On a database of the Japanese medical literature between 1970 and 2000, there were 29 patients with West syndrome showing spontaneous remission. In 25/29 (86%) of the patients, spontaneous remission was preceded by viral infections, among which exanthema subitum predominated. In 16/29 (55%), the spasms recurred a median of 2 months later. However, some of the remaining infants attained lasting remission of the spasms. This link between viral infections and spontaneous remission suggests immuno-inflammatory processes underlie West syndrome in certain patients. Better understanding of such mechanisms may lead to a new therapeutic approach to West syndrome.