Acute transverse myelitis with normal brain MRI - Long-term risk of MS

Objective To investigate the long-term risk of developing MS in patients presenting with acute transverse myelitis (ATM) and normal brain MRI scans at onset. Methods We studied 58 ATM patients with normal brain MRI at presentation for up to 5 years with serial neurologic and imaging studies. All patients underwent CSF analysis at onset which was defined positive if two or more IgG oligoclonal bands and/or elevated IgG index were present. Brain and spinal cord MRI scans were obtained every 6 months for the first 2 years, and annually thereafter unless the patient experienced a second neurologic attack different from the initial episode to confirm CDMS or there was demonstration of MRI lesions confirming dissemination in time and space to fulfill McDonald imaging criteria to diagnose MS. Results Seventeen of 58 (29%) patients developed MS of which 7 (41%) patients developed CDMS and 10 (59%) developed MS using McDonald Imaging Criteria. Mean time to CDMS by a second clinical attack was 11. 1 months compared to 19. 2 months by MRI lesions (P = 0. 03). None of the patients developed MS after 24 months of onset. All 17 patients who developed MS had positive CSF although 15 patients who had positive CSF did not develop MS during the 5 years of follow-up. Conclusions The majority of patients with ATM and normal brain MRI do not develop MS after 5 years of follow-up confirming the relatively low risk compared to patients with abnormal brain MRI scans. CSF is helpful in distinguishing patients more likely to develop MS. Compared to clinical attacks, serial imaging may not lead to an earlier diagnosis in ATM patients with normal brain MRI.