Tactile sensory impairments and prehensile function in subjects with left-hemisphere cerebral lesions

The relation between tactile sensory impairments and functional activity of the hand was studied in a group of 10 subjects with cerebrovascular accidents (CVAs) that involved the left hemisphere. Pressure sensitivity and static and moving two-point discrimination thresholds were measured on the thumbs and index fingers of both hands of these subjects and on a group of 14 control subjects. Functional use of the hand was assessed using object and material recognition tests and the Jebsen test of hand function. Prehensile capacity was evaluated with a pinch-force test that examined the influence of load force and surface texture on the forces used to grasp an object. For this group of subjects with left-hemisphere CVAs, elevated sensory thresholds were associated with slower performance on the recognition tests, but not with the Jebsen test. The ability to control the forces used to grasp an object was also found to be deficient in these subjects, although the forces were still adapted to the loads being supported and the surface properties of the object being held.