Summary
Febrile seizures affect children aged 6 months to 5 years and are associated with fever in the absence of CNS infection. They are one of the most common pediatric emergencies. Simple febrile seizures are generalized seizures that last < 15 minutes and do not recur within 24 hours. Seizures are classified as complex if they have a focal component, last longer than 15 minutes, or recur within 24 hours. Diagnostic examination focuses on addressing the cause of fever. Further diagnostics are required if there are any neurological abnormalities or signs of intracranial infection (e.g., meningeal signs) and may include lumbar puncture and neuroimaging. Most febrile seizures end spontaneously and do not require any treatment. Abortive therapy, typically with benzodiazepines, is indicated if a seizure lasts longer than five minutes. Most children with simple febrile seizures can be discharged. While the risk of recurrence is high, caregivers may be reassured that the overall prognosis of febrile seizures is good.
See “Seizures and epilepsy” for the management of other types of seizures.
Definitions
Seizures in children aged 6 months to 5 years that are associated with fever (≥ 38°C (100.4°F) in the absence of CNS infection, metabolic abnormalities, or a history of afebrile seizures. May be classified based on clinical features of febrile seizures into: [1]
- Simple febrile seizures (∼ 70% of all febrile seizures)
- Complex febrile seizures (∼ 25%)
- Febrile status epilepticus (∼ 5%)
Epidemiology
- Peak incidence: 2 years of age [2]
- Prevalence: Febrile seizures occur in 2–5% of all children. [2]
Epidemiological data refers to the US, unless otherwise specified.
Etiology
The exact pathophysiological mechanisms of febrile seizures are not known. Risk factors:
- Genetic predisposition
- High fever (> 40°C (104°F))
- Viral infection (e.g., HHV-6, influenza)
- Recent immunization (especially MMR vaccine and DTaP)
Clinical features
Simple febrile seizure [1][2]
- Duration: < 15 minutes
- Frequency: : maximum of one seizure within 24 hours
-
Features
- Generalized seizures (no focal component)
- Commonly tonic-clonic
-
Postictal phase
- Quick return to normal
- Confusion and drowsiness may be present for < 30 minutes.
Complex febrile seizure [1][2]
A febrile seizure is classified as complex if it meets any of the following criteria:
- Duration: ≥ 15 minutes or interrupted with abortive therapy
- Frequency: > 1 seizure within 24 hours
- Features: any focal seizure [2]
- Postictal phase: may include focal neurological signs and/or postictal paralysis
Febrile status epilepticus [2][3]
- Any febrile seizure lasting > 30 minutes
- Any series of febrile seizures lasting > 30 minutes in total without full recovery of consciousness between seizures
- May be generalized or focal
Prolonged drowsiness or new neurological abnormalities may be a sign of an underlying infectious disease (e.g., meningitis) or ongoing seizure activity. [4]
Diagnosis
Approach [1][5][6]
- Obtain a thorough history, including:
- Description of seizure activity
- Presence of a postictal period
- Vaccination history
- Perform a physical examination to evaluate for signs of:
- Consider further diagnostics if there are signs of meningitis and/or abnormal neurological findings, e.g.:
- Diagnostics for pediatric fever as indicated to identify the cause of fever [1]
- BMP and POC blood glucose if altered mental status persists between or after seizures [1]
- Neuroimaging and/or lumbar puncture if indicated
- For patients with complex febrile seizures or febrile status epilepticus, consult a pediatric and/or neurologic specialist for further diagnostics (e.g., EEG).
Simple febrile seizures do not require a specific diagnostic workup. [1]
Neuroimaging [1][2][7]
-
Indications
- Abnormal neurological examination
- Focal complex febrile seizures [3]
- Modalities
Neuroimaging is not indicated in the initial workup of febrile seizures if patients have returned to their baseline and do not have a neurological deficit. [6][7]
Lumbar puncture [1][2][6]
The main purpose is to exclude CNS infections, e.g., bacterial meningitis, encephalitis.
-
Indications
- History or physical examination suggesting CNS infection (e.g., meningeal signs)
- Febrile status epilepticus
- Consider for children aged 6–12 months who are not vaccinated against Haemophilus influenzae type b or Streptococcus pneumoniae.
- Consider in children who have already received antibiotics.
- Contraindications: See “Contraindications for lumbar puncture.”
- Procedure: See “Lumbar puncture.”
Differential diagnoses
- Seizures caused by CNS infection (e.g., bacterial meningitis, HSV encephalitis)
- Afebrile seizures and epilepsy
- Other nonepileptic events or movements (see “Differential diagnosis of epilepsy”)
- Brief resolved unexplained events
- Breath-holding spell
- Shivering
The differential diagnoses listed here are not exhaustive.
Treatment
Approach [1][2][5]
- Simple febrile seizures usually resolve spontaneously after a few minutes.
- Administer abortive therapy if a seizure lasts > 5 minutes. [1]
- Treat the underlying cause of fever (e.g., antibiotics for bacterial infections).
- Offer supportive care for pediatric fever, including antipyretics. [1][9][10]
- Reassure caregivers and educate them about the low risk of complications (see “Prognosis”).
Abortive therapy [1][2]
- Indication: seizure activity lasting > 5 minutes (e.g., febrile status epilepticus)
- Agents
Disposition [1][2][5]
- Most children who have returned to baseline can be discharged with close pediatric follow-up.
- Indications for admission include:
- Any child who has had a lumbar puncture
- Severely ill child
- Recurrent seizures
- Neurological abnormalities
- No return to baseline
- Unreliable follow-up
- Provide caregivers with:
- Anticipatory guidance for pediatric fever
- Information on the management of seizure recurrence, e.g.: [2][11]
Prophylaxis with anticonvulsant drugs is not usually indicated in patients with simple febrile seizures. [9][12]
Acute management checklist
- Determine the type of febrile seizure.
- Consider further diagnostics if there are signs of meningitis and/or abnormal neurological findings.
- Administer abortive therapy (lorazepam or diazepam) for seizures lasting > 5 minutes.
- Treat the underlying cause of fever.
- Offer supportive care for pediatric fever.
- Admit patients who have had lumbar puncture, are severely ill, or do not return to baseline.
Prognosis
Although febrile seizures are not typically associated with an increased risk of long-term neurological or cognitive impairment or increased mortality, there is an increased risk of recurrence and a minor risk of developing epilepsy. [1][13]
Risk of recurrence [1][12]
- Risk depends on the child's age at onset.
- Approx. 30% in children > 12 months
- Approx. 50% in children < 12 months
- Risk factors for recurrence
More than one-third of all children with a febrile seizure will experience at least one other febrile seizure. [1]
Risk of developing epilepsy [2][12]
- Approx. 1% in children with a single simple febrile seizure [12]
- 2–3% in children with multiple simple febrile seizures, onset at < 12 months of age, and family history of epilepsy [12]
- 6–8% overall in children with complex febrile seizures [2]
Simple febrile seizures are not associated with an increased risk of neurocognitive or behavioral abnormalities. [1]