Epidemiological and clinical studies of West syndrome in Miyagi Prefecture, Japan

We performed a retrospective epidemiological study of West syndrome (WS) in Miyagi prefecture over a 3-year period (2000-2003). Twenty-two children (6 boys, 16 girls) developed WS. The incidence of WS was 3.4/10,000 live births. It agreed with the incidence of previous report in Japan. The mean age at onset of spasms was 6.5 months (range 1-17 months). Thirteen patients (59%) had symptomatic WS;of these, eight patients had prenatal causes and five had perinatal causes. There were no familial cases, although four patients had family history that included neurological diseases. Periventricular leukomalacia was found in four of nine patients with abnormal magnetic resonance imagings (MRI). Early seizure outcome was good in twenty-one patients (95%). Six patients (29%) had seizure recurrence. There were no significant differences between symptomatic WS and cryptogenic WS in terms of seizure recurrence and persistent EEG abnormalities. The Five patients (20%) with developmental quotients (DQ) more than 70 were all cryptogenic WS, while patients with DQ less than 70 were significantly frequent in symptomatic WS as compared with cryptogenic WS.