Departments of Neurosurgery, Unive-rsity of Cincinnati College of Medicine, Cincinnati, Ohio.
Brain Tumor Center at University of Cincinnati Neuroscience Institute, Cincinnati, Ohio.
Oper Neurosurg (Hagerstown). 2018 Mar 1;14(3):295-302. doi: 10.1093/ons/opx093.
Various approaches can be considered for decompression of the intracanalicular optic nerve. Although clinical experience has been reported, no quantitative study has yet compared the extent of decompression achieved by an endoscopic endonasal versus transcranial approach.
Toward this aim, our morphometric analysis compared both approaches by quantifying the circumferential degree of optic canal decompression that is possible before any meningeal violation, which would result in cerebrospinal fluid (CSF) leak.
From 10 cadaver heads, 20 optic canals were sequentially decompressed using an endoscopic endonasal approach and pterional craniotomy with extradural clinoidectomy. Dissections ended before violation of the sphenoid sinus during the transcranial approach, and before intracranial transgression from the endonasal corridor. Based on our study criteria, decompressions were not maximal for either approach, but were maximal before violating the other compartment. Decompression achieved from each approach was quantified using CT scans for each stage.
Greater circumferential bony optic canal decompression was obtained from transcranial (245.2°) than endonasal (114.8°) routes (P < .001). By endonasal perspective, the anatomical point where the optic nerve traverses intracranially was approximated by the medial border of the anterior ascending cavernous internal carotid artery.
Our morphometric analysis comparing optic canal decompression for endonasal and transcranial corridors provides important guidance for this location. Ample visualization and wide exposure can be achieved via a transcranial approach with limited risk of CSF leak. A landmark, where the intracanalicular segment ends and optic nerve traverses intracranially, can mark the extent of decompression safely obtained before risking CSF leak.
可以考虑各种方法来对眶内段视神经进行减压。虽然已有临床经验报道，但尚无研究定量比较经鼻内镜和经颅两种入路达到的减压程度。
为此，我们通过定量分析视神经管的环周减压程度来比较这两种方法，该减压程度在发生脑膜侵犯（导致脑脊液漏）之前是可行的。
从 10 具尸体头颅中，我们依次使用经鼻内镜入路和翼点开颅术伴外侧蝶骨嵴切除术对 20 条视神经管进行减压。在经颅入路中，当蝶窦被侵犯时，或在经鼻入路中当颅内被侵犯时，解剖结束。根据我们的研究标准，两种方法都不是最大程度的减压，但在侵犯其他间隙之前是最大程度的减压。使用 CT 扫描对每个阶段的两种方法的减压程度进行量化。
经颅入路（245.2°）比经鼻入路（114.8°）获得的眶内段视神经管的环周骨性减压更大（P <.001）。从经鼻的角度来看，视神经在颅内穿行的解剖点由颈内动脉前升段的内侧壁来近似表示。
我们对经鼻内镜和经颅入路视神经管减压的形态计量学分析为该部位提供了重要的指导。经颅入路可以充分显露和广泛暴露，且发生脑脊液漏的风险有限。一个标志，即眶内段结束和视神经在颅内穿行的部位，可以在冒着发生脑脊液漏的风险之前安全地确定减压的程度。
