Seizures—Febrile is a topic covered in the Select 5-Minute Pediatrics Topics.

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Basics

Description

Febrile seizure: seizure in ≤60-month-old child accompanied by a fever (≥100.4°F or 38°C by any method) but without central nervous system infection or prior unprovoked seizure (American Academy of Pediatrics [AAP] guidelines use 6 months as the lower age limit, whereas International League Against Epilepsy uses 1 month)

2 types:

  • Simple: febrile seizures that are generalized, last <15 minutes, AND do not recur in 24 hours
  • Complex
    • Febrile seizures that are focal (including postictal weakness), last ≥15 minutes, OR occur >1 time in 24 hours
    • Febrile status epilepticus: 1 febrile seizure or series of febrile seizures without full recovery in between lasting ≥30 minutes

Epidemiology

  • Age
    • Most febrile seizures occur between 6 months and 3 years of age.
    • Peak age is about 18 months.
  • Type
    • 65–70% are simple febrile seizures.
    • 20–35% are complex febrile seizures.
    • ∼5% are febrile status epilepticus.
  • Timing of seizure
    • ∼20% before or <1 hour of fever onset
    • ∼60% 1–24 hours after fever onset
    • ∼20% >24 hours after fever onset

Prevalence

  • Most common childhood seizure
  • Febrile seizures occur in 2–5% of children in the United States and Western Europe, 9–10% of children in Japan, and 14% of children in Guam.

Risk Factors

Positive family history of febrile seizures

Genetics

Usually multifactorial or polygenic inheritance

General Prevention

Antipyretics do not reduce the recurrence risk of simple febrile seizures.

Pathophysiology

  • Elevated temperatures in developing brain may increase neuronal excitability.
  • Fever increases cytokines that may enhance neuronal excitability.
  • Genetic factors
  • Hyperventilation from fever causes a respiratory alkalosis that may promote seizures.

Etiology

  • Any viral or bacterial infection
    • Human herpesvirus 6 and 7
    • Influenza A
  • Vaccines
    • MMR(V) and DPT
    • Both increase the risk of febrile seizures but not epilepsy.
    • Benefits greatly outweigh any risk, and families should be encouraged to vaccinate.
  • Shigellosis

Commonly Associated Conditions

  • Generalized epilepsy with febrile seizures plus (GEFS+)
    • Febrile seizures beyond 6 years of age or afebrile seizures of varying types ranging from mild to severe
    • Multiple genes identified including SCN1A, SCN2A, SCN1B, GABRG2, GABRD, and PCDH19
  • Febrile infection–related epilepsy syndrome (FIRES)
    • Catastrophic epileptic encephalopathy of unknown etiology that begins with a febrile illness and refractory status epilepticus
    • Has high morbidity and mortality

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Citation

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TY - ELEC T1 - Seizures—Febrile ID - 14212 Y1 - 2015 PB - Select 5-Minute Pediatrics Topics UR - https://im.unboundmedicine.com/medicine/view/Select-5-Minute-Pediatric-Consult/14212/all/Seizures—Febrile ER -