[Histological studies of tympanic membrane rim defects in chronic otitis media mesotympanalis]

In the present study we investigated resected tympanic membranes taken during tympanoplasty. Tissue from 111 patients with chronic otitis media was analyzed after being embedded in paraffin and stained with hematoxylin and eosin. In 67 patients (60%) the tympanic membrane epidermis did not extend beyond the margin of the perforation rim, so that no epithelial migration was observed on the inner side of the tympanic membrane. In 27 specimens (24%) we found an epithelial migration on the inner side of the tympanic membrane, but this did not extend to the margins of the excised tissue. In 17 tissue specimens (16%) epithelial migration extended to the margins of the resected tissue. Clinically, these patients were found to have non-functioning Eustachian tubes. The size of the tympanic membrane perforation was not found to impact on epithelial migration. However, there was a correlation between the extent of the epithelial migration seen in the specimens and the occurrence of a permanent tympanic membrane perforation after tympanoplasty. Of 17 patients with these findings, 4 (23%) had consistent reperforations. The tympanic membrane rims of these patients were completely covered with squamous epithelium. Patients with no or only little epithelial migration to the inner side of the tympanic membrane were found to have a significantly lower postoperative rate of recurrent infection and drum reperforation.