The sample size for the outcome in the microdialysis study was calculated on a difference of the glutamate metabolite of 12 µM between the two groups. For this power analysis, we used a glutamate standard difference of 15 µM resulting from a previous study. It was determined that a sample size of 25 patients per group would be necessary to detect the glutamate difference with 80% power when alpha was set equal to 5%. Anticipating that we would lose 10% of participants enrolled, we plan to enroll 27 patients in each group for microdialysis.