The majority of seizures in children younger than five years are febrile seizures, and children with a positive family history have a higher incidence. A febrile seizure is defined as any seizure occurring in a child who is six months to five years of age accompanied by a current or recent fever (at least 38°C [100.4°F]) and without previous seizure or neurologic events. Febrile seizures can be classified as simple or complex. Simple febrile seizures are characteristically generalized, usually last less than 15 minutes, and occur only once in a 24-hour period. Complex febrile seizures may have focal features, last longer than 15 minutes, and recur within a 24-hour period. Fever and seizure can occur at the same time and be unrelated, such as in patients with underlying seizure disorder, patients who are out of the febrile seizure age range, or patients who have a central nervous system infection.

Warden and associates searched the clinical literature to review the evaluation and management of febrile seizures in children. Viral infections are often present with febrile seizures, with human herpes virus 6 and 7 and influenza A and B being important pathogens. There also is a significant increased risk of febrile seizures within 24 hours of receiving vaccination for diphtheria and tetanus toxoids and whole-cell pertussis, and within eight to 14 days of receiving a measles, mumps, and rubella vaccination. The risk of recurrent febrile seizures is increased in patients whose initial febrile seizure occurred at less than 12 months of age, patients with a lower rectal temperature at first seizure (less than 40°C [104°F]), patients with shorter duration of fever before their first seizure (less than 24 hours), patients with a family history of febrile seizures, and patients with complex features with the first febrile seizure. The risk of development of epilepsy is slightly increased among persons having simple febrile seizures but is significantly increased among those who have one or more complex febrile seizures.

Initial evaluation of children with febrile seizure includes airway and circulatory support, ideally with noninvasive measures until the postictal state resolves. Patients are best evaluated in the hospital setting. A thorough medical history that includes past seizures and other neurologic conditions, exposure to medications or toxins, allergies, or trauma may point to a specific seizure cause. Treatment with antipyretics is rarely necessary in the typical seizure case. Patients with seizures that last longer than five minutes should receive a benzodiazepine. After the seizure ends, the physician should conduct a mental status examination and a physical evaluation. Routine laboratory studies include only a blood glucose test; an electrolyte test may be appropriate if a metabolic abnormality is being considered. No further work-up is necessary, but lumbar puncture is indicated in patients with suspected meningitis.

A lumbar puncture should be considered in children younger than 18 months who have a febrile seizure with the following: (1) a history of irritability, decreased feeding, or lethargy; (2) an abnormal appearance or mental state on initial observation after the postictal period; (3) any physical examination evidence of meningitis; (4) any complex features; (5) any slow postictal clearing of mentation; or (6) pretreatment with antibiotics. Neuro-imaging only is appropriate in patients at risk of cerebral abscess, in those who have clinical evidence of increased intracranial pressure, in patients who have evidence of trauma, or in patients who have status epilepticus or have had a complex seizure. Children with simple febrile seizures can be cared for at home after providing parental education and making plans to follow up with the family.

The authors conclude that evaluation and management of simple febrile seizures can be managed in an outpatient emergency setting and the child can be sent home for further care (see accompanying table). Children with complex seizures might require hospitalization for evaluation. Routine prophylaxis using phenobarbital, valproic acid, oral diazepam, or antipyretics is controversial and not indicated.