PB tests in severe loss stapedectomy candidates. Discrimination scores at levels above the maximum audiometer output as a prognostic aid in preoperative study of stapedectomy candidates with severe hearing loss.

Abstract

IN THE PAST, the otologist has relied heavily on the use of the pure tone air-bone gap in evaluating the benefit to be expected from surgical treatment of otosclerosis. For the fenestration procedure, the Carhart-Shambaugh 1 formula predicted the postoperative level with a high degree of accuracy. Guilford and Haugh 2 applied the same formula successfully in the early stapes mobilization procedures. In 1960, Kos, Shapley, and Iles 3 used both pure tone and speech audiometry to describe the results of 939 stapes mobilization operations. They found that stapes mobilization did not substantially affect the speech discrimination scores following the majority of operations. Of the patients who had originally successful operations, 84% to 85% still had discrimination scores within plus or minus 10% of their preoperative scores. Up to this time, the selection of cases for surgery was largely limited to A and B type candidates (according to the classification