Febrile seizures

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By Renée Shellhaas MD MS, Carol S Camfield MD, and Peter Camfield MD

Febrile seizures are usually brief and self-limited. When the seizure occurs, the child should be placed in a prone position or on his/her side on a protected surface, observed carefully, and brought to an emergency facility if the seizure lasts longer than 10 minutes (Hirtz 1989). In most cases, a feverish child is taken to a medical facility after the seizure has ended. If the convulsion is prolonged, however, the child's airway should be kept clear, oxygenation maintained, and intravenous or rectal anticonvulsants such as diazepam, midazolam, or lorazepam given to halt the seizure. Febrile status epilepticus is often underdiagnosed and undertreated (Hesdorffer et al 2012; Bassan et al 2013) and is unlikely to remit spontaneously (Seinfeld et al 2014).

Parents, emergency medical responders, and clinicians should have a low threshold for using rescue medications for children with prolonged febrile seizures.Parents should be counseled that family routines will be disrupted for several weeks, but that normal life will continue and their child will do well. The only serious sequelae appear to be parental anxiety and subsequent labeling of the child as “vulnerable.” An Iranian study demonstrated that 39% of mothers thought their child was dying during their first febrile seizure and 95% were concerned that the seizure would impact their children’s health in the future (Kolhai 2009). Often parents worry about the potential association of febrile seizures and sudden infant death. Vestergaard and colleagues compared the risk of sudden infant death syndrome in 9977 siblings of children with a febrile seizure and 20,177 siblings who never had febrile seizures (Vestergaard et al 2002). These data did not support a shared susceptibility hypothesis.

A population-based Danish study demonstrated that the mortality rate for children with simple febrile seizures was not different from the general population (Vestergaard et al 2008). However, there was a slightly increased risk of death among children with complex febrile seizures (lasting longer than 15 minutes or recurring within 24 hours), although the result was not statistically significant when children with preexisting neurologic conditions were excluded. In the FEBSTAT study, 2 of 119 children died, both of whom had premorbid developmental delays (Shinnar et al 2008).

Several studies have documented the magnitude of parental anxiety and improvement with education, understanding, and reassurance (van Stuijvenberg et al 1999; Huang et al 2001; 2002; Ju et al 2011). Parent information sheets can be accessed on the internet (American Academy of Family Physicians 2006; National Institutes of Neurologic Disorders and Stroke 2012).

Only rarely is any kind of prophylactic medication indicated for a child with 1 or more febrile seizures (Camfield et al 1997; American Academy of Pediatrics 1996). Prophylactic daily therapy with phenobarbital or valproate may reduce the recurrence of febrile seizures. Daily administration of phenobarbital at a dosage sufficient to achieve a blood level of 15 µg/mL can effectively reduce the risk of a recurrent febrile seizure (Camfield et al 1980; Freeman 1980). However, a metaanalysis of phenobarbital for prevention of febrile seizures suggests that it cannot be recommended (Offringa and Moyer 2001; Offringa and Newton 2013). Valproate has a similar effect (Mamelle et al 1984). However, concerns about reports of fatal hepatitis in children younger than 2 years, or of pancreatitis, although rare, make valproate an inadvisable choice. Compliance with daily medication is often problematic. Daily use of carbamazepine or phenytoin has been found to be an ineffective treatment for prevention of febrile seizures.

There does not seem to be any compelling reason to treat children with daily prophylactic medication after 1 or more febrile seizures (American Academy of Pediatrics 2008; Offringa and Newton 2013). The potential side effects of drugs outweigh the benefits.

If treatment is offered, we recommend liquid diazepam 0.5 mg/kg per dose given rectally at home at the time of an actual seizure (Knudsen and Vestermark 1978; Camfield et al 1989). This may reduce subsequent seizures during the same febrile illness (Hirabayashi et al 2009). Nasal midazolam shows promise and its use may supplant liquid diazepam because of its ease of delivery, although more study is needed. Rectal diazepam gel also is effective, but it is an extremely expensive home management tool (O’Dell et al 2005). A Greek study randomized children with a first simple febrile seizure to intermittent prophylaxis with rectal diazepam or no prophylaxis during subsequent febrile illnesses (Pavlidou et al 2006). In the 3-year follow-up, there were no significant side effects from the 0.33 mg/kg per dose diazepam, and the risk of febrile seizure recurrence was reduced (85% recurrence in high-risk children in the control group versus 38% in the highest risk children randomized to diazepam). There was no difference in recurrence rate between children randomized to oral diazepam versus clobazam for intermittent febrile seizure prophylaxis in a small study from India, but there were fewer reported side effects in the clobazam group (Khosroshahi et al 2011).

The benefit of an intermittent treatment is the prevention of a prolonged febrile seizure; however, this approach is only appropriate for a well-organized family with a few individuals caring for the child. Alternatively, intermittent oral diazepam at the time of illness might be considered to prevent a recurrent febrile seizure. For success, there must be excellent compliance and few caretakers. A dose of 0.2 mg/kg per dose of oral diazepam has been shown to be ineffective (Uhari et al 1995). A mild reduction in recurrence risk is seen with 0.3 mg/kg per dose, but at this dose about one third of children will have significant side effects of somnolence or ataxia (Rosman et al 1993; Camfield et al 1995). It has been estimated that 14 children with a first febrile seizure would have to be treated with intermittent oral diazepam to prevent 1 recurrent febrile seizure.

The inefficacy of antipyretic medications is outlined in the Prevention section.

In This Article

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