The relationship in otosclerotic patients between densitometry measurements,stapes angle and aacial nerve stapes dristance in high resolution computed tomography

Objective: Otosclerosis is the main cause of hearing loss in the adulthood affecting otic capsule. The diagnosis of otosclerosis is made based on patient's medical history, physical examination, audiometry and computerized tomography(CT). Improvements in technology increase the role of CT in the diagnosis of otosclerosis. However, some patients with otosclerosis do not have a clear visible pathology on CT. Despite there are no sclerosis or lysis in some cases, the presence of additional findings is gaining importance in diagnosis of otosclerosis. Recent studies have shown that bone densitometry and audiometry findings are well correlated. There are also studies to show that differences in stapes angle may be a new radiological sign for otosclerosis. In this study, we aimed to compare the relationship between stapes angle, facial nerve stapes head distance and densitometry in patients with otosclerosis and the normal population without otosclerosis with High Resolution Computed Tomography (HRCT). Material-Method: In this retrospective study temporal bone CT imagings of patients were taken between November 2016 and January 2018 reevaluated in workstation. In patients with otosclerosis and without otosclerosis the relationship between densitometry measurements around the otic capsule, stapes angle and facial nerve stapes distance were assessed and the contribution of this relationship to the diagnosis of otosclerosis was investigated. Results: The patient group was found to have lower dencity measured in the posterolateral to the middle turn of the cochlea than the control group. No statistically significant difference was found between the patient and control group in terms of other densitometry measurements. Stapes angle average was 77.72ᵒ±7.23ᵒ in the control group and 73.65ᵒ±6.38 in the patient group. The patient group had a lower average than the control group. Similarly, facial nerve stapes head distance was found to be shorter in patients than in the control group. Conclusion: In patients with otosclerosis, the decrease in the densitometry measurements at the Posterolateral of the Cohlea Middle Turn showed a decrease in the Facial Nerve Stapes Distance and a narrowing of the Stapes angle. In otosclerotic patients, these two parameters corelate with density measurements and can be used in diagnosis of otosclerosis. However, we think that the margin of error is very large because of the small size of the study area in evaluating the stapes angle measurements. For this reason, accurate determination of the reference points is important. Key words: Otosclerosis, Stapes angle, Densitometry, Facial nerve.