Seizures, Febrile

Key Features

Essentials of Diagnosis

• Criteria for febrile seizures

  • Age 3 months to 6 years (most occur between ages 6 and 18 months)

  • Fever > 38.8°C

  • Non–central nervous system (CNS) infection

• More than 90% of febrile seizures are generalized, last less than 5 minutes, and occur early in the illness causing the fever

General Considerations

• Occur in 2–3% of children

• Rarely (1–3%) evolve to recurrent unprovoked seizures (epilepsy) in later childhood and adult life

• If the following complex features are present, the chance of epilepsy developing later is higher

  • Duration longer than 15 minutes

  • More than one seizure in the same day

  • Focal features

• Other predictive factors

  • Abnormal neurologic status preceding the seizures (eg, cerebral palsy or mental retardation)

  • Early onset of febrile seizure (before age 1 year)

  • Family history of epilepsy

• Recurrent febrile seizures occur in 30–50% of cases

Clinical Findings

• Acute respiratory illnesses are most commonly 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

• HHV-6 and HHV-7 are common causes for febrile status epilepticus, both accounting for one-third of cases

• Meningitis and encephalitis must be considered

• Signs of meningitis (eg, bulging fontanelle, stiff neck, stupor, and irritability) may be absent, especially in a child younger than age 18 months

Diagnosis

Laboratory Findings and Imaging

• Routine studies such as serum electrolytes, glucose, calcium, skull radiographs, or brain imaging studies are seldom helpful unless warranted based on clinical history

• A white blood cell count above 20,000/μL or an extreme left shift may correlate with bacteremia

• Complete blood cell count and blood cultures may be appropriate

• Serum sodium is often slightly low but not low enough to require treatment or to cause the seizure

Diagnostic Procedures

• Lumbar puncture

  • Although the yield is low, should be considered if the child is younger than age 18 months, and has been pretreated with antibiotics or is underimmunized

  • Any child with meningeal signs, fever, and seizure should undergo cerebrospinal fluid examination

• EEG

  • Rarely useful

  • May be considered if the febrile seizure is complicated, focal, or otherwise unusual

Treatment

• Measures to control fever such as sponging or tepid baths, antipyretics, and the administration of antibiotics for proven bacterial illness are reasonable but unproven to prevent recurrent febrile seizures

• Diazepam,0.5 mg/kg two or three times per day orally or rectally

  • Started at the first onset of fever for the duration of the febrile illness may be effective

  • However, will sedate a child and possibly complicate the evaluation for a source of the fever

Outcome