Carotid Endarterectomy Surgery
You are having a carotid endarterectomy in order to restore proper blood flow to your brain. During this surgery, the carotid artery must be clamped for the surgeon to open it and clean it out. While the artery is clamped, blood flow to the brain from the carotid on the side of your surgery will stop. In most people, there will still be enough blood getting to the brain from the carotid artery on the other side. In a small number of patients, however, this collateral circulation is insufficient to perfuse the entire brain putting the patient at risk of stroke.
The neurophysiologist will monitor your brain activity during surgery in order to ensure that you maintain adequate blood flow. Two tests are used to monitor the brain: somatosensory evoked potentials (SSEPs) and electroencephalography (EEG). SSEPs are recorded by electrically stimulating nerves in the ankles and wrist and recording the sensory information that reaches your cerebral cortex. EEG is a recording of brain activity and is interpreted by the frequency and amplitude of the electrical signal. Baseline SSEP and EEG signals are obtained prior to the start of surgery and the neurophysiologist will monitor for any changes from baseline that would signal a lack of blood flow to the brain. If a change is noted upon carotid clamping, the neurophysiologist will inform the surgeon and the surgeon will put a shunt around the operative site so that blood may still flow to the brain.