Therapeutic Apheresis for Intravenous Methylprednisolone‐Refractory Neuromyelitis Optica Spectrum Disorder: Clinical and Radiological Outcomes in a Single‐Center Case Series

BACKGROUND: Neuromyelitis optica spectrum disorder (NMOSD) is a relapsing autoimmune disease of the central nervous system. High-dose intravenous methylprednisolone (IVMP) is the standard first-line therapy for acute attacks, although some patients remain refractory. Therapeutic apheresis is often used in such cases, although its efficacy in milder presentations or spinal cord-dominant forms remains less established. Few studies have quantitatively assessed the treatment effects using imaging, particularly magnetic resonance imaging (MRI)-based lesion measurements, leaving a gap in the objective evaluation of therapeutic outcomes. OBJECTIVE: We aimed to evaluate the clinical and radiological outcomes of therapeutic apheresis in patients with NMOSD, including those with mild disabilities, following IVMP. METHODS: We retrospectively analyzed eight patients with NMOSD treated between 2016 and 2023, who underwent therapeutic apheresis after IVMP for acute relapse. The Expanded Disability Status Scale (EDSS) scores and spinal cord lesion areas on T2-weighted MRI were compared before and after apheresis. RESULTS: (p = 0.03). Apheresis was effective even in patients with lower baseline EDSS scores. Seven of the eight patients had nonoptic neuritis, supporting efficacy for spinal cord-dominant NMOSD. CONCLUSIONS: Therapeutic apheresis following IVMP may benefit a broad range of patients with NMOSD, including those with mild symptoms and nonoptic presentations. Our findings underscore the importance of incorporating objective radiological assessments into future evaluations of treatment responses.