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BackgroundThe vagus nerve (VN), also called the pneumogastric nerve, connects the brainstem to organs contained in the chest and abdomen. Physiologically, VN stimulation can rapidly affect cardiac activity and heart rate (HR). VN neuropathy can increase the risk of arrhythmias and sudden death. Therefore, a selective test of VN function may be very useful. Since peripheral neurodynamic tests (NDT) are reliable for the assessment of neuropathies in somatic nerves, we aimed to validate a novel NDT to assess VN activity, namely, the VN-NTD.MethodsIn this cross-sectional double-blind, sex-balanced study, 30 participants (15 females) completed a checklist of autonomic dysfunction symptoms. During the VN-NDT administration, HR and symptoms (i.e., mechanical allodynia) were monitored in parallel to a real-time ultrasonography imaging (USI) and motion capture analysis of the neck. The VN-NDT impact on HR and its accuracy for autonomic symptoms reported in the last 7 days were tested.ResultsThe VN-NDT induced a significant HR reduction of about 12 and 8 bpm in males and females [t(1, 119) = 2.425; p < 0.017; ηp2 = 0.047, 95% confidence interval (CI): 0.93–9.18], respectively. No adverse events were observed during VN-NDT. A substantial interexaminer agreement between the evaluators in symptoms induction by VN-NDT was detected [F(1, 119) = 0.540; p = 0.464; ηp2 = 0.005, low effect]. Notably, mechanical allodynia accuracy for gastrointestinal dysfunctions was excellent (p < 0.05; 95% CI: 0.52–0.73; p < 0.001; 95% CI: 0.81–0.96).ConclusionsThe novel VN-NDT is a valid and accurate test capable of detecting VN activation with high sensitivity. Data provided are suitable for both sexes as a hallmark of HR variation due to VN normal response. The proposed VN-NDT may be reliable as daily routine neurological examination tests for the evaluation of neuropathic signs related to neuroinflammation of the VN.Clinical Trial Registrationwww.ClinicalTrials.gov, identifier NCT04192877.

Background: The Vagus Nerve (VN) neuropathies and autonomic peripheral neuropathies (APN) are responsible for neurodegenerative diseases and immune response alterations. Peripheral nerves selective tension tests (NDT) are clinical tools validated for neuropathies detection in lower and upper limbs. However, a validated NDT to assess VN is lacking. Methods: An estimated sample of 30 healthy subjects completed a questionnaire on vagal symptoms. The VN-NDT was administered, if neurological assessment of the cervical tract was negative. Symptoms and heart rate (HR) were monitored. The test validity was assessed using a motion capture analysis system and a real-time ultrasonography imaging (USI; C6-VN distance) during the test administrations. Inter-examiner accordance was tested (Cohen's Kappa) between two blinded assessors (one expert and one novice). Two-way analysis of variance (ANOVA) were performed with factors experience and side tested (2x2). A checklist with symptoms and signs of autonomic dysfunction was administered to all participants and accuracy, sensitivity, specificity, positive and negative likelihood ratios of the VN-NDT in autonomic dysfunction symptoms detection was calculated (ClinicalTrials.gov number, NCT04192877). The aim of the research was to define normtive data in order to establish a hallmark of physiological spectrum for pathology detection. Findings: The test induced a significant reduction of the C6-VN distance and of the HR (about 10 beats per minutes [bpm]; p< 0.01; d= .2; 95% confidence interval [CI]: 0.03–.3; p