Histological studies of the regenerated mucosa in the mastoid cavity after tympanoplasty.

To observe mucosa regeneration in the mastoid cavity after tympanoplasty using silicone sheeting was examined in 31 patients with cholesteatoma and 7 with chronic otitis media who were operated on with the technique of staged intact canal wall tympanoplasty. In the first operation, the surface of the denuded bone was covered with 0.2-0.5mm silicone sheets. At the second operation 5-14 months after the first operation, 38 specimens from the anterior or posterior wall, and 25 specimens from the innermost wall of the mastoid cavity were taken and studied histologically.The specimens were histologically divided into four groups: granulation tissue, mixed tissue of granulation and scar, scar tissue and normal mucous membrane. Of the 38 specimens from the anterior or posterior wall, three showed granulation tissue, 16 mixed tissue of granulation and scar, and 19 scar tissue; normal mucous membrane was not found. In 8 patients who were operated on about 12 months after the first operation, only the single or multi-layered flattened epithelium had regenerated over the scar tissue.Of the 25 specimens from the innermost wall, 14, which had been attic type cholesteatoma, had normal mucous membranes. In 5 of the normal mucous membrane specimens, ciliated cells were observed on the free surface of the mucous membrane.These results suggest that more than one year is required for regeneration of the mucous membrane in the mastoid cavity after tympanoplasty.