Dravet syndrome

Dravet syndrome (severe myoclonic epilepsy of infancy) is a developmental-and-epileptic encephalopathy caused in ~80% of cases by loss-of-function mutations in SCN1A (voltage-gated sodium channel Naᵥ1.1), presenting in the first year of life with prolonged febrile seizures, drug-resistant convulsive and myoclonic seizures, developmental regression, and elevated mortality including SUDEP. In June 2018 cannabidiol (Epidiolex) became the first cannabis-derived drug approved by the FDA, with Dravet as a pivotal indication. The Devinsky et al. GWPCARE1 trial (NEJM 2017) randomized 120 children and young adults to CBD 20 mg/kg/day or placebo; monthly convulsive-seizure frequency fell from 12.4 to 5.9 with CBD versus 14.9 to 14.1 with placebo (adjusted median reduction ~39% vs. 13%; p=0.01), with 43% vs. 27% achieving ≥50% reduction. NASEM (2017) did not specifically address Dravet beyond its general epilepsy rating. → See also: Epidiolex, CBD, Epilepsy, SCN1A.