Article

By involving additional degrees of freedom, the nervous system may
preserve hand trajectories when making pointing movements with or without trunk
displacement. Previous studies indicate that the potential contribution of trunk
movement to hand displacement for movements made within arm reach is neutralized
by appropriate compensatory shoulder and elbow rotations. For beyond-the-reach
movements, compensatory coordination is attenuated after the hand peak velocity,
allowing trunk movement to contribute to hand displacement. OBJECTIVE: To
investigate if the timing and spatial coordination of arm and trunk movements
during beyond-the-reach movements is preserved in stroke. METHODS: Eleven healthy
control subjects and 11 individuals with mild-to-moderate chronic unilateral
hemiparesis participated. Arm and trunk kinematics during 60 target reaches to an
ipsilaterally placed target were recorded. In 30% of randomly chosen trials,
trunk movement was unexpectedly prevented (blocked-trunk trials) by an
electromagnetic device, resulting in divergence of the hand trajectory from that
in free-trunk trials. Hand trajectories and elbow-shoulder interjoint
coordination were compared between trials. RESULTS: In stroke participants, hand
trajectory divergence occurred at a shorter movement extent and interjoint
coordination patterns diverged at a relatively greater distance compared to
controls. Thus, arm movements in stroke participants only partially compensated
trunk displacement resulting in the trunk movement contributing to arm movement
earlier and to a larger extent during reaching. CONCLUSION: Individuals with
mild-to-moderate stroke have deficits in timing and spatial coordination of arm
and trunk movements during different parts of a reaching movement. This deficit
may be targeted in therapy to improve upper limb function.

Langue : ANGLAIS