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 cani ne glottis. Study Design: A prospective, randomized study of 16 canines. Me thods: 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 o f 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. Aryteno id adduction sutures were placed bilaterally, and the force required to bri ng the vocal folds to midline was measured for each side using tensiometry. Gross and microscopic histological analysis was performed. Statistical ana lysis was accomplished using a two-tailed Student t test of unpaired sample s, and the Wilcoxon Signed Rank Test where appropriate. Results: The mitomy cin-C treated larynges demonstrated improved cricoarytenoid joint mobility (P = .007), decreased granulation tissue development (P = .03), and complet e prevention of secondary "vocal granuloma" formation (P = .0004) when comp ared with eight dogs with identical laser injuries allowed to heal untreate d. No complications were noted. Conclusions: This study demonstrates functi onal preservation and improved histological appearance of the injured glott is after a single treatment with topical mitomycin-C. Potential application s of these findings include prophylactic use of topical mitomycin-C on glot tic insults that commonly progress from granulation tissue formation to sca rring and decreased vocal fold function.