Electroencephalographic and neuroimaging prognosticators in pediatric FIRES with claustrum lesions: A 21-case...

Febrile infection‑related epilepsy syndrome (FIRES) is a severe acute inflammation‑associated encephalopathy in children, characterized by high mortality and poor long‑term outcomes. FIRES with claustrum lesions (FIRES‑C) represents a distinct subtype. However, the relationship between its neuroimaging heterogeneity and electrophysiological phenotype remains unclear, and the association between sleep spindles and acute‑phase severity has not been systematically investigated. This study aimed to characterize the electroclinical features of FIRES‑C to facilitate improvements in diagnosis, treatment, and prognostic evaluation.

This retrospective study enrolled pediatric patients from our previously reported large cohort. We evaluated dynamic electroencephalographic changes across the acute and chronic phases, examined the correlation between sleep spindles and disease severity, and compared differences between isolated claustrum lesions and those with concurrent thalamic/temporal lobe involvement. All statistical analyses were performed using SPSS 26.0.

Twenty-one patients with FIRES-C were included, with a median age of onset of 8.33 years. All presented with focal motor seizures and impaired consciousness. Claustrum lesions appeared >10 days after onset in 90.5% of patients, and 76.2% had additional brain involvement. Among the 19 patients who were followed up, 63.2% achieved favorable long-term outcomes. Acute-phase electroencephalography (EEG) revealed absent occipital rhythm, diffuse delta slowing, disrupted sleep architecture, and migratory focal discharges; EEG abnormalities improved markedly during the chronic phase. Patients without sleep spindles exhibited more severe acute clinical manifestations; however, this finding did not correlate significantly with long-term neurological outcomes. Univariate analyses showed that children with isolated bilateral claustrum lesions had milder acute symptoms and better long-term functional prognosis. In contrast, patients with concomitant thalamic and temporal lobe involvement tended to have impaired consciousness, significantly lower detection rates of sleep spindles on EEG, and poorer long-term functional outcomes.

FIRES-C exhibits characteristic dynamic EEG evolution. The absence of sleep spindles merely indicates a trend toward more severe acute clinical manifestations and cannot serve as a predictor of long‑term functional prognosis. Univariate intergroup comparisons demonstrated that the extent of imaging lesions was correlated with acute disease severity, EEG findings, and long‑term prognosis.