Febrile Seizure

Background

• Febrile seizures are seizures occurring in a child aged 6 months to 5 years with a temperature ≥ 38 degrees C (100.4 degrees F) and no signs of a central nervous system infection or metabolic disturbance, and no history of a prior afebrile seizure.
• The fever is most commonly due to an infection, however the precise mechanism of the febrile seizure is unknown.
• There is an increased risk of febrile seizures after certain immunizations, but the absolute risk is very small.
• Febrile seizure recurrence is common after a first febrile seizure, but risk of future epilepsy is not increased after a first simple febrile seizure.

Evaluation

• Suspect the diagnosis in a previously healthy child aged 6 months to 5 years with seizure and fever.
  • Perform a clinical evaluation directed toward excluding central nervous system infection or other serious underlying condition, and to help identify the cause of the fever.
  • Diagnose simple febrile seizure (65%-90% of febrile seizures) if all of the following criteria are met:
    • generalized tonic-clonic activity with no focal component
    • duration < 15 minutes
    • occurs no more than once in 24 hours
    • no previous neurologic problems
  • Diagnose complex febrile seizure if febrile seizure lasts > 15 minutes, has a focal component, or recurs within 24 hours.
• Blood testing
  • For simple febrile seizure, blood testing should be done only if useful for identifying source of fever, not as part of seizure evaluation (Strong recommendation).
  • For complex febrile seizure, blood testing may be indicated as part of seizure evaluation, or to help identify source of fever.
• Lumbar puncture (LP)
  • Perform LP in any child with fever, seizure, and history or physical exam suggestive of meningitis or intracranial infection (Strong recommendation).
  • Consider LP in children with seizure and fever if pretreated with antibiotics, or if aged 6-12 months with Haemophilus influenzae type b (Hib) or Streptococcus pneumoniae immunizations not up to date or uncertain immunization status (Weak recommendation).
• Neuroimaging and electroencephalogram (EEG) are not recommended for the evaluation of simple febrile seizure in a neurologically healthy child (Strong recommendation), but may be considered in follow-up of children with complex or recurrent febrile seizures or neurologic abnormalities.
• Consider additional testing as indicated to help identify cause of fever, for example urinalysis and urine culture if urinary tract infection is suspected or if no other source of fever is identified on clinical exam.

Management

• Most simple febrile seizures will have stopped before presentation to a healthcare provider and will not require antiseizure medication.
• For active seizures
  • Stabilization and monitoring should be started and continued in parallel with pharmacologic treatment.
  • Antiseizure medications usually indicated for seizure lasting ≥ 5 minutes or repeated seizures.
    • Preferred options include:
      • lorazepam (Strong recommendation) 0.1 mg/kg IV, may repeat dose once
      • midazolam (Strong recommendation) 5 mg intramuscularly if 13-40 kg, 10 mg intramuscularly if > 40 kg, or 0.2 mg/kg intramuscularly
      • diazepam (Strong recommendation) 0.15-0.2 mg/kg IV, may repeat dose once
    • If IV or intramuscular formulations are not feasible or available, consider:
      • buccal or intranasal midazolam (Strong recommendation) 0.5 mg/kg buccally, 0.2 mg/kg intranasally
      • rectal diazepam (Strong recommendation) 0.2-0.5 mg/kg per rectum
• For preventing febrile seizure recurrence:
  • Continuous or intermittent antiseizure medication therapy is not recommended for children with single or recurrent simple febrile seizures (Strong recommendation).
  • Antipyretics may reduce febrile seizure recurrence during same fever episode, but does not appear to reduce long-term recurrence risk.
• Home use of rectal diazepam may be considered in children with initial prolonged febrile seizure or with a very high recurrence risk.