Gastric acid secretion and gastrin release during continuous vagal neuromonitoring in thyroid surgery.

PURPOSE: The vagus nerve (VN) has essential regulatory roles in the gastric acid secretion and gastrin release. Continuous intraoperative neuromonitoring (CIONM) via VN stimulation is a promising technique in thyroid surgery because it potentially avoids injury to the recurrent laryngeal nerve. However, no studies have investigated changes in gastric acid secretion and gastrin release during CIONM. METHOD: This prospective study of 58 thyroid surgery patients compared gastric acid and serum gastrin at five time points: (1) before skin incision, (2) after baseline calibration of CIONM probe, (3) +20 min from baseline, (4) before probe removal, and (5) after extubation. Patients were excluded if they had any history of using tobacco, acid suppression medications, or drugs that affect gastric motility. Patients were also excluded if they had any history of gastroesophageal reflux symptoms, gastroesophageal reflux disease, peptic ulcer disease, helicobacter pylori infection, or chronic kidney disease. RESULTS: Non significant differences in mean gastric pH values were observed at all time points, i.e., (1) before skin incision (2.2 ± 0.2; p = 0.50), (2) after baseline calibration of CIONM probe (2.0 ± 0.8; p = 0.62), (3) +20 min from baseline (2.5 ± 0.5; p = 0.24), (4) before probe removal (2.9 ± 0.9; p = 0.52), and (5) after extubation (2.6 ± 1.0; p = 0.60). Comparisons of pH monitoring parameters revealed no significant differences in age, gender, side of CIONM (left vs. right), sequence of CIONM, or duration of CIONM. Gastrin values were normal in sequential determinations and did not significantly differ at any time points. CONCLUSIONS: CIONM performed via VN stimulation during total thyroidectomy in healthy patients does not influence gastrin secretion and gastric pH.

Continuous monitoring of the recurrent laryngeal nerve in thyroid surgery: a critical appraisal.

BACKGROUND AND PURPOSE: Intraoperative neuromonitoring (IONM) contributes in several ways to recurrent laryngeal nerve (RLN) protection. Notwithstanding these advantages, surgeons must be aware that the current, intermittent, mode of IONM (I-IONM) has relevant limitations. To overcome these I-IONM limitations, a continuous IONM (C-IONM) technology has been proposed. METHODS: A PubMed indexed literature review of the current limitations of I-IONM is presented and a commentary about C-IONM is provided presenting the preliminary results of research on this topic. MAIN FINDINGS: I-IONM, despite the advantages it produces, presents some important limitations; to overcome these drawbacks a C-IONM technology has been introduced. CONCLUSIONS: RLN traction injury is still the most common cause of RLN injury and is difficult to avoid with the application of I-IONM in thyroid surgery. C-IONM is useful to prevent the imminent traction injury by detecting progressive decreases in electromyographic amplitude combined with progressive latency increases. C-IONM seems to be a technological improvement. Likely, C-IONM by vagal nerve stimulation should enhance the standardization process, RLN intraoperative information, documentation, protection, training, and research in modern thyroid surgery. Although C-IONM is a promising technology at the cutting edge of research in thyroid surgery, we need more studies to assess in an evidence-based way all its advantages.