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Febrile Seizures

Febrile seizures are the most common convulsive disorder of childhood. A febrile seizure is defined as a seizure associated with fever in infancy or early childhood (usually between 3 months and 5 years of age), without evidence of intracranial infection or other cause of febrile seizure.

Febrile seizures are a benign syndrome caused primarily by genetic factors, manifest as an age-related susceptibility to seizures, which eventually is outgrown. The problem almost always resolves without sequelae. Only a small minority will develop non-febrile seizures later. Unless seizures are exceedingly long, there is no risk of brain damage.

Febrile seizures occur in 2-4% of young children.

Higher temperature and a history of febrile seizures in a close relative are risk factors for the development of a febrile seizure.


After the first febrile seizure, 33% of children will experience one or more recurrences, and 9% of children who have febrile seizure.

The younger the child's age when the first febrile seizure occurs.

Family history of febrile seizures is a risk.

Short duration of fever before the initial seizure and relatively lower fever at the time of the initial seizure are risk factors.

Epilepsy. Fewer than 5% of children who have febrile seizures actually develop epilepsy.

Febrile seizures tend to occur in families. The risk of febrile seizures in younger siblings of children who have febrile convulsions is 10-20%, and the risk is higher if the parents have a history of febrile convulsions.

Risk factors for the development of epilepsy following febrile seizures include suspicious or abnormal development before the first seizure, family history of afebrile seizures.

Most febrile illnesses associated febrile seizures are caused by common infections (tonsillitis, upper respiratory infections, otitis media).

Children of preschool age are subject to frequent infections and high fevers. These children have a relatively low seizure threshold, resulting in febrile seizures

Clinical Evaluation

Febrile seizures usually occur early in the course of a febrile illness, often as the first sign. The seizure may be of any type, but the most common is tonic-clonic. Initially there may be a cry, followed by loss of consciousness and muscular rigidity. During this tonic phase, apnea and incontinence may occur. The tonic phase is followed by the clonic phase of repetitive, rhythmic jerking movements, which is then followed by postictal lethargy.

Other seizure types may be characterized by staring with stiffness or limpness or only focal stiffness or jerking.

Most seizures last less than 6 minutes; 8% last longer than

An underlying illness that may require treatment should be sought. Symptoms of infection, medication exposure, trauma should be assessed. The develop mental level, and family history of febrile or afebrile seizures should be evaluated. A complete description of the seizure should be obtained.

Physical Examination

The level of consciousness, presence of meningismus, a tense or bulging fontanelle, Kernig or Brudzinski sign, and any neurological findings should be assessed.