What are normal EEG variants?

Updated: Oct 09, 2019
  • Author: Roy Sucholeiki, MD; Chief Editor: Selim R Benbadis, MD  more...
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The phrases "electroencephalogram (EEG) variant waves" or "normal EEG variants" refer to waves that are rare or unusual but not generally abnormal. They may be unusual in shape or in distribution. These variant waveforms include waveforms and patterns that are rare or unusual but are known to be generally benign. They can include complex wave mixtures that can appear unusual and can confuse the casual reader (for example, wave harmonics) as well as artifacts or electrical disturbances from structures that are not in or part of the brain and do not affect the brain or its function but appear in the EEG tracing. [1, 2]

Realizing that the EEG is fundamentally a recording of the electrical activity of a highly complex system is important. Moreover, this electrical activity is being recorded at the scalp and, although accurate, it is not the same as the recording of activity directly from the surface of brain or at the single cell level. Therefore, from person to person, a variation is expected of waveforms and occasional atypical waveforms that still fall within what would be considered normal. [3, 4, 5]

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