Intraoperative electroencephalography.

EEG is useful in several operating room procedures. It has come to be a standard part of monitoring patients during carotid endarterectomy. Monitoring for cerebral hypoperfusion or emboli can also be done in cardiac surgery or other similar settings. For carotid endarterectomy, studies in humans suggest that the risk of stroke can be reduced 10-fold by selective vascular shunting based on major EEG changes compared to no shunting. EEG can be recorded from exposed cerebral cortex, a technique referred to as electrocorticography. Such recordings can help identify damaged cortex, separating it from normal functioning cortex. This can influence the extent of neurosurgical cortical resections. Although much of the technology in the operating room is based on that common in routine EEG testing, some differences exist and are discussed here. The well-trained electroencephalographer should find recording and interpreting EEG in the surgical setting to be a natural extension of routine EEG.