Febrile Convulsions

DEFINITION OF SIMPLE FEBRILE CONVULSIONS In order to appreciate current concepts of febrile convulsions, it is important to consider briefly some of the views expressed by earlier investigators. One of the earliest references to the condition is that of Husler (1921) who stated that febrile convulsions were not related to epilepsy. Faxen (1935) and Herlitz (1942) both agreed that children with febrile convulsions rarely suffered from epilepsy in later life. Buchanan (1946) on the other hand reported that 15 to 20 per cent. of children who suffered from febrile convulsions in early childhood, subsequently developed epilepsy. This view was supported by Lennox (1947) who regarded febrile convulsions and epilepsy as a single disease entity. Livingston (1958) was first to express the view that there are two types of febrile convulsion; namely those of a simple nature which are not epileptic in origin, and those which are. He further maintained that these two types could be distinguished clinically. Of 622 cases of febrile convulsions where such differentiation had been made, 40 per cent. were simple, and 60 per cent. were due to epilepsy. The criteria employed by different authors to define simple febrile convulsions are shown in Table I. The reliability of these definitions can be seen in Table II. Fewer than 3 per cent. of the patients initially classified as having simple febrile convulsions subsequently suffered from epilepsy. Conversely the diagnosis of epilepsy was confirmed in 355 (97 per cent.) of the 366 children with febrile convulsions who were initially classified by Livingston as having epilepsy. While accepting that it is possible to achieve a high degree of reliability in differentiating the two types, it is significant that some 5 per cent.-6 per cent. of all cases were incorrectly diagnosed in the first instance. INCIDENCE Friderichsen and Melchior (1954) found the overall incidence of seizures in children under the age of five years to be 5 per cent. of these, 50 per cent. were associated with a febrile illness. These figures have been confirmed by other authors.