The Possible Relationship Between Sigmoid Dehiscence, Degree of Mastoid Pneumatization, and Sigmoid Sinus Position in...

Objective: This study aimed to determine the relationship between sigmoid sinus dehiscence (SSD), sigmoid sinus topography, mastoid pneumatization, and adjacent temporal bone structures in patients with pulsatile tinnitus (PT). Methods: A retrospective analysis was performed on 344 temporal bone cone-beam computed tomography (CBCT) scans (172 PT patients and 172 age- and sex-matched controls). The degree of mastoid pneumatization, presence and size of SSD, sinus topography, and distances between the sigmoid sinus and key landmarks-the lateral semicircular canal (LSCC), jugular bulb (HJB), and external auditory canal (EAC)-were measured. Quantitative and qualitative characteristics were compared between groups, and independent predictors of PT were identified using multivariate logistic regression. Results: Compared to controls, SSD was substantially more common in the PT group (115/172 vs. 44/172, p < 0.001). Patients with PT had significantly larger anteroposterior and vertical sigmoid sinus dehiscence diameters (4.61 ± 0.99 mm vs. 3.87 ± 0.25 mm and 3.37 ± 0.47 mm vs. 2.92 ± 0.14 mm, respectively; both p < 0.01). Additionally, in the PT group, the sigmoid sinus was situated closer to the lateral semicircular canal, jugular bulb (JB), and external auditory canal (all p < 0.01). Conclusions: Venous pulsatile tinnitus was substantially correlated with sigmoid sinus dehiscence, sinus topography, and decreased sinus-EAC distance. Quantitative CBCT evaluation of these anatomical relationships could help with surgical planning and enhance diagnostic evaluation.