STUDIES IN FEBRILE SEIZURES

In mice, rats, guinea pigs and kittens and in 51 children with recurrent febrile seizures, the height of the body temperature was the important determinant in the induction or occurrence of seizures with hyperthermia. Both clinically and in animal studies, the body temperature at the onset of the convulsion may be used as a measure of the threshold to febrile seizures. The pattern of the experimental febrile seizure was principally clonic in type. It varied with the height of the temperature and with the age and maturity of the animal. Also, the febrile seizure threshold varied with age and maturity. It was independent of the basal temperature of the body. In rats, the threshold was lowest at 3 to 8 days and highest in the adult animal; a small but significant elevation in threshold was observed at birth. In the newborn guinea pig, the threshold convulsive temperature was equal to that of the 20-day-old rat. The rapidity of rise in body temperature was not a predisposing factor. In animals which convulsed, the susceptibility to febrile seizures was independent of the rate of temperature rise and the severity of the pyrogenic stimulus. A measure of the febrile seizure threshold as demonstrated in this study has been found of value in studies of the mechanism and prevention of seizures with hyperthermia. Its clinical importance is discussed.