Multifrequency tympanometry: experimental application after implantation of ossicular replacement prosthesis in rabbits.
OBJECTIVE
We used multiple-frequency tympanometry (MFT) to evaluate the influence of a newly developed ossicular replacement prosthesis on transmission characteristics of middle ear.


BACKGROUND
Multiple-frequency tympanometry is a technique for evaluating the emittance of the middle ear over a wide frequency range. It has been shown to be sensitive to certain middle ear conditions that are not detected by conventional 226-Hz tympanometry. In the field of experimental evaluation, MFT has been shown in certain animal studies to be useful in monitoring diseases.


METHODS
Thirty-six prostheses composed of titanium dioxide ceramic were implanted into the right middle ear of female rabbits. Bilateral measurements using conventional 226-Hz and MFT were performed before implantation and after 28, 84, and 300 days postoperatively. The results of the preoperative examinations yielded reference values for physiological resonance frequency. After dissecting the temporal bone, we opened the middle ear and analyzed both the surrounding tissue and the position of the prosthesis.


RESULTS
The constant values for compliance revealed by both preoperative and postoperative measurements indicate good reproducibility of 226-Hz tympanometry. Postoperatively, resonance frequency increased continuously up to the 300th day. The observation supports the assumption that the higher stiffness level of connective tissue influenced resonance frequency.


CONCLUSIONS
The reference values in this study can serve as guidelines for further experimental trials.
Stieve
Martin
M
Department of Otolaryngology, Medical University of Hannover, Hannover, Germany. stieve.martin@mh-hannover.de
Mojallal
Hamidreza
H
Battmer
Rolf-Dieter
RD
Winter
Mark
M
Lenarz
Thomas
T
D000158:Acoustic Impedance Tests / Q000379:methods*; D000818:Animals; D002516:Ceramics; D003238:Connective Tissue / Q000502:physiology; D005260:Female; D009998:Ossicular Prosthesis; D011817:Rabbits; D012015:Reference Standards; D012016:Reference Values; D015203:Reproducibility of Results; D013701:Temporal Bone / Q000033:anatomy & histology / Q000502:physiology; D013997:Time Factors; D014025:Titanium
C009495:titanium dioxide; D014025:Titanium