Neurology · Medical Literature
Effects of repetitive peripheral magnetic stimulation on poststroke ankle spasticity: a double-blind randomized controlled trial.
Abstract
Repetitive peripheral magnetic stimulation (rPMS) is a noninvasive, painless therapy aimed at improving spasticity, with a proposed mechanism that involves neuromodulation through somatosensory and proprioceptive afferent stimulation. The present study evaluates the effectiveness of rPMS on ankle plantar flexor spasticity in participants with stroke. Included in this prospective, double-blind, randomized, sham-controlled study were 50 participants with poststroke ankle plantar flexor spasticity graded 1-3 according to Modified Ashworth Scale (MAS). Participants were randomized into rPMS (n = 25) and sham (n = 25) groups. All participated in a conventional rehabilitation program, while the rPMS group received 10 rPMS sessions over 2 weeks and the sham group received sham rPMS. Assessments at baseline, posttreatment (2nd week), and follow-up (4th week) included MAS, Modified Tardieu Scale (MTS), Barthel Index (stair/mobility), and electrophysiological H/M ratio. A total of 46 participants completed the study. No adverse events related to the stimulation were reported. The rPMS group showed significant improvements in MAS score, MTS angle and grade, and Barthel Index, while no significant changes were observed in the sham group. A significantly greater proportion of participants in the rPMS group (40%) demonstrated MAS score reduction compared to the sham group (4.8%) (p = 0.004). Between-group analysis favored rPMS for MAS and MTS posttreatment and at follow-up. No significant changes in H/M ratios were observed within or between the groups. rPMS can be a valuable adjunct to a traditional rehabilitation program, potentially improving poststroke spasticity. The reductions recorded in MAS and MTS scores in the absence of electrophysiological changes suggest that rPMS may reduce the biomechanical rather than neural component of spasticity. There is a need to define optimal treatment protocols.
Clinical relevance
Poststroke ankle plantar flexor spasticity is a prevalent and functionally disabling sequela that limits rehabilitation outcomes and quality of life; current interventions such as botulinum toxin and oral antispasmodics carry significant side-effect profiles or require invasive administration. This double-blind RCT addresses the evidence gap for noninvasive, well-tolerated adjunctive neuromodulatory therapies in this population. Given the increasing stroke survivor burden and unmet need for scalable outpatient spasticity management, these findings are clinically timely.
Key findings
1. A significantly greater proportion of participants in the rPMS group (40%) demonstrated a reduction in Modified Ashworth Scale (MAS) score compared to the sham group (4.8%), a difference that was statistically significant (p = 0.004). 2. Between-group analyses favored rPMS over sham for both MAS and Modified Tardieu Scale (MTS) angle and grade at posttreatment (2nd week) and at 4-week follow-up, indicating durable short-term benefit. 3. The rPMS group showed significant within-group improvements in MAS score, MTS angle and grade, and Barthel Index (stair/mobility subscales) from baseline to posttreatment; no significant within-group changes were observed in the sham group. 4. No significant changes in electrophysiological H/M ratios were detected within or between groups at any time point, suggesting the mechanism of benefit is biomechanical rather than neural (i.e., reduced alpha-motoneuron hyperexcitability was not demonstrated). 5. The intervention consisted of 10 rPMS sessions over 2 weeks as an adjunct to a conventional rehabilitation program; 46 of 50 enrolled participants completed the study (92% completion rate). 6. No adverse events related to rPMS stimulation were reported, supporting its safety profile as a noninvasive adjunct therapy. NOTE: Precise effect sizes, confidence intervals, and NNT were not reported in the abstract; these values cannot be cited without access to the full manuscript.
Practice implications
Clinicians managing poststroke ankle plantar flexor spasticity (MAS grade 1–3) may consider rPMS as a safe, noninvasive adjunct to conventional rehabilitation programs, delivered as a 10-session, 2-week course, particularly for patients who are poor candidates for or declining botulinum toxin or pharmacologic antispasmodics. The absence of H/M ratio changes implies rPMS preferentially targets the biomechanical (viscoelastic/connective tissue) component of spasticity rather than reducing spinal motoneuron hyperexcitability, which should inform patient selection and realistic goal-setting in clinical counseling. Optimal stimulation parameters (frequency, intensity, coil placement, session number) remain undefined and require validation in larger trials before standardized protocols can be adopted.