Reinnervation of Bilateral Posterior Cricoarytenoid Muscles Using the Left Phrenic Nerve in Patients with Bilateral Vocal Fold Paralysis

Abstract

ObjectiveTo evaluate the feasibility, effectiveness, and safety of reinnervation of the bilateral posterior cricoarytenoid (PCA) muscles using the left phrenic nerve in patients with bilateral vocal fold paralysis.MethodsForty-four patients with bilateral vocal fold paralysis who underwent reinnervation of the bilateral PCA muscles using the left phrenic nerve were enrolled in this study. Videostroboscopy, perceptual evaluation, acoustic analysis, maximum phonation time, pulmonary function testing, and laryngeal electromyography were performed preoperatively and postoperatively. Patients were followed-up for at least 1 year after surgery.ResultsVideostroboscopy showed that within 1 year after reinnervation, abductive movement could be observed in the left vocal folds of 87% of patients and the right vocal folds of 72% of patients. Abductive excursion on the left side was significantly larger than that on the right side (P < 0.05); most of the vocal function parameters were improved postoperatively compared with the preoperative parameters, albeit without a significant difference (P > 0.05). No patients developed immediate dyspnea after surgery, and the pulmonary function parameters recovered to normal reference value levels within 1 year. Postoperative laryngeal electromyography confirmed successful reinnervation of the bilateral PCA muscles. Eighty-seven percent of patients in this series were decannulated and did not show obvious dyspnea after physical activity. Those who were decannulated after subsequent arytenoidectomy were not included in calculating the success rate of decannulation.ConclusionsReinnervation of the bilateral PCA muscles using the left phrenic nerve can restore inspiratory vocal fold abduction to a physiologically satisfactory extent while preserving phonatory function at the preoperative level without evident morbidity.

Nerve branches to the posterior cricoarytenoid muscle may complicate the laryngeal reinnervation procedure

“…Several mechanisms have been proposed to explain these unfavorable outcomes. Among them, an inappropriate synkinesis between the IA muscle branch and the CBPI is considered to be one of the most important causes . Therefore, a number of methods have been used to investigate the innervation of the PCA muscle over the past decades.…”

“…In the PCA muscle reanimating procedure of Li et al, the nerves supplying the PCA muscle were able to be traced only from the RLN. The terminal tracing of the upper and lower branches was not feasible in the study by Li et al The nerve anastomosis was performed feasibly at the RLN level on the right side and at the adductor level on the left side. In other words, the CBPI may have been intact although the IA muscle branch had been sectioned.…”

“…This implies that the CBPI influences the result or that nerve implantation cannot produce a de novo motor endplate in the PCA muscle as observed for the thyroarytenoid muscle . Third, the ratio of fast‐twitch to slow‐twitch fibers differs between the PCA muscle and the thyroarytenoid muscle and between mammals . This difference might make PCA muscle reinnervation by nerve suture or nerve implantation not as desirable as laryngeal adductor reinnervation.…”

“…The laryngeal reinnervation of the posterior cricoarytenoid (PCA) muscle has received much attention because of its low success rate. Because a mobile vocal fold functions as a regulator of respiration and may enable maximal preservation of voice quality, many procedures have been investigated to ensure PCA muscle reanimation . Such investigations have included phrenic nerve implantation into the PCA muscle, phrenic nerve suture to the abductor branch of the RLN, and even artificial stimulator placement .…”

Selective reinnervation for bilateral vocal cord paralysis using the superior laryngeal nerve

“…The vast majority of techniques currently performed are static techniques, which often trade increased airflow for decreased voice and potential aspiration . Dynamic reconstruction utilizing the phrenic nerve has been performed in humans; however, the potential risks to the hemidiaphragm are often unacceptable to patients who have already compromised respiratory function…”