Recurrent optic neuritis – Different patterns in multiple sclerosis, neuromyelitis optica spectrum disorders and MOG-antibody disease

Background: Optic neuritis is a frequent finding in multiple sclerosis (MS) and in neuromyelitis optica spectrum disorder (NMOSD), as well as in Myelin-Oligodendrocyte Glycoprotein (MOG) –positive disease. While both NMOSD and MOG-antibody disease are known to be associated with a humoral, antibody-mediated attack against a specific antigen, much less is known about the etiology and pathogenesis of MS. The aim of this study was to determine if the localization of recurrent episodes of ON follows the same pattern in MS as in NMOSD and in MOG-positive recurrent ON. Methods: We retrospectively reviewed our database to identify patients with recurrent ON. The eye affected in each episode of ON was recorded, and the findings were analyzed. Results: Forty-seven patients met the inclusion criteria. In the MS group, all episodes of ON recurred on the same side in 15 of the 29 patients (51.7%), accounting for 32 of the total 78 episodes (41%).In the NMSOD group, all episodes of ON recurred on the same side in 2 of the 12 patients (16.6%), accounting for 6 of the total 49 episodes (12.5%).In the MOG-positive group, all episodes of ON recurred on the same side in 1 out of 6 patients (16.6%), accounting for 2 of 21 episodes (9.5%).The between-group difference in the rate of recurrences affecting the ipsilateral side was statistically significant (p =.0007 and p =.0085 for the MS-NMOSD and MS-MOG groups, respectively). Conclusions: The pattern of recurrent ON differs significantly between MS and NMOSD and MOG-positive recurrent ON. This finding suggests that in MS recurrences may be provoked by previous tissue damage, disruption of the blood-brain barrier, and other local factors while in NMOSD and MOG-antibody disease attacks are indeed due to localization of the auto antigen.