The Clinical Outcomes of Tocilizumab Usage in Cryptogenic Febrile Infection-Related Epilepsy Syndrome at Both Acute and Chronic Phase: A Retrospective Study

Purpose: To provide more observational evidence for potential efficacy of tocilizumab (TCZ) in children with cryptogenic febrile infection-related epilepsy syndrome (FIRES) administered during acute and chronic phase. Methods: Data of 22 children with FIRES who received TCZ were collected retrospectively. Patients were categorized into two groups: acute group (TCZ used within 4 weeks post-onset; n = 12) and chronic group (TCZ used beyond 4 weeks post-onset; n = 10). Results: In both groups, patients experienced > 50% reduction in seizure frequency, electroencephalogram (EEG) improvements, alleviation on cranial magnetic resonance imaging (MRI), and significantly decreased mRS scores ( P < 0.05). In acute group, 6 patients became seizure-free by the last follow-up, and 7 patients reduced their number of antiseizure medications (ASMs). TCZ administration in acute phase shortened status epilepticus (SE) duration. At last follow-up, the acute group exhibited higher rates of seizure freedom and > 50% seizure reduction ( P < 0.05), lower incidences of motor and speech deficits ( P < 0.05), and a greater likelihood of returning to school ( P < 0.05). Conclusion: TCZ treatment was associated with reduced seizure frequency, improved EEG and MRI findings, decreased reliance on antiseizure medications, and functional improvement as measured by mRS. Initiation of treatment during the acute phase may be associated with a shortened duration of status epilepticus and, compared to chronic-phase intervention, appears to correlate with more favorable long-term outcomes. Keywords: FIRES, TCZ, outcomes, chronic phase, acute phase