Abstracts

Rationale: With the widespread use of SCN1A genetic tests, patients with SCN1A mutations have been increasingly reported. Accordingly, electroclinical spectrum of SCN1A mutation positive patients seems to be expanding beyond classic Dravet syndrome.. This study reviews the electroclinical features of SCN1A mutation positive patients and discusses the additional core features requiring further validation.Methods: We reviewed the electroclinical features of 44 patients with confirmed SCN1A mutations. SCN1A mutational analysis was performed with direct Sanger sequencing and multiple ligation dependent probe amplification.Results: : Twenty four of 44 patients were male. The median age of seizure onset and follow-up duration were 5.1 months (range 1 day-13.5 months) and 56.1 months (range 7.6-29.2 months). For early clinical features regarding initial seizures, fever was associated in 23 patients (52%, 23/44). Generalized tonic clonic seizures (51%, 21/41) and hemiclonic seizures (29%, 12/41) were among the frequent seizure type. Seizures were prolonged (more than> 15 minutes) in 13 patients (31%, 13/41). For 23 patients with initial febrile seizures, the median onset of following afebrile seizures was 11.5 months (range 3.5-67.6 months). The median seizure onset of afebrile seizures in total was 7.6 months. The seizure types observed during the follow-up period were generalized tonic clonic (90%, 39/43), focal motor and dyscognitive (88%, 38/43), myoclonic (44%, 19/43), and atypical absence seizures (20%, 9/43). Electroencephalography (EEG) was performed approximately 5 times per patients (range 1-12). In 19 and 3 patients, only focal and generalized epileptiform discharges were present, respectively. Both focal and generalized epileptiform discharges were recorded in 10 patients.Conclusions: In more than half of the SCN1A mutation positive patients, afebrile seizures started before 12 months of age. Focal features in terms of seizure type and EEG abnormalities were also predominant.