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<0.01). Under light microscopic examination, lamina propria of pars tensa was found thicker in groups 3 and 4 when compared with groups 1 and 2. There was no significant difference between groups 3 and 4 (P: 0.30).

CONCLUSIONS

Topically applied N-acetylcysteine was found to be effective in the prevention of sclerotic lesions in myringotomized rat tympanic membranes.