Questionnaires regarding the occurrence of seizure remission following infection were sent to pediatric neurologists in 73 university hospitals, children’s hospitals, and epilepsy centers in Japan, and the data obtained in 21 cases from 11 institutions were analyzed at St Marianna University School of Medicine, Kawasaki, and other centers. Patients included were those whose frequent seizures had remitted for at least 1 month after viral infection without change in antiepileptic therapy. Age ranged from 6 months to 17 years. Sixteen (80%) had West syndrome (13 symptomatic and 3 cryptogenic etiology), and the remainder included 2 cases of symptomatic generalized epilepsy, symptomatic partial epilepsy, continuous spike-wave and slow sleep (CSWS), and severe myoclonic epilepsy of infancy. Infections included 4 cases of exanthem subitum, 4 of rotavirus gastroenteritis, 3 of measles, 3 upper respiratory infections, 1 of mumps and cytomegalovirus, and 5 common cold. Seizures disappeared an average of 4.5 days (range, 1-14 days) after onset of infection. Follow-up was 34 months (range, 3 months to 4 years). Seizures recurred in 13 patients after a median of 7 months (range 1-30 months). Of 5 patients without seizure recurrence, 4 had West syndrome and 1 had CSWS. EEGs improved during remission periods in two-thirds of patients. AED serum levels showed no significant change during remission. Possible reasons for seizure remission included increased levels of antibodies after viral infection or suppression of immunological processes by anti-inflammatory cytokines. 
COMMENT. The authors cite 2 previous references to the remission of infantile spasms in West syndrome following viral infection, especially exanthem subitum (West, 1841; Hattori, 2001). Exanthem subitum and infection with human herpesvirus (HHV)-6 accounts for one-third of all first-time febrile seizures in children <2 years old in the US (Hall, Epstein, et al. 1994). The virus that causes seizures may also have a protective effect in some patients. An elevated cytokine response independent of the severity of infection may be a factor in the mechanism of seizures (Kawada et al, 2003; Millichap JG, Millichap JJ, 2003), and suppression of immunological processes by anti-inflammatory cytokines (eg interleukin-10) may explain the seizure remission following viral infection in the above case-reports. Further studies of the role of viral infections in the cause and remission of seizures are needed. (See Ped Neur Briefs April 2001, and Sept 2003, for further comment on cytokines and seizures).