Surgical resection of fourth ventricular ependymomas: case series and technical nuances

Ependymomas are rare neuroepithelial tumors which may arise anywhere along the ventricular system. Tumors arising in the fourth ventricle present unique challenges. Complete tumor resection favors prolonged survival, but may result in inadvertent injury of surrounding neural structures-such as cranial nerve (CN) nuclei. Here, our institutional experience with surgical resection of fourth ventricular ependymomas is described. A single institution, retrospective analysis of consecutive case series of adult surgically resected fourth ventricular ependymomas with the bilateral telovelar approach. Extent of resection, outcomes and postoperative complications are statistically analyzed. From January 2000 to April 2016, 22 fourth ventricular ependymomas underwent surgical resection. Gross total resection was achieved in 18 of 22 cases (82 %). There were six postoperative CN palsies-3 lower CN palsies (IX, X, or XI), 1 CN VII palsy, 1 CN IV palsy, and 1 CN VI palsy. No deaths or cerebellar mutism occurred. Two of 6 CN deficits resolved and the rate of permanent neurologic deficit was 18 %. A CN deficit was not statistically associated with prolonged hospital stay or functional outcome. With exception of one patient, all patients functionally improved or remained unchanged following surgery. Postoperative complications included one wound infection (4.5 %) and four pseudomeningoceles (18 %). The rate of shunt-dependent hydrocephalus was 18 %. Tumors adherence to the fourth ventricular floor is not an absolute contraindication for complete resection. Intraoperative neuro-monitoring is essential, and the development of sustained, but not transient CN activity, and/or hemodynamically significant bradycardia should limit the extent of resection.