Dissecting Motor Domain Responses to Vibration Therapy in Parkinson's Disease: A Systematic Review and...

Motor impairments in Parkinson's disease (PD), including gait dysfunction, postural instability, and freezing of gait, are often inadequately managed by pharmacological therapy alone, particularly in advanced stages. Vibration therapy (VT) has been proposed as a non-pharmacological adjunct to improve motor performance through sensorimotor modulation. However, existing evidence remains inconsistent, and previous systematic reviews have reported substantial heterogeneity, limiting clinical interpretability.

This protocol outlines a systematic review and meta-regression analysis designed to evaluate the effects of VT on motor function in individuals with PD, with a specific focus on domain-specific outcomes and parameter-dependent response patterns.

The review will include randomized and non-randomized controlled trials investigating mechanical VT in adults with PD. Motor outcomes will be categorized into four predefined domains: (1) global motor function, (2) gait quality and freezing, (3) functional mobility, and (4) dynamic balance. A comprehensive literature search will be conducted across major electronic databases. Quantitative synthesis will be performed using random-effects meta-analysis. Subgroup analyses and meta-regression will be applied to examine whether vibration characteristics, such as frequency, amplitude, modality, and total dose, explain variability in effect sizes across studies. Risk of bias will be assessed using RoB 2 and ROBINS-I, and the certainty of evidence will be evaluated using the GRADE approach.

By integrating multidimensional motor outcome categorization with parameter-sensitive analyses, this review aims to clarify whether VT effects in PD are domain-specific and dependent on stimulation characteristics. The findings are expected to provide a more mechanistically interpretable synthesis of the existing evidence and to inform the design of future clinical trials evaluating VT in PD rehabilitation.

PROSPERO CRD420251124906.