Tympanometric pattern classification in relation to middle ear effusions.

Tympanometric evaluation using an otoadmittance meter and X-Y plotter was performed on 129 ears of 70 children with history of recurrent acute otitis media, or evidence otoscopically of persistent middle ear effusion, or both. Myringotomy, performed immediately following the tympanometric procedure, confirmed the presence or absence of effusion. Following myringotomy, tympanometric patterns, as shown by susceptance and conductance tracings at 220 and 660 Hz, were identified and middle ear pressures and otoadmittance peak values were determined. These findings were compared and criteria were developed which best determined the presence or absence of effusion. The results revealed the following: 1) High negative middle ear pressure is not necessarily a reliable indicator of middle ear effusion. 2) Tympanometry can be used reliably as an indicator of effusion. A combination of pattern classification and susceptance criteria enabled correct prediction of effusion in 93% of these children. One pattern at B660 was found to be pathognomonic of effusion. 3) In general, otoadmittance at 660 Hz appears to be a better indicator of effusion than 220 Hz.