The Anti-Oxidant Effect of Alpha-Tocopherol in the Prevention of Experimentally Induced Myringosclerosis

Abstract

The objective of this study was to investigate the possible effect of alpha-tocopherol on the prevention of experimentally induced myringosclerosis. Myringosclerosis is a common sequela of ventilation tube treatment of otitis media with effusion. The relationship between oxygen-derived free radicals and occurrence of myringosclerosis has been proven in experimental models, and it was also shown that the formation of myringosclerosis after experimental myringotomy could be reduced by application of various free radical scavengers. Eighteen Wistar albino rats were myringotomized on the left side and randomly separated into two groups: group A consisted of rats which received intramuscular alpha-tocopherol injections 100 mg/kg daily and group B which were injected with physiological serum only. The occurrence of myringosclerotic plaques in the tympanic membranes of the two groups was compared by otomicroscopy, histopathology, and tympanometry, which is a novel method of quantification. Blood samples were collected for biochemical evaluation, and the tympanic membranes were harvested on the 15th day of the experiment. In otomicroscopic evaluation, tympanic membranes in group B revealed varying degrees of myringosclerotic plaques; on the other hand, tympanic membranes in group A showed faint or no existence of myringosclerosis. The mean malondialdehyde levels were 1.33 +/- 0.11 micromol/L in group A and 7.49 +/- 1.37 micromol/L in group B (Z = -1.906, p = 0.057). In all ears from group B, the magnitude of the maximum admittance measured by tympanometry reduced to approximately 40% of the values obtained from group A (Z = -2,160, p = 0.031). The mean magnitude of the maximum admittance from group A was very close to the standardization values of Wistar albino rats, which predicts a functional outcome. The formation of myringosclerosis after experimental myringotomy can be diminished by intramuscular alpha-tocopherol injections.