Objective:

To evaluate clinical outcomes in a cohort of patients with Opticospinal Demyelination (OSD).

Background:

Classification of central nervous system inflammation has progressed with the identification of aquaporin-4 (AQP4) antibodies in neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein (MOG) antibodies in MOG antibody disease (MOGAD) in addition to multiple sclerosis (MS). However, as defined in 2003, patients with opticospinal demyelination (optic neuritis (ON), short-segment transverse myelitis (TM), and brain imaging not supportive of MS) do not fulfil internationally approved criteria for MS, NMOSD, or MOGAD. 

Design/Methods:

Between 2003-2005, 128 cases of OSD were reported via the British Neurological Surveillance Unit. In 2011, 2015 and 2022 patients and physicians were contacted for clinical, radiological, and serological (e.g., AQP4-IgG and MOG-IgG) data as part of a prospective longitudinal cohort study.

Results:

Of 128 cases, 67 (52%) patients fulfilled OSD diagnostic criteria. At 17 years 39/60 patients (65%) now met NMOSD diagnostic criteria, 14 (23%) had MS and 7 (12%) had OSD. The median time to diagnosis of NMOSD was 107 months (85-261) and to MS was 189 months (79-346). The median age of OSD patients at onset was 37 (25-48) years and 5/7 were male. A relapsing course was observed in 6/7 patients with a median annualised relapse rate of 0.22 (0.13-0.49). At last follow-up the median EDSS was 2.5 (range; 1- 6.5) and only 2/7 patients had an EDSS>3.5. 

Conclusions:

OSD is diagnostically distinct from MS, NMOSD, and MOGAD. However, after 2 decades most OSD patients reached a diagnosis of NMOSD or MS, so OSD may lie on a spectrum with these conditions. Of the 12% of cases that retained OSD classification, all but 1 had a relapsing course but rates of significant disability were low. Future studies should focus on characterising diagnostic and prognostic biomarkers in this unique subtype of non-MS CNS inflammation.