The present study quantified reaching movements in 17 patients with vascular hemiplegia at various stages of recovery and 6 control subjects. The task involved grasping a light cone placed at one of seven positions on a baseboard. 3D analysis of movement was performed. Quantification of the reaching movement in hemiparetic patients showed abnormal features that could be related either directly to the motor impairment or to two kinds of adaptation to the impairment: acquisition of a new motor coordination or acquisition of a new strategy. Two movement strategies were identified in hemiparetic patients. Patients with a predominantly proximal impairment slid their hands toward the target, thus making maximal use of the properties of the environment. Patients with a predominantly distal impairment made a downward grasping movement, which probably used the passive properties of the hand-object contact to ensure grasping. These features contribute to fulfillment of the goal and are thus consistent with the acquisition of adaptive behavior by the hemiparetic patients.
A. Roby-Brami and M. Mokhtari are with INSERM-CREARE, Neurosciences et modélisation, 9 quai St. Bernard, 75005 Paris, France. S. Fuchs and B. Bussel are with Service de rééducation neurologique, Hôpital Raymond Poincaré, 92380 Garches, France.