Control of paretic and non-paretic upper extremity during bimanual reaching after stroke

Kinematic analysis in post-stroke patients with moderate to severe upper limb paresis and non-disabled controls

BACKGROUND

Kinematic analysis has been recommended to quantify the upper limb motor function after stroke. However, previous studies have rarely reported the kinematic data of the post-stroke patients with moderate to severe upper limb paresis due to the poor accomplishment of the complex tasks.

METHODS

27 post-stroke individuals and 20 non-disabled people participated in the study. The trunk and upper limb movements during the Hand-to-mouth task were captured by the motion capture system and upper extremity kinematic analysis software automatically. The subgroup analysis within stroke group were conducted layering by the Fugl-Meyer Assessment for Upper Extremity scores (severe: 16-31; moderate: 32-50).

FINDINGS

The paretic upper limbs in the stroke group tended to use more trunk and shoulder compensatory strategies to offset the impact of spasticity and weakness compared with non-disabled controls. The less-affected limbs in the stroke group also showed abnormal kinematic data. There were significant differences between the kinematic metrics of severe and moderate subgroups.

INTERPRETATION

The Hand-to-mouth task is a good and feasible option for kinematic analysis of these patients. It is essential to layer the severity of the paresis and put more emphasis on trunk movements in the future kinematic studies.

The Strategy of Human Movement Control and Teaching Motor Skills in Norm and Pathology

The strategy used by the brain to organize human goal-directed movements is still debated. Here, I argue that without the knowledge of this strategy, teaching movement skills required in complex sports activities and for rehabilitation of motor disorders remains an art and can often result in inefficient techniques and misleading instructions. However, the leading joint hypothesis offers a solution to this problem. It suggests that the control strategy consists in rotation of a single ('leading') joint actively and using the biomechanical effect produced by the leading joint as the primary contributor to motion of the other ('trailing') joints. This "trailing joint control pattern" was found in a large variety of movement types. This pattern is simple even for seemingly complex movements, it can be easily verbalized, and it requires focusing attention during learning only on one or two movement elements at a time. The use of the trailing joint control strategy therefore allows development of better targeted techniques of motor learning and rehabilitation.