Background
Febrile seizures are the most common seizure disorder in childhood. Since early in the 20th century, people have debated about whether these children would benefit from daily anticonvulsant therapy. Epidemiologic studies have led to the division of febrile seizures into 3 groups, as follows: simple febrile seizures, complex febrile seizures, and symptomatic febrile seizures.
Simple febrile seizure
- The setting is fever in a child aged 6 months to 5 years.
- The single seizure is generalized and lasts less than 15 minutes.
- The child is otherwise neurologically healthy and without neurological abnormality by examination or by developmental history.
- Fever (and seizure) is not caused by meningitis, encephalitis, or other illness affecting the brain.
Complex febrile seizure
- Age, neurological status before the illness, and fever are the same as for simple febrile seizure.
- This seizure is either focal or prolonged (ie, >15 min), or multiple seizures occur in close succession.
Symptomatic febrile seizure
- Age and fever are the same as for simple febrile seizure.
- The child has a preexisting neurological abnormality or acute illness.
Pathophysiology
This is a unique form of epilepsy that occurs in early childhood and only in association with an elevation of temperature. The underlying pathophysiology is unknown, but genetic predisposition clearly contributes to the occurrence of this disorder.[1]
Epidemiology
Frequency
United States
Febrile seizures occur in 2-5% of children aged 6 months to 5 years in industrialized countries. Among children with febrile seizures, about 70-75% have only simple febrile seizures, another 20-25% have complex febrile seizures, and about 5% have symptomatic febrile seizures.
Mortality/Morbidity
- Children with a previous simple febrile seizure are at increased risk of recurrent febrile seizures; this occurs in approximately one third of cases.
- Children younger than 12 months at the time of their first simple febrile seizure have a 50% probability of having a second seizure. After 12 months, the probability decreases to 30%.
- Children who have simple febrile seizures are at an increased risk for epilepsy. The rate of epilepsy by age 25 years is approximately 2.4%, which is about twice the risk in the general population.
- The literature does not support the hypothesis that simple febrile seizures lower intelligence (ie, cause a learning disability) or are associated with increased mortality[2] .
Sex
Males have a slightly (but definite) higher incidence of febrile seizures.
Age
Simple febrile seizures occur most commonly in children aged 6 months to 5 years.
Winawer M, Hesdorffer D. Turning on the heat: the search for febrile seizure genes. Neurology. Nov 23 2004;63(10):1770-1. [Medline].
Vestergaard M, Pedersen MG, Ostergaard JR, Pedersen CB, Olsen J, Christensen J. Death in children with febrile seizures: a population-based cohort study. Lancet. Aug 9 2008;372(9637):457-63. [Medline].
Rosman NP, Colton T, Labazzo J, et al. A controlled trial of diazepam administered during febrile illnesses to prevent recurrence of febrile seizures. N Engl J Med. Jul 8 1993;329(2):79-84. [Medline].
Verity CM, Golding J. Risk of epilepsy after febrile convulsions: a national cohort study. BMJ. Nov 30 1991;303(6814):1373-6. [Medline].
[Best Evidence] Nørgaard M, Ehrenstein V, Mahon BE, Nielsen GL, Rothman KJ, Sørensen HT. Febrile seizures and cognitive function in young adult life: a prevalence study in Danish conscripts. J Pediatr. Sep 2009;155(3):404-9. [Medline].
Baumann RJ. Technical report: treatment of the child with simple febrile seizures. Pediatrics. Jun 1999;103(6):e86. [Medline].
[Guideline] Febrile seizures: clinical practice guideline for the long-term management of the child with simple febrile seizures. Pediatrics. Jun 2008;121(6):1281-6. [Medline].
[Guideline] Practice parameter: the neurodiagnostic evaluation of the child with a first simple febrile seizure. American Academy of Pediatrics. Provisional Committee on Quality Improvement, Subcommittee on Febrile Seizures. Pediatrics. May 1996;97(5):769-72; discussion 773-5. [Medline].
[Guideline] Riemenschneider TA, Baumann RJ, Duffner PK, et al. Practice parameter: the neurodiagnostic evaluation of the child with a first simple febrile seizure. American Academy of Pediatrics. Provisional Committee on Quality Improvement, Subcommittee on Febrile Seizures. Pediatrics. May 1996;97(5):769-72; discussion 773-5. [Medline].
Thoman JE, Duffner PK, Shucard JL. Do serum sodium levels predict febrile seizure recurrence within 24 hours?. Pediatr Neurol. Nov 2004;31(5):342-4. [Medline].

