The Role of Temporal Bone Pneumatization on Fracture Line and Involved Cranial Structures

Objective: Temporal bone pneumatization (TBP) is speculated to serve as a shock absorber in temporal bone fractures (TBF), directing the fracture line away from vital structures. This study correlates TBP extent with TBF patterns and preservations of vital TB structures. Study Design: Retrospective cohort study. Setting: Tertiary referral medical center. Methods: All TBF patients referred to a single tertiary center 2017 to 2023 were evaluated. A pneumatization index score for each of their TBs was derived by counting automated-voxel density in a 0 to 100 scale. Results were correlated to the TBF type and the violated structure(s). The ossification index was compared to previously detailed qualitative classification systems of TBP. Results: One hundred and forty-five patients were enrolled (mean age 43 ± 17 years). Kinematics were motor vehicle accidents (46%), scooter (15%), bicycle (14%), falls (13%), and assaults (8%). The mastoid ossification index we used showed a strong correlation to all qualitative classification systems (sigmoid = 0.829; labyrinthine = 0.849; carotis = 0.863, infralabyrinthine = 0.869, all P <.001). The pneumatization index strongly correlated with capsule-violating TBFs, with a mean of 44 ± 23 for otic capsule-sparing TBF and 61 ± 20 for otic capsule-violating (OCV) TBF (P <.001). The facial nerve was violated in 30 patients. Facial canal (FC) involvement was not correlated to the ossification index: it was 49 ± 23 for FC-sparing and 44 ± 23 for FC-violating (P =.620). Conclusion: TBP serves as a protective mechanism against OCV TBF. The more pneumatized the TB, the less likely the otic capsule will be violated in the event of a TBF with the exception of the carotid and FCs. TBP index is in strong agreement with qualitative TBP classification systems.