Our studies will systematically investigate and establish evidence on whether Cone-beam computed tomography (CBCT) of the temporal bone could be used in the diagnosis and treatment of otosclerosis and in the post-operative follow-up after stapedotomy.

Cone-beam CT has a high resolution and a low effective radiation dose to the patient when compared to conventional CT-scans. Surgical treatment of otosclerosis is primarily by stapedotomy. The decision of surgical treatment is currently based on the history, clinical examination, and audiological tests, but stapes fixation can only be confirmed per-operatively.

This protocol includes the following overall aims for the following studies:

• To establish the diagnostic precision of clinical CBCT in diagnosing otoslcerosis, i.e., the sensibility and specificity for our scanning protocols (n=50).
• To determine if CBCT can support the clinicians' decision making in the diagnosis of otosclerosis (n=100).
• To assess the value of CBCT in the planning of stapes surgery. Two groups will be established: CBCT-based pre-operative planning (e.g., prothesis parameters and anatomic landmarks) and no-planning (standard treatment). Patients will be allocated by 1:1 randomization (n=75).
• To assess the value of CBCT in the post-operative follow-up of 2-3 weeks, 2-3 months, and 12 months. Follow-up includes a clinical examination, audiometry, CBCT (block-randomized), and patient questionnaires (audiometry and patient questionnaire not at the "2-3 weeks" control) (n=75).
• To assess the value of pre-preoperative CBCT on post-surgical result at follow up (2-3 weeks, 2-3, months and 12-months) (n=75).

Inclusion Criteria:

• Adults (>18 years of age).
• Referred to our department suspected for otosclerosis.
• Consents to participation in the project.

Exclusion Criteria:

• A history of surgical treatment for otosclerosis (ipsilateral ear).
• A history of tympanoplasty type 2-4 (ipsilateral ear).
• Other competing middle-ear diseases (ipsilateral ear).

Inclusion and exclusion criteria for patients enrolled for post-surgical follow-up are the same as above in addition to:

Exclusion:

- Intraoperative findings not supporting otosclerosis.