An epidemiological study of children with status epilepticus in Okayama, Japan: Incidence, etiologies, and outcomes

To clarify the incidence of first-ever episodes of status epilepticus (SE), their etiologies and outcomes among Japanese children, we performed an epidemiological study in Okayama City. One hundred and twenty patients (69 males, 51 females) experienced first-ever SE episodes between 2003 and 2005. Overall, the annual incidence of SE was 42.0 per 100,000 population (95% CI: 34.5-49.5). The highest incidence was seen in patients aged <2. years, especially in the second year of life. Febrile SE accounted for 59 (49.2%) cases, and acute-symptomatic etiologies accounted for 21. Ten were considered to have remote-symptomatic etiologies, and eight to have acute-on-remote-symptomatic etiologies. Ten were classified as cryptogenic/idiopathic epilepsy-related, and 12 were unclassified. Nineteen (15.8%) patients were diagnosed with exanthema subitum, including three with encephalitis/encephalopathy, and 17 (14.2%) patients with influenza, including four with encephalitis/encephalopathy. After SE, eight (6.7%) patients suffered from motor disturbance with or without mental disturbance. One of these died during the follow-up period. Ultimately 34 (28.3%) of the 120 patients had been diagnosed with epilepsy by the end of the follow-up. We conclude that the incidence of SE among Japanese children is higher than the reported incidence among Caucasian children. Febrile SE accounted for approximately half of the cases. Among the etiologies, exanthema subitum was the most important infectious disease, followed by influenza. Both types of infection caused encephalitis/encephalopathy associated with SE as well as febrile SE.