Assessment of Vagus Nerve Injury Through Sham Feeding

Background: Vagal nerve injury can cause non-specific symptoms and is challenging to assess. Pancreatic polypeptide (PP) release after sham feeding is a surrogate marker of vagal function. This study evaluated vagal integrity using sham feeding-induced PP measurement, and examined associations between symptoms, PP levels, and gastric emptying. Method: This was a retrospective study of patients who underwent sham feeding from 2018 to present. We collected demographic and clinical data, sham feeding results, indication for study, gastric emptying data. A 50% increase in PP level within 30 mins compared to baseline was considered normal. A gastric emptying scan was classified as delayed if < 75% of the material emptied at 4 hours. Results: 53 patients were included (58.5% women) with a mean age of 57.2 years. The main GI symptoms were nausea and vomiting (21, 40.0%) and diarrhea (14, 26.4%). 36 of 53 patients had a history of abdominal surgery, with Nissen fundoplication including open and laparoscopic being the most common surgeries (10, 27.8%). The fold of PP changes between abnormal and normal groups are significantly different (p = 0). In 23 patients with symptoms of nausea and vomiting, symptoms of nausea and vomiting were found to have a robust correlation with a positive sham feeding result (21, 91.3%), compared with gastric emptying scintigraphy (14, 60.9%). Conclusion: Sham feeding is consistently abnormal in patients with predominant symptoms of nausea and vomiting while the correlation between gastric scintigraphy result and gastroparesis symptoms was not significant. Sham feeding may be a valuable test when assessing patients with symptoms of nausea and vomiting.