Comparison of Clinical and Imaging Parameters in Patients With Neuromyelitis Optica Spectrum Disorder and Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease: A Prospective Observational Study

Aim/background The concept of neuromyelitis optica spectrum disorder (NMOSD) is changing, with a disease spectrum emerging that includes aquaporin 4 (AQP4) IgG-seropositive NMOSD, myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD), and double-seronegative NMOSD. The past years have seen important advances in understanding rare demyelinating central nervous system (CNS) disorders associated with AQP4-IgG and MOG-IgG antibodies. Most of the recent literature has focused on the identification of clinical and magnetic resonance imaging (MRI) features that help distinguish these diseases from each other, simultaneously highlighting major diagnostic pitfalls that may lead to misdiagnosis. The present study aims to understand the epidemiology and disease characteristics of NMOSD and MOGAD in our population and compare them with previously published reports. Materials and methods This was a prospective, single-center, comparative, observational study conducted over 18 months. Thirty patients were recruited and categorized into two groups: NMOSD and MOGAD. Each group consisted of 15 patients. Data regarding neurological assessment, neuroimaging, treatment, and outcome were collected. These patients were followed at one, three, six, and 12 months for treatment response, residual disability, and relapse. Disease severity and disability were assessed by using the Expanded Disability Status Scale (EDSS) and modified Rankin scale (mRS). Results The average age at presentation of the NMOSD group of patients was 34.67 ± 15.66 years, which was significantly higher compared to the 26 ± 5.74 years seen for the MOGAD group (p < 0.0001). The MOGAD group of patients had a significantly higher proportion of men compared to the NMOSD group (66.67% in MOGAD versus 0% in NMOSD). Optic neuritis was seen in a significantly higher proportion of MOGAD patients compared to the NMOSD group of patients (p = 0.0061). Bilateral optic neuritis was more common in the MOGAD group (26.67% vs. 6.67% in the NMOSD group). Isolated myelitis was higher in the NMOSD group. A higher proportion of patients in the NMOSD group received steroids along with rituximab (26.67%) compared to the MOGAD subgroup of patients. In terms of the rescue treatment, intravenous immunoglobulin (IVIG) or plasma exchange (PLEX) therapy was required more in the NMOSD group than the MOGAD group. The EDSS and mRS scores of both groups were comparable at baseline. However, on follow-up, the EDSS and mRS levels were significantly lower for the MOGAD group compared to the NMOSD group (p < 0.05). The overall relapse rate was 33.33% in the NMOSD group compared to 20% in the MOGAD group at 12 months. Conclusion NMOSD and MOGAD are two distinct CNS demyelinating disorders having different demographics, clinical profiles, treatment responses, relapse rates, and short-term outcomes. MOGAD patients appear to have younger age at onset, male predominance, less severe clinical presentation, good response to first-line treatment, fewer relapses, and better one-year functional outcomes whereas NMOSD has female predominance, more severe clinical attacks of myelitis and optic neuritis, less response to first-line management of acute attack requiring rescue therapy more often, less response to conventional immunosuppressive treatment with more relapses requiring escalation of maintenance therapy with rituximab, and significant visual and locomotor residual disability at 12 months.