Objective: To assess the depths of the anterior epitympanic recess (AER) and the sinus tympani (ST) among Filipino adults and to classify the AER and ST according to grade and type, respectively. Methods: Design:Retrospective Review of CT ScansSetting:Tertiary Private Teaching Hospital Participants: Scans of 182 non-pathologic ears from patients aged 18 and above with non-pathologic temporal bones (paranasal sinus, screening sinus, temporal bone, facial and cranial) with 0.62mm cuts seen from CT scans from January 01, 2010 to September 31, 2022 were analyzed. The depths of the AER and ST were measured separately and classified according to AER grade and ST type. Results: The mean depth of the AER (AER-D) was 3.64 mm (SD 1.17). No significant difference was seen between right and left ears. The AER grading of the anterior-posterior depth was found to be Grade 1 (<3mm) in 54 ears (29.7%), Grade 2 (3-5mm) in 106 ears (58.2%), and Grade 3 (>5mm) in 22 ears (12.1%). The mean depth of the sinus tympani (ST-D) was 3.30 mm (SD 0.80). Out of the 182 ears, 121 (66.5%) had Type A, 50 (27.5%) had Type B while 11 (6%) had Type C. Conclusion Majority of the AER depths measured 3-5mm while most of the sinus tympani were Type A. These hidden recesses should be separately analyzed in preoperative planning for cholesteatoma surgery in order to prepare the adequate equipment to be used and approach towards these areas thereby reducing the risk for residual cholesteatomas and recurrence.
Tomography ; Temporal Bone