Mingkwansook V, Curtin H D, Kelly H R
From the Radiology Department (V.M.), Thammasat University Hospital, Pathumthani, Thailand Department of Radiology (V.M., H.D.C., H.R.K.), Massachusetts Eye and Ear Infirmary/Harvard Medical School, Boston, Massachusetts.
Department of Radiology (V.M., H.D.C., H.R.K.), Massachusetts Eye and Ear Infirmary/Harvard Medical School, Boston, Massachusetts.
AJNR Am J Neuroradiol. 2015 May;36(5):982-6. doi: 10.3174/ajnr.A4226. Epub 2015 Jan 29.
Middle ear surgery is often performed through the external auditory canal, and the CT appearance of the external auditory canal after transcanal middle ear surgery can mimic erosive pathology such as carcinoma, external auditory canal cholesteatoma, or necrotizing external otitis. We reviewed the CT findings in a group of patients following transcanal surgery to highlight this potential pitfall in interpretation.
Twenty-seven temporal bones in 25 patients with a history of a transcanal approach to the middle ear and available postoperative CT imaging were identified. Images were assessed for changes along or involving the walls of the external auditory canal, including widening, irregularity, bony defects, and soft tissue opacification.
Osseous changes along the floor of the external auditory canal were demonstrated in 25 of 27 (92.6%) temporal bone CT scans. Similar changes were present in the superior and anterior walls of the external auditory canal in 21 and 18 temporal bones, respectively. The anterior wall was the most common site for complete bony defects (10 of 27 temporal bones). The posterior wall was the least often involved, with osseous changes in 15 of 27 temporal bones and bony defects in 3 cases. Soft tissue thickening was seen most commonly along the floor. No patient was found to have a superimposed pathologic process of the external auditory canal.
CT findings in the external auditory canal after transcanal surgery include thinning, irregularity and/or flattening of the bone, soft tissue thickening, and bony wall defects. Although these changes may be subtle, they may mimic pathology and should be included in the differential diagnosis of osseous abnormality of the external auditory canal.
中耳手术常通过外耳道进行，经耳道中耳手术后外耳道的CT表现可模仿侵蚀性病变，如癌、外耳道胆脂瘤或坏死性外耳道炎。我们回顾了一组经耳道手术后患者的CT表现，以强调这种潜在的解读陷阱。
确定了25例有经耳道入路中耳手术史且有术后CT影像资料的患者的27块颞骨。评估图像中外耳道壁沿线或累及外耳道壁的变化，包括增宽、不规则、骨质缺损和软组织混浊。
27例颞骨CT扫描中有25例（92.6%）显示外耳道底部有骨质改变。分别有21块和18块颞骨的外耳道上壁和前壁出现类似改变。前壁是完全骨质缺损最常见的部位（27块颞骨中有10块）。后壁受累最少，27块颞骨中有15块有骨质改变，3例有骨质缺损。软组织增厚最常见于底部。未发现患者有外耳道叠加的病理过程。
经耳道手术后外耳道的CT表现包括骨质变薄、不规则和/或变平、软组织增厚和骨壁缺损。尽管这些改变可能很细微，但它们可能模仿病变，应纳入外耳道骨质异常的鉴别诊断中。
