Histopathological Evaluation of Mesna Application at Different Concentrations on Middle Ear Mucosa of Rats in Early and Late Stages.

Background: The aim of this study was to determine the safe concentration of Mesna, which is widely used in otologic surgeries, by examining the early and late effects on middle ear mucosa, at different concentrations.

Methods: Fifty-nine healthy ears of 32 rats were included in the study. The rats were divided into eight groups and Mesna at 25%, 50%, and 100% concentrations along with 100% saline were applied. On the third day of the experiment, animals in the first four groups were sacrificed to assess early effects, and on the twentieth day, animals in the last four groups were sacrificed to assess late effects. The middle ear mucosa samples were dissected and delivered blindly to the pathology department.

Results: Thirty-one rats completed the study. The histopathological effects of Mesna when applied in 25% and 50% concentrations were similar to those of saline in the early period. However, the application of 100% Mesna caused severe inflammation and a statistically significant difference was observed (P = 0.004). Furthermore, vascular proliferation was significant in this group (P = 0.014). There was no significant difference between the groups in terms of late effects.

Conclusion: In clinical practice, using up to 50% concentration of Mesna can be said to be reliable in obtaining a faster and more efficient chemical dissection. However, an inflammation of the middle ear mucosa was observed in the early period following the application of 100% concentration. Therefore, further studies are needed on its safe use in this concentration.