Role of Birth History in the Aetiology and Course of Febrile Convulsions. A Twin Study

Abstract

A twin population of 1631 pairs included 64 pairs in which one or both had a history of febrile convulsions (FC). In 48 pairs, discordant with respect to FC, there were no significant differences between twins with FC and their healthy co-twins as regards birth weight, birth order, presentation, assisted delivery or perinatal condition. Within the twin population the incidence of FC was calculated as 3%, a value which hardly exceeds that in the total population. Within the index series there was a fraction of monozygotic (MZ) pairs of 0.41%, corresponding to the ratio in a normal twin population. The clinical course of FC in the twins was generally benign with a low frequency of long-lasting and/or focal seizures. The incidence of subsequent epilepsy, 2.6%, did not differ from the incidence in other Scandinavian studies of the general population. The lacking correlation between the birth history and subsequent FC perhaps indicates that birth trauma is of little or no aetiological importance in FC. As it is known that twins, in particular MZ twins, are more often exposed to birth trauma than nontwins, this hypothesis is supported by another two results: The fraction of MZ pairs was not increased in the index series and the incidence of FC did not seem to be increased in the twin population. It must, however, be stressed that only relatively few birth data could be collected in this study. On the basis of the present results it is therefore not possible to rule out definitively that pre- or perinatally acquired brain damage may play a role in the aetiology of febrile convulsions.

Keyword

Birth - trauma - asphyxia - febrile convulsions - twin study