Episode 169.0 – Febrile Seizures

Show Notes

Background

• The most common type of seizure in children under 5 years of age
• Occur in 2-5% of children
• In children with a fever, aged 6 months to 5 years of age, and without a CNS infection
• Risk Factors
  • 4 times more likely to have a febrile seizure if parent had one
  • Also increase in risk if siblings or nieces / nephews had one
• Common associated infections
  • Human Herpesvirus 6
  • Human Herpesvirus 7
  • Influenza A & B
• Simple Febrile Seizure
  • Generalized tonic-clonic activity lasting less than 15 minutes in a child 6 months to 5 years of age
• Complex Febrile Seizure
  • Lasts longer than 15 minutes, occurs in a child outside of this age range, are focal, or that recur within a 24-hour period.

Diagnostics / Workup

• Gather thorough history and perform thorough physical exam
• Most cases will not require labs, imaging or EEG
• If e/o meningitis, perform LP
• AAP suggests considering LP in:
  • Children 6-12 months who are not immunized for H flu type B or strep pneumo
  • Children who had been on antibiotics
• For complex seizures, clinician may have a lower threshold for obtaining labs
  • Hyponatremia is more common in this group than in the general population.
  • LPs are more commonly done by providers, but these are low yield with one study showing bacterial meningitis being diagnosed in just 0.9% (Kimia 2010), all of whom did not have a normal exam or negative cultures.
  • Neuroimaging is also exceedingly low yield if the patient returns to baseline (Teng 2006)
  • One study that showed that the duration of complex febrile seizure, being greater than 30 minutes, was associated with a higher incidence of bacterial meningitis. (Chin 2005)
  • Of they have history and exam concerning for meningitis, they should get an LP
  • If they look dehydrated or edematous, you would have more of a reason to get a chemistry

Treatment

• Benzodiazepine if seizure lasted for >5 minutes, either IV or IN
• Supportive care
  • Tylenol or motrin if febrile
  • Fluids if signs of dehydration
• Antipyretics “around the clock”
  • A majority of data show no benefit in preventing recurrence of seizure
  • One study (Murata 2018) found that giving tylenol q6h at 10 mg/kg for the first 24 hours following the initial seizure decreased the rate of recurrence when compared to children who did not receive antipyretics.
    • NNT here was 7
    • Questionable whether we can generalize these findings from a single ED in Japan.
  • No role for antiepileptics

Prognosis

• High rate of recurrence (~1/3) within 1 year of initial seizure
• Risk increases for
  • Younger age at which they had initial seizure
  • Lower temperature at which they had seizure
• If initial febrile seizure was prolonged, more likely that the next will be prolonged
• 1-2% develop epilepsy for simple febrile seizure, slightly above risk of general population
• 5-10% develop epilepsy for complex febrile seizure
• Follow up with PMD
• Generally, peds neuro follow up is not necessary

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References

Chin RF, Neville BG, Scott RC. Meningitis is a common cause of convulsive status epilepticus with fever. Arch Dis Child. 2005;90(1):66-9.

Kimia A, Ben-Joseph EP, Rudloe T, Capraro A, Sarco D, Hummel D, et al. Yield of lumbar puncture among children who present with their first complex febrile seizure. Pediatrics. 2010;126(1):62-9.

Murata S, Okasora K, Tanabe T, Ogino M, Yamazaki S, Oba C, et al. Acetaminophen and Febrile Seizure Recurrences During the Same Fever Episode. Pediatrics. 2018;142(5).

Patel N, Ram D, Swiderska N, Mewasingh LD, Newton RW, Offringa M. Febrile seizures. BMJ. 2015;351:h4240.

Pavlidou E, Panteliadis C. Prognostic factors for subsequent epilepsy in children with febrile seizures. Epilepsia. 2013;54(12):2101-7.

Stapczynski, J. S., & Tintinalli, J. E. (2016). Tintinalli’s emergency medicine: A comprehensive study guide, 8th Edition. New York: McGraw-Hill Education.

Subcommittee on Febrile S, American Academy of P. Neurodiagnostic evaluation of the child with a simple febrile seizure. Pediatrics. 2011;127(2):389-94.

Teng D, Dayan P, Tyler S, Hauser WA, Chan S, Leary L, et al. Risk of intracranial pathologic conditions requiring emergency intervention after a first complex febrile seizure episode among children. Pediatrics. 2006;117(2):304-8.

Warden CR, Zibulewsky J, Mace S, Gold C, Gausche-Hill M. Evaluation and management of febrile seizures in the out-of-hospital and emergency department settings. Ann Emerg Med. 2003;41(2):215-22.

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A special thanks to our editors:

Michael A. Mojica, MD

Director, Pediatric Emergency Medicine Fellowship
Bellevue Hospital Center

Christie M. Gutierrez, MD 

Pediatric Emergency Medicine Fellow
Columbia University Medical Center
Morgan Stanley Children’s Hospital
New York Presbyterian