By Ramzy Medaa, MD
Febrile seizures are one of the most common seizures, typically affecting children between six months and five years of age with a peak incidence between 12 and 18 months. They occur in 2 to 4 per cent of children younger than 5 years.
The febrile seizures are diagnosed clinically and defined as a convulsion associated with an elevated temperature (more than 100.4 F), absence of central nervous system (CNS) infection, and absence of acute systemic metabolic abnormality, in addition to no history of a previous febrile seizures. Risk factors include high fever, infection such as human herpes virus 6 (HHV-6), adenovirus, influenza A and respiratory syncytial virus (RSV), as well as immunization.
A genetic susceptibility to febrile seizures has been recognized; however, in most cases the exact mode of inheritance is still unknown.
The febrile seizures are classified as one of two types, simple febrile seizures and complex febrile seizures.
Simple Febrile Seizures
Simple seizures are generalized seizures, usually tonic-clonic, lasting less than 15 minutes (median duration of 3-4 minutes), and which do not recur in a 24-hour period. Children typically return to baseline quickly after a simple febrile seizure. The postictal phase can be associated with confusion or agitation and lethargy. No treatment is required for the seizure itself.
Complex Febrile Seizures
Complex febrile seizures are defined as focal onset or prolonged, lasting more than 15 minutes or recurrent within 24 hours. They are less prevalent, and account for approximately 20 percent of febrile seizures. Children with complex febrile seizures are often younger and more likely to have abnormal development.
These seizures require a more individualized approach and investigations which include electroencephalography (EEG) and MRI of the brain, as well as lumbar puncture (if indicated) to exclude meningitis or encephalitis. Lumbar puncture should be performed in children who are less than 12 months old or have clinical signs of meningitis.
Anti-seizure medications can be given during the acute illness. Diazepam is prescribed for patients 2 years and older, given rectally for seizures lasting more than 5 minutes or for clusters of seizures without returning to baseline in between.
Epilepsy occurs more frequently in children who have had febrile seizures compared to the general population. In a normal child with a simple febrile seizure, the risk is almost similar to that of the general population. However, children with complex febrile seizures, a history of developmental delay, or a family history of epilepsy have an increased risk.
Dr. Ramzy Medaa is Board-certified in Neurology and Epilepsy. His office is at KIDZ Pediatric Multispecialty Center in Naples.
