Quantifying the Ototoxicity of Mitomycin: Before versus after Myringotomy.

Abstract

OBJECTIVES: Recent research has focused on mitomycin C (MMC) application as a means to circumvent complications that arise when using ventilation tubes during myringotomy. This study has two aims: (1) to synergize the current literature to create a standardized clinical approach for using MMC, and (2) to determine at which point during the myringotomy the application of MMC proves the safest (i.e., before or after incision). METHODS: We measured the auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAE) in 9 female chinchillas to determine whether applying MMC before or after incision was also the safest. The tests were then repeated on days 3, 10 and 17. RESULTS: The change in the ABR thresholds from baseline was greater in the experimental than in the control group; however, after stratification, the 'after' group experienced a statistically significant change (19.38 ± 8.26) on day 17, whereas the 'before' group did not (2.00 ± 3.26; p = 0.003). No such changes were seen with DPOAE testing. CONCLUSIONS: Mitomycin is less ototoxic to the middle ear when applied before myringotomy is done. We recommend future studies to apply the clinical approach we have designed to standardize its use in selected cases.