Researchers at Department of Child Neurology, Okayama University Hospital, Japan, have followed 31 patients with Dravet syndrome (DS) (14 typical and 17 borderline DS) from childhood to at least 18 years of age. The study began with 37 patients but 6 (16.2%) died in childhood (5-12 years), 3 in status epilepticus. Clinical findings in the 31 typical and borderline cases became largely similar in adolescence and adulthood. Seizures were intractable in childhood, but suppressed in five (16.1%) during follow-up. Seizures considered generalized convulsive initially in 40 children, when captured by ictal EEG at 7 years of age, were of focal origin in 35 (87.5%). Myoclonic, atypical absence, and photo- and pattern-sensitive seizures disappeared by 20 years of age in most typical cases. Patients with <3 episodes of convulsive status epilepticus in childhood and no EEG spikes on follow-up (P<0.001) had a seizure-free outcome as adults (P=0.018). Seizure freedom was not correlated with SCN1A mutation type, gender, type of DS, or generalized spike-waves on EEG. Of 26 (83.9%) patients with persisting seizures as adults, 19 (73%) had mostly nocturnal seizures; 10 (38.5%) continued to have seizures provoked by fever, none with status epilepticus. At last follow-up, seizures were refractory in 84%, and 5 patients (16.1%) had 10-29 seizures per month. Seven patients (22.6%) spoke no words and 9 (29%) spoke only several words. Five (16.1%) made simple conversation and could read a little. Occipital alpha rhythms in follow-up EEGs at a mean age of 23.8 years correlated with less severe intellectual disability (P=0.002). Prevention of occurrence of convulsive status epilepticus in childhood was critically important for improved seizure outcome in DS in adulthood. 
COMMENT. In this long-term, follow-up study of patients diagnosed with Dravet syndrome, the main factor associated with improvement of seizure prognosis is the prevention of occurrence of convulsive status epilepticus in childhood. Details of treatment were not listed, except that the approval and introduction of topiramate in 2007 controlled seizures in 4 previously unresponsive patients.