Laryngeal Reinnervation: The History and Where We Stand Now.

Injury to the recurrent laryngeal nerve (RLN) can result in impairment of all three laryngeal functions. The RLN is capable of regeneration, but laryngeal functions in cases of severe injury remain impaired. This permanent impairment is caused by either incomplete regeneration and/or occurrence of laryngeal synkinesis. Laryngeal reinnervation can be approached either nonselectively, focusing on nerve reconstruction, or selectively, focusing on separate target muscle reinnervation. Nonselective reinnervation comprises anastomosis to the mainstem of the RLN leading to reinnervation of both abductor and adductor muscle groups (nerve-based reconstruction). In selective reinnervation, abductor and/or adductor muscles are separately reinnervated (function-based reconstruction). A review of laryngeal reinnervation techniques, results in animal models, and the results achieved in patients are given. The clinical implications of reinnervation in unilateral as opposed to bilateral vocal fold paralysis are considered. For unilateral vocal fold paralysis and nonselective reinnervation, good voice results can be achieved. It has the advantage that no foreign materials need to be implanted and may also be used in a growing larynx in the case of children or adolescents. For bilateral vocal fold paralysis, good functional results, recovery of airway as well as voice, can be achieved with selective (or function-based) reinnervation.

Shape of Thyroid Cartilage Influences Outcome of Montgomery Medialization Thyroplasty: A Gender Issue.

OBJECTIVE: This study aimed to determine whether the shape of the thyroid cartilage and gender influence voice outcomes after a Montgomery thyroplasty implant system (MTIS). METHODS: A retrospective cohort study was performed on 20 consecutive patients who underwent MTIS. Voice outcome variables were the relative decrease in Voice Handicap Index (%) and the absolute increase in maximum phonation time (MPT) (in seconds). Material variables were the angle between the thyroid cartilage laminae (α-angle), the size of the prosthesis, and a combination of both (the α-ratio). Continuous variables were analyzed using medians and were compared between groups using the Mann-Whitney U test. Factors associated with the outcome variables were assessed by multivariable linear regression. A Pearson coefficient was calculated between material variables. RESULTS: The absolute increase in MPT between the pre- and postoperative period was significantly different between men and women, with a median absolute increase of 11.0 seconds for men and of 1.3 seconds for women (P < 0.001). A strong inverse correlation between the α-ratio and the absolute increase in MPT is observed in all patients, with a Pearson correlation coefficient R = -0.769 (P < 0.001). No factors were significantly associated with the relative Voice Handicap Index decrease in univariable or multivariable analyses. A better Pearson coefficient between the α-angle and the prosthesis size was found for females (0.8 vs 0.71). CONCLUSION: The MTIS is a good thyroplasty modality for male patients, but inadequate design of MTIS female implants leads to poor MPT outcomes. This represents a gender issue that needs to be further studied and eventually tackled.