ELECTROMYOGRAPHY AND KINEMATIC ANALYSIS OF ARM MOVEMENT DURING REACHING POST-STROKE.

Abstract

PURPOSE/HYPOTHESIS: This purpose of this preliminary project was to compare upper limb EMG patterns and movement patterns of patients with stroke during a reaching task. We compared between limbs, and before and after CI therapy. NUMBER OF SUBJECTS: Three subjects post-stroke (mean 30.6 months), one woman and two men (mean age 62 years) with right hemiplegia participated the study. MATERIALS/METHODS: Subjects were asked to reach as quickly as possible to a 1.5 block 20 cm from the starting position (trunk midline) in three directions: midline, 45 across midline (45 cross), and 45 to the ipsilateral side (45 lateral) for 6 trials in each direction. Surface EMG was collected from the posterior deltoid (PD), anterior deltoid (AD), biceps (BI), triceps (TR), wrist extensors (WE), and wrist flexors (WF) along with 3D kinematics (trunk, shoulder, elbow, and wrist). Each subject was tested before and after completing a two-week intervention of CI therapy for 6 hours per day. EMG and kinematics were collected using a Konigsberg telemetry system (Konigsberg Instruments, Pasadena, CA 91107) and Peak Motus (Peak Performance, Centennial, CO 80112) and were processed using DATAPAC 2000 (Run Technologies, Laguna Hills, CA 92653) and Motionsoft 3D60 (Bing Yu, PhD, UNC-CH). RESULTS: Movement times for the paretic arm were longer than for the non-paretic arm (.389 vs 2.1 sec). Muscle onsets were later in the paretic limb (8%-32.7 %) and muscles were on longer (9-21%) than in the non-paretic limb. The PD, BI, WE, and WF showed continuous cocontration in the paretic limb while they showed double bursting patterns (36%, 39%) in the non-paretic limb. Movement times were longer for the 45 cross reach and the BI and PD activated earlier (5.5% and 25%, respectively) during 45 lateral reach. Kinematic analysis revealed that wrist extension for the paretic limb was small during midline reach (1-3 degrees) and during 45 cross reach (4-18 degrees) compared to non-paretic limb. Elbow extension was restricted in the paretic arm and reaching to the block was accomplished using trunk movement in all 3 directions. After the 2-week intervention, changes in muscle activity were characterized by earlier muscle onsets, less elbow and wrist concontraction, and more frequent double bursting patterns of the biceps. Elbow extension increased and less trunk flexion was used especially in the 45 lateral direction. CONCLUSIONS: Later onsets, longer muscle contraction, and more cocontraction were typical in involved arm. Inadequate elbow extension appeared to be the limiting factor for reach coordination that was compensated with trunk movement in these subjects. Movement to ipsilateral space at 45 appeared most difficult. These preliminary data suggest that muscle cocontraction especially in the elbow and wrist decreased after the CI therapy intervention. CLINICAL RELEVANCE: N/A.