Identification of the non-recurrent inferior laryngeal nerve using intraoperative neurostimulation

INTRODUCTION: The non-recurrent inferior laryngeal nerve occurs at a frequency of about 0.5% and usually on the right side. The identification of a non-recurrent laryngeal nerve may be difficult. We describe a new method for its identification using intraoperative neurostimulation. METHODS: We examined nine patients with a non-recurrent inferior laryngeal nerve and five patients with a normal inferior laryngeal nerve anatomy who were operated on trans-sternally. Neurostimulation of the vagal nerve producing electromyographic signal in the intrinsic laryngeal musculature was performed at different points proximally and distally. RESULTS:: Electromyographic signals were found proximally but not distally of the separation of the inferior laryngeal nerve from the vagus in 14 patients. In nine patients with a non-recurrent inferior laryngeal nerve, we performed neurostimulation of the vagus opposite the lower and the upper thyroid poles. In all patients we found no electromyographic signals at the distal stimulation point. In contrast, proximal neurostimulation of the vagus opposite the upper thyroid pole produced positive electromyographic signals. CONCLUSION: Neurostimulation of the vagal nerve distally of the separation of the inferior laryngeal nerve did not produce electromyographic signals in the intrinsic laryngeal musculature, perhaps due to the different modalities in the vagal fascicles. Negative electromyographic signals following neurostimulation of the distal vagal nerve opposite the lower thyroid pole should lead to proximal neurostimulation of the vagus opposite the upper thyroid pole. Positive electromyographic signals proximally and negative electromyographic signals distally predict the occurrence of a non-recurrent inferior laryngeal nerve which allows its diagnosis before surgical dissection of the thyroid gland and may prevent nerve palsy.     

Clinical influence of vagotomy on postoperative acute phase response

BACKGROUND: Although there is increasing evidence suggesting that the vagus nerve functions as a connector between the nervous and immune systems in animals, little is known about the role of the vagus nerve in postoperative acute phase response in humans. MATERIALS AND METHODS: The extent of fever and acute phase protein response and the production of inflammatory cytokine during the early postoperative period were compared among the patients who had undergone total gastrectomy including truncal vagotomy (n = 13), those having distal gastrectomy with division of vagal branches (n = 14), and the patients with vagal nerve preserving gastrectomy (n = 12). RESULTS: There was no significant difference in serum levels of C-reactive protein, alpha-1-antirypsin, and interleukin-6 among the three groups. Also, postoperative maximum body temperature was similar. CONCLUSIONS: Vagotomy did not influence acute phase response after gastric cancer surgery. A multipathway mechanism for acute phase response including the induction of fever is suggested.     

A Histological and Functional Study of the Gastric Mucosal Innervation in the Dog

The supradiaphragmatic vagus and its abdominal branches have been subjected to fibre counts both in normal dogs and in dogs that have undergone proximal vagal sections resulting in fibre degeneration. As a result of these studies, the absolute numbers of afferent, efferent and adventitial fibres present in the vagus nerve at these levels have been established     

Neural regulation of heterotopic islets of Langerhans

The possibility of vagal reinnervation to intrasplenic islet grafts was examined by measuring portal insulin response to electric stimulation of the dorsal vagus nerve in autografted dogs. Grafted islets responded appropriately to an exogenous cholinergic agent given intravenously. However, no insulin secretory response could be observed in grafted dogs after vagal stimulation, which markedly increased portal insulin levels in control dogs. Therefore, intrasplenic islets are not under direct vagal control. At the basal state, normal oscillatory release of insulin was observed in the animals with grafts, suggesting that the mechanism of rhythmic basal insulin release is intrinsic to the islet of Langerhans with no regulatory input from the vagus nerve or any element of pancreatic structure.     

Graded effect of protein on regional myoelectric activity of the opossum sphincter of Oddi

Although it is known that the sphincter of Oddi exhibits a myoelectric response to intraluminal nutrients, the effect of specific dietary components has not been well characterized. The aim of this study was to determine the effect of intragastric instillation of a protein meal on regional myoelectric activity of the opossum sphincter of Oddi. Seven adult opossums were chronically prepared with self-retaining bipolar electrodes secured to the proximal and distal parts of the sphincter. After a 2-week recovery period, and with the animals fasted and conscious, myoelectric activity was recorded for two cycles of the migrating myoelectric complex. The animals then received graded calories of protein through an orogastric tube and recordings were continued until return of the fasted cyclic activity. Doses of 60, 120, and 240 kcal of protein elicited increases in myoelectric spike activity of the proximal sphincter of 18.7%, 41.9%, and 66.6%, respectively. Similarly, the length of the fed state was prolonged by increasing caloric loads, with mean (plus or minus standard error of the mean) times of 266 +/- 25, 292 +/- 15, and 375 +/- 42 minutes for each dose. A similar relationship was noted in the distal part of the sphincter. Regression analysis between the proximal and distal parts of the sphincter during the fasted and fed states showed a strong and persistent correlation of gradient of spikeburst frequency. We conclude that myoelectric spike frequency of the opossum sphincter of Oddi exhibits a dose-related response to intragastric protein calories. Furthermore, the proximal and distal parts of the sphincter remain electrically coupled, with the proximal region pacing the distal region during the fasted state and after protein administration.     

Neural regulation of auto-grafted islets of Langerhans

The possibility of vagal reinnervation to intrasplenic islets grafts was examined by measuring portal insulin response to electric stimulation of the dorsal vagus nerve in autografted dogs. Grafted islets responded appropriately to methacholine given intravenously. However, no insulin secretory response could be observed in grafted dogs after vagal stimulation, which markedly increased portal insulin levels in control dogs. Therefore, intrasplenic grafted islets are not under direct vagal control. At the basal state, normal oscillatory release of insulin was observed in grafted animals, suggesting that the mechanism of rhythmic basal insulin release is intrinsic to the islet of Langerhans with no regulatory input from the vagus or any element of normal pancreatic structure.     

Studies on colonic motor correlates of spontaneous defecation in conscious dogs

The colonic motilities during defecation were studied by means of extraluminal strain gauge force transducers in six conscious dogs. A set of eight transducers was implanted in each dog: one was on the terminal ileum and the remaining seven were on the whole length of the colon equidistantly. As Karaus & Sarna had already described in 1987, giant migrating contractions (GMC) that were initiated in the proximal colon and rapidly migrated caudad before defecation were reconfirmed also in this study to be motor equivalent of mass movements. Several new findings in addition were obtained. At spontaneous defecation, a reflex relaxation was always observed at the distal end of the colon. This colonic outlet relaxation (COR) usually occurred synchronously with the initiation of GMC at the proximal colon and lasted until GMC had arrived at the distal end. Evacuation of feces occurred during this COR. COR was not observed at defecation induced by neostigmine or prostaglandin F2 alpha. After bilateral pelvic nerve section, both GMC and COR were completely abolished. Instead, group of low amplitude caudad migrating contractions occurred at the proximal or middle colon and were followed by frequent evacuation of small amount of loose stools. COR was not observed at this type of defecation. It is suggested from this study that not only GMC but also COR are the essential motor correlates of spontaneous defecation. Both GMC and COR are under control of pelvic nerves.     

Study on the catecholamine-containing fibers in the vagus

To clarify the nature and the origin of the catecholamine in the vagus, a quantitative estimation of dopamine, norepinephrine and epinephrine in the human abdomen, canine cervical and supradiaphragmatic vagus was performed. The human abdominal vagus was obtained during surgical operations. The canine cervical vagus was taken out with superior cervical ganglion and its branch between superior cervical ganglion and vagal trunk. The canine supradiaphragmatic vagus was ligated doubly. The control segment (between two ligatures) was removed immediately after the ligations. The proximal segment (1 cm above the cranial ligature) and the distal segment (1 cm below the caudal ligature) were taken out four hours after the ligations. The human and canine vagus contained dopamine and norepinephrine not epinephrine. The canine cervical vagus, which was cranial part to the unite of the branch from the superior cervical ganglion, contained dopamine and norepinephrine. Dopamine and norepinephrine levels in the proximal segment was greater than that in the control segment. Dopamine and norepinephrine levels in the distal segment was less than that in the control segment. Based on these results, it is concluded that: (1) catecholamine s in the human and canine vagus are dopamine and norepinephrine not epinephrine; (2) the catecholamine-containing fibers in the canine vagus originate partially in the vagal trunk; (3) dopamine and norepinephrine may be transported distally in the canine vagus.     

Hepatic glycolytic intermediates in fed and fasted rats after severe hemorrhage

The responses of key liver carbohydrate intermediates to severe hemorrhage were investigated in fed and fasted young adult male rats. Forty per cent of intravascular blood was withdrawn and liver was sampled by freeze-clamp at 0, 0.25, 1.0, 3.0, and 4.0-5.0 hours. Fed rats with abundant glycogen showed a threefold increase in glucose-6-phosphate (G6P) concentration, and fasted rats showed a 75% decline in G6P immediately after hemorrhage. This significant difference in response traces to the fact that G6P is one of the first catabolites in fed liver formed by glycogenolysis but is the last intermediate of the gluconeogenic pathway in fasted animals. Phosphoenolpyruvate (PEP), the high-energy intermediate, was markedly depleted in both fed and fasted rats at zero time. In the fasted animal, however, the PEP was rapidly restored, and by 1.0 hour was threefold above normal. The ability of fasted rats to rapidly synthesize glucose from accumulated lactate is attributed to increased amount of gluconeogenic enzymes induced by fasting. In prolonged shock states, this synthetic capacity plays a protective role. Contrariwise, in brief shock states such as hemorrhage, the immediate availability of glucose from stored glycogen appears to be a more important determinant of survival. In the present experiments, fed rats were more resistant to the hemorrhage protocol.     

Intestinal motility changes in experimental large bowel obstruction

Bipolar electrodes for recording electrical discharges of colon smooth muscle and strain gages for recording associated contractions of circular muscle were implanted in six rhesus monkeys. After recovery, baseline records were made. The animals then had an obstruction device implanted in sigmoid colon which resulted in progressive compromise of the lumen terminating in complete obstruction after 13 +/- 2 days. Recording were made daily during development of obstruction. As obstruction became more complete, contraction frequency decreased in right colon, increased in left colon proximal to the obstruction, and was unchanged in left colon distal to the obstruction. The frequency of distentions increased in colon proximal to the obstruction but was unchanged distally. Simultaneous mass actions, a complex of nonperistaltic high amplitude contractions and distentions occurring nearly simultaneously throughout the colon which is not seen in normal colon, appeared in colon both proximal and distal to the obstruction and became more frequent as the degree of obstruction progressed. Colon obstruction results in abnormal motility complexes, but not in hyperperistalsis. Mass actions probably are the basis for colic and rushing bowel sounds noted clinically in colon obstruction.     

Asystole from tetanic stimulation of the accessory nerve

An asystolic cardiac arrest is reported which occurred at the same time as supramaximal tetanic stimulation over the accessory nerve in order to evoke contractions in the trapezius and sternocleidomastoid muscles. The cause may have been the inadvertent stimulation of one or more of the cranial nerves of the carotid sheath at the base of the skull: the cranial root of the accessory nerve, the vagus, the sino-carotid branch of the glossopharyngeal nerve or the hypoglossal nerve. The most likely culprit, if not the vagus itself, was the cranial root of the accessory nerve which both functionally and anatomically should be seen as an integral part of the vagus. It is suggested that stimulation of any nerve in the carotid sheath should be approached with caution and that a tetanic stimulus to this area might best be avoided.     

Electrical stimulation of the vagus nerve restores motility in an animal model of achalasia

Esophageal peristalsis generally does not return to normal after surgical treatment of achalasia. Direct electrical stimulation of the vagus nerve is known to stimulate antegrade peristalsis in the normal esophagus; however, it is not known whether electrical stimulation will induce return of peristalsis once an achalasia-like disorder has been established. The objective of this study was to perform quantitive and qualitative measurements of motility during electrical stimulation of the vagal nerve in an animal model of achalasia. An already established and verified animal achalasia model using adult North American opossums (Didelphis virginiana) was used. Fifteen opossums were divided into three groups. Sham surgery was performed on three animals (group 1). In group 2 (n = 6) a loose Gore-Tex band (110% of the esophageal circumference) was placed around the gastroesophageal junction to prevent relaxation of the lower esophageal sphincter during swallowing. In group 3 (n = 6) a relatively tighter band (90% of the esophageal circumference) was used to further elevate the lower esophageal sphincter pressure. At 6 weeks, after manometric and radiolologic confirmation of achalasia, electrical stimulation of the esophagus was performed before and after removal of the band using a graduated square-wave electrical stimulus. Changes in esophageal neural plexi were assessed histologically. Pre- and postoperative manometric data were compared using standard statistical techniques. No difference was observed in esophageal characteristics and motility after sham surgery in group 1. Animals in group 2 demonstrated a vigorous variety of achalasia (high-amplitude, simultaneous, repetitive contractions), moderate esophageal dilatation, and degeneration of 40% to 60% of intramuscular nerve plexi. Animals in group 3 developed amotile achalasia with typical low-amplitude simultaneous (mirror image) contractions, severely dilated (“bird beak”) esophagus, and degeneration of 50% to 65% of nerve plexi. Vagal stimulation in group 2 demonstrated a significant increase in the amplitude of contractions (P < 0.001) and return of peristaltic activity in 49% of swallows before band removal. After band removal, all of the contractions were peristaltic. In group 3 vagal stimulation before and after removal of the band demonstrated a significant increase in amplitude of contractions (P < 0.0001) but no return of propagative peristalsis before band removal, however, 44% of contractions were progressive in the smooth portion of the esophagus after removal of the band. Electrical stimulation of the vagus nerve improved the force of esophageal contractions irrespective of the severity of the disease; however, peristaltic activity completely returned to normal only in the vigorous (early) variety of achalasia. Removal of the functional esophageal outlet obstruction, as with a surgical myotomy, may be necessary to obtain significant peristalsis with vagal pacing in severe achalasia. Presented at the Forty-Fourth Annual Meeting of The Society for Surgery of the Alimentary Tract, Orlando, Florida, May 18–21, 2003 (oral presentation). Supported by research grants from the Curlan-Jobe Foundation and the Legacy Research Advisory Committee.     

腹腔镜下迷走神经后干及其属支临床解剖研究

目的 观察、测量并分析腹腔镜手术迷走神经后干及其属支与胃左动脉的解剖关系。方法 选择2017-11-13至2018-11-16大连医科大学附属第一医院胃肠外科行腹腔镜保留胃功能的胃切除术41例胃癌病人，腹腔镜下观察迷走神经后干及其属支与胃左动脉关系，并进行分型。测量迷走神经后干、腹腔支的长度以及神经与胃左动脉共干长度、胃左动脉长度。结果 迷走神经后干、腹腔支、胃支出现率为100%。迷走神经后干及其属支与胃左动脉关系分型：紧密型9例（22.0%）、中间型25例（61.0%）、游离型7例（17.0%）。远端切缘为（2.7±1.0）cm，近端切缘为（4.9±2.6）cm，胃左动脉长度为（4.0±0.6）cm，迷走神经后干长度为（5.1±1.2）cm，腹腔支长度为（4.2±0.6）cm，神经与胃左动脉共干长度为（2.1±0.9）cm。结论 充分了解迷走神经后干及其属支与胃左动脉的解剖关系对完成腹腔镜下保留幽门及迷走神经胃部分切除术有重要指导意义。     

Revision of vagal nerve stimulator electrodes: technical approach

Summary Background. As the number of implanted vagal nerve stimulators grows, the need for removal or revision of the devices will become more frequent. Our purpose was to demonstrate the feasibility of complete removal of the vagal nerve stimulator electrode using microsurgical technique.Methods. Operative databases at the University of Utah (1995 through 2002), Westchester Medical Center (1995 through 2001), and University of Arizona Health Sciences Center (1995 through 1999) were retrospectively reviewed. Patients who had undergone removal or revision of a previously placed vagal nerve stimulator electrode were identified. Patients who had a vagal nerve stimulator device removed but had the lead trimmed and incompletely removed were excluded.Findings. Seven patients underwent complete removal of the lead. Microsurgical dissection allowed removal of the helical electrode from the vagus nerve without apparent physiological consequences. Four patients had a new electrode placed just proximal to the original lead site. The operative procedure required an additional 30 minutes to complete compared with initial device placement. The four patients who underwent replacement of the electrode demonstrated normal device function and lead resistance at the time of postoperative follow-up. Each experienced a return to prior stimulation response and seizure control.Conclusions. This series suggests that the electrode can be removed from the vagus nerve and repositioned without significant consequence in most cases.     

Modulation of Brain Dead Induced Inflammation by Vagus Nerve Stimulation

Because the vagus nerve is implicated in control of inflammation, we investigated if brain death (BD) causes impairment of the parasympathetic nervous system, thereby contributing to inflammation. BD was induced in rats. Anaesthetised ventilated rats (NBD) served as control. Heart rate variability (HRV) was assessed by ECG. The vagus nerve was electrically stimulated (BD + STIM) during BD. Intestine, kidney, heart and liver were recovered after 6 hours. Affymetrix chip‐analysis was performed on intestinal RNA. Quantitative PCR was performed on all organs. Serum was collected to assess TNFα concentrations. Renal transplantations were performed to address the influence of vagus nerve stimulation on graft outcome. HRV was significantly lower in BD animals. Vagus nerve stimulation inhibited the increase in serum TNFα concentrations and resulted in down‐regulation of a multiplicity of pro‐inflammatory genes in intestinal tissue. In renal tissue vagal stimulation significantly decreased the expression of E‐selectin, IL1β and ITGA6. Renal function was significantly better in recipients that received a graft from a BD + STIM donor. Our study demonstrates impairment of the parasympathetic nervous system during BD and inhibition of serum TNFα through vagal stimulation. Vagus nerve stimulation variably affected gene expression in donor organs and improved renal function in recipients.     

Alterations in spontaneous contractions of rat proximal and distal colon after peritonitis

Background/Purpose

The aim of this study was to investigate the effect of peritonitis on spontaneous contractions of distal and proximal colon smooth muscle isolated from rats.

Methods

Peritonitis was induced by cecal ligation and puncture in 8 rats. Another group of 8 rats underwent a sham operation and acted as controls. Twenty-four hours after the operation, the rats were killed; and their distal and proximal colon smooth muscle was excised and placed in circular muscle direction in a 10-mL organ bath. Changes in the amplitude and frequency of contractions were analyzed before and after the addition of antagonists.

Results

Peritonitis induced the increase in the amplitude and frequency of spontaneous contractions. In both distal and proximal colon of the control group, the amplitude of spontaneous contractions was elevated by N^G-nitro-l-arginine and tetradotoxin; but the frequency of spontaneous contractions was significantly elevated only in the presence of N^G-nitro-l-arginine. In both distal and proximal colon of the peritonitis group, the enhanced amplitude and frequency were significantly decreased and returned to control values in the presence of celecoxib.

Conclusions

Peritonitis induces the increase in the amplitude and frequency of spontaneous contractions of distal and proximal colon, which can be attributed to a loss of inhibitor nitrergic and other neural control or rise of cyclooxygenase-2 levels.     

End-to-side nerve repair: attachment of a distal, compared with a proximal and distal, nerve segment.

Regeneration occurs if a distal nerve segment is attached end-to-side to an intact donor nerve after the nerve has been injured. We investigated if attachment of a proximal nerve segment as well, as an extra source of axons, had any advantage over the single attachment of a distal nerve segment to the same donor nerve. In rats, a single distal radial nerve, or both the proximal and distal radial nerve segments, were attached end-to-side to the musculocutaneous nerve, and effects were examined up to eight months after the repair. Cell profiles were double-labelled, indicating recruitment of axons by collateral sprouting, but there were few such cells. There was a shift in the distribution of retrograde labelled neuronal cell profiles in spinal cord and in DRGs between the two types of repair. Both procedures resulted in axonal outgrowth and some functional recovery, but there was no improvement if a proximal nerve segment was also used as a source for axons.     

Brain stem topography of vagus nerve to the greater curvature of the stomach

If preganglionic vagus nerve fibers enter the stomach via all of its neurovascular bundles, then proximal gastric vagotomy that divides only the bundles along the lesser curvature of the stomach neglects a potential source of innervation to the parietal cells. To determine whether or not these bundles contained preganglionic efferent vagal nerve fibers, horseradish peroxidase was applied to the central cut end of selected neurovascular bundles along the greater curvature of the stomach in rats and ferrets. Cells in the dorsal motor nucleus of the vagus (dmnX) of the rat were labeled after horseradish peroxidase applications to the right gastroepiploic, the splenic, and the short gastric bundles. The ferrets had horseradish peroxidase applied to the right gastroepiploic bundle and they also had cellular labeling of the dmnX. The labeling in cells of the dorsal motor nucleus of the vagus had a distinct topographic, rostrocaudal distribution in both species, and was maximal in the vicinity of the obex. Cells of the bilateral dmnX were labeled after horseradish peroxidase applications at all bundles. This study showed (1) that the bundles along the greater curvature of the stomach contained preganglionic efferent vagus nerve fibers, (2) that the cells of origin of these fibers were represented in the localized rostrocaudal position of the dmnX, and (3) that these fibers had their origins in the bilateral dmnX. Such nerve fibers may account for incomplete vagal denervation of the parietal cells after proximal gastric vagotomy.     

Effect of vasoactive intestinal peptide on the motility of guinea-pig colon in vitro

The effects of vasoactive intestinal peptide (VIP) on longitudinal and circular muscle strips of guinea-pig proximal and distal colons, and on propulsive activity of guinea-pig distal colon were investigated in vitro. VIP (10(-9)-10(-6) M) produced relaxations of longitudinal and circular muscle strips in proximal colon and of circular muscle strip in distal colon, but produced a contraction of longitudinal muscle strip in distal colon. VIP-induced responses of the muscle strips were not influenced by indomethacin (10(-6) M). Tetrodotoxin (10(-6) M) and atropine (10(-6) M) converted VIP-induced contraction into relaxation in longitudinal muscle strip of distal colon, although these nerve blockers did not influence VIP-induced relaxations of longitudinal and circular muscle strips in proximal colon and of circular muscle strip in distal colon. VIP (10(-6) M) inhibited spontaneous and carbachol (10(-8) M)-stimulated propulsive activities of the isolated segment in distal colon. These results suggest that VIP may directly relax colonic smooth muscle cells and may indirectly contract longitudinal muscle strip of distal colon, mainly via stimulation of cholinergic neurones in the myenteric plexus of the muscle strip. It is also suggested that VIP-induced watery diarrhea in WDHA syndrome may not due to a direct stimulation of colonic motility.     

Altered sphincter of Oddi Phasic Activity following truncal vagotomy

Neural as well as hormonal influences regulate sphincter of Oddi function. Therefore, we tested the hypothesis that truncal vagotomy alters sphincter of Oddi phasic activity and response to hormonal stimulation. Adult, male prairie dogs underwent either sham laparotomy or truncal vagotomy and pyloroplasty. Postoperatively, all animals were fed a trace-cholesterol (nonlithogenic) diet for 3 months. In acute terminal experiments the distal common bile duct was perfused with lactated Ringer's solution at 0.1 ml/min. Sphincter of Oddi (SO) phasic contractions as well as baseline resistance were recorded before and during a 30-minute intravenous infusion of 10 ng/kg/min of cholecystokinin-octapeptide (CCK-OP). Before the CCK-OP infusion, both the frequency and amplitude of SO phasic contractions were significantly greater (P < 0.01) in vagotomized animals. During CCK-OP, the frequency of SO phasic contractions remained significantly greater (P < 0.01) in the vagotomy animals. The amplitude of SO phasic contractions, however, increased significantly (P < 0.03) in response to CCK-OP only in sham animals. Vagotomized animals failed to develop any further increase in the amplitude of SO phasic contractions during CCK-OP infusion. No differences in baseline resistance were noticed between sham and vagotomized animals before or during the infusion of CCK-OP. These findings suggest that (1) vagal tone inhibits sphincter of Oddi phasic contractions, (2) vagotomy increases sphincter of Oddi phasic activity, and (3) parasympathetic denervation alters the sphincter of Oddi's response to CCK-OP. Since the sphincter of Oddi plays an important role in normal gallbladder filling and emptying, altered sphincter of Oddi function may, in part, be responsible for the gallbladder stasis observed following vagotomy.