UCSF

Abstract

INTRODUCTION

We report our experience with intraoperative stimulation mapping to locate the descending subcortical motor pathways in patients undergoing surgery for hemispheric gliomas within or adjacent to the rolandic cortex, and describe the morbidity and functional outcomes associated with this technique.

METHODS

The retrospective analysis included 702 patients undergoing resection of hemispheric perirolandic gliomas within or adjacent to descending motor pathways. Data regarding intraoperative stimulation mapping results and patient postoperative neurological status were collected.

RESULTS

Of 702 patients, stimulation mapping identified the descending motor pathways in 300 cases (45%). New or worsened motor deficit was seen postoperatively in 210 cases (30%). Of these 210 cases, there was improvement in the motor function to baseline by 3 months postoperatively in 160 cases (76%), while the deficit remained in 50 cases (24%). Majority (56%) of long-term deficits were mild or moderate (antigravity or better). Patients in whom the subcortical motor pathways were identified during surgery with stimulation mapping were more likely to develop an additional motor deficit postoperatively compared to those in whom the subcortical pathway could not be found (45% vs. 19% respectively, p<0.001). This difference also remained when considering the likelihood of a long-term deficit (i.e. persisting >3 months; 12% vs. 3.2%, p<0.001). A significant region of diffusion restriction around the resection cavity was seen in 20 patients with long-term deficits and was more common in cases when the motor pathways were not identified. Thus, long term deficits that occur in settings where the subcortical motor pathways are not identified seem in large part due to local ischemic injury to descending tracts.

CONCLUSION

Stimulation mapping allows surgeons to identify the descending motor pathways during resection of tumors in perirolandic regions and to achieve an acceptable rate of morbidity in these high risk cases.