Myelitis: Differences between multiple sclerosis and other aetiologies.

BACKGROUND: Myelitis can appear as an initial symptom in the context of demyelinating diseases, systemic inflammatory diseases, and infectious diseases. We aim to analyse the differences between myelitis associated with multiple sclerosis (MS) and myelitis resulting from other aetiologies.

METHODS: Single-centre, retrospective analysis of patients with initial myelitis (2000-2013). Demographic, aetiological, clinical, radiological and prognostic variables were analysed and compared between patients with myelitis from MS and those with myelitis due to other aetiologies.

RESULTS: We included 91 patients; mean follow-up was 7 years. Diagnoses were as follows: MS 57 (63%), idiopathic transverse myelitis 22 (24%), associated systemic diseases 6 (7%), and other diagnoses (6%). Myelitis due to MS was associated with younger age of onset (35 ± 11 vs. 41 ± 13; P = .02), more pronounced sphincter involvement (40.4 vs. 27.3%; P=.05), greater multifocal involvement in spinal MRI (77.2 vs. 26.5%; P=.001), shorter lesion extension (2.4 vs. 1.4 vertebral segments; P=.001), cervical location (82.5 vs. 64.7%; P=.05) and posterior location (89.5 vs. 41.2%; P=.001). Myelitis due to other aetiologies more frequently showed anterior location (47.1 vs. 24.6%; P=.02), and central cord involvement (47.1 vs. 14.1%; P=.001), with better recovery at one year of follow up (EDSS 2.0 vs. 1.5; P=.01). Multivariate analysis showed that multifocal spinal cord involvement (OR 9.38, 95% CI: 2.04-43.1) and posterior cord involvement (OR 2.16, 95% CI: 2.04-2.67) were independently associated with the diagnosis of MS.

CONCLUSIONS: A high percentage of patients with an initial myelitis event will be diagnosed with MS. The presence of multifocal and posterior spinal cord lesions was significantly associated with the diagnosis of MS.