Continuous Laryngeal Adductor Reflex Versus Intermittent Nerve Monitoring in Neck Endocrine Surgery

Abstract

Objective Intraoperative neuromonitoring (IONM) techniques aim to identify and potentially prevent nerve injury during surgeries. Prior studies into the efficacy of recurrent laryngeal nerve (RLN) IONM convey mixed results, with some claiming equivalence between IONM and no monitoring at all. The goal of the current study was to compare continuous RLN monitoring using the laryngeal adductor reflex (LAR) to intermittent RLN monitoring (intermittent IONM) to determine whether continuous monitoring reduces the incidence of intraoperative RLN injury during neck endocrine surgeries. Methods In this observational, historical case‐control study, a historical cohort of patients monitored with intermittent‐IONM (group 1, n = 130) were compared to prospectively collected data from consecutive nerves‐at‐risk monitored continuously with the LAR (LAR‐CIONM, group 2, n = 205), at a single center by a single surgeon. The test benefit ratio and relative risk reduction (RRR) for LAR‐CIONM over intermittent IONM were calculated. Results For group 1, nine nerves at risk exhibited intraoperative LOS with transient postoperative vocal fold (VF) hypomobility (n = 2) or immobility (VFI, n = 7). For group 2, two nerves at risk (0.98%) had sudden intraoperative LAR LOS following bipolar cautery, resulting in postoperative transient VFI (P = .004). In each group, there was one case of permanent postoperative VFI. The test benefit rate ratio for LAR‐CIONM demonstrated a dramatic effect at 5.23, with an RRR of 81.0%. Conclusion LAR‐CIONM significantly decreased rates of postoperative transient VF paralysis and paresis over intermittent IONM alone (P = .004). Surgeons should be aware of the benefits and limitations of intermittent IONM versus CIONM. Intermittent IONM, although useful in nerve mapping and intraoperative decision making, has minimal benefit for the prevention of nerve injury, whereas CIONM can potentially reduce nerve injury rates and improve patient outcomes. Level of Evidence 3 Laryngoscope, 131:230–236, 2021

Experience with the use of intraoperative continuous nerve monitoring in video‐assisted neck surgery and external cervical incisions

“…Chiang et al suggest that the lack of a standardized IONM procedure could increase the risk of stretch injury to the RLN via Berry's ligament due to excessive traction and propose a standardized IONM procedure as a four‐step protocol 1,3 . The usefulness of intermittent nerve monitoring has been well documented 13‐16 . CIONM overcomes the key methodological limitation inherent to intermittent nerve monitoring, which allows the nerve to be at risk in between stimulations 8,17 .…”

Continuous Intraoperative Recurrent Laryngeal Nerve Monitoring: Techniques, Applications, and Controversies

“…Currently, endotracheal tubes do not yet allow for simultaneous recording of bilateral LAR responses. VN, vagal nerve; RLN, recurrent laryngeal nerve techniques were reported to reduce the transient [36] and permanent [9••] VCP rate more effectively than intermittent IONM. These international results contradict contemporary meta-analyses, which concluded that the use of intraoperative nerve monitoring did not contribute to reduced VCP rates [19][20][21].…”

Anatomical, functional and dynamic evidences obtained by intraoperative neuromonitoring improving the standards of thyroidectomy

“…The other etiological factors of RLN injury such as cauterization, clamping, ligature, transection occur with sudden actions and these actions may not be prevented by C-IONM. [ 68 , 69 ]…”