Vol.96 No.3 contentsPRACTICA OTO-RHINO-LARYNGOLOGICA
Vol. 96 No. 3 March 2003
Functional Examination for Conductive Deafness
without Perforation of the Tympanic Membrane
Akira Hara
(Institute of Clinical Medicine, University of Tsukuba)
Functional otological examinations, including pure tone audiometry (PTA), impedance measurement of the tympanic membrane, tympanometry, liquid test (LT) and acoustic reflex test (AR), were reviewed to evaluate their accuracy in the diagnosis of conductive deafness without perforation of the tympanic membrane. PTA, impedance audiometry, tympanometry and CT did not contribute to the differential diagnosis of ossicular fixation and discontinuity. In contrast to these results, LT showed a significant difference between ossicular fixation and discontinuity, i.e., no improvement of bone conduction threshold at any frequency by filling the external auditory canal with fluid in 86.7％ of the patients with ossicular discontinuity, and deterioration of bone conduction at 1000 Hz in 92.5％ of patients with ossicular fixation. A reversed pattern in the ipsilaterally stimulated AR was observed in 87.3％ of conductive deafness patients examined. The amplitude of this artifact response was larger at higher frequency (2,000 Hz) in ossicular fixation and at lower frequency (500 Hz) in ossicular discontinuity. These results were obtained in all patients showing the reversed pattern, without any exception. Therefore, we concluded that LT and AR are the most reliable examinations for the differential diagnosis between fixation and discontinuity of the ossicles.
Key words : conductive deafness, liquid test, acoustic reflex