[Stapes dislocation and opening in the inner ear due to tympanoplasty]

During tympanoplasty, the stapes is often exposed to considerable manipulations, i.e. the dissection of cholesteatoma matrix from the oval window niche or the insertion of a prosthesis for ossicular chain reconstruction. Too much strain may rupture the annular ligament resulting in an opening of the inner ear. Furthermore it is conceivable that microperilymphatic fistulas, which remain undetected, may develop prior to a visible luxation of the stapes. Therefore, temporal bone experiments with definite manipulations on the stapes were performed to study the rupturing strength of the annular ligament. Increasing the pressure of the methylene blue dyed perilymphatic fluid facilitated the detection of even smallest ruptures. A leakage occurs only in case of a complete rupture of all fibres. Further findings of clinical interest, gained from these experiments with different directions of stapedial manipulation, are discussed.