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Simple Febrile Seizures in Children

From The Child's Doctor, Fall 2008

Charu Venkatesan, MD, PhD
Attending Physician, Neurology, Ann & Robert H. Lurie Children's Hospital of Chicago; Assistant Professor of Pediatrics, Northwestern University Feinberg School of Medicine
Disclosure: Dr. Venkatesan has no industry relationships to disclose and does not refer to products that are still investigational or not labeled for the use in discussion.

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Educational objectives

At the conclusion of this activity, participants will be able to:

  • Distinguish between simple and complex febrile seizures
  • Discuss risks of complications after a simple febrile seizure
  • Discuss recommendations for evaluation and management of simple febrile seizures

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Summary

Simple febrile seizures in children are very common. Due to concerns about potential adverse outcomes, particularly the risk of developing epilepsy, available treatment options have been used in attempts to prevent recurrence of febrile seizures. In a recently issued clinical practice guideline, the American Academy of Pediatrics (AAP) has addressed the relative risks and benefits of the use of anticonvulsants and antipyretics for long-term management of simple febrile seizures, to help pediatricians make evidence-based decisions.[1] This review will focus on the risks associated with simple febrile seizures, as well as discuss the latest recommendations on evaluation and treatment.

Simple vs. complex febrile seizures

A febrile seizure is defined by the International League Against Epilepsy as “an epileptic seizure associated with a febrile illness not caused by an infection of the central nervous system (CNS ), without previous neonatal seizures or a previous unprovoked seizure, and not meeting criteria for other acute symptomatic seizures.”[2] Febrile seizures are classified as either simple or complex.

Simple febrile seizures have the following features[3]:

  • They are brief (lasting less than 15 minutes) and resolve spontaneously.
  • They typically occur as isolated events and not more than once in 24 hours.
  • They are characterized by generalized convulsions of the body.

In contrast, complex febrile seizures have 1 or more of the following features[4]:

  • They are prolonged (greater than 15 minutes) and may not resolve spontaneously.
  • They occur more than once in 24 hours during a febrile illness.
  • There is focal convulsion of 1 side of the body.

Epidemiology and risk factors

The incidence of simple febrile seizures is 2%–4% in children in United States and Western Europe.[5] They are most common between the ages of 6 months and 5 years, and have a peak incidence at 18 months of age. Timing of fever with respect to seizure onset can be variable. Studies have found that while the majority (57%) of children experience a seizure 1–24 hours after fever onset, children can also have a seizure either prior to or more than 24 hours after the onset of fever.[6,7]

There is convincing evidence for a genetic basis for febrile seizures, with 24%–40% of patients reporting a positive family history.[8] There is a higher concordance rate among monozygotic than dizygotic twins.[3] The mode of inheritance may be multifactorial. Susceptibility foci for febrile seizures have been identified on chromosomes 2, 5, 6, 8, 18 and 19.[9]

Risk factors associated with experiencing a first simple febrile seizure include[3,10]:

  • First or second degree relative with a history of febrile convulsions
  • Developmental delay
  • Day care attendance
  • V iral infections (eg, influenza A, human herpesvirus 6)
  • Vaccinations (eg, DTaP and MMR)

After a first simple febrile seizure, approximately 30% of children will have a recurrence and 10% will have 3 or more febrile convulsions.[3]

Risk factors associated with recurrence include[3,10]:

  • Family history of febrile seizures
  • O nset of simple febrile seizures at less than 12 months of age
  • Temperature at less than 40 C

Aside from a high rate of recurrence, simple febrile seizures have not been shown to place children at risk for long-term complications.[1] Studies have not identified cognitive declines, lower school performance, attention difficulties, nor behavioral abnormalities as an outcome of recurrent simple febrile seizures. There are no reports of death as a result of a simple febrile seizure.

The risk of developing epilepsy after a single simple febrile seizure is not substantially different than the risk in the general population. Features associated with an increased risk include[1,3]:

  • Family history of epilepsy
  • Occurrence of complex febrile seizure
  • Occurrence of multiple simple febrile seizures
  • O nset of simple febrile seizures at less than 12 months of age

Evaluation

In order to make a diagnosis of simple febrile seizure, other provocative etiologies such as electrolyte imbalance and primary neurological insults (meningitis or encephalitis) must be excluded. A detailed history and physical examination can aid in eliminating other causes for a child’s seizure. A practice parameter has been issued by the American Academy of Pediatrics (AAP) for evaluation of a child between the ages of 6 months and 5 years who presents within 12 hours of the first simple febrile seizure.[11] Routine blood work including serum electrolytes, calcium, phosphorous, magnesium, complete blood count or blood glucose are of limited value in the absence of a suspicious history (eg, vomiting) or physical examination (eg, suggestive of dehydration). Laboratory work should be directed towards identifying the source of fever rather than evaluating the seizure.[11]

The AAP evaluation guidelines recommend that a lumbar puncture be strongly considered in infants less than 12 months of age. Lumbar puncture should be considered in children between 12 and 18 months of age because clinical signs of meningitis may be subtle. In children older than 18 months, lumbar puncture is recommended in the presence of history or physical examination findings suggesting intracranial infection. A lumbar puncture is recommended after a first complex febrile seizure, in a child with persistent lethargy, and in a child who has received prior antibiotic treatment.[11]

Electroencephalograms (EE Gs) are not recommended in the evaluation of a neurologically healthy child after a first febrile seizure. EE Gs are more likely to be abnormal in children with complex febrile seizure or children with family history of febrile seizures. However, EEG abnormalities are not predictive of the recurrence of febrile seizures or development of epilepsy.[3] The AAP does not recommend neuroimaging in the form of computed tomography or magnetic resonance imaging scans in the evaluation of children with simple febrile seizure.[11]

Treatment

Simple febrile seizures are brief and self-resolving and no intervention is usually necessary. Persistent seizure activity upon arrival to the Emergency Department warrants therapeutic intervention since typically, this seizure activity has been continuing for longer than 15 minutes. This type of prolonged seizure would no longer be categorized as a simple febrile seizure. Intravenous diazepam or lorazepam or rectal diazepam can be used as the first line medication.[3] Persistence of seizure activity warrants initiation of full status epilepticus protocol.

Since the major risk after simple febrile seizures is recurrence, numerous studies have evaluated the use of antipyretic and anticonvulsant drugs for preventing febrile seizures. No study has demonstrated that antipyretics (aspirin, acetaminophen or ibuprofen), in the absence of anti-convulsant drugs reduce the recurrence risk of febrile seizures.[12,13]

The role of anticonvulsant drugs including phenobarbital, valproic acid, carbamazepine, phenytoin and diazepam in preventing recurrent febrile seizures has been studied.[1,14] Phenobarbital, valproic acid, and intermittent diazepam administration have all been shown to reduce the recurrence of subsequent febrile seizures.[1,14] Carbamazepine and phenytoin have not been shown to be effective in preventing the recurrence of febrile seizures.

However, anti-convulsants have significant side-effects and toxicities[1]  (Table 1) and there is no evidence that prevention of febrile seizures reduces the risk of developing subsequent epilepsy.[3] There is also no evidence that links simple febrile seizures to development of cognitive disabilities or premature death. Thus, the AAP does not recommend the use of continuous or intermittent antiepileptic therapy, given that the potential toxicities associated with these medications outweigh the relatively minor risks posed by simple febrile seizures.[1,14]

Counseling

After a child experiences a simple febrile seizure, parents can feel anxious and frightened by this episode. During the episode, they may feel helpless as they are unable to stop the seizure. They may worry that the child will die during the convulsion or that the child may suffer neurological injury secondary to the simple febrile seizure. In these situations, physician reassurance and parental education are very important. Basic facts about simple febrile seizures and how to keep a child safe during an episode should be presented to the family. Specific information on management of seizures should be discussed including when to take the child to the Emergency Department or call the physician’s office.

Conclusion

Simple febrile seizures are a common type of childhood seizures. When evaluating a child, diagnostic studies should be aimed at exploring the cause of fever as clinically indicated. Given the generally favorable prognosis associated with simple febrile seizures, anticonvulsant therapy is not indicated. Counseling and parental education are important to attempt to reduce parental anxiety.

References

[1.] American Academy of Pediatrics: Steering Committee on Quality Improvement and Management, Subcommittee on Febrile Seizures. Febrile seizures: Clinical practice guideline for the long-term management of the child with simple febrile seizures. Pediatrics 2008;121:1281-1286.

[2.] Commission on Epidemiology and Prognosis, International League Against Epilepsy. Guidelines for epidemiologic studies on epilepsy. Epilepsia 1993;34:592-596.

[3.] Shinnar S, Glauser TA. Febrile Seizures. J Child Neurol 2002;17:S44-S52.

[4.] Berg AT, Shinnar S. Complex febrile seizures. Epilepsia 1996;37:126-133.

[5.] Verity CM, Butler NR, Golding J. Febrile convulsions in a national cohort followed up from birth. I. Prevalence and recurrence in the first 5 years of life. BMJ 1985;290:1307-1315.

[6.] Berg AT, Shinnar S, Hauser WA, et al. Predictors of recurrent febrile seizures: A prospective study of the circumstances surrounding the initial febrile seizure. N Engl J Med 1992;327:1122-1127.

[7.] Berg AT, Shinnar S, Darefsky AS, et al. Predictors of recurrent febrile seizures. Arch Pediatr Adolesc Med 1997;151:371-378.

[8.] Hauser WA, Annegers JF, Andersen VE, Kurland LT. The risk of seizure disorders among relatives of children with febrile convulsions. Neurology 1985;35(9):1268-1273.

[9.] Nakayama J, Arinami T. Molecular genetics of febrile seizures. Epilepsy Research 2006;S190-S198.

[10.] Jones T, Jacobsen SJ. Childhood febrile seizures: Overview and implications. Int J Med Sci 2007;4(2):110-114.

[11.] American Academy of Pediatrics: Provisional Committee on Quality Improvement. Practice parameter: The neurodiagnostic evaluation of the child with a simple febrile seizure. Pediatrics 1996;97:769-775.

[12.] Camfield PR, Camfield CS, Shapiro S, et al. The first febrile seizure — Antipyretic instruction plus either phenobarbital or placebo to prevent a recurrence. J Pediatr 1980;97:16-21.

[13.] van Stuijvenberg M, Derksen-Lubsen G et al. Randomized, controlled trial of Ibuprofen syrup administered during febrile illness to prevent febrile seizure recurrences. Pediatrics 1998;102;e51.

[14.] Baumann RJ, Duffner PK. Treatment of children with simple febrile seizures: The AAP Practice Parameter. Pediatric Neurol 2000;23:11-17.


Accreditation Statement

The Northwestern University Feinberg School of Medicine is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

Credit Designation Statement

The Northwestern University Feinberg School of Medicine designates this live activity for a maximum of 2 AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.