What causes febrile seizures?

From the Guidelines

Febrile seizures are caused by a rapid rise in body temperature, typically above 38°C (100.4°F), which affects the brain's electrical activity and leads to a seizure, particularly in developing brains of young children between 6 months and 5 years of age. The exact mechanism of febrile seizures is not fully understood, but it is believed that the brain's sensitivity to sudden temperature changes plays a key role 1. According to the 2024 American Heart Association and American Red Cross guidelines for first aid, febrile seizures are a common benign condition in childhood, affecting approximately 2% to 4% of children 1.

Key Factors

• The brain's sensitivity to sudden temperature changes is a key factor in the development of febrile seizures 1.
• Not all children with fevers will experience seizures, suggesting that some children may have a genetic predisposition or other factors that make them more susceptible 1.
• Febrile seizures are most common when a child's temperature rises above 38°C (100.4°F), often at the beginning of an illness 1.

Management and Prevention

• Fever treatment can help children feel better, but it will not prevent subsequent seizures 1.
• Antipyretics have been shown to be ineffective in preventing recurrent febrile seizures, according to two meta-analyses published in 2021 1.
• The use of anticonvulsant therapy is not recommended for children with simple febrile seizures, due to the potential toxicities associated with these agents outweighing the relatively minor risks associated with simple febrile seizures 1.

Outcome

• Febrile seizures are generally harmless and do not cause long-term damage, with the risk of developing epilepsy being extremely low, although slightly higher than that in the general population 1.

From the Research

Causes of Febrile Seizures

• The exact cause of febrile seizures is still uncertain, but studies suggest that the rapidity of the rise in fever is more significant than the height of the fever itself 2, 3.
• A child is more likely to experience a febrile seizure if their temperature rises rapidly, even if it reaches a lower maximum temperature 2.
• Febrile seizures are associated with disease processes outside the central nervous system, and the primary causative factors appear to be the height and rapidity of temperature elevation 3.
• Genetic factors, immune response to infection, and rise in body temperature are thought to be involved in the occurrence of febrile seizures 4.
• Neurotropic viruses may also play a role in the pathophysiological mechanisms of febrile seizures 4.

Factors Contributing to Febrile Seizures

• Fever is a significant contributing factor to febrile seizures, with most seizures occurring during the temperature rise itself rather than after a prolonged elevation 3.
• The age of the child, typically between 6 months and 5 years, is also a contributing factor to the occurrence of febrile seizures 2, 5, 6.
• Respiratory infections can be a source of fever, leading to febrile seizures 2.

Underlying Mechanisms

• The mechanisms of febrile seizures in developmental abnormalities and disease occurrence during adulthood have not been fully determined 6.
• The hippocampus is the brain region most significantly altered after febrile seizures, and the motor cortex and subcortical white matter may also be involved in the development disorders induced by febrile seizures 6.
• Inflammation and the γ-aminobutyric acid (GABA) system may play a role in the long-term effects of febrile seizures 6.