The etiological factors, clinical aspects and long term prognosis were studied in 200 patients with infantile spasms. Forty-eight (24.0%) died and the rest were aged 6 years or more at the time of final follow-up. In 73 (36.5%) the etiology was prenatal, in 44 (22.0%) perinatal, and in 17 (8.5%) postnatal: 18 cases (9.0%) were cryptogenic. The remaining 4.8 (24.0%) patients were doubtful cases. The mortalily of the pre-and perinatal cases at 35.6% and 34.1% respectively was significantly higher than that in the other etiologic groups (P< 0.001).
With regard to the onset of spasms, these were very early in the pre-and perinatal groups, whereas in the postnatal group the onset was late. The onset in the doubtful and cryptogenic groups was in between. Some 44.4% of the cryptogenic cases showed normal mental and physical development after the age of 6 years, whereas less than 10% of the prenatal and perinatal group did so, Almost all of the doubtful cases became mentally subnormal.
The incidence of a family history of epilepsy or other convulsive disorders in the first, second and third degree relatives was highest in the cryptogenic cases (40.0%), and lowest in the perinatal cases (9.3%) (P<0.01). The incidence of laughing attacks was highest in the postnatal cases (42.9%), against no such attacks in cryptogenic cases (P<0.01). The attacks seemed to be linked with organic brain lesions. Among various factors related to the etiology of infantile spasms, genetic propensity seemed especially important in cryptogenic cases.