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Browsing by Author "Everett IV, Thomas H."
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Item Left cervical vagal nerve stimulation reduces skin sympathetic nerve activity in patients with drug resistant epilepsy(Elsevier, 2017-12) Yuan, Yuan; Hassel, Jonathan L.; Doytchinova, Anisiia; Adams, David; Wright, Keith C.; Meshberger, Chad; Chen, Lan S.; Guerra, Maria P.; Shen, Changyu; Lin, Shien-Fong; Everett IV, Thomas H.; Salanova, Vincenta; Chen, Peng-Sheng; Neurology, School of MedicineBACKGROUND: We recently reported that skin sympathetic nerve activity (SKNA) can be used to estimate sympathetic tone in humans. In animal models, vagal nerve stimulation (VNS) can damage the stellate ganglion, reduce stellate ganglion nerve activity, and suppress cardiac arrhythmia. Whether VNS can suppress sympathetic tone in humans remains unclear. OBJECTIVE: The purpose of this study was to test the hypothesis that VNS suppresses SKNA in patients with drug-resistant epilepsy. METHODS: ECG patch electrodes were used to continuously record SKNA in 26 patients with drug-resistant epilepsy who were admitted for video electroencephalographic monitoring. Among them, 6 (2 men, age 40 ± 11 years) were previously treated with VNS and 20 (7 men, age 37 ± 8 years) were not. The signals from ECG leads I and II were filtered to detect SKNA. RESULTS: VNS had an on-time of 30 seconds and off-time of 158 ± 72 seconds, with output of 1.92 ± 0.42 mA at 24.17 ± 2.01 Hz. Average SKNA during VNS off-time was 1.06 μV (95% confidence interval [CI] 0.93-1.18) in lead I and 1.13 μV (95% CI 0.99-1.27) in lead II, which was significantly lower than 1.38 μV (95% CI 1.01-1.75; P = .036) and 1.38 μV (95% CI 0.98-1.78; P = .035) in the control group, respectively. Heart rate was 65 bpm (95% CI 59-71) in the VNS group, which was significantly lower than 77 bpm (95% CI 71-83) in the control group. CONCLUSION: Patients with VNS had significantly lower SKNA than those without VNS.Item Recording sympathetic nerve activity from the skin(Elsevier, 2017-10) Everett IV, Thomas H.; Doytchinova, Anisiia; Cha, Yong-Mei; Chen, Peng-Sheng; Medicine, School of MedicineSympathetic tone is important in cardiac arrhythmogenesis; however, methods to estimate sympathetic tone are either invasive or require proper sinus node function that may be abnormal in disease states. Because of the direct and extensive connections among various nerve structures, it is possible for the sympathetic nerves in the various structures to activate simultaneously. Therefore, we hypothesized that nerve activity can be recorded from the skin and it can be used to estimate the cardiac sympathetic tone. Preclinical studies in canines demonstrated that nerve activity is detectable using conventional ECG electrodes and can be used to estimate cardiac sympathetic tone. Subsequent clinical studies further supported this concept. In addition to studying the autonomic mechanisms of cardiac arrhythmia, these new methods may have broad application in studying both cardiac and non-cardiac diseases.