An epilepsy syndrome typically presenting in infancy, with a varying aetiology.
Spasms may be flexor, extensor, mixed flexor-extensor, symmetrical, or asymmetrical, and typically occur in clusters.
A hypsarrhythmic electroencephalogram is characteristic but not universally present at all times.
A mortality rate of 5% to 30% is reported. Among survivors, developmental delay ensues in 80% to 90%, and 50% to 70% later develop other seizure types.
Treatment options include hormonal therapy (adrenocorticotropic hormone or corticosteroids) or vigabatrin.
Infantile spasms are the characteristic seizure type of West's syndrome (infantile spasms, developmental plateau, and hypsarrhythmia). Age of onset is typically from 1 month to 1 year with a median age of 3 to 5 months. The seizures are characterised by an initial contraction phase followed by a more sustained tonic phase. The contractions may be flexor, extensor, or mixed flexor-extensor, with sudden, usually bilateral, symmetrical contractions of the neck, trunk, and limbs. There may be an associated brief loss of consciousness. The seizures may be subtle, consisting of brief head nods, or be precipitated by sleep onset and offset or by feeding, leading to diagnostic confusion with gastro-oesophageal reflux. They typically occur in clusters or runs of 20 to 100 spasms at a time, with visible distress. Aetiology is heterogeneous and, in a significant proportion, remains unidentified.
A hypsarrhythmic electroencephalogram pattern is characteristic, although not universally present. Onset of infantile spasms is often followed by plateauing or regression of subsequent development. West's syndrome is thus the archetypal infantile epileptic encephalopathy. It is considered that rapid identification and treatment of the spasms improves prognosis.
History and exam
Key diagnostic factors
- presence of risk factors
- head nodding
- neurodevelopmental delay or regression
- ash leaf macules
Other diagnostic factors
- onset age 3-12 months
- perinatal complication
- abnormal eye movements
- motor system abnormalities
- brain malformation
- neurocutaneous syndrome
- antenatal or perinatal vascular event
- intrauterine or perinatal infections
- inherited metabolic disorder
- genetic disorders
- family history
- neonatal sinovenous thrombosis
- postnatal brain injury
- brain tumours
1st investigations to order
- plasma glucose
- serum calcium
- serum magnesium
- renal function tests
- blood and urine cultures
- microarray comparative genome hybridisation (CGH)
Investigations to consider
- brain MRI
- brain CT
- serum lactate/pyruvate
- serum ammonia
- serum amino acids
- urine amino acids and organic acids
- cytomegalovirus (CMV) culture, polymerase chain reaction (PCR), or serology
- toxoplasmosis serology
- renal ultrasound
- ophthalmology examination
- urine alpha-amino adipic semialdehyde dehydrogenase
- cerebrospinal fluid (CSF) examination
- gene mutation analysis
- chromosomal analysis
- Severe myoclonic epilepsy of infancy (Dravet syndrome)
- Benign familial infantile seizures
- Benign neonatal sleep myoclonus
- Epilepsies in children, young people and adults
- Evidence-based guideline update: medical treatment of infantile spasms
Epilepsy: questions to ask your doctorMore Patient leaflets
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