Impedance Audiometry in the Detection of Secretory Otitis Media

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Abstract
The usefulness of impedance audiometry as a screening method is evaluated. 800 nonselected 7-year-olds have been investigated with ordinary pure tone screening and impedance audiometry (tympanometry and stapedius reflex test). The results showed 6.5% pathological values with pure tone screening, 13.5% pathological values using tympanometry and 32% elevated or not elicitable stapedius reflexes. Analysis of our observations indicates that the stapedius reflex may be too sensitive a test to be used as a screening method. Tympanometry, on the other hand, is recommended as a complement to pure tone audiometry in screening of children. A 6–12 month follow-up was also performed on 357 ears in which initial study showed middle ear pressure ≤–100 mm H2O. At the repeat test 20% had pathological pure tone screening, 40% had middle ear pressure ≤–100 mm H2O, 57% had elevated or not elicitable stapedius reflex and 14% had middle ear effusion. The high frequency of persisting abnormal middle ear pressure and effusion in these 357 ears suggests that a middle ear pressure of ≤–100 mm H2O can be a pre-disposing factor for secretory otitis media. On the basis of our experience we recommend that hearing evaluation in school children should be performed with both tympanometry and pure tone screening. A middle ear pressure of ≤–150 mm H2O, a type B tympanogram and a hearing loss of >20 dB in two or more frequencies are an appropriate indication for referral to an otologist.