Alternating Hemispheric Episodes in Bilateral Rasmussen Encephalitis: The Crucial Role of Sequential Multimodal Neuroimaging

Rasmussen encephalitis (RE) is a rare, progressive inflammatory encephalopathy typically characterized by drug-resistant focal epilepsy, cognitive decline, and unihemispheric brain atrophy. Bilateral involvement remains an exceptional clinical entity with limited documentation in medical literature. We present the case of a 2.5-year-old female who exhibited two separate episodes of febrile status epilepticus impacting alternating hemispheres over a six-month period. Serial neuroimaging was pivotal in tracking the disease; the initial MRI revealed right-sided cytotoxic edema and cortical thickening, while a subsequent scan unveiled new contralateral left-sided cortico-subcortical signal alterations alongside progressive right hemispheric atrophy. Continuous bilateral epileptic activity was further corroborated by electroencephalography (EEG). This case highlights that, while RE is classically unilateral, clinicians must maintain a high index of suspicion for bilateral variants, where sequential multimodal neuroimaging proves indispensable for timely diagnosis, prognostic assessment, and therapeutic planning.