HRCT Imaging to Determine the Frequency of Anatomic Variations in Temporal Bone

Abstract

Introduction: Surgical treatment is the main stay of treatment for various chronic ear pathologies. An ENT surgeon needs to have a precise knowledge of anatomy prior to surgery as each individual can have a varied anatomy and drastic complications like injury to nerve or vessel can be avoided or incomplete evacuation leading to recurrence of disease can be prevented Material and methods: Data was obtained retrospectively from 340 temporal bone high resolution computed tomography (HRCT) of 170 patients referred to Department of Radio diagnosis, Father Muller Medical College and Hospital for HRCT temporal bone scan. Anatomic variants such as facial nerve dehiscence (FND), dural exposure (DE), high jugular bulb (HJB), bulging / anteriorly placed sigmoid sinus, Koerner s septum (KS), aberrant internal carotid artery (AICA)was looked for and documented and frequency of each was estimated. Results: 340 temporal bones of 170 patients were recruited in the study. HJB was encountered in 80 ears (23%) and it was bilateral in 10 (5%) patients. KS was seen in 90 ears (26%)patients. Anteriorly placed sigmoid sinus in 125 ears (36%), low hanging dura in 10 ears (2.9%), aberrant internal carotid artery in 2 ears (0.5%) of total 350 ears. FND was detected in 45 ears (13%), 35 of them with cholesteatoma and 10 of them without cholesteatoma. Conclusion: Radiologist must be well aware of important anatomical variants such as aberrant internal carotid artery, facial nerve dehiscence, low hanging dura, high jugular bulb, anterior placed sigmoid sinus and it’s recognition and reporting prior to surgery is imperative. It decreases the possibility of surgical complications as well as surgical revision for recurrence. A preoperative warning about anatomical variant can help the surgeon to decide the best surgical approach.