Risk factors for deterioration of bone conduction hearing in cases of labyrinthine fistula caused by middle ear cholesteatoma

Objectives: We evaluated the risk factors and outcomes of bone conduction (BC) hearing in cases of labyrinthine fistulas treated under the basic principle of complete removal of the cholesteatoma matrix. Methods: A total of 47 patients with labyrinthine fistulas were analyzed. The fistulas were classified into smaller (no more than 3 mm) and larger fistulas (more than 3 mm). The fistulas were classified by depth into 3 stages. Preoperative symptoms and postoperative results with special reference to BC hearing were analyzed. Results: Total preoperative loss of BC hearing was found in 3 of 36 ears (9%) in the smaller-fistula group and 4 of 11 ears (36%) in the larger-fistula group; this was a statistically significant difference. The BC hearing was preserved after operation in 30 of 31 ears (97%) in the smaller-fistula group and 5 of 7 ears (71%) in the larger-fistula group; this difference was also significant. The stage (depth) of the fistula did not correlate with the postoperative BC hearing. Conclusions: In smaller labyrinthine fistulas, complete removal of the cholesteatoma matrix can be relatively safely performed. However, in patients with larger fistulas, there is a potential for a complete loss of BC hearing.