LAUSR

Background: Spinal cord atrophy in multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) correlates with clinical progression in Caucasian subjects, although such a correlation remains to be established in Asians, including identification of the relevant spinal levels to measure. We aimed to investigate how and where atrophy is associated with disability in Japanese patients with MS and NMOSD. Methods: Cross-sectional spinal cord areas (SCA) at the disc levels of C2/C3, C3/C4, T8/9, and T9/10 were measured in 118 relapsing-remitting MS (RRMS), 27 progressive MS (PMS), and 53 NMOSD patients. Expanded disability status scale (EDSS) scores were used to assess disability. Results: PMS patients showed smaller cervical cord areas than RRMS patients (mean 57.4 vs. 61.1 mm2, p=0.04 at C2/C3; 58.1 vs. 63.6 mm2, p=0.007 at C3/C4). NMOSD patients had significantly smaller thoracic cord areas than MS patients (mean 28.7 vs. 31.2 mm2, p=0.02 at T8/T9; 29.8 vs. 32.0 mm2, p=0.046 at T9/T10), while there were no significant differences in cervical cord areas between the two conditions. In MS, both cervical and thoracic cord areas were significantly associated with EDSS scores after adjusting for sex, age, and disease duration (p<0.0001 at C2/C3; p<0.0001 at C3/C4; p=0.006 at T8/T9; p=0.006 at T9/T10). In NMOSD, only thoracic cord areas were associated with EDSS scores (p=0.001 at T8/T9; p=0.009 at T9/T10). Conclusion: Spinal cord atrophy is a potentially useful marker of disability in Japanese patients with MS and NMOSD. It is important to measure a relevant spinal cord level, according to the disease. • The cervical and thoracic cord area has been known significantly related with Expanded Disability Status Scale (EDSS) scores in Caucasian MS patients. BACKGROUND