Children aged 6 months to 5 years may have tonic-clonic seizures when they have a high fever. These are called febrile seizures and occur in 2% to 5% of children. There is a slight familial (hereditary) tendency toward febrile seizures. Therefore, if parents, brothers or sisters, or other close relatives have had febrile seizures, the chances are slightly increased that a child will have febrile seizures.
The usual situation is a healthy child with normal development, aged 6 months to 2 years, who has a viral illness with high fever. As the child’s temperature rapidly rises, he or she has a tonic-clonic seizure. The seizure usually involves muscles on both sides of the body. In contrast with tonic-clonic seizures in later childhood and adulthood, febrile seizures may tend to last longer than 5 minutes.
In most instances, hospitalisation may not be necessary, although a prompt medical consultation is essential, particularly for the first event or in the very young. Other more serious disorders that cause seizures with fever (e.g. meningitis/encephalitis) may need to be excluded, particularly in the very young.
The prognosis for febrile seizures is usually excellent. Recurrence rates for febrile seizures vary from 50% if the seizure occurred before age 1 year to 25% if the seizure occurred after age 1 year. The vast majority of children with febrile seizures do not have seizures without fever after age 5 years.
Risk factors for later epilepsy include:
- abnormal development before the febrile seizure;
- complex febrile seizures (seizures lasting longer than 15 minutes, more than one seizure in 24 hours, or seizure movements restricted to one side of the body);
- a history of seizures without fever in a parent or brother or sister.
If no risk factors are present, the chances of later epilepsy are the same or nearly the same as in the general population (approximately 1%); the rate is higher if risk factors are present.
Prevention of febrile seizures can be difficult, although some strategies have been tried. If a child who has had a febrile seizure subsequently has a fever, temperature modifying medication (e.g. Paracetamol) are often administered although there is no good evidence that this reduces the rate of febrile seizure recurrence.
Aspirin should not be used in young children because of the potential risk of precipitating a serious disorder called Reye’s syndrome. Febrile seizures are rarely treated with preventative antiepileptic drugs, due to the self limiting nature of the condition, and the potential side effects of such medication. In some situations, including children with very frequent febrile seizures or prolonged seizures, an antiseizure medication (e.g. Diazepam – Valium) can be administered at the time of fever to reduce the recurrence of seizures during the febrile illness.
A GUIDE TO UNDERSTANDING AND LIVING WITH EPILEPSY, ORRIN DEVINSKY, MD PRODUCTION EDITOR CRYSTALS. McNICHOL F.A. Davis Company, Philadelphia, 1994
Rosenbloom E, Finkelstein Y, Adams-Webber T, Kozer E. Do antipyretics prevent the recurrence of febrile seizures in children? A systematic review of randomized controlled trials and meta-analysis. Eur J Paediatr Neurol. 2013 Nov;17(6):585-8.
Strengell T, Uhari M, Tarkka R, Uusimaa J, Alen R, Lautala P, Rantala H. Arch Antipyretic agents for preventing recurrences of febrile seizures: randomized controlled trial. PediatrAdolesc Med. 2009 Sep;163(9):799-804 Rosman NP, Colton T, Labazzo J, Gilbert PL, Gardella NB, Kaye EM, Van Bennekom C, Winter MR. A controlled trial of diazepam administered during febrile illnesses to prevent recurrence of febrile seizures.NEngl J Med. 1993 Jul 8;329(2):79-84.
Reviewed and updated January 2014. To be reviewed January 2016
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