Acoustic-immittance characteristics of children with middle-ear effusion: longitudinal investigation

The purpose of this investigation was to describe, in a longitudinal prospective study, the acoustic-immittance profile during sessions with effusion and during sessions without effusion in children with recurrent middle-ear effusion (MEE). The static-acoustic middle-ear admittance, tympanometric width (TW), tympanometric peak pressure (TPP), and ipsilateral acoustic reflex (IAR) were evaluated in 36 ears of 18 children with recurrent MEE and 24 ears of 12 children without a history of MEE. Recurrent MEE was operationally defined as MEE diagnosed by microtoscopy and/or pneumotoscopy at four or more sessions over the first year of investigation. Subjects in the recurrent MEE group were followed over a time span of 1.1 to 3.0 years with an average intersession interval of 3.0 months. The results revealed that MEE was present at 78.3 percent of the sessions. A pure-tone average (PTA) exceeding 25 dB HL was present at 80 percent of the effusion sessions in the recurrent MEE group. The false-alarm rate for each of the individual acoustic-immittance measures, especially the TPP and IAR, was markedly higher during the otoscopically normal sessions of the recurrent MEE group than in the control group. This suggests that even when MEE is absent at a particular session, recurrent episodes of MEE appear to alter the acoustic-immittance characteristics of the middle ear. Negative findings on all or three of the four acoustic-immittance measures occurred in only 1 percent of the effusion sessions in the total recurrent MEE group as compared with 76 percent of the normal sessions in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)