Dose-Response Meta-Analysis of Neuromuscular Electrical Stimulation for Post-Stroke Dysphagia

Abstract

Objective: To clarify the dose–response relationships of neuromuscular electrical stimulation (NMES) for post-stroke dysphagia and identify the optimal protocols. Methods: A systematic review and dose–response meta-analysis of randomized controlled trials (RCTs) was conducted under the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) 2020 (PROSPERO: CRD420251126373). Twenty-four RCTs with 1,125 stroke patients were included. Primary outcomes evaluated swallowing safety using Penetration–Aspiration Scale (PAS), hyoid movement, Functional Oral Intake Scale (FOIS), and Water Swallow Test (WST). Linear and nonlinear meta-regression were used to assess NMES parameters (dose, duration, onset timing). Results: A higher cumulative NMES dose was linearly associated with improved PAS, suggesting that ≥15 hours of stimulation may be required for meaningful airway protection. Earlier initiation yielded greater hyoid improvements, consistent with the principles of neuroplasticity recovery. Non-linear analyses showed U-shaped dose–response curves for hyoid excursion and the WST, with more potent effects at lower and higher doses. FOIS showed no consistent associations. Adverse events were rare and mild (skin irritation). Conclusion: The efficacy of NMES for post-stroke dysphagia depends on the stimulation dose, timing, and duration. Individualized protocols should align with therapeutic goals, while larger trials are needed to refine practice and inform policy.