Supplementary Material for: Radiological Disease Activity in Secondary Progressive Multiple Sclerosis

Introduction: MRI activity is less frequent among secondary progressive multiple sclerosis (SPMS) patients. In the current study, we aimed to identify SPMS patients with higher radiological disease activity (RDA) and determine their clinical characteristics. Methods: We evaluated the occurrence of RDA in SPMS patients followed at the Sheba Multiple Sclerosis Center between January 1, 2015, and December 31, 2020. All patients underwent brain and spinal cord MRI examinations as a routine follow-up unrelated to clinical disease activity. Patients were subdivided into RDA and non-RDA MRI groups based on the presence of active gadolinium-enhancing T1 lesions and/or new/enlarging T2 lesions. Demographic variables and disease-related data were compared. Results: One hundred consecutive SPMS patients, 74 females, median age of 50 years, disease duration of 19.5 years, and neurological disability by the Expanded Disability Status Scale (EDSS) score of 6.0, were included in the study. The RDA group comprised 35 patients (35%), of them 65.7% (n = 23) exhibited only brain MRI activity, 22.8% (n = 8) only spinal cord MRI activity, and 11.4% (n = 4) had both. Patients in the RDA group were diagnosed at a younger mean (SD) age of 28.2 (8.9) versus 33.7 (10.1) years and were younger with a mean (SD) age of 47.8 (9.9) versus 53.4 (10.1) years, as compared with the non-RDA group. No significant differences were found in relation to disease duration, EDSS, exposure to immunomodulatory treatments, and duration of immunomodulatory treatments. Conclusions: RDA unrelated to clinical symptomatology was more frequent in a subgroup of young SPMS patients.