The Outcome of Febrile Infection-Related Epilepsy Syndrome (FIRES)

Introduction: Febrile Infection-Related Epilepsy Syndrome [FIRES] is a rare, catastrophic epileptic syndrome that strikes previously healthy children, whose pathogenesis is unknown. It starts with a febrile illness and refractory seizures, but without evidence of an identifiable infectious encephalitis. Purpose: To study the course of illness and the outcomes in children with FIRES. Methods: This is a retrospective study conducted at a tertiary healthcare center in southern India between August 2014 and August 2022, which included all children diagnosed with FIRES. The demographic details, clinical manifestation, cerebrospinal fluid [CSF] analysis, neuroimaging findings, electroencephalography (EEG), treatment, and outcome were analyzed. Results: A male preponderance of 66% (12/18) was noted, with the median age of disease onset being 8.55 years. The onset of seizures following fever was noted at a median duration of 3 days. The median duration of hospitalization was 26 days. The average number of anti-seizure medications (ASMs) used was five. The CSF analysis was normal in 72% [13/18], pleocytosis seen in 16% [3/18], and elevated protein in 11% [2/18]. Neuroimaging was done in all children. Of the eighteen cases, 22% showed cerebral edema [4/18], while 5% [1/18] showed irregular hyperintensities, and 72% [13/18]were normal. The EEG was abnormal in all the cases, with multifocal epileptiform discharges being the commonest finding, seen in 77% [14/18]. The outcome was analyzed using a modified Rankin scale(mRS). Among those who survived, the score ranged from 1 to 3, with a median score of 2, reflecting mild disability. Fifty percent of the cases succumbed. The most common cause of death was septic shock, followed by arrhythmias. The surviving nine children underwent magnetic resonance imaging [MRI] during follow-up, and 66% [6/9] had abnormal neuroimaging findings, with cerebral atrophy being the commonest finding. Conclusion: FIRES is a highly fatal condition, occurring in previously normal children, more commonly boys. The condition requires multiple ASMs to halt the seizures. All the infective parameters, including CSF analysis, were normal. Fifty percent mortality and fifty percent morbidity was seen.