Intraoperative Neurophysiologic Testing of the Perigastric Vagus Nerve Branches to Evaluate Viability and Signals along Nerve Pathways during Gastrectomy

Organ- and function-specific anatomical organization of vagal fibers supports fascicular vagus nerve stimulation

Vagal fibers travel inside fascicles and form branches to innervate organs and regulate organ functions. Existing vagus nerve stimulation (VNS) therapies activate vagal fibers non-selectively, often resulting in reduced efficacy and side effects from non-targeted organs. The transverse and longitudinal arrangement of fibers inside the vagal trunk with respect to the functions they mediate and organs they innervate is unknown, however it is crucial for selective VNS. Using micro-computed tomography imaging, we tracked fascicular trajectories and found that, in swine, sensory and motor fascicles are spatially separated cephalad, close to the nodose ganglion, and merge caudad, towards the lower cervical and upper thoracic region; larynx-, heart- and lung-specific fascicles are separated caudad and progressively merge cephalad. Using quantified immunohistochemistry at single fiber level, we identified and characterized all vagal fibers and found that fibers of different morphological types are differentially distributed in fascicles: myelinated afferents and efferents occupy separate fascicles, myelinated and unmyelinated efferents also occupy separate fascicles, and small unmyelinated afferents are widely distributed within most fascicles. We developed a multi-contact cuff electrode to accommodate the fascicular structure of the vagal trunk and used it to deliver fascicle-selective cervical VNS in anesthetized and awake swine. Compound action potentials from distinct fiber types, and physiological responses from different organs, including laryngeal muscle, cough, breathing, and heart rate responses are elicited in a radially asymmetric manner, with consistent angular separations that agree with the documented fascicular organization. These results indicate that fibers in the trunk of the vagus nerve are anatomically organized according to functions they mediate and organs they innervate and can be asymmetrically activated by fascicular cervical VNS.

A new technique for treating hiatal hernia with gastroesophageal reflux disease: the laparoscopic total left-side surgical approach

Introduction

Although the traditional bilateral surgical approach to treat hiatal hernia (HH) with gastroesophageal reflux disease (GERD) can provide local protection of the vagus nerve, the integrity of the entire vagus nerve cannot be evaluated. Therefore, we developed and described the total left-side surgical approach (TLSA), which theoretically reduces injury to the vagus nerve, and described the detailed surgical procedure.

Methods

Initially, we performed a cadaver study to explore the characteristics of the vagus nerve. Then, we prospectively evaluated the TLSA in 5 patients with HH and GERD between June 2020 and September 2020. Demographic characteristics, surgical parameters, perioperative outcomes, and follow-up findings were analyzed.

Results

The TLSA was successfully used in five patients (40–64 years old), and no major complications were noted. The median total operative time was 114 min, median blood loss was 50 mL, and median postoperative hospital stay was 3.8 days. Gastrointestinal function recovered within 4 days of surgery in all the patients. The 6-month follow-up gastroscopy examination showed well-established gastroesophageal flap valves. Compared with the baseline results, the 6-month follow-up results showed lower values for the total GerdQ score (12.4 vs. 6.2) and the total esophageal acid exposure time (3.48% vs. 0.38%). Based on the European Organization for Research and Treatment of Cancer quality of life questionnaire-stomach module 52 results, the incidence of dysphagia and flatulence decreased over time after the TLSA.

Conclusions

The TLSA provides a clear and broad surgical field, less trauma, and rapid recovery; moreover, it is technically simple. Although our results suggest that the TLSA provides safety and short-term efficacy and is feasible for patients with HH and GERD, long-term results from a larger clinical trial are needed to validate these findings.

Trial registration ChiCTR2000034028, registration date is June 21, 2020. The study was registered prospectively

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.

Proximal Anterior-Antrum Posterior (PAAP) Overlapping Anastomosis in Minimally Invasive Pylorus-Preserving Gastrectomy for Early Gastric Cancer Located in the High Body and Posterior Wall of the Stomach

Purpose

To evaluate the feasibility and safety of intracorporeal overlapping gastrogastrostomy between the proximal anterior wall and antrum posterior wall (PAAP; PAAP anastomosis) of the stomach in minimally invasive pylorus-preserving gastrectomy (PPG) for early gastric cancer (EGC).

Materials and Methods

From December 2016 to December 2019, 17 patients underwent minimally invasive PPG with PAAP anastomosis for EGC in the high body and posterior wall of the stomach. Intraoperative gastroscopy was performed with the rotation maneuver during proximal transection. A longer antral cuff (>4-5 cm) was created for PAAP than for conventional PPG (≤3 cm) at the point where a safe distal margin and good vascular perfusion were secured. Because the posterior wall of the proximal remnant stomach was insufficient for intracorporeal anastomosis, the anterior wall was used to create an overlapping anastomosis with the posterior wall of the remnant antrum. The surgical and oncological outcomes were analyzed, and the stomach volume was measured in patients who completed the 6-month follow-up. The results were compared to those after conventional PPG (n=11 each).

Results

PAAP anastomosis was successfully performed in 17 patients. The proximal and distal resection margins were 2.4±1.9 cm and 4.0±2.6 cm, respectively. No postoperative complications were observed during the 1-year follow-up esophagogastroduodenoscopy (n=10). The postoperative remnant stomach (n=11) was significantly larger with PAAP than with conventional PPG (225.6±118.3 vs. 99.1±63.2 mL; P=0.001). The stomach length from the anastomosis to the pylorus was 4.9±2.4 cm after PAAP.

Conclusions

PAAP anastomosis is a feasible alternative for intracorporeal anastomosis in minimally invasive PPG for highly posteriorly located EGC.