Singh Anup, Irugu David Victor Kumar, Sikka Kapil, Verma Hitesh, Thakar Alok
Department of Otorhinolaryngology and Head & Neck Surgery, All India Institute of Medical Sciences, New Delhi, Delhi, India.
Int Arch Otorhinolaryngol. 2019 Jul;23(3):e311-e316. doi: 10.1055/s-0039-1688455. Epub 2019 May 28.
Sigmoid sinus (SS) variations have been classified variously in the literature. These classifications suffer from some form of shortcoming from a clinical point of view for their application. We propose a clinically relevant classification of the SS in relation to the posterior semicircular canal (PSCC) and to the exposure of the presigmoid dural plate. The positioning of the SS was analyzed with reference to the volume of the mastoid and to the level of mastoid pneumatization. A total of 94 formalin-preserved human cadaveric temporal bones were microdissected to carry out a complete mastoidectomy. The SS, the presigmoid dural plate, and the PSCC were exposed, and the position of the former was analyzed in relation to the latter two in order to classify the position of the SS into three grades. Grade I had the best exposure of the presigmoid dura and of the PSCC, while grade III had the poorest exposure of the presigmoid dura and of the PSCC. Grade I SS was associated with good pneumatization and higher mastoid volumes compared with grades II and III. The SS exhibits considerable anatomic variability. A favorable positioning of the SS is associated with a large mastoid volume and pneumatization. A careful preoperative study of the imaging may help in understanding the positioning of the SS and the safety of various transmastoid approaches.
乙状窦（SS）变异在文献中有多种分类。从临床应用角度来看，这些分类都存在某种形式的缺陷。
我们提出一种与后半规管（PSCC）及乙状窦前硬脑膜板暴露相关的、具有临床相关性的乙状窦分类方法。参照乳突体积及乳突气化程度对乙状窦的位置进行分析。
共对94块用福尔马林保存的人类尸体颞骨进行显微解剖以完成全乳突切除术。暴露乙状窦、乙状窦前硬脑膜板和后半规管，并分析前者相对于后两者的位置，以便将乙状窦的位置分为三个等级。
I级对乙状窦前硬脑膜和后半规管的暴露最佳，而III级对乙状窦前硬脑膜和后半规管的暴露最差。与II级和III级相比，I级乙状窦与良好的气化及更大的乳突体积相关。
乙状窦表现出相当大的解剖变异。乙状窦的有利位置与较大的乳突体积和气化相关。术前仔细研究影像学检查可能有助于了解乙状窦的位置及各种经乳突入路的安全性。
