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Abstract
Tympanosclerosis was first described in 1734 by Cassebohm as chalky patches in the tympanic membrane. It was introduced into the English literature by Zőllner (1956) as a common sequella of middle ear infection.
Tympanosclerosis was defined as abnormal condition of the middle ear cleft in which there are calcareous deposits in the tympanic membrane, tympanic cavity, ossicular chain and occasionally in the mastoid (Weilinga and Kerr, 1993).
It is characerized by lying down of large amounts of collagen fibers in the submucosal connective tissue of those sites. Thickening and fusion of the collagen may follow with the formation of a homogenous hyaline mass into which deposition of scattered intra- and extra-cellular calcium and phosphorous crystals may take place (Slack et al., 1984).
The incidence of tympanosclerosis varies widely between 7 to 33% in different series among patients with chronic middle ear infection (Emmet and Shea, 1978).
Myringosclerosis alone is much commoner than intra-tympanic tympanosclerosis ranging from 24% to 51% in chronic otitis media. Bilateral cases occur in around 40-60% of cases (Gibb and Pang, 1994). The incidence of myringosclerosis is highest in children and is related to the increased incidence of secretory otitis media with effusion and the associated use of ventilation tubes.
The exact etiology and pathogenesis of tympanosclerosis is very complex and has not been entirely clarified. It is usually considered as healed inflammation or a particular form of scar tissue following recurrent otitis media (Friedman, 1971).
Several factors are postulated in the pathogenesis of tympanosclerosis, Karlidage & others (2004) studied the effect of nitric oxide, free oxygen radicals, and catalase. The study suggest that NO, free oxygen radicals & catalase may have a role in the development of tympanosclerosis in patients with chronic otitis media.
Sprem & others (2002) injected blood in the ears of 32 guinea pigs in order to find out if blood could be a provocating factor and cause tympanosclerosis. Their experiment has shown that mucosal changes similar to those seen in early stages of tympanosclerosis.
Clinically, tympanosclerosis can be either myringosclerosis or intratympanic. Myringosclerosis occurs when the disease