The authors provide an updated summary of spinal ependymomas, highlighting new molecular features of the most common primary intraspinal tumor of adults as well as imaging characteristics. The update includes published epidemiological data, surgical treatment options, comments on the occurrence of these tumors in pregnancy, and updates in the evolving imaging modalities for diagnosis using diffusion tensor imaging.
Historical note and terminology
In 1887, Horsley performed the first reported successful removal of an intradural, extramedullary tumor (46). With the help of Sir William Gowers, Horsley removed a "fibromyxoma" overlying the spinal cord at the T4 level. Postoperatively, the patient developed a debilitating pain syndrome but later experienced a full neurologic recovery. In the following 50 years, pioneering neurosurgeons such as Elsberg, Frazier, and Cushing took particular interest in extramedullary tumors, recognizing their frequently benign nature and often dramatic recovery from profound neurologic deficit (41; 31; 27). In 1911, Elsberg and Beer reported the first successful removal of an intramedullary spinal cord tumor (32). Frazier also commented on the potential for the removal of encapsulated intramedullary neoplasms (41). However, early attempts at removal of intrinsic intramedullary spinal cord tumors were associated with serious operative morbidity and mortality, such as complete paralysis.
For the next several decades, there was little impetus to modify the approach of biopsy, dural decompression, and radiation therapy, despite the recognition that after a relatively short remission, serious disability or death ensued. This "traditional" attitude was based on the assumption that it was not feasible to carry out extensive removal of tumors from within the center of the spinal cord without inflicting additional neurologic injury (26; 52). In 1954 Greenwood, with the aid of bipolar cautery and loupe magnification, reported 6 patients who underwent complete removal of intramedullary ependymomas (48). By 1963 Greenwood had treated 9 patients with surgery alone. There was no tumor recurrence in his surviving patients (7) with a mean follow-up of 9 years (49). With time, it has become clear that the majority of intramedullary spinal ependymomas can be radically excised with an acceptable morbidity and mortality, and a low incidence of recurrence (51; 83; 75; 119; 40; 52; 24; 23; 04; 78; 129; 39; 19; 34).