Febrile Seizures
Incidence
Febrile seizures (FS) are the most common seizure disorder in childhood. Boys are slightly more affected than girls. The prevalence is approximately 3%.
Clinical Characteristics
Febrile seizures (FS) are the most common seizure disorder in childhood. The age at onset is from 6 months to 5 years of age. FS peak at 18–22 months of age. Boys are slightly more affected than girls. The prevalence is approximately 3%. Febrile seizures are precipitated by fever of at least 38.5°C without evidence of intracranial infection or other CNS cause. Febrile seizures are often familial, they are age related. There is a genetic predisposition, however the mode of inheritance is unknown. Generalized tonic clonic seizures (GTCS) are the most common seizure type (80%). Tonic (13%), atonic (3%), and unilateral or focal onset tonic clonic seizures (4%) may occur in the remaining 20%. Rarely, seizures consist of staring accompanied by stiffness or floppiness, rhythmic jerking movements without prior stiffening, focal stiffness or jerking only. Myoclonic jerks or absences are not part of febrile seizures. Repetitive seizures in the same febrile illness occur in 16%. FS are may be simple or complex. Simple febrile seizures are more common (about 70% of FS) and are generalized tonic clonic convulsions lasting less than 15 min and without recurrence within 24 hours. The overall risk of developing epilepsy after having simple FS is 4%. Complex febrile seizures are prolonged (longer than 15 minutes), or repetitive (2 or more within 24 hours), or have focal features. Patients may have febrile status epilepticus. One-half of children will have recurrences of febrile seizures. Recurrences are more likely if the first FS occurs during the first year of life or if there is a family history of febrile seizures in first degree relatives. They are more likely to recur if the first FS occurred with a low grade febrile illness or the first seizure is complex. There are no long term differences intellectually between children with FS and children without FS. Behavior is not affected. Simple febrile seizures do not need prophylactic treatment. Prophylactic treatment may be indicated if a child has complex febrile seizures or frequent recurrences. Treatment may be used intermittently when the child has fever or treatment may be continous. Intermittent prophylactic treatment with oral or rectal Diazepam can be used when the child has fever. For continuous treatment, Phenobarbital is most often used with Valproic Acid being used less often as an alternative. Treatment of the fever and the underlying illness is also important.
Precipitants
Fever always will precipitate a seizure. The cause of the fever is external to central nervous system (CNS).
Provocation Tests
No specific test confirm Dx. EEG is normal awake and sleep.
Diagnostic Procedures
It is a clinical diagnosis. The diagnosis is based on the history. The EEG is normal.