eMedicine Specialties > Neurology > Pediatric Neurology

Febrile Seizures

Robert Baumann, MD, Program Director, Professor, Departments of Neurology and Pediatrics, University of Kentucky

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.

Differential Diagnoses

Other Problems to Be Considered

Benign epilepsy syndromes
Brain abscess
Bacterial meningitis
Encephalitis
Epilepsy

Workup

Laboratory Studies

• No specific studies are indicated for a simple febrile seizure.
• Physicians should focus on diagnosing the cause of fever.
• Other laboratory tests may be indicated by the nature of the underlying febrile illness. For example, a child with severe diarrhea may benefit from blood studies for electrolytes.

Imaging Studies

Neither computed tomography (CT) nor magnetic resonance imaging (MRI) is indicated in patients with simple febrile seizures.

Other Tests

EEG is not indicated in children with simple febrile seizures. Published studies demonstrate that the vast majority of these children have a normal EEG. In addition, some of those with an abnormal EEG have remained free of seizures for the duration of their follow-up. On the other hand, some of the children with a normal initial EEG have experienced 1 or more afebrile seizures subsequent to the EEG. Finally, no evidence indicates that beginning anticonvulsant therapy for a child with simple febrile seizures and an abnormal EEG will alter the child's eventual outcome.

Procedures

• Strongly consider lumbar puncture in children younger than 12 months, because the signs and symptoms of bacterial meningitis may be minimal or absent in this age group.
• Lumbar puncture should be considered in children aged 12-18 months, because clinical signs and symptoms of bacterial meningitis may be subtle in this age group.
• In children older than 18 months, the decision to perform lumbar puncture rests on the clinical suspicion of meningitis.

Treatment

Medical Care

On the basis of risk/benefit analysis, neither long-term nor intermittent anticonvulsant therapy is indicated for children who have experienced 1 or more simple febrile seizures.

• Continuous therapy with phenobarbital or valproate decreases the occurrence of subsequent febrile seizures.
  • Both therapies confer significant risks and potential adverse effects, whereas additional simple febrile seizures have no proven risk.
  • These medications are not recommended, since the potential benefits do not outweigh the potential risks.
• No evidence suggests that any therapy administered after a first simple seizure will reduce the risk of a subsequent afebrile seizure or the risk of recurrent afebrile seizures (ie, epilepsy).
• Oral diazepam can reduce the risk of subsequent febrile seizures. Because it is intermittent, this therapy probably has the fewest adverse effects. If preventing subsequent febrile seizures is essential, this would be the treatment of choice.
• Although it does not prevent simple febrile seizures, antipyretic therapy is desirable for other reasons.

Activity

No activity restrictions are necessary.

Medication

On the basis of risk/benefit analysis, neither long-term nor intermittent anticonvulsant therapy is indicated for children who have experienced 1 or more simple febrile seizures. In unusual circumstances, oral diazepam can be given with each fever.

Benzodiazepines

These agents have antiseizure activity and act rapidly in acute seizures.

Diazepam (Diastat, Valium, Diazemuls)

Can decrease number of subsequent febrile seizures when given with each febrile episode. By increasing activity of GABA, a major inhibitory neurotransmitter, depresses all levels of CNS, including limbic and reticular formation.
A study reported in New England Journal of Medicine continued therapy until child was afebrile for 24 h. However, this seems excessive.

Dosing

Adult

Pediatric

0.33 mg/kg PO at onset of fever; continue q8h until child is afebrile

Interactions

Toxicity in CNS increased by phenothiazines, barbiturates, alcohols, MAOIs, and other sedative medications; cisapride can increase levels significantly

Contraindications

Documented hypersensitivity, narrow-angle glaucoma

Precautions

Pregnancy

D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus

Precautions

About two thirds of children who receive diazepam for this indication have ataxia, sleepiness, or similar adverse effects; use caution in patients who receive other CNS depressants; be careful with patients who have low albumin levels or hepatic failure, which may increase toxicity

Follow-up

Prognosis

• Prognosis for normal neurologic function is excellent.
  • About one third of children who experience a single simple febrile seizure will have another.
  • The lifetime rate of epilepsy in these children is slightly above that of the general population.

Patient Education

• Inform parents that these dramatic events do not indicate future neurologic dysfunction or disease.
• For excellent patient education resources, visit eMedicine's Brain and Nervous System Center. Also, see eMedicine's patient education articles Seizures and Fever and Seizures in Children.

Miscellaneous

Medicolegal Pitfalls

Not recognizing bacterial meningitis or herpes simplex encephalitis and falsely diagnosing as a simple febrile seizure

Special Concerns

• Parental anxiety or other factors may cause a child to be placed on long-term anticonvulsant medicine. This will not benefit the patient.
• When administered on a daily basis, 2 medications have demonstrated effectiveness in preventing recurrent febrile seizures.
  • Phenobarbital can cause adverse behavioral effects in about 40% of children and allergic reaction.
  • Valproate is associated with liver failure plus injury to other organs such as bone marrow, kidney, and pancreas.
  • Neither medication is proven to be of long-term benefit to children with simple febrile seizure.

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].

Keywords

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

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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