Abstract
The diversity of multiple sclerosis (MS) and the nosology of the conventional form of MS (CMS), optico-spinal MS (OSMS)1 and neuromyelitis optica (NMO) have been subject to controversy. This study retrospectively reviewed and analysed 842 cases with CNS demyelinating disease in Western Australia (WA).2 The patient population was predominantly Caucasian, representing approximately two-thirds of MS cases in WA. The study confirmed the relatively low frequency of OSMS as a proportion of total demyelinating disease in WA, with 31 OSMS (3.7%) in contrast to 703 CMS (83.5%). It is likely however that our retrospective classification significantly underestimated the proportion of OSMS when compared to prospectively classified Asian cohorts. There were 11 OSMS cases that could also be classified as NMO. The clinical characteristics of OSMS in our study were compatible with so-called Asian MS: oligoclonal bands were less frequent in OSMS (29.4%) than in CMS (66.4%, p = 0.003), long spinal cord lesions (LESCL) were more prevalent in OSMS (22.2%) than in CMS (3.4%, P < 0.001), Brain abnormalities were seen in 48.4% of OSMS patients, and 96.2% of CMS patients (p < 0.001). This cross-sectional study presents the full spectrum of demyelinating disease in WA, and suggests that characteristics of the WA MS population were similar to those reported in Asian patients.