Abstract
Thirty-three patients (62 ears) with surgically confirmed otosclerosis underwent a preoperative CT examination in order to determine the presence of any correlation between the audiometric and CT findings. Based on the CT findings, the ears were classified into five groups as follows: group A: 25 ears (40.3%) with normal CT findings, group B1: 15 ears (24.2%) with demineralization in the region of the fissula antefenestram, group B2: 12 ears (19.4%) with demineralization around the anterior to the oval window, group B3: 4 ears (6.5%) with demineralization surrounding the cochlea, and group C: 6 ears (9.7%) with thick anterior and posterior plaques. The expansion of demineralization led to an increase in average bone conduction hearing level: group A; 27.1 dB, group Bl: 30.6 dB, group B2: 34.6 dB, group B3: 36.7 dB, group C 30.3 dB. This increase is most likely due to progressive labyrinthine otosclerosis. Group C in the average airbone gap was greater (37.5 dB) than that in the patients with demineralization, group B1 (21.6 dB), group B2 (28.2 dB), group B3 (26.7 dB), the Carhart effect of group C was smaller than that of any other groups, thus suggesting the mode of otosclerosis progression in group C to be different from that in patients with demineralization. The results of the present study indicate that the preoperative CT findings of otosclerosis correlate with the audiometry findings, thus proving the usefulness of CT in diagnosing otosclerosis.
