Definition of Febrile Seizure
A febrile seizure is defined as a seizure accompanied by fever (temperature ≥100.4°F or 38°C by any method) occurring in children between 6 and 60 months of age, without evidence of intracranial infection, metabolic disturbance, or history of afebrile seizures. 1
Classification of Febrile Seizures
Febrile seizures are categorized into two types:
Simple Febrile Seizures
- Brief (<15 minutes)
- Generalized (without focal component)
- Occur once during a 24-hour period
- Account for approximately two-thirds of all febrile seizures 1
Complex Febrile Seizures
- Prolonged (>15 minutes)
- Focal features
- Recur more than once in 24 hours
- Account for about one-third of all febrile seizures 1
Epidemiology and Risk
- Most common seizure disorder in childhood
- Affects 2-5% of children between 6 and 60 months of age 1, 2
- About one-third of children with febrile seizures will experience at least one recurrence 1
- Risk factors for recurrence include:
- Age younger than 12 months at first seizure (50% recurrence risk)
- Age older than 12 months at first seizure (30% recurrence risk) 1
Important Clinical Considerations
Differential Diagnosis
- It's crucial to distinguish febrile seizures from seizures with fever due to:
Prognosis
- Simple febrile seizures have excellent prognosis 4
- No evidence of decline in IQ, academic performance, or neurocognitive function 1
- Risk of developing epilepsy:
- Children with simple febrile seizures: approximately 1% (similar to general population)
- Children with multiple simple febrile seizures, first seizure before 12 months, and family history of epilepsy: 2.4% risk by age 25 1
Common Pitfalls to Avoid
- Overdiagnosis: Not all seizures with fever are febrile seizures. Exclude intracranial infections, metabolic disturbances, and other causes.
- Unnecessary imaging: Neuroimaging is not indicated for simple febrile seizures 1
- MRI studies have shown abnormalities in 11.4% of children with simple febrile seizures, but these findings did not affect clinical management 1
- Overtreatment: Neither continuous nor intermittent anticonvulsant therapy is recommended for children with simple febrile seizures, as the potential toxicities outweigh the relatively minor risks 1
Late Febrile Seizures
While the classic definition restricts febrile seizures to children between 6 and 60 months, some research indicates they can rarely occur after 5 years of age (late febrile seizures). These tend to have similar characteristics to typical febrile seizures but with over 90% experiencing no recurrence after age 5 5.
Parental Education
Parents often find febrile seizures extremely frightening and may believe their child is dying or suffering brain damage 6, 4. Healthcare providers should address parental anxiety with appropriate education about the benign nature of simple febrile seizures and excellent long-term prognosis.