Abstract
Impedence audiometry is gaining rapid popularity as a clinical differential diagnostic technique for conductive auditory lesions.However, it is not clearly shown whether the diagnostic standard reported so far is appropriate for Japanese ears or not.
Therefore, impedance audiometry using Madsen ZO-72 was performed on 109 normal ears of 66 individuals in order to determine the normal ranges of the peakpoint value of tympanogram and of the static compliance.The difference between right and left ears were also studied.
In type A tympanogram, following data were obtained as normal ranges with 95% reliability.
i.The peakpoint value on tympanogram:1.5-7.4
2.The difference of the peakpoint values between both ears:less than 2.0
3.Static compliance:0.23-1.22c.c.
4.The difference between both ears:less than 0.25c.c.
After the survey on normal and pathological ears, it is our conclusion that pathological patterns should be defined when peakpoint value is larger than 7.4 or less than 1.5 in type A tympanogram, and Japanese seems to have-less static compliance of the ear than Caucasians.
In our study on 87 patients with conductive auditory lesions with intact tympanic membrane, more than 90%(38/40) of ears of exsudative otitis media was correctly diagnosed by impedance audiometry.However, the impedance audiometry did not always lead to correct diagnosis of ossicular discontinuity or fixation.For instance, five ears out of six ears with ossicular discontinuity did not show type AD tympanogram, which had peakpoint value of less than 1.5, and they had static compliance within normal limits.No cases of 7 patients with ossicular fixation showed type As tympanogram of peakpoint values more than 7.5 and four out of the seven cases have normal static compliance
