[Intra-operative monitoring of EEG]

The fundamentals and clinical applications of intra-operative EEG monitoring are described. EEG monitored on line at bedside is useful for the evaluation of the depth of anesthesia and sedation, and also for the early detection of cerebral ischemia and seizure. However, EEG monitoring is not easy in the operating room, where a number of electrical machines and medical personnel are working. The authors have introduced a basal lead for the recording of brain-stem electrical activity and a fiberoptic EEG instrument for the exclusion of electrical noises. Recently, EEG instruments with computer-processing function, which are small in size and easy to manage, have been developed one after another. Computer-processed EEG is sequentially expressed as a digitalized value. Today, computer-processed EEG is more popular than raw EEG as an intra-operative monitoring of cerebral function, while raw EEG is superior to computer-processed EEG in the detection of seizure waves. The authors recommend multi-modality monitoring including non-invasive measurements of oxygen saturation and blood flow for the safe maintenance of cerebral