Low Incidence of Asymptomatic Contrast-Enhancing Brain Lesions in Japanese Patients with Multiple Sclerosis

Abstract

Background: The number of contrast-enhancing brain lesions is used as an endpoint in multiple sclerosis (MS) clinical trials. However, the incidence of asymptomatic contrast-enhancing brain lesions (AEBLs) in Japanese patients with MS has not been determined. Objective: To describe the number of AEBLs per scan in Japanese patients with relapsing-remitting MS (RRMS). Methods: We reviewed the medical records of 23 Japanese patients with RRMS who showed (1) a stable or improving condition for at least 30 days before a magnetic resonance imaging (MRI) examination and (2) at least one relapse in the preceding year or two relapses in the preceding 2 years. Results: The percentage of patients with AEBLs was 39.1% (9/23 patients) and the number of AEBLs per scan was 0.37. Conclusions: The results suggest that the disease activity shown by brain MRI was lower in Japanese patients with MS compared with that in Caucasian patients.