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.