Fever with seizures

Febrile seizures: Reaction of the immature brain to temperature

Febrile seizures are attacks that occur in children aged 6 months to 5 years, triggered by fever, in the absence of signs of central nervous system infection (meningitis) or other neurological diseases. Although this spectacle is extremely frightening for parents, it is important to know that simple febrile seizures are a benign condition, do not cause brain damage and are not epilepsy. This is a specific reaction of the child's immature brain to a rapid temperature spike.

What happens in the brain?

The exact mechanism of febrile seizure generation is not fully understood. The main theory is that the immature brain of a child has a lower "seizure threshold" compared with an adult. Neurons in a child's brain are more excitable. A sudden and rapid rise in body temperature can disrupt the normal balance of excitatory and inhibitory signals in the brain, causing an excessive, synchronized electrical discharge — a seizure. The key factor is not so much the maximum temperature reached, but the speed of its rise.

Simple vs. Complex febrile seizures

For prognosis and management it is important to distinguish two types of seizures:

• Simple febrile seizures (the vast majority):
  • Last less than 15 minutes (usually 1–3 minutes).
  • Are generalized (symmetrically involve the whole body).
  • Do not recur within 24 hours during the same illness.
• Complex febrile seizures: Have at least one of the following features: duration longer than 15 minutes, focal nature (involve only one part of the body) or recurrence within a single day.

Children who have experienced complex febrile seizures require closer observation by a neurologist. However, even after a simple seizure each child should be examined by a physician to rule out other, more dangerous causes of seizures. Read more about this phenomenon in infants on the page "Fever with seizures in children".