Distinct white matter lesion patterns associated with previous relapse activity in multiple sclerosis and neuromyelitis optica spectrum disorder

Background: Multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD) are both chronic inflammatory demyelinating diseases of the central nervous system, but they have distinct pathophysiological features that distinguish their clinical phenotypes and lesion characteristics. The objective of this study was to investigate the correlation between white matter (WM) lesion location and previous relapse activity, as well as disease duration, in these two diseases. Methods: This study included 64 patients with relapsing-remitting MS and 49 with NMOSD. We used the voxel-based lesion-symptom mapping (VLSM) method to determine the correlations of the presence of WM lesions with the number of attacks and the disease duration in each disease group. Results: We found that WM lesions were correlated with the number of attacks; the deep WM of the right parietotemporal region including parts of the superior longitudinal fasciculus in MS patients and the right superior corona radiata, corticospinal tract, and inferior fronto-occipital fasciculus in NMOSD patients. However, there were no specific locations associated with disease duration in patients with either disease. Conclusion: Our VLSM analysis confirmed that prior relapse activity was associated with distinct WM lesion locations in MS and NMOSD, respectively. In contrast, disease duration, independent of disease activity, showed no association with specific lesion patterns in either disease.