Effects of Acute Negative Middle Ear Pressure on Hearing: New Answers to Old Questions and a Review of the Literature

Abstract

The magnitude of hearing loss caused by negative middle ear pressure is a controversial issue. We present a clinical, prospective and controlled study on the effect of negative middle ear pressure on hearing in human ears. Sixty-two ears of patients undergoing uvulopalatopharyngo-plasty were examined pre- and postoperatively. The test group consisted of 31 ears in which negative postoperative middle ear pressure ranging between -150 and -400 mmH₂O had developed. The control group consisted of 31 ears in which no middle ear pressure change was recorded after the same operation. Bone conduction hearing loss up to 20 dB (with a mean of 11 dB) at 250 Hz, up to 25 dB (with a mean of 13.1 dB) at 500 Hz and up to 10 db (with a mean of 7.6) at 1000 Hz was the dominant finding. An additional air-bone gap up to 15 dB (with a mean of 4.3 dB) was found only at 250 Hz. Basic theories about the acoustic response of the ear are discussed and new theories proposed.

Key Words:

• hearing loss
• uvulopalatopharyngoplasty