Feasibility and prognostic utility of laryngeal adductor reflex monitoring in anterior cervical spine surgery

초록

Objective: To evaluate the feasibility and clinical relevance of intraoperative laryngeal adductor reflex (LAR) monitoring for detecting recurrent laryngeal nerve (RLN) dysfunction during anterior cervical discectomy and fusion (ACDF). Methods: LAR monitoring was performed in 104 patients undergoing ACDF using an electromyographic endotracheal tube. R1 amplitudes were recorded, and significant reductions were classified as transient or permanent. Swallowing and voice outcomes were assessed on postoperative day 7 (POD7), and at 3 and 6 months (POM3, POM6). Receiver operating characteristic (ROC) analysis was used to identify amplitude-reduction thresholds associated with RLN dysfunction. Results: LAR signals were successfully obtained in 89.4 % of patients. Transient amplitude reductions occurred in 55 patients and were associated with short-term symptoms at POD7 (sensitivity 100 %, specificity 46.6 %, area under the curve [AUC] = 0.88), which resolved by POM6. Permanent reductions (n = 4) corresponded to persistent RLN dysfunction, with 100 % specificity and positive predictive value. Sensitivity increased over time, reaching 100 % at POM6. Post hoc ROC analysis identified an 81 % amplitude-reduction threshold that accurately predicted persistent RLN dysfunction at final follow-up (AUC = 1.000). Conclusions: Intraoperative LAR monitoring was feasible and demonstrated strong predictive value for RLN dysfunction during ACDF. Significance: LAR monitoring may enhance intraoperative neurophysiological monitoring by enabling real-time assessment of vagus nerve function in cervical spine surgery.

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