Febril Seizure

Febrile Seizures
Criteria for febrile seizures are (1) age 3 months to 6 years (most occur between ages 6 and 18 months), (2) fever of greater than 38.8°C, and (3) non-CNS infection. More than 90% of febrile seizures are generalized, last less than 5 minutes, and occur early in the illness causing the fever. Febrile seizures occur in 2–3% of children. Acute respiratory illnesses are mostcommonly associated with febrile seizures. Gastroenteritis, especially when caused by Shigella or Campylobacter, and urinary tract infections are less common causes. Roseola infantum is a rare but classic cause. One study implicated viral causes in 86% of cases. Immunizations may be a cause. It is very important especially in younger children to exclude CNS infection as a source; these children are notclassified as having a febrile seizure.
Rarely status epilepticus may occur during a febrile seizure. Febrile seizures rarely (1–3%) lead to recurrent unprovoked seizures (epilepsy) in later childhood and adult life (risk is increased two- to fivefold compared with children who do not have febrile seizures). The chance of later epilepsy is higher if the febrile seizures have complex features, suchas duration longer than 15 minutes, more than one seizure in the same day, or focal features. Other adverse factors are an abnormal neurologic status preceding the seizures (eg, cerebral palsy or mental retardation), early onset of febrile seizure (before age 1 year), and a family history of epilepsy. Even with adverse factors, the risk of epilepsy after febrile seizures is still only in therange of 15–20%, although it is increased if more than one risk factor is present. Recurrent febrile seizures occur in 30–50% of cases. Therefore, families should be prepared to expect more seizures. In general, recurrence of febrile seizures does not worsen the long-term outlook.
Generalized epilepsy with febrile seizures plus (GEFS+) is an autosomal dominant form of epilepsy first described in1997. The most frequently observed GEFS+ phenotype includes childhood onset of multiple febrile seizures persisting beyond the age of 6 years, and unprovoked (afebrile) seizures, including absence, myoclonic, or atonic seizures, and rarely, myoclonic-astatic epilepsy. Originally associated with a point mutation in SCN1B, GEFS+ is now known to have other channelopathies.
CLINICAL FINDINGS
DiagnosticEvaluation
The child with a febrile seizure must be evaluated for the source of the fever, in particular to exclude CNS infection. Routine studies such as serum electrolytes, glucose, calcium, skull radiographs, or brain imaging studies are seldom helpful. A white count above 20,000/L or an extreme left shift may correlate with bacteremia. Complete blood count and blood cultures may beappropriate. Serum sodium is often slightly low but not low enough to require treatment or to cause the seizure. Meningitis and encephalitis must be considered. Signs of meningitis (eg, bulging fontanelle, stiff neck, stupor, and irritability) may all be absent, especially in a child younger than age 18 months.
Lumbar Puncture
After controlling the fever and stopping an ongoing seizure, the physician mustdecide whether to do a lumbar puncture. The fact that the child has had a previous febrile seizure does not rule out meningitis as the cause of the current episode. The younger the child, the more important is the procedure, because physical findings are less reliable in diagnosing meningitis. Although the yield is low, a lumbar puncture should probably be done if the child is younger than age 18months, if recovery is slow, if no other cause for the fever is found, or if close follow-up will not be possible. Occasionally observation in the emergency department for several hours obviates the need for a lumbar puncture. A negative finding does not exclude the possibility of emergence of CNS infection during the same febrile illness. Sometimes a second procedure must be done.
TREATMENT...