What is the role of EEG in focal lesion imaging?

Updated: Aug 06, 2019
  • Author: Selim R Benbadis, MD; Chief Editor: Helmi L Lutsep, MD  more...
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Before the advent of modern neuroimaging, EEG was the best noninvasive tool to use in searching for focal lesions. In the last few decades, with progress in imaging techniques, the role of EEG is changing; its use for localization of a brain lesion is being superseded by neuroimaging. The use of EEG outside of epilepsy has declined markedly.

The use of EEG in monitoring brain activity in the operating room and also in intensive care settings needs to be redefined and its utility reassessed. In clinical situations in which the primary question is the electrical functioning of the brain and not primarily localization, EEG remains a necessary test. EEGs are performed routinely in various clinical situations; therefore, the neurophysiologist is expected to be familiar with the EEG findings even in situations in which they are of relatively limited value.

Like most neurophysiologic tests, EEG is a test of cerebral function; hence, for the most part it is nonspecific as to etiology. Although at one time authors discussed the application of EEG in differentiating various types of lesions, this clearly has not been clinically useful in the modern era. The exercise of describing EEG abnormalities by pathology (eg, stroke, abscess, tumor, even various types of tumors), which was common in old EEG texts, is therefore not followed here. Instead, the different patterns of focal (nonepileptic) disturbances of brain function and their clinical significance are reviewed.

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