Botulinum Toxin-A Effects on the Muscle Architecture of Hemiplegic Upper Extremity in Stroke Patients: An Ultrasonographic Study

Abstract

Introduction: Muscle architecture is main determinant of muscle function and there was no study about the change of muscle architecture in spastic upper extremity after botulinum toxin-A (BoNT-A) injection. The aim of this study was to evaluate the effects of BoNT-A injection on the hemiplegic upper extremity muscle architecture of stroke patients using ultrasonography. Methods: Fifteen consecutive hemiplegic patients (mean age: 60.3±8.8 years) who were injected with BoNT-A for the treatment of upper extremity spasticity in April to June 2014 were enrolled. Flexor carpi radialis muscle of hemiplegic side was evaluated using ultrasonography. Muscle length, anterior and posterior pennation angle, muscle thickness, cross-sectional area of muscle and muscle volume were measured. Ultrasonographic evaluations were performed before BoNT-A injection and repeated 1 month and 3 months after injection. Results: Muscle thickness at a neutral position and posterior pennation angle at maximal extension significantly decreased 3 months after injection (p=0.001, p=0.023, respectively), fascicle length increased at neutral, maximal flexion and maximal extension positions after 1 month (p=0.001, p=0.004, p=0.002, respectively) and this increase was maintained at neutral and maximal extension after 3 months (p=0.041). Proximal muscle volume around the injection site significantly decreased after 3 months (p=0.036) and distal volume from injection site increased 1month and 3 months after injection (p=0.002, p=0.027). Conclusions: These results confirm the change in muscle architecture in spastic upper extremity hemiplegia after BoNT-A injection, elucidating the effects of BoNT-A injection on spastic muscle of stroke patients.

Keywords: Muscle Architecture, Pennation Angle, Muscle Volume, Hemiplegia, Stroke, Botulinum Toxin-A

Student Number: 2010-21822