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Febrile seizure in pediatrics

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"febrile seizure"[MeSH Terms] AND management

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febrile seizure pediatric management

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Febrile Seizures in Pediatrics

Definition and Epidemiology

A febrile seizure is a seizure triggered by fever (≥38°C / 100.4°F) in children aged 6 to 60 months, in the absence of CNS infection, metabolic disturbance, or prior history of afebrile seizures. It is the most common seizure disorder of childhood, affecting 2–5% of children, with peak incidence at 14–18 months of age. About one-third will have at least one recurrence over their lifetime. - Tintinalli's Emergency Medicine, p. 936; Goodman & Gilman's, p. 1266

Classification

1. Simple Febrile Seizure (majority of cases)

Defined by ALL of the following criteria (AAP definition):
FeatureCriterion
Seizure typeGeneralized (tonic-clonic)
Duration< 15 minutes
RecurrenceDoes NOT recur within 24 hours
Age6–60 months
Neurological examNormal, returns to baseline

2. Complex (Complicated) Febrile Seizure

Defined by ANY ONE of the following:
  • Focal ictal features or lateralized postictal weakness (Todd's paralysis)
  • Duration > 15 minutes (febrile status epilepticus if > 30 minutes)
  • Recurs within 24 hours or within the same febrile illness
  • Occurs in a child < 6 months or > 6 years without signs of serious infection
  • Harriet Lane Handbook, p. 741; Bradley & Daroff's Neurology, p. 863; Tintinalli's, p. 936

Etiology / Triggers

Common causes of the underlying fever include:
  • Viral URTIs (most common)
  • Roseola (HHV-6) - classically associated
  • Otitis media
  • Post-vaccination fever (especially MMR, MMRV, and combined influenza + PCV13 or DTaP - small increased risk, but vaccines overall protect by preventing febrile illness)
  • Goodman & Gilman's, p. 1265

Risk Factors for Recurrence

~30–50% of children < 12 months will have a recurrence (30% if > 12 months). Predictors include:
  • Age < 1 year at first febrile seizure
  • Family history of febrile seizures or epilepsy in first-degree relatives
  • Attendance at daycare (greater febrile illness exposure)
  • Developmental delay
  • First febrile seizure with a low peak temperature
  • Most recurrences occur within 1 year of the initial event
  • Bradley & Daroff's Neurology, p. 863; Tintinalli's, p. 936

Risk of Later Epilepsy

Febrile seizures mildly increase the risk of epilepsy, but the absolute risk remains low:
ScenarioEpilepsy Risk
Simple febrile seizure~1% (same as general population)
Any complex feature present6–8%
Two complex features17–22%
All three complex features~49%
Any febrile seizure (overall)Up to 7% by age 25
Additional risk factors for epilepsy: pre-existing neurodevelopmental abnormality, family history of epilepsy, recurrent febrile seizures. Complex features predict focal epilepsy; large number of recurrences + family history of epilepsy predicts generalized epilepsy. - Bradley & Daroff's Neurology, p. 864

Febrile Status Epilepticus and the Hippocampus

Febrile status epilepticus (> 30 min) may injure the hippocampus - ~11.5% of affected children show unilateral increased hippocampal T2 signal on MRI acutely, often followed by hippocampal sclerosis on follow-up imaging, a known substrate for mesial temporal lobe epilepsy. - Bradley & Daroff's Neurology, p. 865

Dravet Syndrome - Red Flag

When febrile seizures are prolonged, asymmetrical, and begin before 15 months, consider Dravet syndrome (SCN1A or GABRG2 mutation). These children progress to afebrile seizures and neurological decline - very different prognosis from typical febrile seizures. - Bradley & Daroff's Neurology, p. 865

Evaluation

Simple Febrile Seizure - What is NOT needed

Per AAP guidelines (confirmed across multiple sources):
InvestigationRecommended?
Blood work (CBC, electrolytes, glucose)No (not routine) - only if evaluating fever source
Urine culture / UAOnly to identify fever source
Neuroimaging (CT / MRI)No
EEGNo
Routine LPNo (if well-appearing, fully immunized, no meningeal signs)

When to Perform Lumbar Puncture

Strongly indicated / mandatory:
  • Clinical signs or symptoms of meningitis (neck stiffness, Kernig/Brudzinski, bulging fontanelle, petechiae, ill-appearing)
  • Febrile status epilepticus
Should be considered:
  • Age < 6–12 months
  • Incomplete immunization for H. influenzae type b or S. pneumoniae
  • Child pretreated with antibiotics (can mask meningitis signs)
  • Tintinalli's, p. 936; Harriet Lane Handbook, p. 741; Rosen's Emergency Medicine, p. 3206

Complex Febrile Seizure Workup

The Harriet Lane Handbook recommends for complex seizures:
  • EEG (obtain)
  • Nonemergent MRI (to evaluate for associated focal lesion)
  • LP if concern for CNS infection
  • Consider prescribing rectal diazepam for home emergency use

Treatment

Acute Management

For a seizure that is ongoing at the time of evaluation, treat as per convulsive status epilepticus protocol:
Proposed algorithm for convulsive status epilepticus in children
Key steps from the American Epilepsy Society algorithm (Rosen's, Fig. 169.3):
0–5 min (Stabilization): Airway, breathing, circulation; O₂; ECG monitoring; check glucose (give D10W 5 mL/kg if hypoglycemic); IV access; labs.
5–20 min (Initial Therapy) - Benzodiazepines (Level A):
  • IM midazolam: 10 mg (>40 kg), 5 mg (13–40 kg), 0.2 mg/kg (<13 kg)
  • IV lorazepam: 0.1 mg/kg (may repeat once)
  • IV diazepam: 0.15–0.2 mg/kg (max 10 mg, may repeat once)
  • If IV unavailable: rectal diazepam 0.2–0.5 mg/kg (max 20 mg) or intranasal/buccal midazolam
20–40 min (Second Therapy):
  • IV fosphenytoin 20 mg PE/kg (max 1500 mg PE)
  • IV valproate 40 mg/kg (max 3000 mg)
  • IV levetiracetam 60 mg/kg (max 4500 mg)
40–60 min (Third Therapy / Refractory): Anesthetic doses of thiopental, midazolam, pentobarbital, or propofol under continuous EEG monitoring.

Antipyretics

Treat the fever with antipyretics, but there is no evidence that antipyretics prevent subsequent febrile seizures. - Tintinalli's, p. 936

Long-term Anticonvulsant Prophylaxis

Not recommended for simple febrile seizures. Side effects (especially cognitive effects of phenobarbital) outweigh the minor risk of recurrence. Prophylaxis does not prevent later epilepsy. - Goodman & Gilman's, p. 1267
For high-risk children with recurrent febrile seizures: rectal or oral diazepam at the time of fever onset is the preferred intermittent prophylactic agent, used to abort seizures rather than as chronic therapy. - Swanson's Family Medicine, p. 313; Goodman & Gilman's, p. 1268

Discharge and Family Counseling

Children who fully recover after a simple febrile seizure can almost always be sent home. Key counseling points:
  • High likelihood of recurrence (> 33%) - parents must be aware
  • Small increased risk of epilepsy (2–5%, or roughly double the baseline) - but absolute risk is low
  • Extensive anticipatory guidance and reassurance
  • Teach fever control measures and seizure first aid
  • Consider prescribing rectal diazepam for home emergency use in complex or recurrent cases
  • Close follow-up with their pediatrician
  • Specialty referral (neurology) if complex features are present
  • Rosen's Emergency Medicine, p. 3287

Genetic Basis

Febrile seizures have a strong genetic influence - inheritance is usually polygenic, but autosomal dominant transmission occurs in some families. Key genetic syndromes:
  • GEFS+ (Generalized Epilepsy with Febrile Seizures Plus): autosomal dominant, heterogeneous expression, febrile seizures persisting beyond age 6
  • Dravet syndrome: SCN1A truncating mutation, begins as prolonged febrile seizures in infancy, progresses to refractory epilepsy
  • Bradley & Daroff's Neurology, p. 869

Recent Evidence Note

A 2024 systematic review (Corsello et al., Pediatric Neurology, PMID 38653182) comparing different international guidelines on febrile seizures confirmed broad consensus that routine workup (EEG, neuroimaging, LP, antiseizure drugs) is not indicated for simple febrile seizures in well-appearing children. This is consistent with all textbook guidance above.
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