Reversible and permanent bone conduction threshold shift in cases of chronic suppurative otitis media.

Bone conduction thresholds were measured in sixty-six cases of chronic suppurative otitis media before and after successful oral antimicrobial chemotherapeutic treatment. Comparison of pre- and post-treatment cumulative clinical audiograms of the diseased and the control ears of the same patients disclosed the presence of sensorineural hearing loss with a reversible and a permanent component in the diseased ears. The reversible threshold shift was observed over the higher frequencies, while the permanent threshold shift was equally imposed upon the whole range of the five tested frequencies.