02-24 – Does ‘benign NMOSD’ exist? A case series from a national referral centre

Introduction: Most patients with neuromyelitis optica spectrum disorder (NMOSD) harbour antibodies to aquaporin-4 (AQP4-IgG). AQP4-IgG NMOSD typically follows a relapsing disease course, resulting in significant stepwise disability accumulation with each relapse. Previous studies have demonstrated that patients with NMOSD experience disabling relapses several years after achieving disease stability if they discontinue immunosuppression, necessitating lifelong immunosuppression.
Objectives/Aims: We present a series of patients who experienced a benign disease course from NMOSD despite not receiving immunosuppressive therapy.
Methods: Patients with a benign disease course were selected from the Walton’s Centre’s highly specialised NMOSD service (a national referral centre for NMOSD in the United Kingdom). Benign disease was defined as an estimated disability status score (EDSS) of 3 or lower despite being off immunosuppressive therapy for at least 4 years. Patients with and without relapses during this period were included.
Results: Amongst 124 AQP4-IgG NMOSD patients, 6 individuals (4.8%) exhibited a benign disease course. Five of the patients were of White ethnicity and one was of Black ethnicity. Patients experienced either relapsing myelitis (2), monophasic optic neuritis (3) or multiple sites of involvement (1) during their disease course. The mean age was 42 years (95% CI 33.7-50.3), with a disease duration of 12.3 years (95% CI 9.2-15.5) and duration off therapy of 8.3 years (95% CI 5.0-11.5 years). The mean EDSS at the final follow up was 1.8 (95% CI 0.7-2.8). Five patients experienced no relapses whilst off therapy for at least 4 years.
Conclusion: Although the majority of AQP4-IgG NMOSD patients experience a non-benign disease course, we demonstrate that a small number of patients can remain stable without significant relapses even without immunotherapy. Further investigations into biomarkers of patients with a benign disease course could be revealing.