Previously Severe myoclonic epilepsy of infancy. Charlotte Dravet described in 70s. Characterised by:
- Refractory epilepsy
- Onset in infancy
- Associated neurodevelopmental problems
Due to defect in SCN1A gene on chromosome 2q24 (a sodium channel), usually de novo. Many mutations, don’t predict severity, unfortunately.
Accounts for about 7% of epilepsy presenting in first 3 years of life.
Onset around 5-8 months, often with febrile illness so can look like typical febrile convulsion. But often prolonged. Neurodevelopmental problems come later…
Later though, multiple seizure types. Hypotonia, ataxia, spasticity all seen. Dysautomnia can be a feature. ADHD and autistic traits common later.
EEG can be normal, or vary over time, with multifocal or generalised changes, photosensitivity too.