Several investigators have shown that propylene glycol is effective in producing experimental cholesteatoma and such cholesteatoma may originate from migration of tympanic membrane epidermis or middle ear metaplasia. Numerous factors, such as
middle ear
infection, eustachian tube dysfunction, etc, are related to cholesteatoma formation in experimental animals.
The purpose of this study was to evaluate the effects of middle ear ventilation and tympanic membrane perforation induced by ventilation tube on propylene glycol induced-cholesteatoma formation in guinea pigs.
In 10 guinea pigs, 60% propylene glycol was instilled through the intact tympanic membrane. In other 10 guinea pigs. 60% propylene glycol was instilled through the intact tympanic membrane and then ventilation tube was inserted to the tympanic
membrane.
All animals were sacrificed at 6th weeks and histopathology was observed by a light microscopy.
Of 10 animals to which 60% propylene glycol was instilled, 2 ears(20%) developed middle ear cholesteatoma. However, 8 ears(80%) developed middle ear cholesteatomas in 10 ventilation tube inserted guinea pigs. Epithelial migration from perforated
margin
was the most common finding.
The results indicate that in propylene glycol induced cholesteatoma, middle ear ventilation is not related, but 1) tympanic membrane perforation, 2) middle ear inflammation by propylene glycol and probably secondary infection are necessary
factors
to
cholesteatoma development.
|