Jean Walter C, Abdel Aziz Khaled M, Keller Jeffrey T, van Loveren Harry R
The Neuroscience Institute, Department of Neurosurgery, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0515, USA.
Neurosurgery. 2003 Apr;52(4):860-6; discussion 866. doi: 10.1227/01.neu.0000053146.83780.74.
Conventional approaches to tumors of the foramen of Luschka are limited because the foramen is viewed from either the fourth ventricle laterally (transvermian approach) or the cerebellopontine angle medially (suboccipital approach). The definitive approach is subtonsillar, because the foramen of Luschka is actually the end of the natural cleavage plane between the cerebellar tonsil and the medulla. We describe the microsurgical anatomic features of the foramen of Luschka region and the operative technique for the subtonsillar approach to this region.
In the anatomic study, five formalin-fixed, silicone-injected, cadaveric heads were used. In the clinical study, the records for five patients treated via the subtonsillar approach were examined; several illustrative cases are presented.
The foramen of Luschka is formed by the tela choroidea and the rhomboid lip and exists at the lateral end of the cerebellomedullary fissure, which is a natural cleavage plane between the cerebellar tonsil and the medulla. The subtonsillar approach is performed via a suboccipital craniotomy; the patient is positioned in the lateral decubitus position, with the tumor side down. After the cerebellar tonsil is freed from arachnoid adhesions, it can be retracted rostrodorsally from the medulla, to expose the cerebellomedullary fissure. Clinically, the tela choroidea and rhomboid lip are significantly attenuated by tumor expansion. Therefore, by dissecting in a subtonsillar manner around the tumor, one can reach the foramen of Luschka without traversing any neural tissue.
The subtonsillar approach yields a panoramic view to the foramen of Luschka laterally and up to the middle cerebellar peduncle superiorly. This approach minimizes the distance between the tumor and the surgeon, while maximizing neural preservation. We think this is the definitive approach to this difficult region of the posterior fossa.
由于传统上对Luschka孔区肿瘤的处理方法有限，因为该孔只能从第四脑室外侧（经小脑蚓部入路）或脑桥小脑角内侧（枕下入路）观察。确切的入路是扁桃体下入路，因为Luschka孔实际上是小脑扁桃体与延髓之间自然分离平面的终点。我们描述了Luschka孔区的显微外科解剖特征以及该区域扁桃体下入路的手术技术。
在解剖学研究中，使用了5个用福尔马林固定、注入硅胶的尸体头部。在临床研究中，检查了5例经扁桃体下入路治疗患者的记录，并展示了几个典型病例。
Luschka孔由脉络丛和菱形唇构成，位于小脑延髓裂的外侧端，该裂是小脑扁桃体与延髓之间的自然分离平面。扁桃体下入路通过枕下开颅进行；患者取侧卧位，肿瘤侧在下。在小脑扁桃体与蛛网膜粘连松解后，可将其从延髓向前上方牵拉，以暴露小脑延髓裂。临床上，脉络丛和菱形唇因肿瘤扩张而明显变薄。因此，通过围绕肿瘤进行扁桃体下方式的解剖，可在不穿过任何神经组织的情况下到达Luschka孔。
扁桃体下入路可提供Luschka孔外侧直至小脑上脚上方的全景视野。该入路可使肿瘤与术者之间的距离最小化，同时最大限度地保护神经。我们认为这是处理后颅窝这一困难区域的确定性入路。
