Febrile seizures

Historical note and nomenclature
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By Renée Shellhaas MD MS, Carol S Camfield MD, and Peter Camfield MD

Febrile seizures (febrile convulsions) are the most common convulsive events in human experience. They were recognized as distinct from other seizures in the mid-19th century, and at that time, treatment was redirected to the underlying causes of fever rather than the symptom of a seizure. With the introduction of the thermometer at the end of the 1800s, fever was understood to be the primary factor producing the convulsion. Until the early 20th century, infantile convulsions were thought to be severe and often fatal. Unfortunately, few effective treatments were available. Sentinel studies in the 1940s by Lennox and Livingston investigated risk factors for recurrence and later epilepsy (Livingston et al 1947; Lennox 1949).

In the 1970s 2 population-based studies formed the foundation of the current view of febrile seizures (van der Berg and Yerushalmy 1969; Nelson and Ellenberg 1978): they are common, many recur, developmental outcome is not altered, and few children later develop epilepsy. In 2008 and 2011, updated evidence-based practice parameters were published by the American Academy of Pediatrics Committee on Quality Improvement, Subcommittee on Febrile Seizures. This, along with the original 1996 publication, and a consensus statement by the International League Against Epilepsy (Capovilla 2009), reflects the current evidence for diagnosis, and treatment recommendations for febrile seizures (American Academy of Pediatrics 2008; 2011).

About 3% to 4% of all children will have at least 1 febrile seizure (Nelson and Ellenberg 1976; Vestergaard and Christensen 2009). Although the seizures are associated with fever (greater than 38.5°C by rectal or tympanic membrane measurement), those provoked by CNS infection are excluded. The peak age for febrile seizures is 18 to 22 months with a range between about 6 months and 5 years (American Academy of Pediatrics 1996).

Febrile seizures can be subdivided into “simple” (generalized tonic-clonic semiology, duration less than 15 minutes, and without recurrence within the next 24 hours) or “complex” (focal, duration more than 15 minutes, or occurring in a cluster of 2 or more convulsions within 24 hours). Febrile seizures are generally thought to be benign, and only 2% to 3% of affected children will later develop epilepsy (Nelson and Ellenberg 1976). The risk of epilepsy following a simple febrile seizure is about 2%, and following a complex febrile seizure, it is still only 5% to 10%. Therefore, febrile seizures can be viewed as a syndrome of acute symptomatic seizures rather than as a true epilepsy syndrome (Engel 2001).

In This Article

Historical note and nomenclature
Clinical manifestations
Pathogenesis and pathophysiology
Differential diagnosis
Diagnostic workup
Prognosis and complications
References cited