Severe myoclonic epilepsy of infancy
Caused usually by lack of function mutations of SCN1A with onset about 6 months of age. The convulsions and hemiconvulsions, often with fever do not respond well to current treatments and are associated with impaired intellect. Benzodiazepines, topiramate and valproate are most useful. Consider avoiding carbamazepine, lamotrigine and vigabatrin as they are seizure promotors and phenytoin because of risk of choreaoathetosis.