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

Abstract

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.

Telovelar approach to pediatric fourth ventricle tumors: feasibility and outcome.

“…Opposed to that, we did not find any problem with GTR of tumors extending to the rostral third of the fourth ventricle, because we routinely remove the posterior arch of the atlas, which provides a wider working angle. This finding is supported by Deshmukh et al's conclusion that the telovelar route together with removing of the posterior arch of the atlas results in a wider working angle to the upper third imply that tumor adherence to the brainstem is not an absolute contraindication for total tumor resection, which is consistent with Winkler et al's report (28).…”

Intraventricular neuroepithelial tumors: Surgical outcome, technical considerations and review of literature

“…To access the fourth ventricle, historically the trans-vermian approach was very popular. Still, this approach harbors the risk of cerebellar mutism and disequilibrium (15,16) leading to the development of the less invasive median suboccipital telovelar approach (25,26).…”

“…Nevertheless, surgical morbidity of tumors of the fourth ventricle, mostly ependymomas, remains high with up to 30% adverse events. This is probably due to adhesive nature of the lesion and proximity of cranial nerves and their nuclei (15,27,28). To reduce the risk for cranial nerve lesions, monitoring of cranial nerves and electrical intraoperative mapping of the oor of the fourth ventricle can be performed (29).…”

“…Intracranially they show predominant occurrence in the posterior fossa e.g. the fourth ventricle (60%) compared to supratentorial location (40%) (2,15,32,33). The majority (>50%) of supratentorial ependymomas are intra-axial lesions, only few reports on extra-axial ependymomas exist (34).…”

“…Regarding the fourth ventricle, approaches as the transvermian approach (10), a subtonsillar-transcerebellomedullary approach (11), a superior transvelar approach (12) or also endoscopic techniques (13,14) were described with claiming to be the superior one. The transvermian approach has been performed frequently in history, but data showed high rates of cerebellar mutism and disequilibrium (15,16). To enter the lateral and/or third ventricle a variety of approaches have been described including the frontal-transcortical, the anterior/posterior interhemispheric-transcallosal and the contralateral interhemispheric-transfalcine-transprecuneal approach (17)(18)(19)(20)(21)(22).…”