Laryngeal nerve function after total laryngeal transplantation.

The first successful composite human laryngeal transplantation was performed by a team led by the senior author on January 4, 1998. The recipient was a 40-year-old male who had sustained a crush injury to his larynx 20 years prior, rendering him aphonic. Multiple previous attempts for reconstruction at an outside hospital were unsuccessful. The donor was a 40-year-old male who had died from a ruptured cerebral aneurysm. The specifics of the procedure have been detailed elsewhere. Throughout the patient's postoperative course, serial fiberoptic evaluations and voice testing were performed to evaluate laryngeal reinnervation reflected in phonatory function. We herein report the results of these exams, as well as the results of electromyographic recordings of the laryngeal musculature 4 years posttransplantation.

Motion-specific laryngeal reinnervation using muscle-nerve-muscle neurotization.

There is no current treatment method that can reliably restore physiologic movement to a paralyzed vocal fold. The purposes of this study were to test the hypotheses that 1) muscle-nerve-muscle (M-N-M) neurotization can be induced in feline laryngeal muscles and 2) M-N-M neurotization can restore movement to a paralyzed vocal fold. Muscle-nerve-muscle neurotization can be defined as the reinnervation of a denervated muscle via axons that are induced to sprout from nerves within an innervated muscle and that then traverse a nerve graft interposed between it and the target denervated muscle. A paralyzed laryngeal muscle could be reinnervated by axons from its contralateral paired muscle, thus achieving motion-specific reinnervation. Eighteen adult cats were divided into sham, hemilaryngeal-denervated, and M-N-M-reinnervated thyroarytenoid muscle groups. Five of the 6 reinnervated animals had histologic evidence of axons in the nerve graft, 4 of the 6 had evoked electromyographic evidence of crossed reinnervation, and 1 of the 6 had a return of appropriately phased adduction. This technique has great potential and should be further investigated.

Comparison of nerve banking techniques in delayed laryngeal reinnervation.

Successful laryngeal transplantation will require adequate reinnervation of the larynx to allow phonation, coordinated swallowing, and respiration. A delay between laryngectomy and transplantation would be necessary in oncology patients because of the need for immunosuppression. In these patients, reinnervation of the donor organ would require "banking" and recovery of dormant recipient recurrent laryngeal nerves (RLNs). This pilot study was undertaken to compare the effectiveness of RLN storage using 1 of 2 techniques: 1) inserting the nerve into a muscle pocket or 2) anastomosing the proximal RLN stump to the ansa cervicalis. Six months following nerve transection and "banking," the proximal anterior branch of the RLN was reanastomosed to the distal anterior segment and the posterior branch was anastomosed directly to the posterior cricoarytenoid muscle. Tensionometry, image analysis, and electromyographic data were collected 1 year later. Results show reinnervation of adductors and abductors with both techniques. Banking of the RLN branches during total laryngectomy is effective and should permit delayed physiological reinnervation following laryngeal transplantation.

Laryngeal transplantation: current status 1974.

There are four major areas of concern that must be examined before human laryngeal transplantation can be considered feasible in clinical practice. These are: 1. surgical mechanics of revascularization; 2. reinnervation; 3. prevention of host rejection; and 4. justification. Of these criteria, the first two habe been met sucessfully at present. Safe suppression of rejection without increased risk of cancer recurrence remains to be achieved. Until this third criterion is satisfied, one is probably not justified to make further attempts at laryngeal transplantation in humans.