Migirov Lela, Kronenberg Jona
Department of Otolaryngology and Head and Neck Surgery, Sheba Medical Center, Tel Hashomer, Israel.
Otol Neurotol. 2006 Apr;27(3):410-3. doi: 10.1097/00129492-200604000-00019.
The petromastoid canal is a thin structure that connects the mastoid antrum with the posterior cranial fossa and houses subarcuate blood vessels and prolongation of the dura. The current retrospective study was designed to investigate radiology of the petromastoid canal in different age groups and to determine whether increasing the scanner's resolution could enhance the detection capability of this structure.
Axial sections of 504 high-resolution computed tomographic images obtained with 0.6-, 1.1-, or 1.3-mm-thick slices through the petrous bones were reviewed. Sixteen asymmetric images were excluded from the statistical analysis. Type I petromastoid canal was invisible; Type II and Type III appeared as thin channels less than 0.5 and 0.5 to 1 mm in width, respectively, and Type IV was greater than 1 mm wide.
The petromastoid canal Type II was detected more frequently in patients older than 5 years (p<0.0001) and Type IV was demonstrated more often in children up to age 5 years (p<0.0001). The occurrence of a Type I petromastoid canal was not dependent on the age of the patients or the resolution of the images (p=0.82). Increasing the resolution failed to improve the visibility of the petromastoid canal or the ability to detect it. A wide petromastoid canal (>2 mm) was significantly more common in younger patients (22.2% versus 2.4% in the older group) (p<0.0001). A petromastoid canal beginning medially directly from the internal auditory canal was detected in 4 of 488 (0.8%) images. The lateral opening of the petromastoid canal can be found posteriorly to the medial orifice, anteriorly to it, or at the same level. The posterior lateral opening was demonstrated to be more common than the other two types in patients younger than 5 years, and the anterior opening was detected more frequently in older patients (p=0.0006).
The shape and width of the petromastoid canal differ radiologically between populations younger and older than 5 years of age. The findings of the current study may be important for otolaryngologists engaged in cochlear implantation or involved in treating otogenic intracranial complications, especially in young children.
岩乳管是一种连接乳突窦与后颅窝的薄结构，容纳弓下血管和硬脑膜的延续部分。本回顾性研究旨在调查不同年龄组岩乳管的影像学表现，并确定提高扫描仪分辨率是否能增强对该结构的检测能力。
回顾了504例通过颞骨获取的0.6毫米、1.1毫米或1.3毫米厚切片的高分辨率计算机断层扫描图像的轴位图像。16张不对称图像被排除在统计分析之外。I型岩乳管不可见；II型和III型分别表现为宽度小于0.5毫米和0.5至1毫米的细通道，IV型宽度大于1毫米。
II型岩乳管在5岁以上患者中更常被检测到（p<0.0001），IV型在5岁以下儿童中更常出现（p<0.0001）。I型岩乳管的出现不依赖于患者年龄或图像分辨率（p=0.82）。提高分辨率未能改善岩乳管的可见性或检测能力。宽岩乳管（>2毫米）在年轻患者中明显更常见（22.2%对老年组的2.4%）（p<0.0001）。在488张图像中的4张（0.8%）中检测到岩乳管直接从内耳道内侧起始。岩乳管的外侧开口可在内侧开口的后方、前方或同一水平找到。后外侧开口在5岁以下患者中比其他两种类型更常见，前开口在老年患者中更常被检测到（p=0.0006）。
5岁以上和5岁以下人群的岩乳管在影像学上的形状和宽度有所不同。本研究结果对于从事人工耳蜗植入或治疗耳源性颅内并发症的耳鼻喉科医生可能具有重要意义，尤其是在幼儿中。
