Febrile seizures

Summary

• Febrile seizures or fever fits are very rarely associated with epilepsy or any other seizure disorder.
• Febrile seizures are convulsions (fits) associated with fever.
• They typically occur between the ages of six months and three years.
• The seizures usually last less than five minutes and seldom longer than 15 minutes.
• They are the most common form of seizure in childhood.
• Although febrile seizures are not a problem, the child must be carefully examined, as there may be a serious disease that caused the fever.

Definition

A febrile seizure is usually a generalised (the entire body is involved) convulsion associated with fever occurring in a child between the ages of six months and three years. Occasionally the seizure may be confined to just one side of the body. The seizure does not usually last for more than several seconds up to a maximum of about 10 minutes. Most febrile seizures last for less than five minutes. After the seizure the child may be a bit drowsy, but there is no other abnormality such as weakness. These seizures usually stop by themselves and do not require anti-epileptic drugs.

Febrile seizures are very rarely associated with epilepsy or other seizure disorder. They are the most common cause of seizures during childhood and occur in 2-5% of normal children.

Factors suggesting an associated epilepsy include a family history of epilepsy, recurrent seizures, prolonged seizures (>15 minutes), one-sided seizures and any abnormality on examination of the nervous system.

Cause

The cause is unknown, but any illness causing a significant fever may be associated with febrile seizures in young children. The seizures appear to be triggered by a rapid rise in the temperature rather than by a sustained high fever. The seizure is often the first indication that the child is ill, which makes prevention difficult.

Who gets it and who is at risk?

Any child between the age of six months and three years with a high fever (>38⁰C) is at risk. The peak is at about 18 months.

There is often a history that febrile seizures occurred in a parent or other sibling.

About half of the children who have had a febrile seizure are at risk for a recurrence, but very few children will have multiple recurrent febrile seizures.

Symptoms and signs

By its very nature, the seizure is often over before the parents can even react. The child may have appeared unwell earlier in the day or the seizure may suddenly occur. Most children with a febrile seizure will have a temperature >38⁰C.

 The seizure may start off as a mere twitching of the arms and legs through to a full-blown generalised convulsion. Usually both sides of the body are involved, but occasionally only one side or one limb may be affected.

Diagnosis

The diagnosis of febrile seizure is mainly one of exclusion. If the child has had a previous febrile seizure it may be easier to make the diagnosis.

By the time the child is seen by a doctor the seizure has usually stopped and quite often the temperature has fallen.

The child will be examined to find the cause of the fever and to rule out a serious illness. Because of the concern regarding meningitis, it may be necessary for the child to have a lumbar puncture, but only if  the  doctor suspects this as a possible diagnosis.

An electroencephalogram (EEG) is not a routine investigation and is only considered if the seizure was in any way atypical, e.g. longer than 15 minutes or if there were recurrent seizures.

Prevention

Often little can be done to prevent a febrile seizure because it usually occurs at the onset of the illness and may be the first sign that the child is ill.

Generally, the child’s temperature should be kept as close to normal as possible if he/she becomes ill .It helps to remove excess clothing and bedding and sponging the child down with tepid (not cold) water. Paracetamol is usually given to reduce the fever.

Treatment

A true febrile seizure is self-limiting and does not require any special treatment.

The basic principles of handling any child having a seizure is to ensure that the child cannot be hurt, i.e. fall off the bed. The child should be gently rolled over onto their side and under no circumstances should one attempt to restrain or force open the child’s mouth.

The child should be examined for the cause of the fever and the appropriate management started together with paracetamol to reduce the fever.

Anti-epileptics are not routinely used and are only prescribed when a child has many recurrent seizures and after further investigation.

When to call the doctor

Any child who has a seizure for the first time with a high fever or repeated seizures should be properly diagnosed. It is important to exclude epilepsy or meningitis as possible causes, and the child must be seen by a doctor in order to identify the cause.

Previously reviewed by Dr John D. Burgess, Red Cross Children's Hospital

Reviewed by: Prof  Eugene Weinberg, FCPaeds [SA}, FAAAAI, Paediatrics and Paediatric Allergology, Allergy Diagnostic Unit,UCT Lung Institute, September 2011