Long-term observation of ears with reduced middle ear pressure.

335 ears from 210 childred in which tympanometry initially indicated middle ear pressure less than or equal to -100 mm H2O or a flat tympanogram have been reinvestigated 3 years later. When the inital investigation was performed all children were 7 years old. The present study reveals that 25% of these ears still have middle ear pressure less than or equal to -100 mm H2O and 16% middle ear pressure less than or equal to -150 mm H2O. In normal material of the same age group 9% have middle ear pressure less than or equal to -100 mm H2O and 4% middle ear pressure less than or equal to -150 mm H2O. The study also reveals effusion in 10% of ears with normal screening audiograms. In ears with normal screening audiograms and middle ear pressure greater than or equal to -145 mm H2O effusion was found in 5% and in ears with abnormal screening audiograms and middle ear pressure less than or equal to -150 mm H2O effusion was found in 81%. As tympanometric criterion for otologist referral, middle ear pressure less than or equal to -150 mm H2O or a flat tympanogram is suggested. The inclusion of tympanometry in routine screening for middle ear pathology in children is recommended.