RecruitingProcedureFeasibility of Intra- and Post-operative Microdialysis During Neurosurgery for Central Nervous System LesionsThis clinical trial evaluates the use of microdialysis catheters during surgery to collect biomarkers, and studies the feasibility of intra- and post-operative microdialysis during neurosurgery for central nervous system malignancies. A biomarker is a measurable indicator of the severity or presence of disease state. Information collected in this study may help doctors develop new strategies to better diagnose, monitor, and treat brain tumors.