The semiology of febrile seizures (FS), their focality, relation to hippocampal damage, and heterogeneous origin are critically reviewed by researchers at the Institute of Child Health, and Great Ormond Street Hospital, London, UK. Early semiology, the most important clue to focal origin, has been neglected. Aural features have temporal lobe characteristics consisting of fear and lip smacking, and rare motor manifestations. FS arise in the hippocampus with transient and mild temporal lobe features and rapid spread to neocortex. FS include an unknown proportion of non-epileptic reflex and asystolic attacks. The definition of FS with fever not directly involving the nervous system may need to be modified by possible direct cerebral toxin involvement eg Shigella, HHV6 and malaria infections. The early seizure semiology should be used to separate the various seizures included as FS and to determine whether atypical FS such as Dravet syndrome and generalized epilepsy with FS plus have similar focal/temporal lobe features. 
COMMENT. Drs Neville and Ginder emphasize the importance of early seizure semiology in our understanding of the FS origin, and refer to the FS as a “specific epilepsy syndrome.” Investigators have debated the definition of FSs and their relation to epilepsy for more than a century. Is a FS a distinct disease entity or a form of epilepsy? The early literature was divided between those who favor the former or the latter definition. WG Lennox (1953) used the terms “mild” and “pure” forms of epilepsy, whereas Livingston (1954) reverted to the older concept of a specific entity, the “simple febrile convulsion,” distinct from the epilepsies . Genetic studies show that inheritance of FS is polygenic with no significant differences between simple and complex FS patients. The cytokine gene ILIB-511 is associated with sporadic but not familial simple FS. Cytokine genes may act as enhancers or attenuators of FS susceptibility. Genetic association studies may lead to a better understanding of the molecular basis of FS and the relation to epilepsy.