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
- 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
Consultant Paediatric Neurologist
Great Ormond Street Hospital
RR declares that he has no competing interests.
Clinical Fellow in Epilepsy
Great Ormond Street Hospital
KV declares that she has no competing interests.
Dr Robert Robinson and Dr Katharina Vezyroglou would like to gratefully acknowledge Dr Marjorie Illingworth, Dr Pradnya Gadgil, Dr Teesta Soman, and Dr Shelly Weiss, previous contributors to this monograph. MI, PG, TS, and SW declare that they have no competing interests.
Section Chief of Neurology
Dartmouth-Hitchcock Medical Center
GLH declares that he has no competing interests.
Attending Pediatric Neurologist
Division of Neurology
Bambino Gesu Children's Hospital
MRC declares that she has no competing interests.
Professor of Neurology
Department of Pediatrics
University of Montreal
Director of Epilepsy Clinic and Research Group
Saint Justine Hospital
LC declares that he has no competing interests.
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