Türe U, Yaşargil M G, Al-Mefty O
Department of Neurosurgery, University of Arkansas for Medical Sciences, Little Rock 72205, USA.
J Neurosurg. 1997 Nov;87(5):706-15. doi: 10.3171/jns.1997.87.5.0706.
Surgical approaches to lesions located in the anterior and middle portions of the third ventricle are challenging, even for experienced neurosurgeons. Various exposures involving the foramen of Monro, the choroidal fissure, the fornices, and the lamina terminalis have been advocated in numerous publications. The authors conducted a microsurgical anatomical study in 20 cadaveric brain specimens (40 hemispheres) to identify an exposure of the third ventricle that would avoid compromising vital structures. An investigation of the variations in the subependymal veins of the lateral ventricle in the region of the foramen of Monro was performed, as these structures are intimately associated with the surgical exposure of the third ventricle. In 16 (80%) of the brain specimens studied, 19 (47.5%) of the hemispheres displayed a posterior location of the anterior septal vein-internal cerebral vein (ASV-ICV) junction, 3 to 13 mm (average 6 mm) beyond the foramen of Monro within the velum interpositum, not adjacent to the posterior margin of the foramen of Monro (the classic description). Based on this finding, the authors advocate opening the choroidal fissure as far as the ASV-ICV junction to enlarge the foramen of Monro posteriorly. This technique achieves adequate access to the anterior and middle portions of the third ventricle without causing injury to vital neural or vascular structures. The high incidence of posteriorly located ASV-ICV junctions is a significant factor influencing the successful course of surgery. Precise planning of the surgical approach is possible, because the location of the junction is revealed on preoperative neuroradiological studies, in particular on magnetic resonance venography. It can therefore be determined in advance which foramen of Monro qualifies for posterior enlargement to gain the widest possible access to the third ventricle. This technique was applied in three patients with a third ventricular tumor, and knowledge of the venous variations in this region was an important resource in guiding the operative exposure.
即使对于经验丰富的神经外科医生而言，处理位于第三脑室前部和中部的病变的手术入路也颇具挑战性。众多出版物中都提倡采用涉及室间孔、脉络膜裂、穹窿和终板的各种暴露方法。作者对20个尸体脑标本（40个半球）进行了显微外科解剖学研究，以确定一种能避免损伤重要结构的第三脑室暴露方法。对室间孔区域侧脑室室管膜下静脉的变异情况进行了研究，因为这些结构与第三脑室的手术暴露密切相关。在所研究的16个（80%）脑标本中，19个（47.5%）半球的前隔静脉-大脑内静脉（ASV-ICV）交界处位于后方，在中间帆内距室间孔3至13毫米（平均6毫米）处，不与室间孔后缘相邻（经典描述）。基于这一发现，作者主张打开脉络膜裂直至ASV-ICV交界处，以向后扩大室间孔。该技术可在不损伤重要神经或血管结构的情况下，充分暴露第三脑室的前部和中部。ASV-ICV交界处位于后方的高发生率是影响手术成功进程的一个重要因素。由于术前神经影像学检查，尤其是磁共振静脉成像可显示交界处的位置，因此可以精确规划手术入路。因此，可以预先确定哪个室间孔适合向后扩大，以获得尽可能广泛的第三脑室暴露。该技术应用于3例第三脑室肿瘤患者，了解该区域的静脉变异情况是指导手术暴露的重要依据。
