[Acoustic variation after surgery for severe Bell's palsy].

Auditory thresholds were studied before and after surgical decompression of the facial nerve in 35 patients following either transmastoidal (20 cases) or transmastoidal and suprapetrosal (15 cases) operations. Seventeen of the patients were under 40 years of age at the time of surgery, which did not affect hearing in the opposite ear. However, auditory threshold levels fell in the operated ear. These were of the bone conduction type, and possessed characteristics of an acute hearing lesion (maximal in the 4000 frequency range and improving progressively) of 0 to 35 dB (mean 5 dB). Possible causes of the hearing loss are discussed.