Electroclinical and neuroradiological evolution in pediatric and adult patients with Rasmussen encephalitis

Rasmussen encephalitis (RE) is a rare progressive inflammatory disorder characterized by drug-resistant focal epilepsy and unilateral cerebral atrophy. This study aimed to evaluate the longitudinal electroclinical, neuroradiological, treatment, and surgical characteristics of pediatric and adult patients with RE followed at a tertiary referral center.

Fourteen patients (10 females) with a median follow-up of 75.5 months were retrospectively reviewed. Clinical characteristics, serial electroencephalography (EEG), brain magnetic resonance imaging (MRI), immunotherapy regimens, surgical interventions, and seizure outcomes were analyzed.

Median age at symptom onset was 102 months. Focal motor seizures were the initial presenting symptom in 86% of patients, and epilepsia partialis continua developed in 57%. Serial EEG demonstrated progression from focal epileptiform abnormalities to regional and hemispheric slowing confined to the affected hemisphere. Left-hemispheric involvement was observed in 71% of patients in this relatively older cohort. Initial MRI frequently demonstrated cortico-subcortical T2-weighted and fluid-attenuated inversion recovery (FLAIR) hyperintensities preceding progressive cortical atrophy. Serial MRI revealed heterogeneous radiological evolution, including diffuse hemispheric and limited regional cortical atrophy patterns. Despite immunotherapy, most patients showed progressive disease and refractory seizures. Hemispherectomy resulted in seizure freedom in two of three operated patients.

RE demonstrated heterogeneous electroclinical and neuroradiological evolution across pediatric and adult patients. The coexistence of an older age profile and a predominance of left hemisphere involvement may suggest age-related phenotypic variability. Early MRI abnormalities may precede overt hemispheric atrophy, highlighting the importance of longitudinal evaluation for timely diagnosis. Although immunotherapy may provide temporary stabilization, surgical treatment appears to provide the most favorable seizure outcomes in selected patients.