Feasibility of Intra- and Post-operative Microdialysis During Neurosurgery for Central Nervous System Lesions

Inclusion Criteria: * Age \>= 18 years * Diagnosis of the following, based on clinical and radiographic evidence: * Any glioma * Metastatic brain tumor of any primary origin * Epileptic focus requiring surgical resection * Planned neurosurgical procedure for purposes of biopsy or resection of suspected or previously diagnosed brain tumor (primary or metastatic) or epileptic focus as part of routine clinical care * Willing to undergo neurosurgical resection or biopsy at Mayo Clinic \[Rochester, Minnesota (MN)\] * For patients with gliomas recruited for post-operative microdialysis, willingness to stay in the hospital through post-operative day (POD) 3-5 (timing per physician and patient's shared decision making) * Ability to understand and the willingness to sign a written informed consent document * Enrollment into the Biobank study (IRB#12-003458) Exclusion Criteria: * Vulnerable populations: pregnant women, prisoners or the mentally handicapped * Patients who are not appropriate candidates for surgery due to current or past medical history or uncontrolled concurrent illness