A febrile seizure, also known as a fever fit or febrile convulsion, is a convulsion associated with a significant rise in body temperature. They most commonly occur in children between the ages of 6 months and 5 years of age. They are more common in boys than girls.
Signs and symptoms
During generalized febrile seizures, the body will become stiff and the arms and legs will begin twitching. The child loses consciousness, although their eyes remain open. Breathing can be irregular. They may become incontinent (wet or soil themselves); they may also vomit or have increased secretions (foam at the mouth). The seizure normally lasts for less than five minutes.
Febrile seizures are due to fevers, usually those greater than 38 °C (100.4 °F). The cause of the fevers is often a viral illness. The likelihood of a febrile seizure is related to how high the temperature reaches rather than the rate of increase.
The diagnosis is arrived at by eliminating more serious causes of seizure and fever: in particular, meningitis and encephalitis. However, in locales in which children are immunized for pneumococcal and Haemophilus influenzae, the prevalence of bacterial meningitis is low. If a child has recovered and is acting normally, bacterial meningitis is very unlikely.
There are three types of febrile seizures.
- A simple febrile seizure is characterized by shorter duration (lasting less than 15 minutes), no focal features (meaning the shaking is general rather than restricted to a part of the body such as an arm or leg), and if they do occur in series, the total duration is less than 30 minutes (classically a generalized tonic-clonic seizure).
- A generalized febrile seizure also known as a complex febrile seizure is one in which the seizure lasts longer than 15 minutes or multiple episodes occur within 24 hours and generally does have focal features.
- A febrile status epilepticus is a febrile seizure that lasts for longer than 30 minutes. It can occur in up to 5% of febrile seizure cases.
In those with a history of febrile seizures medications (both antipyretics and anticonvulsants) have not been found effective for prevention; however, some appear to be associated with harm. They are thus not recommended as an effort to prevent further seizures.
Long term outcomes are generally good with little risk of neurological problems or epilepsy. Those who have one febrile seizure have an approximately 40% chance of having another one in the next two years, with the risk being greater in those who are younger.
Simple febrile seizures do not tend to recur frequently (children tend to outgrow them); and do not make the development of adult epilepsy significantly more likely (about 3–5%), compared with the general public (1%). Children with febrile convulsions are more likely to have a febrile seizure in the future if they were young at their first seizure (less than 18 months old), a family history of a febrile convulsions in first-degree relatives (a parent or sibling), have a short time between the onset of fever and the seizure, had a low degree of fever before their seizure, or a seizure history of abnormal neurological signs or developmental delay. Similarly, the prognosis after a complex febrile seizure is excellent, although an increased risk of death has been shown for complex febrile seizures, partly related to underlying conditions.
Febrile seizures happen between the ages of six months and five years in 2-5% of children.
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