Longitudinal imaging for monitoring disease activity in late‐onset Rasmussen's encephalitis during multimodal rehabilitation and immune therapy

Rasmussen's encephalitis (RE) is a rare autoimmune encephalopathy typically manifesting in early childhood, causing unilateral autoimmune inflammation of the cerebral cortex, leading to progressive neurological deficits, notably focal epileptic seizures. The late‐onset variant of RE in adults progresses slower and presents atypical features. Despite extensive research, the etiology remains elusive, hindering accurate diagnosis and treatment options.We present a biopsy‐confirmed late‐onset variant of RE case in a 71‐year‐old man with a disease course of 12 years. After the initiation of intravenous immunoglobulin therapy and immunosuppressive treatment, disease stabilization was achieved, as evidenced by clinical assessments and imaging. Initially, the affected hemisphere swelled hyperacutely, followed by years of atrophic encephalopathy stabilizing into a residual state, with emerging focal disease signs in the contralateral hemisphere. Multimodal rehabilitation and immune therapy attenuated brain atrophy and reduced signal enhancement.Late‐onset variant of RE rehabilitation remains underdeveloped, focusing on symptom management and functional recovery post‐surgery. Longitudinal imaging is crucial for monitoring immune therapy response in clinical practice.