Prospective Surgical Study on the Pattern of Electrical Activity in High Grade Glioma as a Predictor of Progression

Inclusion Criteria: * Participants who have the appearance of high-grade glioma (HGG, WHO Grade 3 and 4, including GBM) on MR imaging are allowed to consent and will undergo the procedure if the frozen is consistent with HGG OR * Participants with a history of histologically-confirmed diagnosis of high- grade glioma that are undergoing resection of a recurrent/progressive tumor that is likely recurrent/progressive high- grade glioma as identified on preoperative MR imaging * Age ≥ 18 years old * Volumetric MRI within 1 month prior to surgery * Karnofsky performance status of 60 or higher * The participant (or legally acceptable representative if applicable) provides written informed consent for the trial. * Participants must be considered appropriate neurosurgical candidates with the following screening/baseline laboratory values within 1 month prior to surgery: * Absolute neutrophil count ≥ 1500/µL * Platelets ≥ 100 000/µL * International normalized ratio (INR) OR prothrombin time (PT) Activated partial thromboplastin time (aPTT) ≤1.5 × Upper limit of normal (ULN) unless participant is receiving anticoagulant therapy as long as PT or aPTT is within therapeutic range of intended use of anticoagulants * Urine or Serum Pregnancy Test = Negative (Not applicable to participants with bilateral oophorectomy and/or hysterectomy or to those participants who are postmenopausal). Exclusion Criteria: * Severe co-morbidity that would confer excess risk of surgery as determined by the treating physician. * Any other major medical illnesses or psychiatric impairments that in the investigator's opinion will prevent administration or completion of protocol therapy. * Is pregnant * Coagulopathy or platelet dysfunction that increases the risk of intra and postoperative hemorrhage * Tumor location requiring DE placement/biopsy in eloquent or critical region of the brain (e.g. primary motor and sensory cortices, speech and vision centers, thalamus, basal ganglia, cerebellum, brain stem) as deemed by the neurosurgeon designing the surgical plan