Figure 1.

New cortical lesion formation is rare in people with stable white matter lesions. New cortical and white matter lesion formation was frequent (56 and 100%, respectively) in people with active relapsing-remitting multiple sclerosis (defined as having at least one new or enhancing white matter lesion in the year prior to enrolment) but was infrequent in people with radiographically stable relapsing-remitting multiple sclerosis (9% for cortical lesions, 24% for white matter lesions) or progressive multiple sclerosis (24% and 17%) (P = 0.008 for cortical lesions, P < 0.0001 for white matter lesions, chi-square test). New cortical lesion formation was not related to baseline cortical lesion number (median baseline cortical lesion number 16 versus median 20 for those without new cortical lesions, P = 0.97, Mann–Whitney test). Baseline cortical lesions are represented by grey bars; each bar represents a single participant. PPMS, primary progressive multiple sclerosis; RRMS, relapsing-remitting multiple sclerosis; SPMS, secondary progressive multiple sclerosis.