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.