Prevention of anterior glottic restenosis in a canine model with topical mitomycin-C

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.

Preservation of function and histologic appearance in the injured glottis with topical mitomycin-C

OBJECTIVE

To evaluate the functional and histological effects of a single application of topical mitomycin-C after laser injury in the posterior canine glottis.

STUDY DESIGN

A prospective, randomized study of 16 canines.

METHODS

A supersaturated (1%) solution of topical mitomycin-C was applied to a unilateral, laser-induced injury near the cricoarytenoid joint in eight dogs. The mitomycin-soaked pledget was placed immediately after induction of the injury and was left in contact with exposed cartilage for 3 minutes. The opposite side was not injured to provide an internal control. In eight additional dogs, the same laser injury was allowed to heal untreated. After 6 weeks, the animals were sacrificed and their larynges harvested. Arytenoid adduction sutures were placed bilaterally, and the force required to bring the vocal folds to midline was measured for each side using tensiometry. Gross and microscopic histological analysis was performed. Statistical analysis was accomplished using a two-tailed Student t test of unpaired samples, and the Wilcoxon Signed Rank Test where appropriate.

RESULTS

The mitomycin-C treated larynges demonstrated improved cricoarytenoid joint mobility (P = .007), decreased granulation tissue development (P = .03), and complete prevention of secondary "vocal granuloma" formation (P = .0004) when compared with eight dogs with identical laser injuries allowed to heal untreated. No complications were noted.

CONCLUSIONS

This study demonstrates functional preservation and improved histological appearance of the injured glottis after a single treatment with topical mitomycin-C. Potential applications of these findings include prophylactic use of topical mitomycin-C on glottic insults that commonly progress from granulation tissue formation to scarring and decreased vocal fold function.