Spinal Cord Atrophy in Neuromyelitis Optica Spectrum Disorders Is Spatially Related to Cord Lesions and Disability

Background The spinal cord is commonly involved in patients with neuromyelitis optica spectrum disorders (NMOSDs). However, the relationship between inflammation and atrophy remains unclear. Purpose To characterize the spatial distribution of T1-hypointense lesions in the spinal cord at MRI, its association with cord atrophy, and its correlation with disability in participants with NMOSDs. Materials and Methods This prospective study evaluated three-dimensional T1-weighted spinal cord MRI scans in seropositive participants with NMOSDs and in age-matched healthy control participants acquired between February 2010 and July 2018. Binary masks of T1-hypointense lesions and lesion probability maps were produced. Cross-sectional area of the cervical and upper thoracic cord (down to T3 level) was calculated with the active-surface method. Full factorial models were used to assess cord atrophy in participants with NMOSDs. Correlations between cord atrophy and clinical and brain MRI measures were investigated with multiple regression models. Results A total of 52 participants with NMOSDs (mean age ± standard deviation, 44 years ± 15; 45 women) and 28 age-matched healthy control participants (mean age, 44 years ± 13; 16 women) were evaluated. Thirty-eight of 52 (73%) participants with NMOSDs had T1-hypointense cord lesions. No cord lesions were detected in the healthy control participants. Lesion probability maps showed a predominant involvement of the upper cervical (C2-C4) and upper thoracic (T1-T3 level) cord. The greater involvement of C1-C4 survived Bonferroni correction (<i>P</i> value range, .007-.04), with a higher percentage lesion extent in the gray matter (<i>P</i> < .001). Atrophy colocalized with focal cord lesions and correlated with pyramidal subscore (<i>r</i> ranging from -0.53 to -0.40; <i>P</i> < .001) and sensitive subscore (<i>r</i> ranging from -0.48 to -0.46; <i>P</i> = .001) of the Expanded Disability Status Scale. Participants without cord lesions had no cord atrophy. Conclusion In participants with neuromyelitis optica spectrum disorders, focal areas of spinal cord atrophy at MRI were topographically associated with lesions and correlated to motor and sensory disability. Participants without visible cord lesions had no atrophy. © RSNA, 2020 <i>Online supplemental material is available for this article.</i>