A highly desired result during carotid endarterectomy (CEA) is the ability to predict and warn the surgeon if the brain is at risk of damage during the period of time that the carotid artery is cross-clamped for surgical repair of the vessel narrowing. A number of approaches for cerebral monitoring have been developed, including EEG, cerebral oximetry, and measurement of arterial to jugular venous concentration differences of oxygen, glucose or lactate. This study will utilize and compare multiple monitoring approaches for detecting when and if the brain is at risk of injury during CEA. As such, this robust approach to monitoring may permit a more prompt intervention to prevent or limit damage should cerebral ischemia occur. In this study we will compare a processed EEG monitor -- the EEGo, which uses nonlinear analysis to a bispectral (BIS) index monitor, and to the FORE-SIGHT cerebral oximeter to assess the ability of each to identify cerebral ischemia should it occur with carotid artery cross-clamping during CEA. These monitors will be correlated with arterial to jugular venous lactate concentration difference, which has recently been shown to be a sensitive indicator of hemispheric ischemia during CEA.