This study aimed to investigate the underlying pathological muscle damage in neuromyelitis optica spectrum disorder (NMOSD) patients without muscular symptoms. We prospectively enrolled 15 patients with aquaporin 4 (AQP4) antibody seropositive NMOSD and 16 patients with non-NMOSD diseases as a control group. Biceps biopsy samples from 18 patients were examined. Six NMOSD patients exhibited inflammatory lesions/edema in lower muscles on muscle MRI. On histopathological examination, NMOSD samples showed significantly decreased IgG-targeting AQP4 expression on sarcolemma compared with non-NMOSD samples in terms of the area of positive staining and integrated optical density. Muscle biopsy can support the differential diagnosis of NMOSD.
Keywords: Aquaporin 4; Immunohistochemical staining; Neuromyelitis optica spectrum disorders; Pathology; Skeletal muscle.
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