Acute Effect of Transcutaneous Auricular Vagus Nerve Stimulation on Hand Tremor in Parkinson's Disease: A Pilot Study of Case Series

Objectives: The aim of this study is to investigate the effects of non-invasive vagus nerve stimulation (VNS) on tremor in Parkin-son's disease (PD).Methods: This single-center, prospective, and implementation study with before-after design included five participants diag-nosed with PD. Auricular VNS was applied to each participant 3 times on different days. VNS was applied to the participants as the right ear, left ear, and bilateral ear. The cardiovascular parameters of the participants were evaluated with Kubios HRV Standard and tremor with UPDRS tremor subscale and smartphone application before and after the intervention.Results: Significant decrease in diastolic blood pressure (p=0.043) was found in participants who underwent bilateral auricular VNS. Although there was no significant change in the UPDRS tremor subscale, decreases in the maximum tremor amplitude in the x (p=0.043) and y (0.014) planes were detected in the measurements made with the smartphone application.Conclusion: In this study, a decrease in the tremor amplitude measured in the 3D plane with auricular VNS was found in patients with PD.