Spinal cord lesions are frequently asymptomatic in relapsing-remitting multiple sclerosis: a retrospective MRI survey

Background Spinal cord (SC) involvement correlates with poor prognosis in patients with multiple sclerosis (MS). Nevertheless, there is no consensus on the use of SC-MRI at follow-up, mainly because of the belief that SC lesions are nearly always symptomatic. Objectives The aim of the present study was to investigate the frequency of asymptomatic SC combined unique activity (CUA, new/enlarging T2 or gadolinium-positive [Gd+] lesions) on MRI in a cohort of patients diagnosed with clinically isolated syndrome (CIS) or relapsing-remitting MS (RRMS). Methods We retrospectively investigated all scans showing SC-CUA in patients with CIS or RRMS referred to a single Italian MS centre. We determined whether they were symptomatic and whether they had associated brain radiological activity. Results In 340 SC-MRI scans with SC-CUA (230 patients), SC-CUA was asymptomatic in 31.2%; 12.1% of SC-CUA had neither clinical activity nor brain radiological activity (44.5% and 25.4%, respectively, considering only follow-up SC-CUA). At multivariate analysis asymptomatic SC-CUAs were associated with older age at onset (34.0 +/- 10.37 vs 31.0 +/- 9.99 years, p = 0.006), non-spinal onset (76.4 vs 47.4%, p < 0.001), lower EDSS score at MRI (1.8 +/- 0.93 vs 2.4 +/- 1.28, p = 0.001) and lower number of Gd+ SC lesions (0.1 +/- 0.33 vs 0.3 +/- 0.54, p = 0.04), compared to symptomatic SC-CUAs. Conclusions A substantial proportion of our patients had SC-CUA without clinical symptoms and/or without concomitant brain MRI activity. In these patients, SC-CUA was the only sign of disease activity, suggesting that regular SC-MRI follow-up is required for reliable assessment of radiological activity and may improve the management of patients with MS.