Experience from 102 patients with continuous intraoperative vagus nerve stimulation during minimally invasive esophagectomy

Abstract

Background: The incidence of recurrent laryngeal nerve (RLN) injury after esophagectomy can be as high as 60–70% especially when lymphadenectomy is performed along bilateral RLN. Vocal cord paralysis is associated with increased pulmonary complication rate, longer hospital stay, and impaired quality-of-life. The authors have modified the Continuous Intraoperative Nerve Monitoring (CIONM) method for minimally invasive esophagectomy. This study reviews our experience in the first 102 patients. Methods: From May 2014 to January 2018, patients who underwent thoracoscopic esophagectomy were recruited. CIONM and intermittent nerve stimulation were routinely used during left RLN lymphadenectomy. For right RLN dissection, only intermittent nerve stimulation was used because of much lower chance of nerve injury. Routine direct laryngoscopy was performed on postoperative day one to assess the vocal cord status. Patients with RLN palsy are referred to otorhinolaryngologist for assessment and treatment. Surgical outcome, especially RLN palsy and recovery rates were documented. Results: 102 patients were recruited and 73 patients had more than one year follow up. Twenty-two patients had RLN palsy (21.6%); right side in 3, left side in 18, and bilateral in one. Thirty-eight patients (37%) had only unilateral or no RLN dissection performed. This was because of R2 resection negating the benefits of RLN dissection (15.6%), poor pulmonary exposure (9.8%), other technical difficulties (7.8%), preoperative vocal cord palsy (2%), intraoperative complications (1%) and uncertain contralateral nerve integrity (1%). For those 90 patients with successful CIONM, 20 RLN palsy (22.2%), 10 of whom underwent injection thyroplasty within 2–80 days. Thyroplasty was not performed in 12 patients as they had good compensation from the contralateral cord (58.3%), early recovery within 2 weeks (16.7%) tracheostomized status (16.7%) or refusal (8.3%). Thirteen patients (59%) recovered within 2–72 weeks (Median 6 weeks). For the 73 patients with more than 1 year follow up, only 4 has residual vocal cord paralysis, making a genuine cord palsy rate of 5.5%. Conclusion: Lymphadenectomy along bilateral RLN is technically demanding. CIONM is a sensitive tool to guide surgeons for safer dissection. Proper patient selection, postoperative assessment and treatment protocol can reduce the morbidity of RLN injury. Majority of the vocal cord paralysis is temporary.