Prevention of Anterior Glottic Restenosis in a Canine Model with Topical Mitomycin-C

Abstract

To develop a model for recurrent anterior glottic stenosis and to test the efficacy of topical mitomycin-C in preventing restenosis, we induced anterior glottic stenosis with a CO2 laser in 5 dogs. In 3 dogs, recurrence was established after surgical lysis. Subsequently, the 3 dogs received a single topical 3-minute treatment with a 1% solution of mitomycin-C after a second surgical lysis. In a parallel experiment, the other 2 dogs received a single topical 3-minute treatment with a 1% solution of mitomycin-C after the initial surgical lysis. An anterior glottic web was induced in all 5 dogs with the CO2 laser. The 3 dogs experienced restenosis at the anterior glottis after surgical lysis alone. Mitomycin-C prevented anterior glottic restenosis in 2 of the 3 dogs treated twice and in both of the dogs treated once (p = .02). We conclude that a recurrent stenosis of the anterior glottis may be induced reproducibly in the canine model with the CO2 laser. Application of topical mitomycin-C after lysis of an anterior glottic stenosis produces a statistically significant reduction in the rate of restenosis as compared to surgical lysis alone.

Prevention of Anterior Glottic Stenosis After Bilateral Vocal Fold Stripping With Mitomycin C

“…[8][9][10] The concentration used in this study was less than the 10 mg/mL of MMC concentration reported by Spector et al 7 but is comparable to the concentrations used clinically. The safe use of MMC is also supported by a recent report showing that the use of MMC at concentrations in excess of 0.4 mg/mL did not alter the protein concentrations in the extracellular matrix or the apoptosis rate.…”

“…9,10 In a previous experiment, MMC was used only to prevent recurrence after the lysis of anterior glottic webs that were originally induced by laser injury of the vocal folds. 7 These clinical and experimental studies of MMC suggest that MMC can be used for prevention of AGS following microsurgical removal of lesions involving both anterior vocal folds. However, to our knowledge, there have been no reports of experiments in which MMC was applied at the time of initial surgery to prevent the development of AGS.…”

“…Microforceps and microscissors (Karl Storz GmbH & Co) were used to remove the entire epithelium and a layer of the lamina propria from both sides of the membranous vocal folds, from the anterior commissure to the vocal process, and from the upper lateral margin of the true vocal folds to a point 2 mm below the edge of the vocal folds. 7 After the vocal folds were stripped, the anterior glottic area of the lesions was immediately treated for 5 minutes by application of a cottonoid pledget soaked in a solution of 1.0 mg/mL of MMC in sterile water or soaked in isotonic sodium chloride solution (control) (6 in each group) ( Table 1). After treatment with MMC, the glottis was washed with a isotonic sodium chloride solution-soaked cottonoid pledget.…”

“…This finding supports previous observations that surgical manipulation of both anterior vocal folds can lead to postoperative AGS. 1,7 Our animal model of AGS was created to simulate such clinical situations. The extent and depth of injury to the glottis that we used in the model were suggested by a study 11 of endolaryngeal microsur- gery for laryngeal cancer, in which subligamental cordectomy (type II) was performed on both sides according to a proposed classification of endoscopic cordectomy of the European Laryngological Society.…”

“…The results of that study showed that a single microsurgical stripping of the entire length of the membranous vocal folds induced more severe AGS than had been induced in a previous experiment using repeated laser vaporization of the mucosa in the same area. 7 The present study also focused on the prevention of AGS following bilateral endolaryngeal surgery of the anterior vocal folds. The conventional methods used to prevent AGS [4][5][6] are listed in the introduction.…”