The inhibitory effect of topical N-acetylcysteine application on myringosclerosis in perforated rat tympanic membrane

Objective: Myringosclerosis often occurs in patients in whom ventilation tube insertion and tympanoplasty procedures are performed. Recent studies have revealed a relationship between the development of myringosclerosis and oxygen-derived free radicals, and some investigations have demonstrated that free radical scavengers prevent the development of myringosclerosis. N-acetylcysteine is a well-known anti-oxidant and anti-inflammatory agent. In this study, we aimed to investigate the preventive effect of N-acetylcysteine on myringosclerosis in myringotomized rat tympanic membranes. Methods: Twenty Sprague–Dawley rats were bilaterally myringotomized and divided into four groups. Group 1 received no treatment, group 2 was treated with topical saline solution in Spongostan, group 3 received topical 0.6 mg N-acetylcysteine in Spongostan and group 4 received 1.2 mg N-acetylcysteine in Spongostan daily for 12 days. Tympanic membranes were examined by otomicroscopy on day 12. Then, the membranes were harvested and evaluated histologically by light microscopy. Results: The tympanic membranes of groups 1 and 2 (saline and non-treated) showed extensive occurrence of myringosclerosis, whereas groups 3 and 4 (treated with N-acetylcysteine) showed lesser occurrence of myringosclerosis in otomicroscopic evaluation (P