LAUSR

BACKGROUND AND PURPOSE Myelitis is an important clinical component of myelin oligodendrocyte glycoprotein-antibody (MOG-ab)-associated disease (MOGAD) and aquaporin 4-antibody (AQP4-ab)-positive neuromyelitis optica spectrum disorder (NMOSD). The aim was to evaluate the differentiating features of myelitis between the two diseases. METHODS Myelitis-related clinical and radiologic data from 130 patients with MOGAD and 125 patients with AQP4-ab-positive NMOSD were retrospectively reviewed and compared. A scoring model was established to differentiate MOG-ab-associated myelitis from AQP4-ab-associated myelitis. RESULTS 29.2% (38/130) of patients with MOGAD and 66.4% (83/125) of patients with AQP4-ab-positive NMOSD had ever experienced myelitis. Compared with those with NMOSD, patients with MOGAD exhibited a lower frequency of myelitis, either during the first episode (P<0.0001) or throughout the disease duration (P<0.0001). Compared with AQP4-ab-associated myelitis, MOG-ab-associated myelitis manifested a higher male to female ratio (P<0.0001), younger age at disease onset (P=0.0004), more prodromic influenza-like symptoms (P=0.030), more prodromic fever (P=0.0003), more bowel and bladder dysfunction (P=0.011), less painful tonic spasms (P<0.0001), and lower Expanded Disability Status Scale scores after treatment (P<0.0001). On MRI, lower spinal cord lesions (P=0.023), short-segment lesions (P=0.021), conus involvement (P=0.0001), and "H" sign (P<0.0001) were more common in MOG-ab-associated myelitis. A scoring model with a cut-off value of 4 differentiated MOG-ab-associated myelitis from AQP4-ab-associated myelitis with a sensitivity of 87.9% and a specificity of 90.1%. CONCLUSION Myelitis was less commonly observed in MOGAD, and exhibited distinct features compared to those of AQP4-ab-positive NMOSD.