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

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.