Title: Transcutaneous Vagus Nerve Stimulation for Gait and Motor Function in Parkinson’s Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
Authors: Jamir Pitton Rissardo and Ana Leticia Fornari Caprara
Conference: 2025 International Congress of Parkinson's Disease, Honolulu, HI
Objective: To evaluate the effects of transcutaneous vagus nerve stimulation (tVNS) on gait, motor function, and freezing of gait (FOG) in patients with Parkinson’s disease (PD).
Background: Gait disturbances and FOG are significant contributors to mobility impairment and fall risk in PD. Non-invasive neuromodulation approaches, such as transcutaneous auricular (taVNS) and cervical (tcVNS) vagus nerve stimulation, have been investigated as potential therapeutic options. However, their impact on motor performance and gait parameters remains unclear.
Methods: A systematic review and meta-analysis were conducted according to PRISMA guidelines. Randomized controlled trials (RCTs) evaluating the effects of tVNS compared to sham stimulation in PD were identified through database searches. Standardized mean differences (SMD) were calculated for key outcomes, including UPDRS-III scores, FOG severity, Timed Up & Go (TUG) performance, step length, stride length, and walking speed. A random-effects model was used to pool effect sizes, and heterogeneity was assessed using the I² statistic.
Results: Four RCTs (PMID: 30889295, 37554394, 37311693, 38925314) met the inclusion criteria, comprising a total of 82 patients receiving tVNS and 74 receiving sham stimulation. tVNS led to improvements in several gait and motor function parameters. Step length significantly increased in the active stimulation group (SMD: 31 ± 58.58), while UPDRS-III scores showed improvements with auricular stimulation (SMD: -4.82 ± 2.35 and -2.87 ± 3.00). FOG severity demonstrated a moderate reduction (SMD: 0.7 ± 0.61), and mobility, assessed by the Timed Up & Go (TUG) test, improved with stimulation (SMD: -0.5 ± 1.32). Walking speed increased (SMD: 0.32 ± 0.07), along with step length (SMD: 13.67 ± 3.91) and stride length (SMD: 28.32 ± 8.1).
Conclusions: tVNS demonstrated modest to moderate improvements in gait, motor function, and FOG severity in PD patients. Both auricular and cervical stimulation showed potential benefits, but variability in effect sizes highlights the need for larger, well-controlled trials to confirm efficacy, determine long-term benefits, and optimize stimulation protocols for gait dysfunction in PD.
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Figure. Forest and Baujat plots of transcutaneous vagus nerve stimulation on UPDRS-III in patients with Parkinson’s Disease.