[Examination for prediction of residual cholesteatoma]

Residual cholesteatoma, recurrent cholesteatoma, and the open cavity problem still remain to be solved in the surgical treatment of middle ear cholesteatoma. To avoid residual cholesteatoma, complete removal of the cholesteatoma matrix is necessary, but it is sometimes difficult to completely remove it at the initial operation. It is important to estimate the amount of residual cholesteatoma and to completely remove it before its enlargement causes several complications. We established some criteria in order to estimate the residual cholesteatoma at the initial operation, and analyzed the relationship between the criteria and the actual residual cholesteatoma at the second operation. We divided the degree of expectation of residual cholesteatoma into 4 groups: 'none', 'low-rate', 'high-rate', and 'certain'. 'Certain' means that we intentionally left a small part of the matrix to avoid inner ear damage during the procedures. Of 200 cholesteatoma patients who had undergone tympanoplasty between 1985 and 1993, we reviewed 118 who had also undergone a second look or a second stage surgical procedure. Residual cholesteatoma had developed in 25 patients. In those patients, 5 had two pieces of residual cholesteatoma. The incidence of residuum was 0%, 16.5%, 30% and 83.6% in the 'none', 'low-rate', 'high-rate', and 'certain' groups, respectively. The criteria were statistically analyzed and are discussed from the viewpoint of several parameters which would be expected to influence the development of residual cholesteatoma. The analysis disclosed that only one factor influenced the development. The factor was whether the operator could or could not maintain the continuity of the cholesteatoma matrix during the procedure. According to the result, we revised the criterion. The new criterion was considered to be valuable when residual cholesteatoma was predicted, and when adaptation of an exploratory operation was decided.