Objective: In this observational pilot study we explored the long term effect of Non-Invasive VNS to improve the FOG and reduce oxidative stress in PD patients.

Background: Freezing of gait (FOG) is a unique and disabling clinical phenomenon in Parkinson’s disease (PD). Vagus nerve stimulation (VNS) is a galvanic stimulation to Vagus nerve possibly modifying the cortical excitability. We hypothesize that VNS could improve FOG and reduce oxidative stress in PD patients with FOG.

Methods: Ten patients of PD with freezing recruited from the movement disorders clinic of Institute of Neurosciences, Kolkata. Their motor function, gait parameters and anti-oxidant enzymes (CAT, SOD, MDA) were assessed PRE and post VNS. VNS (GammaCore) was applied to them for one month time and thrice a day.  Differences between the parameters before and after VNS were assessed using Wilcoxon Sign Rank test with significance level of P < 0.05.

Results: The mean age of the patients were 62.8. The mean pre and post UPDRS (III) score were 42.5 and 33.8. UPDRS(III) which significantly improved after VNS application. Statistical results suggested significant improvements in gait parameters including velocity (Pre VNS 62.80, Post VNS 79.5, p value 0.006), stride velocity (L) (Pre VNS 65.348, Post VNS 79.878, p value  .002) and stride length (L) (Pre VNS 37.554, Post VNS 40.974, p value  .048). The risk of fall, RBD and freezing components were assessed using FES, RBD screening questionnaire and FOGQ which showed significant improvement after VNS application. The freezing parameters were video recorded and it revealed significant improvement in time taken for start hesitation (P 0.012), steps taken for start hesitation(P 0.011) and total freezing episode(P 0.015). The level of MDA(Pre VNS 5.269, Post VNS 4.690) was reduced which indicates that lipid peroxidation decreases and level of catalase (Pre VNS 183.30, Post VNS 195.57)  and superoxide dismutase (Pre VNS 7.24, Post VNS 9.54)  was increased  after one month VNS compared to baseline showing that VNS reduces oxidative stress level in these patients.

Conclusions: The study showed VNS  significantly improves gait parameters in FOG  in patients. It also improves the motor functions and fear of falling in these patients. Beside this VNS also plays a crucial role in reduction of oxidative stress. This could provide way for non invasive therapeutic alternative for freezing.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/effect-of-non-invasive-vagus-nerve-stimulation-in-freezing-and-oxidative-stress-in-parkinsons-disease-patients/