Zador Zsolt, Coope David J, Kamaly-Asl Ian D
Department of Pediatric Neurosurgery, Royal Manchester Children's Hospital, Manchester;
Department of Neurosurgery, Greater Manchester Neuroscience Centre, Salford Royal NHS Foundation Trust, Salford, United Kingdom.
J Neurosurg Pediatr. 2015 Dec;16(6):626-32. doi: 10.3171/2015.4.PEDS14430. Epub 2015 Sep 4.
Endoscopic third ventriculostomy (ETV) has become a widely used method for CSF diversion when treating obstructive hydrocephalus. There are multiple recommendations on the transcortical ETV entry points, and some are specifically designed to provide a trajectory that avoids displacement to the eloquent periventricular structures. However, the morphology of the ventricular system is highly variable in hydrocephalus, and therefore a single best ETV trajectory may not be applicable to all cases. In the current study, 3 frequently quoted ETV entry points are compared in a cohort of pediatric cases with different degrees of ventriculomegaly.
The images of 30 consecutive pediatric patients with varying degrees of ventriculomegaly were reviewed. Three-dimensional models were created using radiological analysis of anatomical detail and preoperative MRI scans in order to simulate 3 frequently quoted ETV trajectories for rigid neuroendoscopes. These trajectories were characterized based on the frequency and depth of tissue displacement to structures such as the fornix, caudate nucleus, genu of the internal capsule, and thalamus. The results are stratified based on ventricle size using the frontal horn ratio (FHR).
Eloquent areas were displaced in nearly all analyzed entry points (97%-100%). Stratifying the data based on ventricle size revealed that (1) lateral structures were more likely to be displaced in cases of intermediate ventriculomegaly (FHR < 0.4) using all 3 trajectories, whereas (2) the fornix was less likely to be displaced using more posteriorly placed trajectories for severe ventriculomegaly (FHR > 0.4). Allowing for minimal (2.4 mm) tissue displacement, a more posterior entry point was less traumatic for severe ventriculomegaly.
There is no single best ETV trajectory that fully avoids displacement of the eloquent periventricular structures. Larger ventricles require a more posteriorly placed entry point in order to reduce injury to the eloquent structures, and intermediate ventricles would dictate a medial entry point. These results suggest that the optimal entry point should be selected on a case-by-case basis after incorporating ventricle size.
内镜下第三脑室造瘘术（ETV）已成为治疗梗阻性脑积水时广泛应用的脑脊液分流方法。关于经皮质ETV入路点有多种推荐，有些是专门设计以提供避免移位至明确的脑室周围结构的轨迹。然而，脑积水患者脑室系统的形态高度可变，因此单一最佳的ETV轨迹可能不适用于所有病例。在本研究中，在一组不同程度脑室扩大的儿科病例中比较了3个经常引用的ETV入路点。
回顾了30例连续的不同程度脑室扩大的儿科患者的图像。使用解剖细节的放射学分析和术前MRI扫描创建三维模型，以模拟刚性神经内镜的3个经常引用的ETV轨迹。这些轨迹根据向穹窿、尾状核、内囊膝部和丘脑等结构的组织移位频率和深度进行表征。使用额角比率（FHR）根据脑室大小对结果进行分层。
几乎所有分析的入路点（97%-100%）都出现了明确区域的移位。根据脑室大小对数据进行分层显示，（1）在中度脑室扩大（FHR<0.4）的病例中，使用所有3种轨迹时，外侧结构更有可能移位，而（2）对于重度脑室扩大（FHR>0.4），使用更靠后的轨迹时，穹窿移位的可能性较小。允许最小（2.4mm）的组织移位，对于重度脑室扩大，更靠后的入路点创伤较小。
不存在能完全避免明确的脑室周围结构移位的单一最佳ETV轨迹。较大的脑室需要更靠后的入路点以减少对明确结构的损伤，中度脑室扩大则需要内侧入路点。这些结果表明，应在考虑脑室大小后根据具体情况选择最佳入路点。
