Difference in fatigue and pain between neuromyelitis optica spectrum disorder and multiple sclerosis

To investigate the difference of fatigue and pain in patients with neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS). Data from the Modified Fatigue Impact Scale (MFIS) and Pain Effects Scale (PES) were compared between 51 NMOSD and 85 MS patients. Each score was compared in each disease group with or without clinical abnormalities. Since almost no MS patients are without brain magnetic resonance imaging abnormalities, volumetry analysis by the Lesion Segmentation Tool and statistical parametric mapping 12 were added to obtain total lesion volume and intracranial volume in MS patients, and the correlations between total lesion volume/intracranial volume and each score were investigated. Compared to the MS group, the NMOSD group showed a higher PES score (median, 15.0 vs. 7.0, P = 0.045), no difference in MFIS, and an increased percentage of patients with extended spinal cord lesions (58.8% vs. 8.2%, P < 0.001). Moreover, NMOSD and MS patients with extended spinal cord lesions tended to demonstrate higher PES scores than those without. A positive correlation between MFIS and PES were found in patients with NMOSD and MS. On the other hand, MS patients showed a higher percentage of brain abnormalities (80.4% vs. 97.6%, P = 0.001) and a positive correlation between total lesion volume/intracranial volume and MFIS (Spearman's ρ = 0.50, P = 0.033). The origin of fatigue may be associated with spinal cord lesions causing pain in NMOSD patients, but with brain lesions in MS patients.