eMedicine Specialties > Neurology > Pediatric Neurology

Febrile Seizures

Author: Robert Baumann, MD, Program Director, Professor, Departments of Neurology and Pediatrics, University of Kentucky
Contributor Information and Disclosures

Updated: Dec 11, 2008

Introduction

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.

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.

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.

Clinical

History

  • Children with simple febrile seizures are neurologically and developmentally healthy before and after the seizure.
  • They do not experience a seizure in the absence of fever.
  • The seizure is described as either a generalized clonic or a generalized tonic-clonic seizure.
    • Signs of a focal seizure during the onset or in the postictal period (eg, initial clonic movements of 1 limb or of the limbs on 1 side, a weak limb postictally) would rule out a simple febrile seizure.
    • Similarly, simple febrile seizure activity does not continue for more than 15 minutes, although a postictal period of sleepiness or confusion can extend beyond the 15-minute maximum.
  • Simple febrile seizures often occur with the initial temperature elevation at the onset of illness. The seizure may be the first indication that the child is ill. While no clear cutoff is known, a rectal temperature under 38°C should raise concern that the event was not a simple febrile seizure.

Physical

Physical examination findings reveal a neurologically and developmentally healthy child. It is especially important that the child have no signs of meningitis or encephalitis (eg, stiff neck or persistent mental status changes).

Causes

Simple febrile seizures are considered a genetic disorder, but neither a specific locus nor a specific pattern of inheritance has been described. The mode of inheritance is likely to vary between families and may be multifactorial.

More on Febrile Seizures

Overview: Febrile Seizures
Differential Diagnoses & Workup: Febrile Seizures
Treatment & Medication: Febrile Seizures
Follow-up: Febrile Seizures
References
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References

  1. Baumann RJ. Technical report: treatment of the child with simple febrile seizures. Pediatrics. Jun 1999;103(6):e86. [Medline].

  2. 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].

  3. 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].

  4. 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].

  5. 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].

  6. 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].

  7. Verity CM, Golding J. Risk of epilepsy after febrile convulsions: a national cohort study. BMJ. Nov 30 1991;303(6814):1373-6. [Medline].

  8. 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].

  9. Winawer M, Hesdorffer D. Turning on the heat: the search for febrile seizure genes. Neurology. Nov 23 2004;63(10):1770-1. [Medline].

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Further Reading

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Keywords

febrile convulsions, fever fits, epilepsy, seizure, simple febrile seizures, complex febrile seizures, symptomatic febrile seizures

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Contributor Information and Disclosures

Author

Robert Baumann, MD, Program Director, Professor, Departments of Neurology and Pediatrics, University of Kentucky
Robert Baumann, MD is a member of the following medical societies: American Academy of Neurology, American Academy of Pediatrics, American College of Epidemiology, American Epilepsy Society, and Child Neurology Society
Disclosure: Nothing to disclose.

Medical Editor

James J Riviello Jr, MD, George Peterkin Endowed Chair in Pediatrics, Professor of Pediatrics, Section of Neurology and Developmental Neuroscience, Professor of Neurology, Peter Kellaway Section of Neurophysiology, Baylor College of Medicine; Chief of Neurophysiology, Director of the Epilepsy and Neurophysiology Program, Texas Children's Hospital
James J Riviello Jr, MD is a member of the following medical societies: American Academy of Pediatrics
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Kenneth J Mack, MD, PhD, Senior Associate Consultant, Department of Child and Adolescent Neurology, Mayo Clinic
Kenneth J Mack, MD, PhD is a member of the following medical societies: American Academy of Neurology, Child Neurology Society, Phi Beta Kappa, and Society for Neuroscience
Disclosure: Nothing to disclose.

CME Editor

Selim R Benbadis, MD, Professor, Director of Comprehensive Epilepsy Program, Departments of Neurology and Neurosurgery, University of South Florida School of Medicine, Tampa General Hospital
Selim R Benbadis, MD is a member of the following medical societies: American Academy of Neurology, American Academy of Sleep Medicine, American Clinical Neurophysiology Society, American Epilepsy Society, and American Medical Association
Disclosure: Nothing to disclose.

Chief Editor

Amy Kao, MD, Assistant Professor, Department of Neurology, Division of Pediatrics, Department of Pediatrics, Oregon Health and Science University; Consulting Staff, Shriners Hospital for Children
Amy Kao, MD is a member of the following medical societies: American Academy of Neurology, American Academy of Pediatrics, American Epilepsy Society, and Child Neurology Society
Disclosure: Nothing to disclose.

 
 
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