Dramatic improvement in seizures with phenytoin treatment in an individual with refractory epilepsy and a SCN1B variant

We describe an individual with refractory epilepsy with myoclonic-atonic seizures (EMAS) and a suspected pathogenic variant in SCN1B, who had substantial improvement with phenytoin treatment. It is unknown whether SCN1B-related epilepsy improves or worsens with sodium channel blockers (SCBs), and this case demonstrates their potential benefit.