Abstracts

Rationale: Dravet syndrome (DS) is an epileptic encephalopathy characterized in the first year of life by prolonged febrile or afebrile seizure and resultant progressive developmental delay & cognitive dysfunction. Mutations in SCN1A, encountered with the DS, but there are significant proportion of DS without mutations of SCN1A. We compared the characteristics of DS with SCN1A mutation with those without mutation.Methods: We reviewed the medical records of 32 DS patients between 2005 and 2007 at Severance Children’s Hospital. We analyzed the clinical characteristics, EEG findings, MRI findings, and developmental test in two groups. Results: Among 32 DS patients, 22 (69%) patients have mutations of SCN1A, 10 (31%) have no mutations. There are no significant differences between SCN1A gene (+) group and SCN1A gene (-) group in clinical characteristics including family history of febrile seizure, seizure classification, seizure onset age, sex, response to antiepileptic drug and ketogenic diet, seizure frequency, and developmental state. EEG findings showed no difference between two groups. Among 10 SCN1A gene (-) patients, 4 (40.0%) have abnormal MRI findings (1 calcification, 1 hippocampal sclerosis, 1 harmatomatous lesion), compared to 2 (9.1%) out of 22 SCN1A gene (+) patients (1 cortex lesion, 1 hippocampal sclerosis) (p=0.017). Conclusions: We concluded that there are similar clinical manifestation in DS patients, irrespective of mutation of SCN1A except MRI findings. MRI abnormal finding were significantly more frequent in patients without SCN1A mutation.