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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


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


  • 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


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