Importance: Recognizing the differences between transverse myelitis (TM) associated with myelin oligodendrocyte glycoprotein (MOG) antibody (Ab) disease vs aquaporin-4 (AQP4)-Ab disease and prognosticating patients within each group may be an important factor for better clinical treatment for these respective patients.

Objectives: To compare the clinical and radiological findings of the first TM episode in patients with MOG-Ab disease vs patients with AQP4-Ab disease and to assess factors associated with worse outcomes and relapse risk.

Design, setting, and participants: This retrospective cross-sectional study used data collected from the Oxford Neuromyelitis Optica Service database, a national service that serves the south of England, including detailed clinical data, and high-quality imaging from within 4 weeks of the first TM episode from patients with MOG-Ab disease or AQP4-Ab disease and a confirmed history of TM from April 2018 to January 2019. Data analyses were conducted from February 2019 to April 2019.

Main outcomes and measures: Onset features of each condition measured using the Expanded Disability Status Scale (EDSS) score, time to an EDSS score of 6, time to relapse, and residual sphincter dysfunction at least 6 months after the first TM episode and at last follow-up.

Results: The total cohort included 115 adult patients, including 46 patients with MOG-Ab disease and 69 patients with AQP4-Ab disease. Patients with AQP4-Ab disease, compared with patients with MOG-Ab disease, tended to be older at onset of disease (mean [SD] age, 48.5 [14.9] years vs 33.7 [1.2] years) and female (57 [83%] women vs 24 [52%] women). Transverse myelitis occurred at onset of disease for 32 patients (70%) with MOG-Ab disease and 57 patients (78%) with AQP4-Ab disease. Onset severity did not differ between groups. An acute disseminated encephalomyelitis-like presentation occurred at the time of the TM in 4 patients (9%) with MOG-Ab disease but no patients with AQP4-Ab disease. Compared with patients with AQP4-Ab disease, patients with MOG-Ab disease were more likely to have short cord lesions (22 patients [48%] vs 10 patients [15%]; P < .001) and multiple cord lesions (18 patients [39%] vs 7 patients [10%]; P < .001). Approximately 50% of patients with MOG-Ab disease had only short cord lesions when the TM occurred as a relapse. Median (range) recovery EDSS score was lower in patients with MOG-Ab disease than patients with AQP4-Ab disease (1.8 [1.0-8.0] vs 3.0 [1.0-8.0]). Persistent bladder dysfunction associated with an increased prevalence of conus lesions occurred more frequently in patients with MOG-Ab disease than in patients with AQP4-Ab disease (27 patients [59%] vs 33 patients [48%]). Long-term catheter requirement was roughly equal between groups (9 patients [20%] vs 16 patients [23%]). Relapses after TM occurred in 17 patients with MOG-Ab disease (37%) and 36 patients with AQP4-Ab disease (52%). Concomitant brainstem lesions in patients with MOG-Ab disease were associated with a higher mean (SD) EDSS score at recovery (3.5 [2.3] vs 1.4 [0.9]; P < .001). In patients with AQP4-Ab disease, those younger than 50 years were more likely to relapse (27 of 36 patients aged <50 years [75%] vs 9 of 33 patients aged ≥50 years [27%]; P < .001) and those 50 years and older were more likely to reach an EDSS score of 6 (19 of 33 patients aged ≥50 years [58%] vs 11 of 36 patients aged <50 years [31%]; P = .03).

Conclusions and relevance: This study found that in patients who experienced a TM episode, short and multiple lesions at onset were more common in those with MOG-Ab disease than among those with AQP4-Ab disease. The presence of a brainstem lesion at the time of a TM episode in patients with MOG-Ab disease was associated with a worse recovery. In patients with AQP4-Ab disease, those 50 years and older at disease onset had more disability, and those younger than 50 years at disease onset had more relapses.