Preoperative evaluation of ossicular chain abnormality in patients with conductive deafness without perforation of the tympanic membrane.

Objective: To evaluate the usefulness of pure-tone audiometry, tympanometry, and liquid and acoustic reflex (AR) tests in the differential diagnosis of ossicular fixation and discontinuity.

Design: A prospective clinical trial.

Setting: Tertiary referral center.

Patients: Thirty-nine patients (46 ears) undergoing operations at University of Tsukuba Hospital, Tsukuba, Japan, from 1990 through 2003 for conductive deafness without perforation of the tympanic membrane. Clinical examinations for the preoperative diagnosis included pure-tone audiometry, tympanometry, and liquid and AR tests. We compared the preoperative diagnosis with the surgical findings.

Results: Although neither pure-tone audiometry nor tympanometry contributed to the differential diagnosis of ossicular chain abnormality, liquid and AR test results showed a significant difference between fixation and discontinuity of the ossicular chain. With the liquid test, bone conduction at lower frequencies was improved by filling the external auditory canal with water at lower frequencies in cases of ossicular fixation. In contrast to the findings observed in ossicular fixation, no improvement of the threshold of bone conduction was recognized at any frequency in the ears with ossicular discontinuity. In ipsilaterally stimulated AR, the reversed pattern was the most marked at 2000 and 500 Hz in ossicular fixation and discontinuity, respectively.

Conclusion: Liquid and AR tests are reliable examinations for the differential diagnosis of ossicular fixation and discontinuity.