The relationships of the fourth ventricle to the cerebellar surfaces and the fissures through which the fourth ventricle is approached surgically are among the most complex in the brain. The area in and around the fourth ventricle may be affected by a variety of neoplasms. Some are unique to the fourth ventricle; others are also found in different locations. The two most common surgical approaches to the fourth ventricle are the transvermian and the telovelar approaches. The aim of this study is to compare the results of telovelar and transvermian approaches in the management of fourth ventricular tumors with regard to clinical outcome and extent of tumor excision. This study includes 40 patients presented at Ain Shams University Hospital and Nasser Institute with the diagnosis of fourth ventriclular tumors in a 4-year period between 2011 and 2015. Surgical treatment was done in all cases in form of (1) a CSF diversion for hydrocephalic patients through insertion of V-P shunt or EVD. (2) Completely randomly choosing an approach, 20 patients were operated through the transvermian approach (50% of all patients) and 20 patients were operated through the telovelar approach. Patients were examined clinically, radiologically, and functionally using the Karnofsky performance scale at the postoperative period, every 3 months for the first year, and then 6 months thereafter. Total excision of the tumor was achieved in 27 patients (67.5% of all patients) and 15 patients (75% of 20 patients operated via telovelar approach).There were 13 patients (32.5%) with different postoperative complications, 6 patients underwent telovelar approach,1 case of superficial infection, 3 cases of bulbar palsy (15% of patients operated via telovelar approach), and 3 cases of cerebellar mutism (15% of patients operated via transvermian approach and 7.5% of all patients). The telovelar approach can give better exposure to the fourth ventricle in craniocaudal direction and lateral direction without splitting of the vermis. For lesions in the upper half, the ventricletelovelar approach can be used but we have to shift to the transvermian approach for complete resection. The transvermian approach has a higher risk of postoperative cerebellar mutism syndrome particularly in children.

中文翻译：

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Telovelar入路与Transvermian入路治疗第四脑室肿瘤

第四脑室与小脑表面的关系以及通过外科手术接近第四脑室的裂隙在大脑中最为复杂。第四脑室及其周围区域可能受多种肿瘤的影响。有些是第四脑室所特有的。其他的也位于不同的位置。第四脑室的两种最常见的手术入路是经Vermian入路和Telovelar入路。这项研究的目的是就临床结局和肿瘤切除的程度，比较特洛韦拉法和经超温法治疗第四脑室肿瘤的结果。该研究包括2011年至2015年的4年期间在Ain Shams大学医院和Nasser研究所就诊的40例第四脑室肿瘤患者。在所有情况下均以（1）通过插入VP分流管或EVD对脑积水患者进行脑脊液转移的形式进行手术治疗。（2）完全随机选择一种方法，其中20例患者通过经络途径入路（占所有患者的50％），而20例患者通过特洛韦拉尔入路进行手术。术后第一年每3个月，然后每6个月使用Karnofsky绩效量表对患者进行临床，放射学和功能检查。完全切除肿瘤的有27例（占全部患者的67.5％）和15例（占20个患者的全部通过telovelar手术）的患者，其中13例（32.5％）具有不同的术后并发症，其中6例行了telovelar手术，1例表面感染，3例延髓性麻痹（15％的患者通过Telovelar入路手术）和3例小脑性ism默症（15％的患者通过经Vermian入路手术，占所有患者的7.5％）。乳牙入路可在颅尾方向和侧向方向更好地暴露于第四脑室，而不会使ver裂。对于上半部分的病变，可以使用心室小肠瓣膜入路，但是我们必须转向经跨膜入路才能进行完全切除。经vermian方法有较高的术后小脑mutism综合征的风险，特别是在儿童中。乳牙入路可在颅尾方向和侧向方向更好地暴露于第四脑室，而不会使ver裂。对于上半部分的病变，可以使用心室小肠瓣膜入路，但是我们必须转为经跨膜入路才能完全切除。经vermian方法有较高的术后小脑mutism综合征的风险，特别是在儿童中。乳牙入路可在颅尾方向和侧向方向更好地暴露于第四脑室，而不会使ver裂。对于上半部分的病变，可以使用心室小肠瓣膜入路，但是我们必须转向经跨膜入路才能进行完全切除。经vermian方法有较高的术后小脑mutism综合征的风险，特别是在儿童中。