Effects of Different Numbers of Stimulations in Single-Session Radial Extracorporeal Shock Wave Therapy on Spasticity Improvement in Individuals With Subacute Hemiparetic Stroke: Protocol for a Pilot Randomized Controlled Trial

Background Radial extracorporeal shock wave therapy (rESWT) improves lower-limb spasticity after stroke. However, the efficacy of rESWT in individuals with hemiparetic stroke in the subacute phase, in whom neural components of spasticity are thought to predominate, has not been sufficiently investigated. In addition, the effects of different numbers of stimulations on the magnitude and duration of spasticity improvement remain unclear. Objective We aim to explore the effects of different numbers of stimulations during a single rESWT session on lower-limb spasticity in individuals with subacute stroke and assess the feasibility and safety of the evaluation and treatment procedures for future large-scale trials. Methods This single-center, open-label pilot randomized controlled trial will enroll 24 individuals with subacute stroke and spasticity who will be randomly assigned to either the rESWT 3000- or 6000-stimulation group for 1 treatment at the triceps surae muscle, with stimulation applied at 3 locations: the medial and lateral heads of the gastrocnemius muscle and the triceps surae muscle–Achilles tendon junction. The stimulation intensity will be the maximum intensity tolerated by the individual (≤3.0 bar), with a 10-Hz fixed frequency. Evaluations will be performed the day before treatment; immediately before and after completion of treatment; at 1 and 8 hours after treatment; and at 1, 2, 3, 5, 7, and 14 days after treatment. The primary clinical outcome is the intergroup difference in the Modified Ashworth Scale score of the triceps surae immediately after completion of treatment. Secondary clinical outcomes include intergroup differences in Modified Ashworth Scale scores at 1 and 8 hours and on days 1, 2, 3, 5, 7, and 14 after treatment, as well as intragroup differences from baseline to each evaluation point. Additional measures include the range of motion, angle of catch, tendon reflexes, and clonus scores. Feasibility will be assessed using the recruitment, enrollment, adherence, and retention rates. Safety will be assessed by recording the occurrence of serious and treatment-related adverse events. Results This study was approved by the Fujita Health University Institutional Review Board on September 26, 2024 (CR24-033). Participant enrollment commenced on November 19, 2024. By November 25, 2025, a total of 14 participants had been enrolled. Data analysis has not commenced, and the results will be reported in a separate article in 2026. Conclusions This exploratory dose comparison pilot study is designed to explore whether the number of stimulations delivered during a single rESWT session influences the extent of short-term improvement in spasticity following subacute hemiparetic stroke and obtain preliminary clinical outcomes and feasibility and safety data for future large-scale trials. Trial Registration Japan Registry of Clinical Trials jRCTs042240098; https://jrct.mhlw.go.jp/en-latest-detail/jRCTs042240098 International Registered Report Identifier (IRRID) DERR1-10.2196/88443