Objective: To assess the efficacy and safety of 20/4 Hz transcutaneous auricular vagus nerve stimulation (taVNS) in improving gastrointestinal (GI) function in Parkinson’s disease (PD) patients.

Background: Gastrointestinal dysfunction, particularly constipation, is a prevalent non-motor symptom in PD, severely impacting quality of life. Conventional treatments often provide inadequate relief. Recent studies suggest taVNS may alleviate non-motor symptoms in PD, though its effects on GI function are not well-studied.

Method: A single-center, randomized controlled trial enrolled 72 PD patients with GI dysfunction. Participants were randomized into the taVNS group (n=36) or control group (n=36). The taVNS group received daily 20/4 Hz taVNS for one month, while the control group received no intervention. The primary outcome was change in Gastrointestinal Symptom Rating Scale (GSRS) scores. Secondary outcomes included Chronic Constipation Severity Scale (CSS), Patient Assessment of Constipation Symptoms (PAC-SYM), PAC-QOL, and proportion of GSRS responders (≥30% improvement). ANCOVA and intent-to-treat (ITT) analyses were used. Ethical approval and informed consent were obtained.

Results: Baseline characteristics were comparable.After one month, the taVNS group showed a significant reduction in GSRS scores (ΔGSRS= -7.63 ± 5.24) compared to the control group (ΔGSRS= -3.56±4.98), with an adjusted difference of -3.76 (95%CI: -6.24 to -1.28, P= 0.003). PAC-SYM scores also improved significantly in the taVNS group (ΔPAC-SYM= -4.26 ± 3.44) compared to the control group (ΔPAC-SYM= -0.60±2.81), with an adjusted difference of -3.75 (95%CI: -5.26 to -2.24, P < 0.001). CSS and PAC-QOL scores improved significantly (P < 0.05). The proportion of GSRS responders was significantly higher in the taVNS group (63.9%) compared to the control group (27.8%), with a relative risk of 2.30 (P = 0.004). The intervention was well-tolerated, with only mild ear discomfort in a few participants, and no severe adverse events.

Conclusion: 20/4 Hz taVNS significantly improves gastrointestinal symptoms, particularly constipation, and enhances quality of life in PD patients. This preliminary study supports the safety and efficacy of taVNS for non-motor symptom management in PD. Further research is needed to explore the mechanistic pathways and long-term effects of this intervention.

References: 1. Abbott RD, Petrovitch H, White LR, et al. Frequency of bowel movements and the future risk of Parkinson’s disease. Neurology 2001;57(3):456–462. https://doi.org/10.1212/wnl.57.3.456
2. Adams-Carr KL, Bestwick JP, Shribman S, et al. Constipation preceding Parkinson’s disease: a systematic review and meta-analysis. J Neurol Neurosurg Psychiatry 2016;87(7):710–716. https://doi.org/10.1136/jnnp-2015-311680
3. Marano M, Anzini G, Saltarocchi L, et al. Left Vagus Stimulation Modulates Contralateral Subthalamic β Power Improving the Gait in Parkinson’s Disease. Mov Disord 2024;39(2):424–428. https://doi.org/10.1002/mds.29690

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MDS Abstracts - https://www.mdsabstracts.org/abstract/efficacy-and-safety-of-transcutaneous-auricular-vagus-nerve-stimulation-on-gastrointestinal-function-in-parkinsons-disease-a-preliminary-randomized-controlled-trial/