Anatomical variation and distribution of the vagus nerve in the esophageal hiatus: a cross-sectional study of post-mortem cases in Uganda.

PURPOSE: Vagus nerve injuries during gastroesophageal surgery may cause significant symptoms due to loss of vagal anti-inflammatory and neuromodulator function. Many previous studies have shown high anatomical variability of the vagus nerve at the esophageal hiatus, but information on its variability in Uganda specifically and Africa in general is scanty. This study provides a reliable and detailed description of the anatomical variation and distribution of the vagus nerve in the esophageal hiatus region of post-mortem cases in Uganda. METHODS: This was an analytical cross-sectional survey of 67 unclaimed post-mortem cases. Data collection used a pretested data collection form. Data were entered into Epi-Info version 6.0 data base then exported into STATA software 13.0 for analysis. RESULTS: The pattern of the anterior vagal trunk structures at the esophageal hiatus was: single trunk [65.7%]; biplexus [20.9%]; triplexus [8.9%] and double-but-not-connected trunks [4.5%]. The pattern of the posterior trunk structures were: single trunk [85.1%]; biplexus 10.4% and triplexus [4.5%]. There was no statistically significant gender difference in the pattern of vagal fibres. There was no major differences in the pattern from comparable British studies. CONCLUSION: The study confirmed high variability in the distribution of the vagus nerve at the esophageal hiatus, unrelated to gender differences. Surgeons must consider and identify variants of vagal innervation when carrying out surgery at the gastroesophageal junction to avoid accidental vagal injuries. Published surgical techniques for preserving vagal function are valid in Uganda.

Preservation of hepatic branch of the vagus nerve reduces the risk of gallstone formation after gastrectomy.

BACKGROUND: Injury to the vagus nerve has been proposed to be associated with occurrence of gallstones after gastrectomy. We investigated the effect of preservation of hepatic branch of the vagus nerve on prevention of gallstones during laparoscopic distal (LDG) and pylorus-preserving gastrectomy (LPPG). METHODS: Preservation of the vagus nerve was reviewed of cT1N0M0 gastric cancer patients underwent LDG (n = 323) and LPPG (n = 144) during 2016-2017. Presence of gallstones was evaluated by ultrasonography (US) and computed tomography (CT). Incidences of gallstones were compared between the nerve preserved (h-DG, h-PPG) group and sacrificed (s-DG, s-PPG) group. Clinicopathological features were also compared. RESULTS: The 3-year cumulative incidence of gallstones was lower in the h-DG (2.7%, n = 85) than the s-DG (14.6%, n = 238) (p = 0.017) and lower in the h-PPG (1.6%, n = 123) than the s-PPG (12.9%, n = 21) (p = 0.004). Overall postoperative complication rate was similar between the h-DG and s-DG (p = 0.861) as well as between the h-PPG and s-PPG (p = 0.768). The number of retrieved lymph nodes station #1 and 3-year recurrence-free survival were not significantly different between the preserved group and sacrificed group. Injury to the vagus nerve (p = 0.001) and high body mass index (BMI) (≥ 27.5 kg/m2) (p = 0.040) were found to be independent risk factors of gallstone formation in multivariate analysis. CONCLUSIONS: Preservation of hepatic branch of the vagus nerve can be recommended for LDG as well as LPPG of early gastric cancer patients to reduce postoperative gallstone formation.

Reduction in Pulmonary Vein Stenosis and Collateral Damage With Pulsed Field Ablation Compared With Radiofrequency Ablation in a Canine Model.

BACKGROUND: Pulmonary vein (PV) stenosis is a highly morbid condition that can result after catheter ablation for PV isolation. We hypothesized that pulsed field ablation (PFA) would reduce PV stenosis risk and collateral injury compared with irrigated radiofrequency ablation (IRF). METHODS: IRF and PFA deliveries were randomized in 8 dogs with 2 superior PVs ablated using one technology and 2 inferior PVs ablated using the other technology. IRF energy (25-30 W) or PFA was delivered (16 pulse trains) at each PV in a proximal and in a distal site. Contrast computed tomography scans were collected at 0, 2, 4, 8, and 12-week (termination) time points to monitor PV cross-sectional area at each PV ablation site. RESULTS: Maximum average change in normalized cross-sectional area at 4-weeks was -46.1±45.1% post-IRF compared with -5.5±20.5% for PFA (P≤0.001). PFA-treated targets showed significantly fewer vessel restrictions compared with IRF (P≤0.023). Necropsy showed expansive PFA lesions without stenosis in the proximal PV sites, compared with more confined and often incomplete lesions after IRF. At the distal PV sites, only IRF ablations were grossly identified based on focal fibrosis. Mild chronic parenchymal hemorrhage was noted in 3 left superior PV lobes after IRF. Damage to vagus nerves as well as evidence of esophagus dilation occurred at sites associated with IRF. In contrast, no lung, vagal nerve, or esophageal injury was observed at PFA sites. CONCLUSIONS: PFA significantly reduced risk of PV stenosis compared with IRF postprocedure in a canine model. IRF also caused vagus nerve, esophageal, and lung injury while PFA did not.

What Happens in (the) Vagus, Stays in (the) Vagus.

Many cardiothoracic operations put the nerves of the thorax at risk. In fact, nerve injuries are one of the most common reasons cited in malpractice cases brought against cardiothoracic surgeons. While all physicians learn about the nerves of the thorax during anatomy courses in medical school, little is written about avoiding injury to these important nerves in the cardiothoracic surgical literature. We have, therefore, embarked on an effort to collate information on the anatomy, function, and protection of these nerves, with which every cardiothoracic surgeon should be familiar. We will call this effort "The Nerve Protection Project." Acknowledging that the material to be covered is considerable, we will break the project into a series of editorials. The first installment in this series will address the anatomy and function of the vagus nerve and the protection of this nerve and its branches during cardiothoracic surgical operations, as they are in harm's way during many of these procedures.

A novel approach to neurologic function sparing surgical management of vagal schwannomas: Continuous intraoperative nerve monitoring of the laryngeal adductor reflex.

BACKGROUND: Vagal schwannomas are rare, benign tumors of the head and neck. Nerve damage during surgical resection is associated with significant morbidity. A new technique of continuous intraoperative nerve monitoring (IONM) that allows for real-time intraoperative feedback has recently been used for thyroid and cervical spine surgeries but has not previously been used in vagal schwannoma surgery. METHODS: Case series of three patients who underwent vagal schwannoma excision utilizing this novel IONM technique. The recurrent laryngeal and vagus nerves were monitored via the laryngeal adductor reflex (LAR) using an electromyographic endotracheal tube. RESULTS: Three patients with suspected vagal schwannomas were treated surgically using the intracapsular enucleation approach with a combination of intermittent IONM and continuous IONM of the LAR. CONCLUSION: This combination of continuous and intermittent IONM can be used to preserve vagal laryngeal innervation and function and may represent the future standard of care for vagal schwannoma excision.

Effect of Tailored Perigastric Lymph Node Dissection on Gastric Motility in a Canine Model.

BACKGROUND: Combination laparoscopic lymph node (LN) dissection and endoscopic resection is a promising treatment for early gastric cancer. However, LN dissection could cause nerve injury and deterioration of motility in the preserved stomach. This experimental study aims to evaluate changes in gastric motility after tailored perigastric regional lymph node dissection without gastrectomy. MATERIALS AND METHODS: We identified four most frequently involved LN combinations considering tumor location from retrospective reviews of 4697 gastrectomy patients. We randomly assigned 55 dogs to five groups: control (laparotomy only) and four experimental groups with LN dissection without gastrectomy: group 1 (LNs 3, 7, and 8), group 2 (LNs 3, 4, and 6), group 3 (LNs 1, 3, and 7), and group 4 (LNs 3, 4, and 11). Gastric emptying time (GET) was measured using barium-impregnated polyethylene spheres. GET50 and GET75 were the time points when 50% and 75% of the markers, respectively, had emptied from the stomach. RESULTS: On postoperative days (PODs) 2 and 3, GET50, GET75, and proportion of GET50 <4 h in groups 1 and 2 were comparable with controls. However, group 3 showed delayed GET50 and GET75, and groups 3 and 4 demonstrated significantly smaller proportions of GET50 <4 h compared with controls on PODs 2 and 3. This effect resolved by POD 6 and there were no significant differences in GET50, GET75, or proportion of GET50 <4 h between the groups. CONCLUSIONS: Tailored perigastric LN resection without gastrectomy was feasible and acceptable in terms of postoperative motility in the preserved stomach.

Resection of a Superior Mediastinal Mature Teratoma Using Intraoperative Neural Monitoring.

A 33-year-old woman presented with a right cervical mass. Contrast computed tomography showed a multilocular tumor with a clear border and heterogeneous contents including fat and calcification. The tumor was located adjacent to the vagus and recurrent nerves. To avoid injury of these nerves, we resected the tumor through a median sternotomy and right cervical lateral incision. Intraoperative neural monitoring was performed using an NIM TriVantage EMG tube (Medtronic, Minneapolis, MN). After the surgery, no neuropathy such as hoarseness was recognized. Pathological diagnosis showed a benign mature teratoma. Intraoperative neural monitoring is useful for superior mediastinal surgery around the vagus and recurrent nerves.

Vagal schwannomas of the head and neck: A comprehensive review and a novel approach to preserving vocal cord innervation and function.

BACKGROUND: Schwannomas, benign tumors arising from neurolemmocytes, are the most common type of peripheral nerve tumors. Extracranial schwannomas are most often found in the parapharyngeal space, commonly involving the vagus nerve to cervical sympathetic trunk. Vagal schwannomas present several unique clinical and therapeutic challenges. METHODS: A comprehensive literature review was conducted on 197 articles reporting 235 cases of cervical vagal schwannomas. Presenting symptoms, treatment approach, and postoperative outcomes were recorded and analyzed. RESULTS: Vagal schwannomas commonly present as asymptomatic neck masses. When they become symptomatic, surgical resection is the standard of care. Gross total resection is associated with higher postoperative morbidity compared to subtotal resection. Initial reports using intraoperative nerve monitoring have shown improved nerve preservation. Recurrence rates are low. CONCLUSION: The combination of intermittent nerve mapping with novel continuous vagal nerve monitoring techniques may reduce postoperative morbidity and could represent the future standard of care for vagal schwannoma treatment.

Feasibility of Continuous Intraoperative Neural Monitoring During Transoral Endoscopic Thyroidectomy Vestibular Approach in a Porcine Model.

Background: Experimental study to evaluate feasibility of continuous intraoperative neural monitoring (C-IONM) in transoral endoscopic thyroidectomy vestibular approach (TOETVA). Methods: Duroc-Landrace pigs were orally intubated with electromyogram endotracheal tube. Automatic periodic stimulation (APS) electrode was allocated in the operative field through the 5-mm ports. APS was then repose on vagal nerve (VN) with different approaches: (1) median, that is, between sternothyroid and thyroid gland; and (2) lateral, that is, between sternocleidomastoid and sternothyroid. VN was stimulated proximally and distally to the APS location to verify whether the dissection and/or placement determined VN injury. Video presentation is offered. Results: Assembled APS accessory was feasible in large-brained animals. The two basic options for VN approaches were tested. Baseline obtained had amplitude values >1000 µV, bilaterally. Conclusions: C-IONM was feasible in TOETVA in porcine models, but simplification of electrode design and application is needed.

The significance of the pharyngeal veins during carotid endarterectomy: description of an anatomical triangle.

Injuries to the hypoglossal and vagus nerves are the most commonly reported injuries during carotid endarterectomy. While unilateral single nerve injury is usually well tolerated, bilateral or combined nerve injuries can pose a serious threat to life. This study aims to increase awareness of the inferior pharyngeal vein, which usually passes posterior to the internal carotid artery but sometimes crosses anterior to it. Injury to either or both hypoglossal and vagus nerves can occur during control of unexpected haemorrhage from the torn and retracted edges of the inferior pharyngeal vein. We recommend careful ligation and division of this vein. In addition, we observed in 9 (17.3%) of the 52 operations that the pharyngeal vein formed a triangle with the vagus and hypoglossal nerves when it passes anterior to the internal carotid artery.

Topography and extent of pulmonary vagus nerve supply with respect to transthoracic oesophagectomy.

Pulmonary complications are frequently observed after transthoracic oesophagectomy. These complications may be reduced by sparing the vagus nerve branches to the lung. However, current descriptions of the regional anatomy are insufficient. Therefore, we aimed to provide a highly detailed description of the course of the pulmonary vagus nerve branches. In six fixed adult human cadavers, bilateral microscopic dissection of the vagus nerve branches to the lungs was performed. The level of branching and the number, calibre and distribution of nerve branches were described. Nerve fibres were identified using neurofilament immunohistochemistry, and the nerve calibre was measured using computerized image analysis. Both lungs were supplied by a predominant posterior and a smaller anterior nerve plexus. The right lung was supplied by 13 (10-18) posterior and 3 (2-3) anterior branches containing 77% (62-100%) and 23% (0-38%) of the lung nerve supply, respectively. The left lung was supplied by a median of 12 (8-13) posterior and 3 (2-4) anterior branches containing 74% (60-84%) and 26% (16-40%) of the left lung nerve supply, respectively. During transthoracic oesophagectomy with en bloc lymphadenectomy and transection of the vagus nerves at the level of the azygos vein, 68-100% of the right lung nerve supply and 86-100% of the inferior left lung lobe nerve supply were severed. When vagotomy was performed distally to the last large pulmonary branch, 0-8% and 0-13% of the nerve branches to the right middle/inferior lobes and left inferior lobe, respectively, were lost. In conclusion, this study provides a detailed description of the extensive pulmonary nerve supply provided by the vagus nerves. During oesophagectomy, extensive mediastinal lymphadenectomy denervates the lung to a great extent; however, this can be prevented by performing the vagotomy distal to the caudalmost large pulmonary branch. Further research is required to determine the feasibility of sparing the pulmonary vagus nerve branches without compromising the completeness of lymphadenectomy.

Thyroidectomy in the professional singer-neural monitored surgical outcomes.

BACKGROUND: Voice changes commonly occur from thyroidectomy and may be due to neural or nonneural causes. Such changes can be a source of significant morbidity for any patient, but thyroidectomy in the professional singer carries special significance. We test the hypothesis that the career of singers and professional voice users is not impaired after neural monitored thyroid surgery. METHODS: A quantitative analysis of pre- and postoperative neural monitored thyroid surgery voice outcomes utilizing three validated vocal instruments-Voice Handicap Index (VHI), Singing Voice Handicap Index (SVHI), and Evaluation of Ability to Sing Easily (EASE)-in a unique series of professional singers/voice users was performed. Additional quantitative analysis related to final intraoperative electromyography (EMG) amplitude, the time to return to performance, and vocal parameters affected during this interval was performed. RESULTS: Twenty-seven vocal professionals undergoing thyroidectomy were identified, of whom 60% had surgery for thyroid cancer. Pre- and postsurgery flexible fiberoptic laryngeal exams were normal in all patients. Return to performance rate was 100%, and mean time to performance was 2.26 months (±1.61). All three vocal instrument mean scores, pre-op vs. post-op, were unchanged: VHI, 4.15 (±5.22) vs. 4.04 (±3.85), p=0.9301; SVHI, 11.26 (±14.41) vs.12.07 (±13.09), p=0.8297; and EASE, 6.19 (±9.19) vs. 6.00 (±7.72), p=0.9348. The vocal parameters most affected from surgery until first performances were vocal fatigue (89%), high range (89%), pitch control and modulation (74%), and strength (81%). Final mean intraoperative EMG amplitude was within normal limits for intraoperative stimulation and had no relationship with time to first professional performance (p=0.7199). CONCLUSIONS: Neural monitored thyroidectomy, including for thyroid malignancy, in professional voice users is safe without any changes in three different voice/singing instruments, with 100% return to performance. Intraoperative EMG data at the conclusion of surgery and postoperative laryngeal exam were normal in all patients. Specific vocal parameters are transiently affected during the postoperative recovery phase, which is important to outline in the consent process of this unique patient population and may provide insight into the physiologic state of the larynx subsequent to thyroid surgery.

Usefulness of neuromonitoring in thyroid surgery.

INTRODUCTION: Identifying the recurrent laryngeal nerve is the gold standard for reducing injury in thyroidectomy. OBJECTIVE: To evaluate the usefulness of neuromonitoring in identifying the recurrent laryngeal nerve. METHODS: This was a study of 259 recurrent laryngeal nerves at risk during thyroidectomy performed with neuromonitoring (group A: 129 nerves) and without neuromonitoring (control group B: 130 nerves). RESULTS: The percentage of visually unidentified nerves was 18% in group A and 20% in group B, with no statistical difference. From the moment of non-identification, identification with neuromonitoring was achieved in group A in 100% of cases. The difference was statistically significant. The positive and negative predictive value of neuromonitoring was 100%. CONCLUSIONS: Neuromonitoring helps to identify the recurrent laryngeal nerve and increases the security of the surgeon in the technique. It is advisable to perform neuromonitoring routinely in thyroid surgery.