The Impact of Intraoperative Monitoring on Extent of Resection and Long-Term Neurological Outcomes: A Series of 39 Intramedullary Ependimomas.

Abstract

To analyze the impact of intraoperative neurophysiological monitoring (IONM) on the extent of removal and long-term neurological outcomes in a series of grade II ependymomas. We retrospectively reviewed 88 consecutive patients who underwent surgical resection of an intramedullary spinal cord tumor (IMSCT) at the Clinic of Neurosurgery of the Clinical Center of Serbia in Belgrade between January 2012 and December 2017. In all, 39 patients (25 males and 14 females; mean age 46.16 years) with grade II ependymomas were enrolled in this study; the mean follow-up time was 49.84 months. The modified McCormick Scale (mMCS) was used to assess the short- and long-term outcomes, and the patients were divided into two groups based on whether they underwent IONM. The gross-total removal rate was 89.7%, and it was not influenced by use of IONM, location or tumor size. Upon admission,43.2% of the patients were dependent (grades IV and V), while 56.8% were independent (grades I, II and III), according to the mMCS. After 3 months of follow-up, 76.9% of the patients maintained or improved their neurological status, but this percentage was reduced after long-term follow-up. Total surgical resection with good neurological outcomes can be achieved in the vast majority of patients with grade II ependymomas; it is important to emphasize that the use of IONM allows acceptable extent of resection and provides better results in terms of functional outcomes, with lower morbidity rates. Therefore, no correlation was demonstrated between the decrease in the basal amplitudes of IONM and D-waves and poor neurological outcomes.