Characteristics of the initial seizure in familial febrile seizures.

Complex seizure characteristics in patients with a positive family history were studied to define familial phenotype subgroups of febrile seizures. A total of 51 children with one or more affected first degree relatives and 177 without an affected first degree relative were compared for history of complex characteristics of the initial febrile seizure. No difference was found in the frequency of febrile status epilepticus (OR = 1.1 (95% confidence interval (CI) 0.3 to 4.3)), multiple type (OR = 0.6 (CI 0.3 to 1.2)), and focal characteristics (OR = 0.4 (CI 0.2 to 1.2)). The presence of any complex characteristic (OR = 0.5 (CI 0.3 to 1.0)) was higher in those without an affected first degree relative, although differences did not reach significance. The familial type of febrile seizures is not associated with complex characteristics of the initial febrile seizure. Complex seizure characteristics are unlikely to help in discriminating phenotype subgroups for genetic studies of febrile seizures.