Clarifying optimal outcome measures in intermittent and continuous laryngeal neuromonitoring

Abstract

Background Intraoperative neuromonitoring (IONM) techniques have evolved over the past decade into intermittent IONM (I‐IONM) and continuous IONM (C‐IONM) modes of application. Despite many prior publications on both types of IONM, there remains uncertainty about what outcomes should be measured for each form of IONM. The primary objective of this paper is to define categories of benefit for I‐IONM/C‐IONM and to clarify and standardize their reporting outcomes. Methods Expert review consensus statement utilizing modified Delphi methodology. Results I‐IONM provides diagnosis, classification, and prevention of nerve injury through accurate and early nerve identification. C‐IONM provides real‐time information on nerve functional integrity and thus may prevent some types of nerve injury but cannot assist in nerve localization. Sudden mechanisms of nerve injury cannot be predicted or prevented by either technique. Conclusions I‐IONM and C‐IONM are complementary techniques. Future studies evaluating the utility of IONM should focus on outcomes that are appropriate to the type of IONM being utilized.

US residents experiences with intraoperative nerve monitoring in thyroid and parathyroid surgery

“…However, in reality, I-IONM is less able to prevent nerve injury than C-IONM due to the intermittent, surgeon-driven nature of the stimulation in I-IONM. 16 I-IONM allows the surgeon to evaluate nerve integrity at distinct time points during the surgical procedure. It may help prevent nerve injury through its utilization for nerve localization and mapping.…”

“…C-IONM is not useful for nerve localization and mapping and thus the information provided by I-IONM and C-IONM is complementary. 16 The V1R1R2V2 algorithm and troubleshooting algorithm as proposed by the International Neural Monitoring Study Group (INMSG) standardizes how IONM protocols are performed and helps ensure that adequate information to prognosticate laryngeal nerve function post-operatively is obtained at the start and end of a given procedure. This algorithm entails the following sequence-V1: verification of vagus nerve integrity prior to dissection, R1: verification of RLN integrity prior to dissection, R2: verification of RLN integrity after dissection and V2: verification of vagus nerve integrity after dissection.…”

“…However, despite its reported efficacy in reducing permanent or transient neural injury 4,6,11,13 and its endorsement by several academic societies, 14,15 a number of studies have concluded that IONM does not reduce nerve palsy rates compared with visual identification alone. A recent consensus statement discussed this controversy in depth, noting uncertainty among surgeons regarding optimal use patterns for intermittent (I‐IONM) and continuous IONM (C‐IONM) 16 . Much of this uncertainty stems from mixed conclusions as most publications focus on vocal fold paralysis (VFP) as the primary outcome measure when in reality the rate of VFP in isolation provides minimal information regarding the preventative utility of a particular IONM technique 16 .…”

“…A recent consensus statement discussed this controversy in depth, noting uncertainty among surgeons regarding optimal use patterns for intermittent (I‐IONM) and continuous IONM (C‐IONM) 16 . Much of this uncertainty stems from mixed conclusions as most publications focus on vocal fold paralysis (VFP) as the primary outcome measure when in reality the rate of VFP in isolation provides minimal information regarding the preventative utility of a particular IONM technique 16 . It is therefore important to understand the distinct definitions of benefits of the different forms of IONM.…”

“…C‐IONM yields continuous feedback on the nerve function and is dependent on the surgeon being receptive to changes in nerve signal and reversing or stopping the inciting maneuver before the signal change becomes permanent. C‐IONM is not useful for nerve localization and mapping and thus the information provided by I‐IONM and C‐IONM is complementary 16 …”