Relief of post-stroke spasticity with acute vibrotactile stimulation: controlled crossover study of muscle and skin stimulus methods

Caitlyn Seim; Bingxian Chen; Chuzhang Han; David Vacek; Laura Song Wu; Maarten Lansberg; Allison Okamura

doi:10.3389/fnhum.2023.1206027

Relief of post-stroke spasticity with acute vibrotactile stimulation: controlled crossover study of muscle and skin stimulus methods

Front Hum Neurosci. 2023 Aug 29:17:1206027. doi: 10.3389/fnhum.2023.1206027. eCollection 2023.

Authors

Caitlyn Seim¹, Bingxian Chen², Chuzhang Han¹, David Vacek¹, Laura Song Wu¹, Maarten Lansberg³, Allison Okamura¹

Affiliations

¹ Stanford University Department of Mechanical Engineering, Stanford, CA, United States.
² Stanford University Department of Bioengineering, Stanford, CA, United States.
³ Stanford University Department of Neurology and Neurological Sciences, Stanford, CA, United States.

Abstract

Background: Prior work suggests that vibratory stimulation can reduce spasticity and hypertonia. It is unknown which of three predominant approaches (stimulation of the spastic muscle, antagonist muscle, or cutaneous regions) most reduces these symptoms.

Objective: Determine which vibrotactile stimulation approach is most effective at reducing spastic hypertonia among post-stroke patients.

Methods: Sham-controlled crossover study with random assignment of condition order in fourteen patients with post-stroke hand spasticity. All patients were studied in four conditions over four visits: three stimulation conditions and a sham control. The primary outcome measure was the Modified Ashworth Scale, and the secondary outcome measure was the Modified Tardieu Scale measured manually and using 3D motion capture. For each condition, measures of spastic hypertonia were taken at four time points: baseline, during stimulation, after stimulation was removed, and after a gripping exercise.

Results: A clinically meaningful difference in spastic hypertonia was found during and after cutaneous stimulation of the hand. Modified Ashworth and Modified Tardieu scores were reduced by a median of 1.1 (SD = 0.84, p = 0.001) and 0.75 (SD = 0.65, p = 0.003), respectively, during cutaneous stimulation, and by 1.25 (SD = 0.94, p = 0.001) and 0.71 (SD = 0.67, p = 0.003), respectively, at 15 min after cutaneous stimulation. Symptom reductions with spastic muscle stimulation and antagonist muscle stimulation were non-zero but not significant. There was no change with sham stimulation.

Conclusions: Cutaneous vibrotactile stimulation of the hand provides significant reductions in spastic hypertonia, compared to muscle stimulation.

Clinical trial registration: www.ClinicalTrials.gov, identifier: NCT03814889.

Keywords: muscle spasticity; stimulation; stroke; stroke rehabilitation; vibration.

Associated data

ClinicalTrials.gov/NCT03814889

Grants and funding

This work was supported by the Stanford Wu Tsai Neurosciences Institute Neuroscience: Translate Program, National Institutes of Health grant #1F32HD100104, and a Stanford Wu Tsai Neurosciences Institute Interdisciplinary Scholar Award. Zihuai He of the Stanford Quantitative Science Unit contributed counsel on our statistical analysis plan. Julius Dewald of Northwestern University provided input on study design.