Objective: To compare the reach-to-grasp (RTG) planning, kinematics and coordination of the less- (left) and more affected (right) hand in Individuals with Parkinson’s disease (PD) who had asymmetrical symptoms and to compare these variables to non-disabled controls.

Background: Previous finding indicated symmetrically bilateral impairment of reaching movement in PD with asymmetrical motor symptoms. It is still questionable if planning, grasping kinematics and RTG coordination are impaired symmetrically in these patients.

Methods: The 18 PDs who had more-affected hand on the right (assessed by UPDRS) and 10 non-disabled controls were assessed on RTG planning, kinematics and coordination during RTG under barrier avoidance condition by left and right hand. The planning was measured by reaction time (RT), The kinematics variables were movement time (MT), maximum velocity (Vmax), time to Vmax (TVmax), Deceleration time (DT), maximum aperture (Amax), time to Amax (TAmax), Aperture closure time (ACT). The coordination was assessed using a cross correlation analysis between transport velocity and aperture size which consisted of 2 variables; correlation coefficient (rmax) and associated time lag (tmax).

Results: In PDs group, the average UPDRS score for right hand was 6.50±0.49, and for left hand was 2.61±0.29. In non-disabled controls, all variables were similar between both hands, except ACT. Whereas ACT were not different between both hands in PD group. In PD group, all variables were similar between both hands, except RT and Vmax. When compared between PD and non-disabled group, all variables were different between 2 groups for each matched hand, except Amax of the left hand.

Conclusions: These results indicate that non-disabled controls spend longer time to close finger for grasping by using left hand when compare to right hand. In contrast, there was not different for this time in PD group which might partly due to the more deficit ACT in right (more-affected) hand. Although the deficits in all RTG kinematics and coordination were symmetrically presented in PDs, the deficit in initiating movement (or akinesia) and bradykinesia was markedly showed in more-affected hand. The possible explanation is that the impairment in movement initiation and execution of PDs might be related to UPDRS score.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/reach-to-grasp-impairments-of-both-hands-in-individuals-with-parkinsons-disease/