Incudo-stapedial joint pathology: a tympanometric approach.

Two-component tympanometry with a high probe-tone frequency enables a better distinction to be made between mobile but normal middle-ear systems and middle-ear systems suffering from necrosis, luxation, or disruption. Susceptance and conductance tympanograms obtained from 14 patients with confirmed pathological middle-ear lesions and 8 postmortem temporal bones, experimentally manipulated either surgically or with a 1 N HCl solution, were compared to tympanograms obtained from 80 normal subjects of an earlier study. With a 660-Hz probe tone, normal middle ears generate bell-shaped or normal sharp W-shaped patterns, whereas the pathologies of the middle ear give rise to irregular multi-extrema tympanograms. The differences between the two types of multi-extrema curves are discussed in detail. The use of phase-angle tympanometry is recommended to enable a quick and accurate distinction between normal and abnormal types of multi-extrema tympanograms. This study also points out clearly that 220-Hz tympanograms do not allow clear differentiation between pathological and normal middle ears.