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CASTS AND CRUSTS OF THE TYMPANIC MEMBRANE:
INTRODUCTION
| Description | : | Crusts and casts arising from the lateral surface of the tympanic membrane are sometimes found in patients who have had a previous episode of otitis media.
The formation of these crusts and casts occurs more commonly in children. A cast is defined as a crust that has separated spontaneously from the surface of the drum. Crust formation on the surface of the tympanic membrane is the result of a local inflammation or myringitis which occurs when the infection within the middle ear spreads into the tissues of the tympanic membrane. The underlying infection within the middle ear (acute otitis media) produces both inflammation and proliferation of the surface epithelium of the tympanic membrane. Due to a localized inhibition of those enzymes that are responsible for normal epithelial separation and migration, there is a rapid accumulation of stratified keratinocytes on the surface of the tympanic membrane. The serous fluid exuded by the inflamed membrane is imbibed by the hydrophilic keratinocytes, which swell. This rapidly accumulating mixture of inflammatory exudate and keratinocytes outstrips the reserves of the normally efficient epithelial migration, and a crust is formed on the lateral surface of the tympanic membrane |
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