Browsing by Subject "vagus nerve"
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Item A CADAVERIC STUDY OF HEAD AND NECK NEUROVASCULAR ANATOMICAL VARIATIONS(2014-03) Wehring, Spencer; Kirchhoff, Claire A.This study reports the incidence of head and neck neurovascular branching variations. While there is an extensive literature on the incidence of many anatomical variations because of their relevance to surgical cases, the incidence of some variations are still unknown. In addition, whether the incidence of variations differs between samples is under-explored. We therefore set out to determine whether incidence of neurovascular branching variations in a cadaveric sample in north Texas match previously reported findings, and also to document variations in the location of the vagus nerve, which has not been reported previously. Purpose (a): While anatomical variations have long been documented because of their surgical relevance, some remain unknown. In addition, between-sample differences in the incidence of variations is under-explored. We tested whether incidence of head and neck neurovascular branching variations in a cadaveric sample from UNTHSC match previous findings. We also document previously unreported positional variations for the vagus nerve. Methods (b): First-year students from the Texas College of Osteopathic Medicine recorded neurovascular variations using a standardized data sheet during their dissections. Cadavers in this study (n=29) were donated through the University of North Texas Health Science Center Willed Body Program. Results (c): The ascending pharyngeal artery branched from the external carotid artery (ECA) in 74% of cases, from the common carotid artery (CCA) in 11%. The lingual artery branched from the ECA in 82% of cases; 6% shared a common trunk with the facial artery. The vagus nerve was located between the CCA and internal jugular vein in 62% of cases, posterior to the internal jugular vein in 24%, and anterior to the CCA in 4%. Conclusions (d): Incidence of arterial branching variations mostly fell within previously reported ranges (Bergman, 1996). Differences with previous work are attributable to the small sample size of this study, which emphasizes the need for large samples when estimating the frequency of a variation. We also report information on positional variation of the vagus nerve. These data must be treated with caution due to possible inter-observer error, but further investigation of vagus nerve positional variation is warranted due to implications for patient safety.Item Effects of Cervical Manipulation on Cardiac Autonomic Control(2006-05-01) Giles, Paul David; Michael Smith; Scott Stoll; Walter WitryolGiles, Paul David, Effects of Cervical Manipulation on Cardiac Autonomic Control. Master of Science (Clinical Research and Education – OMM), May 2006, pp, 1 table, 8 figures, references. Objective: Osteopathic Manipulative Medicine treatment (OMT) regimes often focus on treating the Autonomic Nervous System (ANS) in addition to biomechanics. Techniques focused on the upper cervical spine are theorized to affect the function of the vagus nerve and thereby influence the parasympathetic branch of the ANS. This study was conducted to observe the effect of upper cervical spine manipulation on cardiac autonomic control as measured by heart rate variability (HRV). Methods: Nineteen healthy, young adult subjects were randomly assigned an order in which they would undergo three different experimental protocols: OMT, Sham, and a time control. Six minutes of electrocardiographic data was collected before and after each intervention to be analyzed by power spectral analysis. Results: All baseline data for each protocol and all parameters studied were the same. The OMT protocol and all parameters studied were the same. The OMT protocol caused a change in the standard deviation of the normal-to-normal (SDNN) intervals (0.121 +/- 0.0822 sec, p=0.005) and the change in the high frequency HRV was different from the changes caused by other interventions (p=0.038). Conclusions: This preliminary data supports the hypothesis that under cervical spine manipulation affects the parasympathetic nervous system; however, more data on more subjects needs to be collected in order to clarify some points, and to reach statistical significance in certain measures.Item Effects of Parasympathetic Nerve Activity on Ventricular Irregularity during Atrial Fibrillation(2009-07-01) Pacchia, Christina F.; Smith, Michael L.Atrial fibrillation (AF) is the most common sustained arrhythmia in clinical practice and is an independent predictor of sudden cardiac death (SCD). AF is characterized by an irregular ventricular rhythm which may produce elevated sympathetic nerve activity (SNA) and increase the risk for SCD. However, limited data suggest that irregular ventricular rhythm during AF is inversely correlated with SCD. It is well established that increased vagal control reduces risk of SCD. However, it is unclear if the ventricular irregularity in AF is a function of vagal control. The purpose of this study was to determine if sinusoidal fluctuations in parasympathetic nerve activity on the ventricle result in an entrainment of the ventricular rhythm in both humans and porcine models of atrial fibrillation. Forced vagal oscillations at two different frequencies were produced by employing deep breathing (0.125 Hz) and neck suction (0.25 Hz) in humans and pigs with AF. In the pig model, glycopyrrolate was administered to block peripheral muscarinic receptors, thus inhibiting vagal transmission to the heart. Heart rate variability was evaluated using power spectral analysis to determine the contribution of the vagus to ventricular irregularity in AF. In all of our human subjects, power spectral analysis identified significant differences between oscillations in heart rhythm during neck suction (0.25Hz) and deep breathing (0.125 Hz) compared to baseline. In addition, the standard deviation of RR intervals was significantly different with neck suction compared to baseline. In our pig model, neck suction and deep breathing increased power at 0.25 and 0.15 Hz respectively and vagal blockade abolished power in both frequencies. In humans and pigs, all frequency-mediated vagal maneuvers increased heart rate variability, suggesting the vagus does, in part, mediate ventricular irregularity during AF. These findings have important clinical implications considering the utility of heart rate variability analysis in patients with sinus rhythm. Reduced vagal tone, measured as heart rate variability, may be used to predict risk of sudden cardiac death in patients with AF.Item Lipopolysaccharide Challenge Reveals Hypothalamic-Pituitary-Adrenal Axis Dysfunction in Murine Systemic Lupus Erythematosus(MDPI, 2018-10-04) Pham, Grace S.; Mathis, Keisa W.Crosstalk between the brain and innate immune system may be dysregulated in systemic lupus erythematosus (SLE), a chronic autoimmune disease that presents with dysautonomia and aberrant inflammation. The hypothalamic-pituitary-adrenal (HPA) axis is an endogenous neuro-endocrine-immune pathway that can regulate inflammation following activation of vagal afferents. We hypothesized that chronic inflammatory processes in SLE are in part due to HPA axis dysfunction, at the level of either the afferent vagal-paraventricular nuclei (PVN) interface, the anterior pituitary, and/or at the adrenal glands. To study this, we challenged female control and SLE mice with lipopolysaccharide (LPS) and measured c-Fos expression as an index of neuronal activation, plasma adrenocorticotrophic hormone (ACTH) as an index of anterior pituitary function, and plasma corticosterone as an index of adrenal function. We found that c-Fos expression in the PVN, and plasma ACTH and corticosterone were comparable between unchallenged SLE and control mice. PVN c-Fos was increased similarly in control and SLE mice three hours after LPS challenge; however, there were no changes in plasma ACTH amongst any experimental groups post inflammatory challenge. Plasma corticosterone was markedly increased in LPS-challenged SLE mice compared to their vehicle-treated counterparts, but not in controls. Paradoxically, following LPS challenge, brain and spleen TNF-alpha were elevated in LPS-challenged SLE mice despite heightened plasma corticosterone. This suggests that, despite normal c-Fos expression in the PVN and activation of the HPA axis following LPS challenge, this cumulative response may not adequately defend SLE mice against inflammatory stimuli, leading to abnormally heightened innate immune responses and peripheral inflammation.