Classification of Temporal Bone Pneumatization on High-Resolution Computed Tomography: Prevalence Patterns and Implications.

Objective The degree of pneumatization of the temporal bone has implications in the pathophysiology and surgical considerations of many temporal bone disorders. This study aims to identify common pneumatization patterns in the petrous apex, mastoid, and infralabyrinthine compartments of the temporal bone. Variables associated with temporal bone pneumatization were also identified. Study Design Case series with chart review. Setting Single tertiary hospital. Subjects and Methods In total, 299 high-resolution computed tomography scans of the temporal bone performed on patients between 2013 and 2016 were reviewed. Only normal temporal bone scans in patients aged 13 years and older were included. Previously published grading systems were used to classify pneumatization patterns in the petrous apex, mastoid, and infralabyrinthine region. Results The most common pneumatization pattern in the petrous apex was group 2 (less than half of the petrous apex medial to the labyrinth is pneumatized), that in the mastoid was group 4 (hyperpneumatization), and that in the infralabyrinthine region was type B (limited pneumatization), at 54.8%, 55.4%, and 76.0% of patients, respectively. Patients with increased pneumatization of 1 temporal bone compartment tended to have increased pneumatization of the same compartment on the contralateral side and the other compartments on the ipsilateral side ( P < .05). Younger age ( P < .001) and male sex ( P = .001) were associated with increased pneumatization in the petrous apex and infralabyrinthine compartments. Conclusion The degree of temporal bone pneumatization varies among the different compartments. Age and sex have a significant association with the degree of pneumatization of the petrous apex and infralabyrinthine compartment.