Pallidal and caudate volumes correlate with walking function in multiple sclerosis.

Background: Walking dysfunction is common in multiple sclerosis (MS). The thalamus and basal ganglia seemingly have important associations with walking performance. The contribution of these subcortical gray matter (SGM) structures for walking dysfunction is poorly understood in MS.

Purpose: This study examined associations among volumes of the thalamus and basal ganglia with walking outcomes in MS.

Method: We enrolled 61 MS patients who underwent brain MRI and completed the 6-minute walk (6MW) and timed 25-foot walk (T25FW). Volumes of the thalamus, caudate, putamen, and pallidum as well as whole-brain white matter (WM) and gray matter (GM) were calculated from 3D T1-weighted structural brain images. We examined associations using bivariate correlations (r) and partial correlations (pr) that controlled for age, MS clinical course, and whole-brain WM and GM volumes. We further performed hierarchical linear regression (HLR) for identifying the strongest SGM correlate of walking performance.

Results: The 6MW and T25FW correlated significantly with volumes of the thalamus (r's=.382 & .383), caudate (r's=.388 & .416), pallidum (r's=.457 & .457), and putamen (r's=.258 & .293) in bivariate correlations. The 6MW and T25FW remained significantly correlated with caudate (pr's=.243 & .312) and pallidum (pr's=.321 & .345) volumes in partial correlations. Pallidum volume was the strongest SGM correlate of 6MW (β=.39) and T25FW (β=.40) performance in HLR.

Conclusion: We provide novel evidence of possible SGM structures, particularly the pallidum and perhaps caudate, as correlates of walking performance in MS.