Febrile seizures: Review article

ABSTRACT

Demographic, Genetic and clinical profiles Febrile seizures are broadly defined as seizures' occurring in the presence of fever, but in the absence of central nervous system infection. They occur in children aging from 6 months to 5 years with a mean age of onset of 18-24 months and they occur slightly more commonly in boys than in girls. 1 It is the most common reason for convulsions in children less than 6 years of age, and they occur in 2 to 5% of all children, although it has been reported to be more frequent in Asian countries. In Japan, the rate has been reported to be 7% and in Jordan 6.5%.2 It is thought that the rates in these areas are higher because some of the common infections of childhood may occur earlier in life when children are most susceptible to febrile seizures. 3 Febrile seizures can be divided into two types simple and complex. Simple febrile seizures are characterized by the following duration less than 15 minutes generally, and it occurs in normal children neurologically and developmentally. Complex febrile seizures have the following features duration greater than 15 minutes, multiple within 24 hours, and/or focal. [2] The risk of recurrence after the first febrile seizure is about 33%. The risk factors for recurrence are occurrence of the first febrile seizure at a young age; family history of febrile seizures; short duration of fever before the seizure; relatively low fever at the time of the initial seizure; and possibly a family history of an afebrile seizure. It has been observed that the time of recurrence is usually within the first year of onset. Although complex febrile seizures are not usually associated with an increased risk of recurrent febrile seizures, they may be a risk factor for epilepsy later in life. Febrile seizures seem to run in families, but their mode of inheritance is unknown. The risk for other siblings developing febrile seizures is about 10-20%, but may be higher if the parents also have a history of febrile seizures themselves. 4 In large families, the FS susceptibility trait is inherited by autosomal dominant pattern with a reduced penetrance. It has long been recognized that there is a significant genetic component for susceptibility to this type of seizure and this may be caused by a mutation in several genes.[2] In the presence of cases of FS and epilepsy in the same family one study the concept of a genetic epilepsy syndrome termed Generalized Epilepsy with FC plus [GEFS+]. GEFS has a spectrum of phenotypes including FC, and FC plus.[2]. Febrile seizures usually occur in the first 24 hours of the onset of fever. It has been suggested that it is the rapid rise in the child's temperature, which causes a febrile seizure rather than the actual height of the fever itself; however, there is no substantial proof to support this suggestion. The seizures are usually generalized and tonic-clonic, but other types may be present as well. There may be variations to this such as staring without stiffness, jerking movements without prior stiffening, and localized stiffness or jerking