

   • Prednisolone 40-60 mg/day for 14 days has shown effectiveness 3
   • Generally better tolerated than ACTH

Treatment Algorithm:

1. Start with vigabatrin (especially if tuberous sclerosis is present)
2. If spasms persist after 15 days at maximum dose (150 mg/kg), consider ACTH 1
3. If both fail, consider alternative anticonvulsants or ketogenic diet

Prognosis

Prognosis is generally poor and depends on several factors:

1. Underlying etiology: The strongest predictor of outcome

   • Symptomatic cases have worse outcomes than cryptogenic/idiopathic
   • Hypoxic-ischemic encephalopathy cases often develop other seizure types and neurological deficits 1
   • Malformations of cortical development and Sturge-Weber syndrome have particularly poor prognoses 1

2. EEG patterns: Persistent hypsarrhythmia indicates worse outcomes

3. Pre-existing seizures: Presence of seizures before spasms indicates poorer prognosis 4

4. Treatment response: Rapid response to treatment is associated with better outcomes

5. Treatment lag: Shorter time between symptom onset and treatment may improve outcomes, though this remains controversial 4

Long-term Outcomes:

• Mortality rate: ~7% 1
• Development of other seizure types: ~43% 1
• Lennox-Gastaut syndrome development: ~14% 1
• Severe psychomotor retardation: ~76% in symptomatic cases 1
• Intractable epilepsy: ~24% in symptomatic cases 1

Key Considerations for Management

1. Early diagnosis and treatment are crucial for improving outcomes
2. Regular monitoring for treatment side effects (retinal examinations for vigabatrin, blood pressure monitoring for ACTH)
3. Developmental support services should be initiated early
4. Family support is essential as there is significant psychosocial impact on families 4

Conclusion

West Syndrome represents a medical emergency requiring prompt diagnosis and treatment to minimize developmental impact. The underlying etiology is the strongest predictor of long-term outcome, with symptomatic cases generally having poorer prognoses. Treatment should be initiated rapidly, with the choice between ACTH and vigabatrin often determined by the underlying cause and potential side effect profile.