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The purpose of the present study was to evaluate the efficacy of cricoid regeneration via in situ tissue engineering in a canine larynx for the treatment of subglottic stenosis. As the tissue scaffold, a Marlex mesh tube coated by collagen sponge was used for a rigid airway framework and for tissue regrowth around the tube. On 5 dogs, the larynx was exposed and the anterior third of the cricoid cartilage was resected. The tube was anastomosed to the lower edge of the thyroid cartilage and to the first tracheal cartilage. By postoperative endoscopic examination at 3 to 7 months, no airway obstruction was observed in any of the dogs. There was granulation tissue in 2 dogs and slight mesh exposure in 1 dog, but they were asymptomatic. Confluent regeneration of the epithelium over the scaffold and good incorporation of the scaffold mesh into the host tissue were observed after surgery.

We developed a technique of fiberoptic laryngeal surgery for the treatment of vocal process granulomas. In this system, the granuloma can be removed relatively easily and repeatedly under topical anesthesia on an outpatient basis. We treated 27 patients for a total of 4 intubation granulomas and 23 contact granulomas. Ten of the 23 contact granulomas recurred after the initial surgery, but the intubation granulomas did not recur. Most of the recurrent lesions were resolved by fewer than 3 procedures, and all patients were finally cured. Although conservative therapies such as voice therapy and proton pump inhibitors have recently prevailed, surgical removal remains useful in treating vocal process granulomas. Fiberoptic laryngeal surgery facilitates repeated surgical procedures.

Surgical treatment of laryngeal webbing varies with the extent and site of the web. An extensive one seems to be best treated by laryngofissure and skin or mucosa transplantation. Recent experiences with four cases of thick glottal webbing indicated that a mucosa graft was better for the voice result than a skin graft. For success in the airway and voice results, the salient points in surgery include 1) precise midline thyrotomy, 2) shaping of the vocal cord under fiberoptic control, and 3) mucosa grafting with the combined use of a pliable stent or fibrin glue for fixation.

In order to explore the possibility of clinical application of laryngeal pacing as a treatment for unilateral vocal cord paralysis, we examined the reactivity of atrophic muscle to electrical stimulation in dogs whose recurrent laryngeal nerves were damaged by crushing, dissection followed by resuturing, or a 3-cm neurectomy. The threshold level to induce enough vocal cord adduction reached the maximum at 2 weeks after nerve injury, decreased with time, and never surpassed 7 V in each case. On the basis of results of these preliminary probings, laryngeal pacing was conducted on a dog 15 months after resection of the laryngeal nerve. Adduction of the paralyzed vocal cord for synchrony with the intact cord was achieved by 7 V of electrical stimulation of the thyroarytenoid muscle that was triggered by signals from the cricothyroid muscle.