Febrile seizure

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 6 years and are twice as common in boys as in girls.

Causes
The direct cause of a febrile seizure is not known; however, it is normally precipitated by a recent upper respiratory infection or gastroenteritis. A febrile seizure is the effect of a sudden rise in temperature (>39°C/102°F) rather than a fever that has been present for a prolonged length of time. As well as this, parents caring for children who may be febrile, wrap them up in warm blankets in an attempt to comfort the child, unknowingly increasing their fever and therefore the problem.

Febrile seizures occurring in children between the ages of 6 months and about 6 years can be due to a hypersensitive hypothalamus in the brain. The hypothalamus is responsible for homeostatic core temperature regulation, (amongst other factors) and in younger children it is still a developing portion of the brain, meaning it is susceptible to hypersensitive reactions to slight raises in body temperature.

Febrile seizures represent the meeting point between a low seizure threshold (genetically and age-determined; some children have a greater tendency to have seizures under certain circumstances) and a trigger, which is fever. The genetic causes of febrile seizures are still being researched. Some mutations that cause a neuronal hyperexcitability (and could be responsible for febrile seizures) have already been discovered.

Several genetic associations have been identified. These include:

Certain forms are considered channelopathies.

Diagnosis
The diagnosis is one that must be arrived at by eliminating more serious causes of seizure and fever: in particular, meningitis and encephalitis must be considered. 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. The diagnosis of a febrile seizure should not prevent evaluation of the child for source of fever, although this is usually limited to evaluation of the urine in the younger age groups.

Types
There are two types of febrile seizures.
 * A simple febrile seizure is one in which the seizure lasts less than 15 minutes (usually much less than this), does not recur in 24 hours, and involves the entire body (classically a generalized tonic-clonic seizure).
 * A complex febrile seizure is characterized by longer duration, recurrence, or focus on only part of the body.

The simple seizure represents the majority of cases and is considered to be less of a cause for concern than the complex.

Simple febrile seizures do not cause permanent brain injury; 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 suffer from a febrile epileptic attacks in the future if they have a complex febrile seizure, a family history of a febrile convulsions in first-degree relatives (a parent or sibling), or a preconvulsion history of abnormal neurological signs or developmental delay. There is an 80% chance that children who have complex febrile seizures will have seizures later on in life. Similarly, the prognosis after a simple febrile seizure is excellent, whereas an increased risk of death has been shown for complex febrile seizures, partly related to underlying conditions.

Symptoms
During simple febrile seizures, the body will become stiff and the arms and legs will begin twitching. The patient 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.

Treatment
The vast majority of patients do not require treatment for either their acute presentation with a seizure or for recurrences. The best way to manage is to control the temperature with acetaminophen (Paracetamol) or by sponging. When anticonvulsant therapy is judged by a doctor to be indicated, anticonvulsants can be prescribed. Sodium valproate or clonazepam are active against febrile seizures, with sodium valproate showing superiority over clonazepam.