Laryngeal adductor reflex hyperexcitability may predict permanent vocal fold paralysis

Abstract

Laryngeal adductor reflex-continuous intraoperative neuromonitoring (LAR-CIONM) is a novel method of continuous intraoperative neuromonitoring. In contrast to other vagal nerve monitoring techniques, which elicit a laryngeal compound muscle action potential, LAR-CIONM elicits a laryngeal reflex response (LAR). In 300 nerves at risk monitored with LAR-CIONM, two patients have had postoperative permanent vocal fold immobility (VFI). Both patients exhibited a significant LAR amplitude increase prior to complete loss of signal. No other patients have exhibited LAR hyperexcitability. If confirmed in a larger sample, this represents the first time that a vagal intraoperative neuromonitoring technique can distinguish transient from permanent VFI, which could improve patient outcomes.

Vagus Nerve Stimulation in the Carotid Triangle: An Effective Method for Monitoring the Recurrent Laryngeal Nerve in Thyroid and Parathyroid Surgery

“…However, this technique also has significant drawbacks, and it requires dissection of the carotid sheath for its placement on the vagus nerve, which must be conducted bilaterally in total thyroidectomies, requiring a larger skin incision, greater risk of iatrogenesis, increased surgical time, and possible complications [ 23 , 29 , 30 , 31 ]. Other techniques have been described for IOM in thyroid and parathyroid surgery, such as the recording of CMAP in the posterior cricoarytenoid muscle [ 32 ], using anterior laryngeal electrodes [ 32 ] or the study of the laryngeal adductor reflex through electrical stimulation of the laryngeal mucosa and recording of the reflex response of the VC using surface electrodes in the endotracheal tube [ 33 , 34 , 35 , 36 ]. Although this technique monitors the sensory and motor pathways of the laryngeal nerves, it does not allow direct response (CMAP) to be obtained in the VC, which are always more reliable.…”