Efficacy of focal muscular vibration in the treatment of upper limb spasticity in subjects with stroke outcomes: randomized controlled trial

Focal muscular vibration (FMV) is a non-invasive technique that showed positive effects on spasticity of the upper limb in stroke subjects but different protocols have been proposed so the studies are not comparable and, to date, it is not clear which muscles should be treated, agonist, or antagonist muscles to obtain the better result on spasticity. The objective of this study is to evaluate the effects on spasticity of FMV on the upper limb flexor spastic muscles compared to the effects of FMV on the upper limb extensor muscles in subacute stroke patients. We treated 28 subacute stroke patients (mean age 64.28±13.79) randomized into two groups: Group A and Group B. Group A was treated by applying FMV to the flexor muscles of the upper limb, while Group B was treated by applying FMV to the extensor muscles of the upper limb. The effects on spasticity were assessed by Modified Ashworth Scale (primary outcome) and the upper limb motor function by instrumental robotic outcomes; moreover, muscle strength and pain were evaluated using Motricity Index and Numerical Rating Scale, respectively (secondary outcomes). Patients were subjected to FMV for three consecutive days and were evaluated three times: before treatment (T0), after a week (T1) and after a month (T2) from the end of treatment. Within group, analysis showed statistically significant changes over time of the MAS at the three joints (shoulder, elbow and wrist) in both groups, but post-hoc analysis showed that, only in Group A, MAS was significantly lower at T2, when compared with T0 at the shoulder and elbow. NRS, significantly changed over time only in the Group B. Motricity Index, did not change over time neither in the Group A, nor in the Group B. No statistically significant differences were detected in the between group analysis. Regarding the instrumental robotic outcomes, we detected a statistically significant reduction of the time required to complete the task (Duration) in both group a T2. In conclusion, this study highlighted how the same treatment protocol can determine an improvement in muscle tone and in the Duration to perform a task, regardless of the muscles treated, while the pain improves if we treat the agonist muscles.