目的：探讨儿童髓母细胞瘤的显微手术方法及相关问题。方法：回顾性分析经四脑室顶部切开联合四脑室正中孔入路显微手术切除并经病理证实的小儿髓母细胞瘤27例。结果：手术全切除22例(81.5%)、次全切5例(18.5%)。术后26例颅高压症状消失，临床体征改善，1例恶化，无与手术有关的严重并发症和手术死亡。肿瘤位于小脑蚓部6例，四脑室内9例，小脑蚓部和四脑室内者11例，小脑半球1例。肿瘤供血来源于双侧小脑后下动脉分支19例。术中打通导水管26例，1例术中同时行枕大池分流。术后25例病人随访5个月至3年4个月，并接受放疗。其中23例未见复发或转移，1例转移至骨髓，3例原位复发。结论：正确认识小儿髓母细胞瘤的病理解剖结构及其周围组织结构有利于肿瘤切除，采用显微手术全切除肿瘤组织, 妥善保护好小脑后下动脉及分支，避免伤及脑干和四脑室底的结构，术中解除导水管梗阻，是降低复发和转移率、延长生存期的关键。

OBJECTIVE: To study the therapeutic effects of microsurgery on medulloblastoma and the related points in children. METHODS: A retrospective review was conducted in 27 children with medulloblastoma confirmed pathologically. All the patients had transcerebellomedullary fissure and inferior vermis approach to the fourth ventricle. All the patients underwent craniotomy and the tumors were removed under the microscope. RESULTS:Tumors were totally resected in 22 cases ( 81.5% ) and subtotally removed in 5 cases ( 18.5% ) with microsurgical precedures. After the operation, neurological symptoms were improved in 26 patients and deteriorated in 1. No severe operative complications occurred and no patient died from operation. The cerebral aqueduct reopened in 26 cases, and Torkilsen's shunt was carried out at the same time in 1 case. The tumor was located in the cerebellar vermis in 6 cases, fourth cerebral ventricle in 9 cases, and cerebellar hemisphere in 1 case, and occurred in both the cerebellar vermis and fourth cerebral ventricle in 11 cases. The blood supply of tumors was provided by branches of the posterior inferior cerebellar artery in 19 cases. Complete follow up information was obtained in 25 patients for a period of 5 months to 3 years and 4 months. During the follow up, 25 patients received postoperative irradiation. Of them, 2 patients died of relapse or metastasis between 13 months and 3 years after the initial surgery, and the remainder recovered. CONCLUSIONS: A clear understanding of the microanatomy of the tumor and its adjacent tissue and structure is advantageous to the removal of tumor. Microsurgery is effective and safe for medulloblastoma excision. For total removal of the tumour, due care to safeguard the posterior inferior cerebellar artery and its branches, avoiding the bin stem and the base of the fourth ventricle injury, and relieveing obstruction of the mesencephalic aqueduct can decrease the incidence of relapse and metastasis and improve patients' survival period.