Kellogg J X, Piatt J H
Department of Pediatrics, Oregon Health Sciences University, Portland 97201-3098, USA.
Pediatr Neurosurg. 1997 Jul;27(1):28-33. doi: 10.1159/000121221.
Standard surgical practice for excision of fourth ventricle tumors entails splitting the inferior vermis, but incision of the vermis and lateral retraction on the dentate nuclei and their outflow tracts have been implicated in the development of the so-called 'cerebellar mutism syndrome'. We describe a surgical approach in which the cerebellar vermis is preserved.
Clinical experiences with 11 patients harboring fourth ventricle tumors were supplemented by fixed and fresh cadaver dissections. Anatomic illustrations, prosections and intraoperative photographs are presented. The authors' case material is tabulated, and clinical examples are discussed.
Dissection of the arachnoid membranes and division of filamentous arachnoidal attachments allow separation and elevation of the cerebellar tonsils and exposure of the tela choroidea along its attachment to the dorsal surface of the medulla at the taenia ventricularis. The tela can be opened by sharp microdissection from the foramen of Magendie to the foramen of Luschka to expose the lateral recess of the fourth ventricle. Division of the tela allows additional elevation of the cerebellar tonsils, which can be mobilized further by opening of the tonsillovermian fissures. Performance of this dissection bilaterally opens the entire inferior end of the fourth ventricle and, particularly after excision of a large fourth ventricle tumor, gives a panoramic view from one lateral recess to the other and from the obex to the aqueduct without incision of the vermis.
The cerebellomedullary fissure approach yields exposure comparable to what can be achieved by splitting the vermis and may minimize the risk of neurological complications.
切除第四脑室肿瘤的标准手术操作需要劈开小脑蚓部下半，但切开蚓部以及向外侧牵拉齿状核及其传出纤维束被认为与所谓的“小脑缄默综合征”的发生有关。我们描述了一种保留小脑蚓部的手术入路。
通过对11例第四脑室肿瘤患者的临床经验，并辅以固定和新鲜尸体解剖。展示了解剖图、断层解剖和术中照片。列出了作者的病例资料，并对临床实例进行了讨论。
解剖蛛网膜并切断蛛网膜丝状附着，可分离并抬高小脑扁桃体，暴露脉络丛组织沿其在第四脑室外侧隐窝附着于延髓背表面处的情况。可通过锐性显微解剖从马根迪孔至路施卡孔打开脉络丛组织，以暴露第四脑室的外侧隐窝。切开脉络丛组织可进一步抬高小脑扁桃体，通过打开扁桃体蚓部裂可使其进一步游离。双侧进行此解剖可打开第四脑室的整个下端，特别是在切除大型第四脑室肿瘤后，可提供从一个外侧隐窝到另一个外侧隐窝以及从闩部到导水管的全景视野，而无需切开蚓部。
小脑延髓裂入路所提供的暴露程度与劈开蚓部相当，且可能将神经并发症的风险降至最低。
