Pathophysiology of Febrile Seizure

Summary

Febrile seizures, affecting 2-5% of children, typically occur between 6 months and 5 years, often during respiratory or gastrointestinal illness seasons. Risk factors include family history, age under 18 months, daycare attendance, and rapid fever spikes. Mechanisms involve changes in ion channel kinetics, increased interleukin-1β, and hyperventilation leading to alkalosis, all of which heighten neuronal excitability. While recurrent seizures are common, they do not directly correlate with epilepsy, though frequent seizures may increase the risk. Understanding fever duration, peak temperature, and age can help predict recurrence and manage febrile seizure risks.

Takeaways

• 😀 Febrile seizures affect 2-5% of children, typically between 6 months and 5 years old.
• 😀 Higher incidence of febrile seizures occurs from November to January (respiratory illnesses) and June to August (GI illnesses).
• 😀 Family history of febrile seizures increases a child's risk of experiencing them.
• 😀 Children under 18 months are more likely to experience febrile seizures.
• 😀 Daycare attendance raises the risk of febrile seizures due to increased exposure to infections.
• 😀 Rapid spikes in fever are associated with a higher risk of febrile seizures and recurrence.
• 😀 Increased temperature affects ion channels, lowering the seizure threshold and making neurons more excitable.
• 😀 Interleukin-1b (IL-1b), produced during fever, increases neuronal excitability through changes in glutamate and GABA production.
• 😀 Hyperventilation during fever can lead to respiratory alkalosis, which also increases neuronal excitability.
• 😀 Recurrence of febrile seizures occurs in about one-third of affected children, with shorter fever durations and lower peak temperatures increasing the likelihood.
• 😀 No direct evidence links febrile seizures to the development of epilepsy, though recurrent seizures slightly raise the risk.

Q & A

What is the prevalence of febrile seizures in children?

Febrile seizures occur in approximately 2-5% of children.

What age group is most commonly affected by febrile seizures?

Febrile seizures most commonly affect children aged between 6 months and 5 years, with the highest incidence in those under 18 months.

Which seasons see an increase in febrile seizures, and why?

Febrile seizures are more common during the months of November to January, due to the rise in respiratory illnesses, and from June to August, linked to increased gastrointestinal infections.

How does a family history influence the risk of febrile seizures?

A family history of febrile seizures significantly increases the likelihood of a child experiencing a febrile seizure, suggesting a hereditary component.

Why are children attending daycare at higher risk for febrile seizures?

Children in daycare are at increased risk due to higher exposure to infectious agents, leading to illnesses that can cause fever, which in turn increases the risk of febrile seizures.

What role does fever duration play in the likelihood of a febrile seizure?

The shorter the duration of the fever, the higher the risk of febrile seizure, as rapid spikes in temperature are more likely to trigger a seizure.

How do temperature-sensitive ion channels contribute to febrile seizures?

As body temperature increases, the kinetics of temperature-sensitive ion channels change, leading to an increased flow of ions through these channels. This lowers the seizure threshold, making seizures more likely.

What is the role of interleukin-1b in febrile seizures?

Interleukin-1b, a pyrogen released during fever, increases neuronal excitability by promoting the release of glutamate and GABA. This increases brain excitability, which raises the risk of seizures.

How does hyperventilation during fever contribute to febrile seizures?

Hyperventilation leads to a loss of CO2, causing a shift in the body’s acid-base balance towards respiratory alkalosis. Even a small increase in pH (0.2-0.3) can increase neuronal excitability, making seizures more likely.

What factors contribute to the recurrence of febrile seizures?

Recurrence of febrile seizures is influenced by factors such as a lower peak temperature during the initial seizure and a shorter duration of fever prior to the seizure.

Is there a connection between febrile seizures and epilepsy?

There is no strong evidence to suggest that febrile seizures directly lead to epilepsy. However, children with recurrent febrile seizures may have a slightly higher risk of developing epilepsy.