Preoperative bone-conducted electrocochleography in otosclerosis.

Prior to surgery, pure-tone audiometry and bone-conducted (BC) electrocochleography (ECOG) were performed on 17 patients with preoperatively diagnosed otosclerosis. Short tone bursts, approximately 5 ms in duration and presented by means of a bone conductor on the exposed surface of the mastoid, were used as stimuli in BC ECOG. The thresholds thus obtained were compared by regression analysis with conventional psychoacoustic thresholds. Thresholds recorded at BC ECOG showed a close correlation to preoperative pure-tone BC thresholds, and there was no difference in predictability of postoperative hearing thresholds between preoperative BC ECOG and conventional preoperative pure-tone BC thresholds. The results lend support to the conclusion that BC ECOG, offering a monaural, objective estimation of cochlear function, is a valuable complement to conventional audiometry in the preoperative evaluation of hearing in otosclerosis.