The exact cause of febrile convulsions is unknown. Because they occur when a child has a high temperature, some researchers speculate that the biological processes associated with a high temperature may be responsible.
A high temperature is thought to be caused by a bacterial or viral infection that stimulates the release of cytokines. Cytokines are proteins that affect the parts of the brain and nervous system responsible for regulating the body’s temperature. Their release causes a rise in the normal temperature.
One theory is that in certain people, high levels of cytokines may temporarily ‘scramble’ the workings of the brain and nervous system, triggering a seizure.
Risk factors
Although the condition is poorly understood, a number of risk factors for febrile convulsions have been identified.
Family history is the most important risk factor. If a child has a first-degree relative (mother, father, sister or brother) who has a history of febrile seizures, their risk of having symptoms increases. The more relatives affected, the higher that risk, which can range from 1 in 10 to 1 in 2.
The fact that febrile seizures run in families is probably the result of one or more genetic mutations that a child inherits from their parents, which makes them more vulnerable to seizures. A genetic mutation occurs when the normal instructions that are carried in certain genes become ‘scrambled’. This means that some of the body’s processes will not work in the normal way.
A number of potential mutations have been linked to an increased risk of febrile seizures. However, exactly how and why these mutations develop is unclear.
Associated infections
The majority of cases of febrile convulsions occur when your child has a high temperature that is caused by an infection. The three most common types of infection that are associated with febrile convulsions are:
Other infections that are associated with febrile seizures (listed in order of most to least common) are:
- upper respiratory tract infection – an infection of the mouth, nose and throat, and associated tissues and structures
- gastroenteritis – an infection of the digestive system
- lower respiratory tract infections, such as pneumonia (an infection of the lungs) and bronchitis (an infection of the airways that supply the lungs)
