Anatomical and Clinical Evaluation of Tympanic Tegmen and Mastoid Bone with Multidetector Computed Tomography

Tegmen level and mastoid bone thickness are important parameters of surgical risk in middle ear and mastoid region surgeries. This retrospective cohort study was conducted to provide a risk classification for the mastoid and middle ear regions. The study population comprised of 300 patients who underwent multidetector computed tomography (MDCT) for various indications. Patients with no pathology that disrupted the structure of the temporal region were included in the study. A risk classification was generated by analyzing the data obtained from mastoid and tympanic tegmen depths and the mastoid bone thickness by MDCT. The mastoid and tympanic tegmen were lower on the right side than on the left. In women, the right-sided mastoid bone thickness and mastoid tegmen were lower, and low-level tympanic and mastoid tegmen on the left and thin right mastoid bones were more common. According to the risk classifications for mastoid and middle ear region surgeries, women demonstrated a higher risk than men. In addition, as the thickness of the mastoid bone increased, the levels of the mastoid and tympanic tegmen increased. The present study provides a proper risk classification that may be helpful for preoperative risk assessment prior to middle ear and mastoid region surgery.