Alterations in reaching after stroke and their relation to movement direction and impairment severity.

Abstract

To examine the effects of stroke severity and target location on reaching (1) to identify regions in space that are difficult to reach, (2) to determine whether specific alterations in reaching are associated with particular clinical impairment levels, and (3) to characterize relationships between reaching alterations. Participants reached toward a screen of 75 targets spanning an approximate range from +/-90 degrees side to side and from waist to head. Rehabilitation research center. Sixteen chronic stroke patients with a wide range in residual arm function and 4 control subjects. Not applicable. Chedoke-McMaster Stroke Arm Assessment, distance, velocity, smoothness, straightness, and direction of the hand path during each reach. Hand position trajectories were recorded with an electromagnetic sensor. Reaches performed with the impaired arms showed significant degradation in all performance measures. Although only modestly dependent on the target location, these features correlated strongly with impairment level, as well as with each other. Reaching distance showed the strongest correlations with the other parameters. Stroke alters a broad array of features of reaching, yet largely the same degree of movement control is preserved across a range of target locations. The only consistently problematic task is to reach far out from the torso, independent of the movement direction. Thus, active range of motion (AROM), rather than control over a specific subset of movement directions, is a logical focus for therapy. In addition, measuring AROM is a simple clinical measure that yields much information.