Kinematic Analysis of Obstacle Crossing During Reach- Grasp-Retract Movement in Highly Functioning Patients with Chronic Stroke
Date Issued
2008
Date
2008
Author(s)
Yi-Miau Chen
Abstract
Objective: The reaching movement of stroke patient has been studied widely in order to understand the mechanism and effective treatment approach. To our knowledge, no prior study has disclosed how the obstacles near the target affect the motor performance of reaching. Besides, most studies explored only the reaching movement without the bring back component. The purposes of this study were to investigate the motor performance of U/E according to the obstacle while reaching for grasping and retracting for placing an object in stroke patients. esearch method: Our study enrolled 7 highly functioning participants with chronic stroke. All participants seated and were asked for reaching the target and then bring it back to put on the table. Obstacle with its height equal to 30% of upper arm length was placed at about 65% of the full arm length. Another condition was to put the obstacle with height of 0 as controlled. Kinematic data were measured using a 6-camera motion analysis system (Vicon 512, Oxford Metrics Group, U. K.). The following parameters were compared between the unaffected and affected upper limb of the stroke participants including reaction time, movement time, transport path, peak velocity (PV), percentage of movement where PV occurs, maximum grip aperture, percentage of reaching time where maximum grip aperture occurs, wrist–obstacle clearance, movement unit, object pick up time, object–obstacle clearance and object placing time in reach to grasp movement and retraction movement in control and obstacle crossing condition, Paired t-test (α=0.05) was used and the effect size was also calculated.esults: In the obstacle crossing condition, the performances of the kinematic parameters of unaffected and affected upper limbs were both changed by the obstacle. Shorter transport path, smaller percentage of reaching time where maximum grip aperture angle occurs and lower wrist clearance in reach to grasp, whereas longer movement time, slower average speed and higher object clearance in retraction movement were found in affected than in unaffected side. The result might imply that the motor control of affected and unaffected upper limb was different in the obstacle crossing condition. When kinematic parameters of both unaffected and affected upper limb were analyzed in conditions with obstacle height of 0% & 30%, significant differences were found in the unaffected upper limb but not the affected side. The result maybe imply that the affected upper limb lacking the flexibility to adjust the arm movement according to the obstacle height, but when carried an object, it moved higher to prevent hitting the obstacle.onclusions: The subjects in this study were with highly motor function and invisible motor deficit observed through clinical evaluation, but when asked them to carry an object crossing an obstacle without hitting it, the motor differences between the unaffected and affected upper limb emerged. The existed of an obstacle as well as an object increased the complexity and demand of the task, the moving body needed to adapt the motor control of reaching hand in order to achieve the task goal, by the way, the motor deficit of the stroke patients would be amplify by the obstacle. When providing the treatment programs to the highly functioning patients with chronic stroke, more complicated and goal directed tasks should be used to treat the motor control of affected upper limb in clinical settings.
Subjects
Obstacle
reach-grasp-retract
motor control
upper limb
stroke
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