Spinal Mixopapillary Ependymoma: the Sapienza University Experience and Comprehensive Literature Review concerning the Clinical Course of 1602 Patients

Background: Spinal myxopapillary ependymoma (sMPE) is an uncommon primary spinal neoplasm infiltrating the spinal cord, conus medullaris (CM), and nerve roots. It is associated with low resection and high recurrence rates. The purpose of this literature review is to evaluate the exact impact of the involvement of the CM and the role played by gross total resection (GTR) on overall survival (OS). Methods: The English literature was systematically investigated using MEDLINE, the NIH Library, PubMed, and Google Scholar search engines with relevant queries. Case series reporting details concerning OS, GTR, and CM involvement rate were included, with a differential statistical weight given by the number of patients enrolled. A final cohort of 1602 clinical records was analyzed according to the 3 selected end point variables. Results: The average age was 36.44 ± 3.41 years, and the CM was involved in 28.4% ± 28.2% of cases. The average GTR rate was 53.94% ± 22.20%. Five- and 10-year OS rates were respectively available in 1170 and 1167 cases, with an average 5- and 10-year OS rate of 94.99% ± 3.87% and 92.31% ± 5.73%. By means of analyses performed both on aggregated and disaggregated data a strong positive statistical connection between GTR and increased OS was demonstrated despite the real clinical advantage could range as low as around 1% of increased OS rate. Conclusions: Given the indolent sMPE behavior, it is difficult to evaluate the exact impact of GTR and CM involvement on OS; however, GTR could be associated with a limited survival advantage, whereas CM involvement could be associated with a survival disadvantage.