Basic Theory of EEG

Abstract

EEG is the most sensitive method to reflect the functional state of the brain. In neurocritical care units (NICUs), most patients often cannot express their feelings because of consciousness disorders, clinical physical examination and imaging examination cannot achieve continuous evaluation, and routine electrocardiogram (ECG)-blood pressure-cerebral oxygen saturation monitoring has difficulty reflecting the changes in patients’ brain function sensitively, which easily leads to a delay in treatment and the deterioration of the patient’s condition; therefore, continuous and sensitive (EEG) monitoring is important for neurocritical patients. On the other hand, the EEG waveform is complex because different patterns may represent different stages of a disease, and even different sleep-wake states in the same stage of a disease may also lead to deviation in the EEG interpretation. In the NICU, many monitoring instruments and clinical operations can easily lead to various EEG artifacts. How to explain the significance of changes in EEGs reasonably and distinguish artifact interference accurately will have an important impact on the decisions of clinicians. This chapter briefly introduces the basic concepts of EEG, normal EEG waves, and key points in EEG interpretation and emphasizes the common artifact recognition techniques in the NICU. Throughout the chapter, we put forward our own views, and we hope to provide a solid foundation for the contents described in the following chapters in this book.