Komaitis Spyridon, Koutsarnakis Christos, Lani Evgenia, Kalamatianos Theodosis, Drosos Evangelos, Skandalakis Georgios P, Liakos Faidon, Liouta Evangelia, Kalyvas Aristotelis V, Stranjalis George
1Athens Microneurosurgery Laboratory, Evangelismos Hospital, Athens.
2Department of Neurosurgery, Evangelismos Hospital, National and Kapodistrian University of Athens, Greece.
J Neurosurg. 2021 Jan 1;135(3):815-827. doi: 10.3171/2020.7.JNS201287. Print 2021 Sep 1.
The authors sought to investigate the very existence and map the topography, morphology, and axonal connectivity of a thus far ill-defined subcortical pathway known as the fronto-caudate tract (FCT) since there is a paucity of direct structural evidence regarding this pathway in the relevant literature.
Twenty normal adult cadaveric formalin-fixed cerebral hemispheres (10 left and 10 right) were explored through the fiber microdissection technique. Lateral to medial and medial to lateral dissections were carried out in a tandem manner in all hemispheres. Attention was focused on the prefrontal area and central core since previous diffusion tensor imaging studies have recorded the tract to reside in this territory.
In all cases, the authors readily identified the FCT as a fan-shaped pathway lying in the most medial layer of the corona radiata and traveling across the subependymal plane before terminating on the superolateral margin of the head and anterior part of the body of the caudate nucleus. The FCT could be adequately differentiated from adjacent fiber tracts and was consistently recorded to terminate in Brodmann areas 8, 9, 10, and 11 (anterior pre-supplementary motor area and the dorsolateral, frontopolar, and fronto-orbital prefrontal cortices). The authors were also able to divide the tract into a ventral and a dorsal segment according to the respective topography and connectivity observed. Hemispheric asymmetries were not observed, but instead the authors disclosed asymmetry within the FCT, with the ventral segment always being thicker and bulkier than the dorsal one.
By using the fiber microdissection technique, the authors provide sound structural evidence on the topography, morphology, and connectional anatomy of the FCT as a distinct part of a wider frontostriatal circuitry. The findings are in line with the tract's putative functional implications in high-order motor and behavioral processes and can potentially inform current surgical practice in the fields of neuro-oncology and functional neurosurgery.
鉴于相关文献中关于这一迄今定义不明确的皮质下通路——额尾状束（FCT）的直接结构证据匮乏，作者试图探究其是否存在，并描绘其拓扑结构、形态及轴突连接情况。
通过纤维显微解剖技术对20个正常成年福尔马林固定的脑半球（10个左侧和10个右侧）进行研究。在所有脑半球中依次进行从外侧到内侧以及从内侧到外侧的解剖。由于先前的扩散张量成像研究记录到该束位于前额叶区域和中央核心区，因此重点关注这两个区域。
在所有病例中，作者很容易就识别出FCT是一条扇形通路，位于放射冠最内侧层，穿过室管膜下平面，然后终止于尾状核头部的上外侧边缘和体部前部。FCT能够与相邻纤维束充分区分，并且一致记录到其终止于布罗德曼第8、9、10和11区（前辅助运动区以及背外侧、额极和额眶前额皮质）。作者还能够根据观察到的各自拓扑结构和连接情况将该束分为腹侧段和背侧段。未观察到半球不对称现象，但作者发现FCT内部存在不对称性，腹侧段总是比背侧段更厚、更粗大。
通过使用纤维显微解剖技术，作者为FCT作为更广泛的额纹状体回路的一个独特部分的拓扑结构、形态及连接解剖学提供了可靠的结构证据。这些发现与该束在高级运动和行为过程中的假定功能意义相符，并可能为神经肿瘤学和功能神经外科领域当前的手术实践提供参考。
