Towards quantitative diagnosis of ossicular fixation: Measurement of stapes fixations using magnetically driven ossicles in human temporal bones.

CONCLUSION

Information on the degree of stapes fixation can be found by measuring the ratio of stapes to umbo and stapes to incus velocity.

OBJECTIVES

To evaluate a method of quantifying ossicular fixation in an ear with elevated tympanic membrane.

METHOD

Measurements were made on four fresh-frozen human temporal bones. After elevating the tympanic membrane, a small magnet was attached to the manubrium and an electromagnetic excitation coil was used to vibrate the ossicles. The vibration response of the umbo, the tip of the incus long process, and the posterior crus of the stapes were measured before and after partially fixing the footplate with luting cement.

RESULTS

The velocities at the different measurement points were unequally affected by the fixation. The difference in the velocity ratio between different points provides an indication of the degree of footplate fixation.