A Systematic Review and Meta-Analysis on the Impact of Preserving the Hepatic Branch of the Vagus Nerve in Upper Gastrointestinal Surgeries

Background: Upper gastrointestinal surgeries encompass procedures on the esophagus, stomach, liver, pancreas, and gallbladder. To access the surgical area, it is standard to dissect the hepatogastric ligament, transecting the hepatic branch of the vagus nerve contained within it. Yet, the hepatic branch, which innervates the liver and gallbladder, contributes to digestion, bile secretion, and glucose metabolism. Hence, recent surgical studies have explored the potential benefits of hepatic branch preservation in comparison to non-preservation. This systematic review and meta-analysis endeavors to compile and analyze the outcomes of these studies. Methods: PubMed, EMBASE, Scopus, and Cochrane, were searched for cohort studies and randomized control trials comparing hepatic nerve preservation and division during upper gastrointestinal surgery in adults, up to April 2023. Two independent reviewers evaluated abstracts and full-text reviews, extracted pertinent information, and conducted risk-of-bias assessments using the RoB 2 and Newcastle-Ottawa instruments. Results: Thirteen studies involving 3001 participants were included for meta-analysis. Hepatic branch preservation was linked to a decrease in appetite loss (OR 0.04, 95% CI 0.01-0.18), reflux symptoms (OR 0.16, 95% CI 0.06-0.43) and gallstone formation (OR 0.25, 95% CI 0.09-0.69). However, preservation was associated with an increased incidence of Clavien-Dindo Grade 2 complications (OR 1.73, 95% CI 1.01-2.96) in gastrectomies. Conclusion: Hepatic branch preservation is associated with favorable post-surgical metabolic outcomes, notably appetite preservation. This may be due to the hepatic branch’s role in facilitating brain-liver crosstalk, thus, influencing homeostatic processes like appetite control and glucose metabolism. Reduced gallstone incidence is likely due to preservation of gallbladder motility and function, achieved through retention of parasympathetic innervation.