Evaluation of Temporal Bone Anatomical Variations Using High-Resolution Computed Tomography: A Cross-Sectional Observational Study

Abstract

Background: High-resolution computed tomography (HRCT) is the imaging modality of choice for evaluating temporal bone anatomy because of its excellent spatial resolution and ability to delineate intricate osseous structures. Recognition of anatomical variants before otologic surgery is crucial to avoid potentially serious intraoperative complications involving the facial nerve, jugular bulb, dura, sigmoid sinus, and internal carotid artery. Knowledge of these variants facilitates accurate diagnosis, appropriate surgical planning, and improved patient safety.

Objectives: To evaluate the prevalence and spectrum of anatomical variations of the temporal bone using high-resolution computed tomography and to determine their distribution in patients undergoing HRCT temporal bone examination.

Materials and Methods: A prospective cross-sectional observational study was conducted in the Department of Radiodiagnosis, Vinayaka Mission's Kirupananda Variyar Medical College and Hospitals (VMKV MCH), Salem, Tamil Nadu, India, over a period of 18 months. A total of 155 consecutive patients referred for HRCT temporal bone examination were included. HRCT imaging was performed using a 16-slice multidetector CT scanner after obtaining informed consent. Ten temporal bones demonstrating extensive pathology causing distortion of normal anatomy were excluded. Consequently, 300 temporal bones were analyzed for the presence of anatomical variants including high-riding jugular bulb, facial nerve dehiscence, Korner's septum, dural exposure, aberrant internal carotid artery, and other anatomical variations.

Results: Among 155 patients, the majority belonged to the 21–40-year age group (54.19%), followed by 41–60 years (23.22%), 0–20 years (19.35%), and >60 years (3.22%). There were 91 males (58.7%) and 64 females (41.3%). Anatomical variants were observed in 155 temporal bones, while 145 (48.3%) demonstrated normal anatomy. The most common anatomical variant was high-riding jugular bulb, identified in 67 temporal bones (22.3%), followed by Korner's septum in 33 (11.0%), facial nerve dehiscence in 28 (9.3%), dural exposure in 9 (3.0%), aberrant internal carotid artery in 1 (0.3%), and other anatomical variants in 17 temporal bones (5.6%). Anatomical variants were slightly more frequent on the left side (52.2%) than on the right side (47.7%).

Conclusion: HRCT provides comprehensive evaluation of temporal bone anatomical variations and remains indispensable for preoperative assessment. High-riding jugular bulb was the most frequent anatomical variant encountered, whereas aberrant internal carotid artery was extremely rare. Routine identification and reporting of these anatomical variants can significantly reduce operative morbidity, facilitate surgical planning, and improve outcomes in otologic and skull-base procedures.