Ultrasound Elastography to Assess Botulinum Toxin A Treatment for Post-stroke Spasticity: A Feasibility Study

Abstract

The aim of the study was to evaluate the feasibility of using ultrasound elastography to assess the effect of botulinum toxin A (BoNT-A) treatment on post-stroke spasticity of the upper limb. In this prospective study, we performed ultrasound elastography (strain imaging and acoustic radiation force impulse-based shear wave elastography) of the spastic biceps brachii muscle in seven patients (five men and two women, mean age: 45y) who underwent BoNT-A injection treatment for post-stroke spasticity of the upper limb. We measured ultrasound elasticity parameters including axial strain ratio (SR) (SR = muscle strain/reference strain), longitudinal SR and shear wave velocity of the biceps muscle immediately before and 17-30 d (mean: 22 d) after BoNT-A injection. Statistical analyses included a two-tailed paired t-test to examine the difference in ultrasound elasticity parameters of bilateral biceps muscles before and after BoNT-A treatment and a Spearman rank correlation coefficient (rs) to analyze the correlation of ultrasound elasticity parameters to clinical assessment with the Modified Ashworth Scale (MAS) and Tardieu Scale (TS). The difference in ultrasound elasticity parameters before and after BoNT-A treatment was significant (p < 0.05) in the treated spastic muscle. The correlation of ultrasound elasticity parameters with MAS and the angle of catch and range of motion in TS were also significant (rs = 0.55-0.95, p < 0.05). Our results suggest that ultrasound elastography is feasible in assessment of the effectiveness of BoNT-A treatment for post-stroke spasticity of the upper limb.