The effect of interferon beta-1b treatment on MRI measures of cerebral atrophy in secondary progressive multiple sclerosis

The recently completed European trial of interferon beta-1b (IFN beta -1b) in patients with secondary progressive multiple sclerosis (SP multiple scle rosis) has given an opportunity to assess the impact of treatment on cerebr al atrophy using serial MRI. Unenhanced T-1-weighted brain imaging was acqu ired in a subgroup of 95 patients from five of the European centres; imagin g was performed at 6-month intervals from month 0 to month 36. A blinded ob server measured cerebral volume on four contiguous 5 mm cerebral hemisphere slices at each time point, using an algorithm with a high level of reprodu cibility and automation. There was a significant and progressive reduction in cerebral volume in both placebo and treated groups, with a mean reductio n of 3.9 and 2.9%, respectively, by month 36 (P = 0.34 between groups). Exp loratory subgroup analyses indicated that patients without gadolinium (Gd) enhancement at the baseline had a greater reduction of cerebral volume in t he placebo group (mean reduction at month 36: placebo 5.1%, IFN beta -1b 1. 8%, P < 0.05) whereas those with Gd-enhancing lesions showed a trend to gre ater reduction of cerebral volume if the patient was on IFN<beta>-1b (place bo 2.6%, IFN beta -1b, 3.7%; P > 0.05). These results are consistent with o ngoing tissue loss in both arms of this study of secondary progressive mult iple sclerosis. This finding is concordant with previous observations that disease progression, although delayed, is not halted by IFN beta. The diffe rent pattern seen in patients with and without baseline gadolinium enhancem ent suggests that part of the cerebral volume reduction observed in IFN bet a -treated patients may be due to the anti-inflammatory/antioedematous effe ct of the drug. Longer periods of observation and larger groups of patients may be needed to detect the effects of treatment on cerebral atrophy in th is population of patients with advanced disease.