Febrile infection-related epilepsy syndrome (FIRES) describes an explosive-onset, potentially fatal acute epileptic encephalopathy that develops in previously healthy children and adolescents following the onset of a non-specific febrile illness.
FIRES has an estimated European prevalence of 1/100,000 children and adolescents and an annual incidence of 1/1,000,000.
FIRES usually presents in 3-15 year olds that have previously been healthy and developmentally normal. It always comes after a simple febrile illness. Manifestations include the sudden onset of convulsive and recurrent focal seizures. This is followed by refractory focal epilepsy along with a decline in memory, cognition and behavior. Psychiatric disorders and occasionally motor disability can be present in some cases. In serious cases, the disease progression can lead to a vegetative or semi-conscious state or even death.
At present the etiology is unknown. An infection-related pathogenesis is suspected but no direct causes have been established. There may be a genetic etiology for the disease, as seen in Dravet syndrome (see this term), but as yet, no causative genes have been identified. An immune basis for FIRES has also been speculated as certain autoimmune antibodies (such as VGKC, anti-GAD and anti GluR-3) have been found to be elevated in some patients. However, most FIRES patients are mainly autoantibody-negative and immunotherapy-resistant. A metabolic disorder (e.g. mitochondrial encephalopathy) is being discussed as a possible etiological factor.
FIRES should be suspected when the acute onset of refractory seizures follows a few days after a simple febrile illness in previously healthy children. Analysis of cerebrospinal fluid shows normal findings or mild pleocytosis but no presence of pathogens. Tests for metabolic diseases are usually performed with negative results. MRI usually shows no specific abnormalities.
Differential diagnoses include Dravet syndrome, Alpers syndrome, epilepsy and mental retardation limited to females (due to PCDH19 mutations), infectious or limbic encephalitis (e.g., with VGKC antibodies or NMDA receptor antibodies) and metabolic diseases (e.g., biotin-responsive basal ganglia disease, citrullinemia) (see these terms).
Patients with FIRES require immediate hospitalization. Antiepileptic drugs are given to treat seizures but are often ineffective. High-dose phenobarbital and clobazam are most likely to be effective. Barbiturate coma may worsen the outcome in FIRES. A ketogenic diet has been beneficial in some cases, especially if initiated early.
FIRES often has a poor prognosis but a few patients have fully recovered.
Last update: July 2012