What causes febrile seizures in pediatric patients?

Causes of Febrile Seizures in Pediatric Patients

Febrile seizures occur due to a combination of fever and genetic predisposition affecting a vulnerable, developing nervous system, with no evidence of intracranial infection or other defined neurological causes. 1, 2

Definition and Epidemiology

Febrile seizures are:

• The most common seizure disorder in childhood, affecting 2-5% of children
• Occurring between 6 months and 5 years of age
• Associated with fever (temperature ≥100.4°F/38°C)
• Not caused by central nervous system infection, metabolic disturbance, or history of afebrile seizures 1

Pathophysiology of Febrile Seizures

Primary Mechanisms

1. Fever-Induced Neural Excitability

   • Rapid rise in temperature lowers seizure threshold in the developing brain
   • Temperature-sensitive ion channels may become dysregulated during fever

2. Genetic Predisposition

   • Family history is a significant risk factor
   • Children with first-degree relatives who had febrile seizures have nearly 50% risk of recurrence 1
   • Genetic factors likely determine seizure threshold rather than structural abnormalities 1

3. Age-Related Vulnerability

   • Immature brain has different excitatory/inhibitory balance
   • Most common between 6 months and 2 years of age 1
   • Developing nervous system is more susceptible to temperature-induced excitability

Common Triggers

• Viral illnesses (most common cause)
• Certain vaccinations
• Rapid rise in body temperature rather than absolute temperature 2

Risk Factors for Febrile Seizures

• Age between 6 months and 5 years (peak incidence 12-18 months)
• Family history of febrile seizures
• Younger age at first febrile seizure (under 12 months increases recurrence risk to ~50%)
• Certain genetic predispositions 1

Types of Febrile Seizures

Simple Febrile Seizures

• Brief (<15 minutes)
• Generalized (without focal component)
• Occur once in a 24-hour period
• Represent approximately two-thirds of all febrile seizures 1

Complex Febrile Seizures

• Last >15 minutes
• Have focal features
• Recur within 24 hours
• Represent approximately one-third of all febrile seizures 1

Clinical Implications

Prognosis

• Excellent prognosis with no long-term adverse effects on:
  • Intellectual development
  • Academic performance
  • Behavior
  • Mortality 1

Risk of Epilepsy

• Children with simple febrile seizures have approximately the same risk of developing epilepsy as the general population (1%)
• Risk factors for later epilepsy include:
  • Complex febrile seizures
  • Family history of epilepsy
  • Age <12 months at first seizure
  • Multiple febrile seizures 1

Recurrence Risk

• Overall recurrence risk is about 30%
• Higher recurrence risk if:
  • First seizure before 12 months of age (~50% risk)
  • Family history of febrile seizures
  • Lower temperature at first seizure 1

Management Considerations

• Antipyretics (acetaminophen, ibuprofen) do not prevent febrile seizures but may improve comfort 1
• Routine neuroimaging is not indicated for simple febrile seizures 1
• Anticonvulsant therapy is generally not recommended due to potential toxicities outweighing benefits 1

Common Parental Concerns

Parents often experience significant anxiety and fear when witnessing their child's febrile seizure 3. Healthcare providers should:

• Provide reassurance about the benign nature of febrile seizures
• Educate about proper first aid during a seizure (placing child on side, not restraining)
• Explain the excellent long-term prognosis
• Address concerns about brain damage (which does not occur with simple febrile seizures)

Conclusion

Febrile seizures result from a complex interplay between genetic predisposition and fever in a developing nervous system. Despite their frightening appearance, they are benign events with excellent prognosis and minimal long-term consequences for most children.