Comparison of Objective Indicators of Proprioception of Single–joint Arm Movements in Healthy Subjects and Post–Stroke Patients in Sitting and Lying Positions

Testing of sensory-motor performance and motor rehabilitation training in post-stroke patients are often executed in lying position. At the same time, influence of the body position on proprioceptive perception is poorly studied. In this study, we have investigated proprioceptive perception of single-joint arm movements in 10 healthy subjects and 17 post-stroke patients with unilateral arm paresis in the sitting and lying positions using the method we developed. Movements of flexion–extension in shoulder, elbow and wrist joints and abduction–adduction in shoulder and wrist joints were tested. The subjects were made to perform a series of the passive single-joint movements with the eyes closed and had to copy these movements simultaneously by active movements of another arm. We recorded the angles at the tested joint and the homonymous joint of the other arm, and the status of proprioceptive sensitivity was evaluated basing on the degree of similarity of these “passive” and “active” movements. Qualitative and quantitative indicators were used to assess the similarity. It was found that healthy subjects reproduce the passive movements without rough qualitative errors in both the sitting and lying positions. The movement reproduction was less accurate in the lying position by values of some quantitative indicators, however only 3% of trails did not match the conventional criterion for proprioceptive sensitivity intactness. On the contrary, the movement reproduction in almost half of tests in the group of post-stroke patients was performed with qualitative and quantitative errors and did not match the requirements of the conventional criterion. A deficit of proprioception was observed in 1 to 5 different test-movements in 88% of patients in the sitting position and 71% of patients in the lying position. Most frequent and rough errors in the movement reproduction were observed in distal segments of the paretic arm. It was found that the body position could have different effects on the proprioceptive perception of the same test-movement in patients: the proprioceptive perception was evaluated as intact in the sitting position and as distorted in the lying position in 14% of all test trials and vice versa it was evaluated as distorted in sitting position and as intact in lying positions in 17% of trials. Such individual differences must be considered when choosing conditions for motor rehabilitation procedures in patients with paresis of the arm.