Sensorineural hearing loss and otosclerosis: A clinical and radiologic survey of 437 cases

The aim of this study was to determine if a relationship exists between bon e level thresholds and the extension of otosclerotic foci within the otic c apsule. The study consisted of a retrospective case review in a university hospital. We included patients who underwent surgery for otosclerosis in ou r department and who had a CT scan prior to surgery. We analyzed the data c harts and CT scans of 437 cases (386 patients). On CT scan, we distinguishe d patients with fenestral otosclerosis and-or with a pericochlear focus. A pericochlear focus could be extended (Group 2) or not (Group 1) to the coch lear endosteum. Data for Groups 1 and 2 were compared with those for the co ntrol group of all patients for whom CT scan showed no cochlear focus (Grou p 3). Of the 437 CT scans. 399 were positive (91.3%). An anterior focus was reported in 305 cases (69.8%), a footplate thickening in 21 cars (4.8%) an d both anomalies were encountered in 60 cases (13.7%). A pericochlear focus was reported in 53 examinations. This focus was extended to the endosteum in 14 cases (26.4% of the pericochlear foci). In Group 1, preoperative air conduction (AC) thresholds were significantly lower than in the control gro up (p < 0.05). The air-bone gap was also significantly larger in Group 1 (p < 0.05). Bone conduction (BC) thresholds were lower in Group 1 than in the control group but the difference was not significant. In Group 2, preopera tive AC thresholds were significantly lower than in the control group (p < 0.05). BC thresholds were also lower in Group 2 than in the control group a nd the difference was significant (p < 0.05). As a result of this study, we assume that there may be a relationship between bone level thresholds and the radiological extension of otosclerosis within the otic capsule.