An update on the status of nerve monitoring for thyroid/parathyroid surgery.

PURPOSE OF REVIEW: Recurrent laryngeal nerve (RLN) injury is one of the most common and serious complications associated with thyroid and parathyroid surgery. Although routine visual identification of the RLN is considered the current standard of care, the role of intraoperative neuromonitoring (IONM) of the RLN is more controversial. RECENT FINDINGS: Despite initial enthusiasm that IONM might substantially reduce the rate of RLN injury, most studies failed to show a significant difference in the rate of RLN injury when the use of IONM was compared with visualization of the RLN alone. However, a small number of investigators have reported statistically significant differences in the rates of nerve injury when IONM is used to augment visualization alone, particularly in certain high-risk situations. Despite a lack of conclusive data showing benefit, the use of IONM as an adjunct to visual identification of the RLN has gained increasing acceptance among surgeons. IONM remains an excellent tool to help verify the identity of the RLN, confirm its functional integrity, and pinpoint the site of nerve injury in the event of dysfunction. SUMMARY: The utility of IONM in reducing the rate of RLN injury is largely unproven and remains controversial. However, the use of IONM may be helpful in certain high-risk cases. Promising new technology, such as vagal nerve monitoring, may allow more real-time monitoring of the functional integrity of the RLN and allow the surgeon to react in a timely manner to evolving dysfunction in order to abort maneuvers that may risk definitive injury.

Increased and safer detection of nonrecurrent inferior laryngeal nerve after preoperative ultrasonography.

OBJECTIVES/HYPOTHESIS: Right nonrecurrent inferior laryngeal nerve (NRLN) is an anatomical variant reported with a variable prevalence (0.3%-6%). It is associated with some arterial abnormalities (absence of the brachiocephalic trunk and presence of a right aberrant subclavian lusorian artery) that may be identified by preoperative ultrasonography (pUS). NRLN represents a major morbidity risk factor during neck surgery. The aim of this study was to verify pUS accuracy in predicting NRLN and to assess the impact of this technique on NRLN detection rate and laryngeal morbidity. STUDY DESIGN: Retrospective. METHODS: The study included 1,477 patients undergoing thyroid and parathyroid surgery with right-side inferior laryngeal nerve exploration. pUS was performed in 878 patients (pUS group); no preoperative attempts were performed in the remaining 599 patients (controls). Demographics, disease type, intraoperative inferior laryngeal nerve anatomy, and laryngeal morbidity were compared. RESULTS: No differences occurred between the two groups concerning demographics and disease type. NRLN was detected in 17 patients (1.9%) of the pUS group and in four patients (0.6%) of controls (P < 0.05). pUS predicted NRLN in all cases, with an overall accuracy > 98%. Overall laryngeal nerves morbidity was 1.8% in the pUS group and 4.2% in the controls (P < 0.05). NRLN palsy never occurred in the pUS group, whereas it occurred three times in the controls (P < 0.005). CONCLUSION: NRLN is accurately predicted by pUS. It occurs more frequently than expected because it may be misdiagnosed when no preoperative suspicion is available. Preoperative NRLN detection by pUS prevents inferior laryngeal nerve injuries.

Preoperative diagnosis and intraoperative protection of nonrecurrent laryngeal nerve: a review of 5 cases.

BACKGROUND: Nonrecurrent laryngeal nerve (NRLN) is a risk factor for nerve injury during thyroidectomy or parathyroidectomy. It is usually associated with abnormal vasculature that can be identified by several imaging methods. The aim of this study was to retrospectively analyze the preoperative diagnosis and intraoperative protection of NRLN. MATERIAL AND METHODS: Of the 7169 patients who underwent thyroid surgery at our hospital between August 2008 and January 2013, 5 patients with NRLN were identified. Preoperative chest X-rays, neck ultrasonography (US), and computed tomography (CT) findings were reviewed. NRLNs were carefully and systematically searched for in surgery. RESULTS: Preoperative CT predicted NRLN in all 5 cases (100% accuracy). The detection rate of NRLN by CT was 0.4% (5/1170). NRLNs were confirmed in surgery. All of them were right-sided NRLN with type IIA variant. The CT scans clearly revealed the vascular anomalies. The review of US images suggested that vascular anomalies could be identified on the images in 1 patient. No postoperative complications occurred in any patient. CONCLUSIONS: The preoperative CT scan was a reliable and effective method for identifying abnormal vasculature to indirectly predict NRLN. Combining the CT and US findings with adequate surgical technique may help to reduce the risk of nerve damage, in addition to preventing nerve palsy.