Abstract TP69: Change Over Time Feature Of A Range Of The Recruited Motor Unit In The Recovery Period Of Hemispheric Stroke

Abstract

The paralysis after the stroke makes loss adjustment of the force in the voluntary movement and disturbs the physical activity. The voluntary force is regulated by the motor unit (MU) recruitment and firing rate. Therefore, we should evaluate MU firing patterns to understand a part of the mechanism of the force adjustment disorders of the paralysis side. It might be possible to evaluate the change of the force adjustment function on the paralysis side in the convalescence if we considered a range of the recruited MU over time. This pilot study hypothesizes that a range of the recruited MU spreads depending on a recovery stage. Two-stroke patients participated in this study. We measured the muscle activity of the biceps using surface EMG with three-time points during the recovery period after stroke. The raw EMG data were decomposed into motor unit action potential (MUAP). Then mean firing rate (MFR) and peak amplitude of MUAP were calculated by decomposed MUAP. Additionally, coefficients of the regression line were calculated by MFR and MUAP's peak amplitude. The coefficient of the linear regression line was adopted as the outcome to evaluate a range of the recruited MU size. We also analyzed the change over time of a range of the recruited MU size. The range of the recruited MU of the recovery stage changed over time but became wide during the recovery stage. These data showed that it varied from a restrictive style to a comprehensive recruitment style over time. Therefore, a range of the recruited MU with the stroke of the recovery stage was suggested to be a tendency to enlarge over time. Expanding the diachronic range of the recruited MU may let you enrich a variation of the force in the recovery process.