[Impedancemetry. Clinical applications].

Abstract

The authors call attention to the importance of the data provided by impendancemetry, both in its classified applications, by tympanogram, and in impedance-audiometry, by the study of elicited stapedius reflex. They warn against the tendency to consider impedancemetry as a synonym for examination in conductive deafness and to reserve impedance-audiometry exclusively for perceptive deafness. These two techniques must be coupled and their multiple clinical applications are very often intricated. Tympanograms based in their clinic on the study of relative impedance, provide equally interesting diagnostic data in post-otorrhea states with open eardrum as well as closed eardrum for which until now tympanogram was the classic test. Of course tubal disfunctions, serous effusions of the middle-ear, fibro-adhesive otitis and ossicles disruptions are part of the current diagnosis clarified by impedancemetry in conductive deafness. On the other hand, for otospongiosis, the tympanogram is not of absolute value, but impedancemetry permits an extremely interesting diagnosis in three cases: in associated syndroms, where it acts as warning before the operation; in airbone gap reopenings after surgery, where the knowledge of the precise etiology conditions the therapy;-- and in postoperative cochlear drops, where an easy differential diagnosis is allowed between perilymph fistula and labyrinthe hydrops. Impedance-audiometry is based on the elicitation of stapedius reflex. It has numerous applications in perceptive deafness, where the detection of recruitment is very easy and of great value. So the diagnosis between cochlear and retro-cochlear deafness may be made evident. This method also applies to conductive deafness, to crura ruptures, as well as to the diagnosis of the beginning of otospongiotic stapedial fixations by the detection of a typical on-off effect. Besides otospongiosis is one of the most paradoxical applications of impedance-audiometry, which is revealed to be richer in information than the study of compliance, masking problems, diagnosis of associated syndroms and early detection of the disease are easily solved by impedance-audiometry. For these many reasons, the authors insist once more upon the importance and value of the data provided by impedancemetry and impedance-audiometry. They specify that this method is the most interesting complement to classic audiometry since the appearance of the audiometer.