Seizures, Febrile

BASICS

Definition: Seizures in children aged 6 months–6 years with fever ≥100.4°F (38°C), without underlying neurologic/metabolic disease or CNS infection.
Types:
Simple Febrile Seizure (SFS): (70–75%)
- Generalized tonic/clonic, <15 min, nonrecurring in 24 hrs, resolves spontaneously, no previous afebrile seizures or neuro problems.
Complex Febrile Seizure (CFS): (20–25%)
- Focal, >15 min but <30 min, recurs in 24 hrs, or with postictal focal deficits.
Febrile Status Epilepticus (FSE): (5%)
- Lasts >30 min.

Incidence: ~500,000 FS/year in US.
Prevalence: 3–5% of children 6 months–6 years; peak at 18 months, 90% before age 3.
Seasonality: Mirrors peaks of febrile respiratory/GI illness (Nov–Jan; June–Aug).

Pathophysiology: Unclear; age-dependent vulnerability, fever triggers increased neuronal excitability (cytokines, temp-sensitive ion channels).
Genetics: ↑ risk with family history of FS (esp. monozygotic twins); some genes overlap with epilepsy syndromes.

Fever characteristics: Height (more than rate of rise)
Viral infection: 80% due to virus (HHV-6, influenza A, adenovirus, parainfluenza)
Recent vaccination: MMR, DTwP, PCV13, coadministration increases risk
Family history: FS in first/second degree relatives (25–40%)
Others: Male sex, NICU >28d, developmental delay, daycare, prenatal nicotine, iron deficiency, low zinc

Use vaccines with lower FS risk if available; consider spacing out MMR and varicella; use DTaP (acellular) over DTwP.
Prophylactic antipyretics not recommended before vaccines.

Viral: HHV-6, influenza, parainfluenza, adenovirus, RSV
Bacterial: Otitis media, pharyngitis, UTI, pneumonia, Shigella gastroenteritis
Vaccines: ↑ risk with MMRV, DTwP, coadministration of flu + PCV13 or DTaP.

Key features: Fever, generalized tonic-clonic (SFS), focal/prolonged/recurrent (CFS), postictal state, underlying infection symptoms.
Risk factors: Vaccine history, family/personal hx, previous neurodevelopment.
Red flags: Prolonged postictal confusion, persistent neuro deficits, or focal findings.

Monitor vitals and neurologic status.
Look for meningeal signs, petechial rash, trauma.
Postictal drowsiness resolves <10 min; longer or focal findings → evaluate for meningitis/CNS infection.

Routine labs: Not required if child appears well.
Blood/urine: Only if other symptoms or high UTI risk.
Lumbar puncture: If meningeal signs, 6–12 months with incomplete Hib/Strep pneumo vaccination, or prior antibiotics.
Neuroimaging: Not routinely recommended; indicated for prolonged/focal or concerning presentation.
EEG/MRI: Only for complex cases, especially with focality or recurrent/prolonged seizures.

Acute management: Monitor airway, breathing, circulation (ABCs); lateral position; suction secretions; O₂ as needed.
Most FS self-limited.
Abortive therapy for ≥5 min seizure:
Pre-hospital: Rectal diazepam (0.5 mg/kg), buccal/nasal midazolam (0.2–0.4 mg/kg)
Hospital: IV/IM lorazepam (0.05–0.1 mg/kg), IV diazepam (0.1–0.2 mg/kg)
If persistent: IV fosphenytoin (20 mg PE/kg); consider additional dose if needed.
Second line: IV phenobarbital, valproic acid, or levetiracetam if seizure continues
Antipyretics: For comfort only, may reduce recurrence during same fever episode but not for prophylaxis.

Anticonvulsant prophylaxis not recommended during future febrile episodes (AEs outweigh benefits).
Parental reassurance: Benign nature, excellent prognosis, low risk of sequelae or death.
Education: Benefits of vaccination outweigh risk; risk depends more on history than vaccine itself.

Favorable for children with normal neurodevelopment.
Recurrence: 1/3 have second FS; 15% have third.
Risk of epilepsy after FS: 1% for SFS, 4–6% for CFS.
Risk factors for recurrence: Younger onset, lower temp at onset, short fever-to-seizure interval, family hx, CFS features.
Risk factors for epilepsy: Onset >3 yrs, CFS, developmental delay, abnormal neuro exam, family hx epilepsy.

Febrile seizures are generally benign and without sequelae if underlying causes are excluded.
Labs, lumbar puncture, neuroimaging, and EEG are not routinely needed unless indicated.
Prophylaxis with anticonvulsants or antipyretics during subsequent febrile episodes is not recommended.