Influence of Hypercalcemia in the Formation of Tympanosclerosis in Rats

Abstract

Hypercalcemia is thought to perform an important role in the etiopathogenesis of tympanosclerosis. The purpose of the present study was to assess the influence of hypercalcemia in the development of tympanosclerosis in rats with or without acute otitis media. The pathogenesis of tympanosclerosis is still unclear. Histologically, it is characterized by a hyaline degeneration in the lamina propria of the middle ear and mastoid mucosa and may lead to a calcification process. The process of calcification is similar to that of other pathologically calcified tissues, such as vessels, heart valves, cornea, and others, which depend on calcium serum levels. Twenty-four Wistar rats were divided into two different groups, with one group submitted to hypercalcemia status through calcium diet supplementation and the other used as a control group (normal calcium content diet). Both were submitted to induction of tympanosclerosis by inoculation of Streptococcus pneumoniae on the right middle ear only. Otomicroscopy was conducted every 15 days, and after 7 weeks of inoculation, the animals were killed and the tympanic bullae were resected to be analyzed through light and electron microscopy. The group submitted to hypercalcemia presented a prevalence of tympanosclerosis of 25% against 16.7% in the control group, presenting a relative risk of 1.27 (p=0.72). The results suggest that hypercalcemia can have an influence in the development of tympanosclerosis.