50. Subcortical mapping and intraoperative DTT 3.0T of the corticospinal tract in supratentorial intrinsic tumor surgery. What should we rely on?

Abstract

Introduction The course of the corticospinal tract (CST) can be identified using subcortical mapping (sc-MEP). The threshold technique (MEP-trsh) is considered to be reliable in setting the safe zone. Intraoperative DTT and sc-MEP correlation is thought to be more precise because of brainshift elimination. Goal of the study Evaluate intraoperative DTT 3.0T reliability comparing to CST mapping in nonselected patient series. Methods 25 patients were enrolled consecutively and prospectively from 7/2010 to 7/2012. Inclusion criteria: solitary supratentorial intracerebral lesion compressing or infiltrating the CST. Sc-MEP was performed by monopolar (cathodal) stimulation (500 Hz, 400 μ s, 5 pulses) with navigated probe. CST DTT was made both at preoperative and intraoperative 3.0T MRI. MEP-trsh current and probe-CST distance were recorded at 155 points before iMRI (preoperative scans), and at 103 points after iMRI (intraoperative scans). Current-distance correlations were performed both for pre-iMRI and for post-iMRI data separately. Results The correlation coefficient pre-iMRI was R = 0.470 (p 0.001), post-iMRI was R = 0.338 (p 0.001). MRI radical resection was achieved in 17 (68%), subtotal in 5 (24%) and partial in 3 (12%). Postoperative paresis developed in 8 (32%), permanent remained in one case (4%). Intraoperative DTT was unreliable because of image distortion in 9 (36%). Conclusion The linear current-distance correlation was found both in pre-iMRI and in post-iMRI data. Correlation of post-iMRI data was weaker. Intraoperative DTT was unreliable in 36%. Sc-MEPs remains superior, because of direct mapping of neural fibers and lack of technical failure. Supported by IGA MZ CR 12253–5.