Newsletters

POSTED: October 14th, 2022
POSTED IN: EM Pulse - The Official Newsletter of MOCEP, September/October 2022,

Rohan Akhouri, MD, MPH and Arjun Sarin, MD
Pediatric Emergency Medicine Fellow, Children’s Mercy Hospital

Febrile seizures are seizures occurring between the ages of 6 months to 5 years of age in association with a fever (≥38° C) without another identifiable source for seizures[1]. Febrile seizures affect 2-5% of children between the ages of 6 months and 5 years [2,3] , making it the most common neurological disorder in this age group. Febrile seizures can be differentiated into two categories – simple and complex – based on their presentation. Across all ages, seizures make up 1-2% of all emergency department (ED) visits per year, a subset of which are febrile seizures [4,5].

Simple febrile seizures present as generalized tonic-clonic seizures lasting < 15 minutes without recurrence in a 24-hour period. These account for about 80—85% of all febrile seizures [3,6].

Complex febrile seizures are focal, prolonged (> 15 minutes), with a prolonged post-ictal state, and/or recurrence within a 24-hour period [3,6].

There is ongoing discussion on the underlying etiology of febrile seizures. There is a genetic basis, however, the mode of inheritance is not yet known. The prevailing thought is acute infections with high fevers, in the setting of a lower seizure threshold in young children, lead to febrile seizures [7]. Approximately 80% of febrile seizure cases have a viral infection. Additionally, there is an increase in risk of febrile seizures a few days after the administration of DTaP-IPV-Hib, MMRV, PCV, however this risk is transient and small [1]. Diagnosis and evaluation of a febrile seizure requires a thorough history and physical examination to identify and rule out other causes for seizures including trauma, meningitis, and genetic syndromes. A subset of patients with febrile seizures outside of the expected ages are considered part of a rare familial epilepsy syndrome called genetic epilepsy with febrile seizures plus (GEFS+). Affected individuals have a range of phenotypes from simple febrile seizures to severe epileptic encephalopathy [8,9], and will require assessment and follow up with a neurologist. Depending on the degree of severity, patients diagnosed with GEFS+ warrant further evaluation with an outpatient EEG and MRI, and occasionally require anti-epileptic medications.

Most patients presenting after a simple febrile seizure has occurred, have often returned to baseline by the time of arrival. According to the AAP guidelines, a simple febrile seizure in a well appearing child does not require additional lab or imaging evaluation³. In patients who are ill appearing, lab and imaging evaluation should focus on diagnosis of the underlying cause. Similarly, guidelines for complex febrile seizures focus on evaluating for an underlying cause. There is limited evidence for performing a lumbar puncture (LP) in both simple and complex febrile seizures; the AAP recommends considering an LP for unimmunized patients 6-12 months, for older patients it recommends an LP if there is concern for meningitis [6,10].

There is no recommended role for emergent head imaging (CT, MRI) for well appearing patients with a simple febrile seizure, though a non-urgent outpatient MRI is recommended for complex febrile seizures with postictal neurological deficits and concerns for abnormal neurodevelopment [6,10]. One-third of patients with simple febrile seizures are at risk for recurrence, however there is no significant increased risk as compared to the general population for development of epilepsy, encephalitis, or long-term neurological deficits. Patients with complex febrile seizures are at increased risk for future epilepsy [1,10], and those with high risk factors – abnormal neurodevelopment, family history of epilepsy – should follow up with a neurologist and complete an outpatient EEG [11].

In summary, febrile seizures are the most common neurological disorder in healthy infants between 6 months and 5 years of age, with the majority being simple febrile seizures. Simple febrile seizures in well-appearing children do not require additional evaluation, and management is focused on symptomatic care. Children who have a complex febrile seizure should be evaluated for underlying causes with outpatient EEG and MRI if there are associated high-risk factors. Management is focused on treatment of the underlying causes, and anti-epileptic medications are not routinely started with normal findings.

1. Leung AKC, Hon KL, Leung TNH. Febrile seizures an overview. Drugs in Context. https://doi.org/10.7573/dic.212536
2. Paul SP, Seymour M, Flower D, Rogers E. Febrile convulsions in children. Nurs Child Young People. 2015;27(5):14–15. https://doi.org/10.7748/ncyp.27.5.14.s16
3. Steering Committee on Quality Improvement and Management, Subcommittee on Febrile Seizures; Febrile Seizures: Clinical Practice Guideline for the Long-term Management of the Child with Simple Febrile Seizures. Pediatrics June 2008; 121 (6): 1281–1286. 10.1542/peds.2008-0939
4. Martindale JL, Goldstein JN, Pallin DJ. Emergency Department Seizure Epidemiology. Emergency Medicine Clinics of North America, Volume 29, Issue 1, 2011 (15-27) ISSN 0733-8627, https://doi.org/10.1016/j.emc.2010.08.002.
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9. https://www.epilepsy.com/learn/types-epilepsy-syndromes/genetic-epilepsy-febrile-seizures-plus.
10. Whelan H, Harmelink M. Chou E, Sallowm D, Khan N, et al. (2017). Complex febrile seizures-A systematic review. Disease-a-month: DM, 63(1), 5–23.
11. Hofert SM, Burke MG. Nothing Is Simple About a Complex Febrile Seizure: Looking Beyond Fever as a Cause for Seizures in Children. Hosp Pediatr May 2014; 4 (3): 181–187. https://doi-org.ezproxy.cmh.edu/10.1542/hpeds.2013-0098