Department of Anesthesiology, University of Bonn Medical Center, Bonn, Germany.
Neurosurgery. 2010 Dec;67(2 Suppl Operative):385-90. doi: 10.1227/NEU.0b013e3181f7424b.
Visual field defects are a common side effect after mesial temporal resections such as selective amygdalohippocampectomy (SelAH).
To present a method of diffusion tensor tractography (DTT) of the Meyer loop for preoperative planning of the surgical approach for SelAH and for intraoperative visualization on a navigation-guided operating microscope.
Twelve patients were selected for SelAH to treat mesial temporal lobe epilepsy. All received preoperative MRI with diffusion tensor imaging sequences. The Meyer loop was determined and reconstructed as an object with DTT. Images were utilized for preoperative planning in which a safe approach not affecting the Meyer loop was specified. A navigation-guided operating microscope was used for image-guided surgery.
DTT was a reliable method for visualization of the Meyer loop. Reconstruction of the Meyer loop had a direct impact on the approach planning. In all 12 cases, the optic tract could only be spared using a basal approach. Ten patients underwent SelAH by the subtemporal approach, and 2 underwent SelAH by the transcortical approach through the inferior temporal gyrus. During the critical early phase of the operation image guidance remained accurate until entry into the ventricle. Nine of 12 patients had no postoperative field deficits (75%). Three patients (25%) experienced peripheral incomplete quadrantanopia.
DTT and intraoperative visualization of the Meyer loop is a helpful tool for preoperative planning and during surgery to find a safe trajectory to mesial temporal structures while avoiding the optic radiation. This technique in combination with a basal approach seems to be a promising strategy to prevent postoperative visual field deficits in most patients.
内侧颞叶切除术后（如选择性杏仁核海马切除术，SelAH）常出现视野缺损等并发症。
介绍一种利用弥散张量纤维束成像（DTT）对 Meyer 环进行追踪的方法，用于 SelAH 手术入路的术前规划以及导航引导手术显微镜下的术中可视化。
选择 12 例因内侧颞叶癫痫而行 SelAH 的患者，所有患者均接受了术前 MRI 加弥散张量成像序列检查。确定并通过 DTT 重建 Meyer 环，将其作为目标。利用这些图像进行术前规划，确定不影响 Meyer 环的安全入路。使用导航引导手术显微镜进行图像引导手术。
DTT 是可视化 Meyer 环的可靠方法。Meyer 环的重建对入路规划有直接影响。在所有 12 例中，只有基底入路才能保留视束。10 例患者采用经颞下入路行 SelAH，2 例患者经颞下回皮质下入路行 SelAH。在手术的关键早期，图像引导仍然准确，直至进入脑室。12 例中有 9 例（75%）患者术后无视野缺损。3 例（25%）患者出现外周不完全象限盲。
DTT 和 Meyer 环的术中可视化是术前规划和手术过程中的有用工具，可以找到一条避开视辐射到达内侧颞叶结构的安全轨迹。该技术结合基底入路似乎是一种有前途的策略，可以防止大多数患者术后出现视野缺损。
