At what age do febrile seizures typically resolve?

Age of Resolution for Febrile Seizures

Febrile seizures typically resolve by 60 months (5 years) of age, as they are defined as seizures occurring in children between 6 and 60 months of age with fever and without evidence of intracranial infection, metabolic disturbance, or history of afebrile seizures. 1, 2

Definition and Epidemiology

Febrile seizures are the most common seizure disorder in childhood, affecting approximately 2-5% of children. They are characterized by:

• Occurrence between 6 months and 60 months (5 years) of age
• Association with fever (temperature ≥100.4°F or 38°C)
• Absence of intracranial infection, metabolic disturbance, or history of afebrile seizures

The peak age for febrile seizures is 14-18 months, with approximately 97% occurring in children under 4 years of age 1.

Types of Febrile Seizures

Febrile seizures are classified into two categories:

1. Simple febrile seizures (approximately two-thirds of cases):

   • Last less than 15 minutes
   • Generalized (without focal features)
   • Occur once in a 24-hour period

2. Complex febrile seizures (approximately one-third of cases):

   • Last more than 15 minutes
   • Have focal features
   • Occur more than once in a 24-hour period

Risk of Recurrence

The risk of recurrence varies by age:

• Children younger than 12 months at first febrile seizure: approximately 50% probability of recurrence
• Children older than 12 months at first febrile seizure: approximately 30% probability of recurrence
• Of those who have a second febrile seizure, 50% have a chance of at least one additional recurrence 1

Prognosis After Age 5

The American Academy of Pediatrics and other guidelines clearly define febrile seizures as occurring between 6 and 60 months of age 1, 2. This age range definition implies that:

1. Seizures with fever occurring after 60 months (5 years) of age are not classified as febrile seizures and warrant different evaluation
2. The condition typically resolves by age 5, with the vast majority of children outgrowing the tendency to have seizures with fever

Long-term Outcomes

The prognosis for children with febrile seizures is excellent 3:

• No evidence of decline in IQ, academic performance, or neurocognitive function
• No evidence of structural damage to the brain from simple febrile seizures
• Children with simple febrile seizures have approximately the same risk of developing epilepsy by age 7 as the general population (approximately 1%)
• Children with risk factors (multiple simple febrile seizures, first seizure before 12 months, family history of epilepsy) have a slightly higher risk (2.4%) of developing epilepsy by age 25 1

Common Pitfalls in Management

1. Misclassifying seizures after age 5: Seizures with fever occurring after 60 months should not be classified as febrile seizures and may require different evaluation

2. Unnecessary investigations: For simple febrile seizures, routine diagnostic testing (laboratory tests, neuroimaging, or electroencephalography) is not recommended 1, 2

3. 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, 2

4. Parental anxiety: Parents often consider febrile seizures more severe than physicians do. Proper education about the benign nature and excellent prognosis is essential 1

In summary, febrile seizures are a benign, self-limiting condition that typically resolves by 5 years of age, with excellent long-term outcomes and no significant impact on neurological development or future health.