Unrath A et al. (2007) Cortical grey matter alterations in idiopathic restless legs syndrome: an optimized voxel-based morphometry study. Mov Disord [doi: 10.1002/mds.21608]

The involvement in idiopathic restless legs syndrome (RLS) of brain regions associated with central somatosensory processing has been suggested, but has not been confirmed by high-resolution MRI studies of the whole brain. Previous studies have indicated the involvement of basal ganglia, thalamus, infratentorial structures and spinal cord in this condition. Unrath et al. have used a voxel-based morphometry approach to test the hypothesis that patients with RLS exhibit volume changes in sensorimotor and pain processing areas of the cortex, and in the thalamus.

Analysis of 63 patients with idiopathic RLS (mean disease duration 22.3 years) and 40 healthy controls identified regional decreases in gray matter volume that were significantly associated with RLS. Regional decreases were located bihemispherically in the primary somatosensory cortex; local volume decrease was more widespread in the left hemisphere (cluster size 2,563 vs 1,363 voxels for left side vs right side). Left hemispheric changes were also observed in primary motor areas (precentral gyrus). Gray matter volume at the centroids of the three significant clusters correlated positively with duration of disease, and negatively with patients' scores on the International Restless Legs Severity Scale. No local increases in gray matter volume were observed in RLS patients compared with controls.

The authors conclude that their study provides the first in vivo evidence of involvement of the somatosensory cortex in idiopathic RLS. Their data will contribute to the ongoing task of elucidating the pathophysiology of the condition.