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Artifact Mimicking Ictal Epileptiform Activity in EEG

McKay, Jake H.; Tatum, William O.

Journal of Clinical Neurophysiology: July 2019 - Volume 36 - Issue 4 - p 275–288
doi: 10.1097/WNP.0000000000000597
Invited Review

Summary: Although the EEG is designed to record cerebral activity, it also frequently records activity from extracerebral sources, leading to artifact. Differentiating rhythmical artifact from true electrographic ictal activity remains a substantial challenge to even experienced electroencephalographers because the sources of artifact able to mimic ictal activity on EEG have continued to increase with the advent of technology. Knowledge of the characteristics of the polarity and physiologic electrical fields of the brain, as opposed to those generated by the eyes, heart, and muscles, allows the electroencephalographer to intuitively recognize noncerebrally generated waveforms. In this review, we provide practical guidelines for the EEG interpreter to correctly identify physiologic and nonphysiologic artifacts capable of mimicking electrographic seizures. In addition, we further elucidate the common pitfalls in artifact interpretation and the costly impact of epilepsy misdiagnosis due to artifact.

Department of Neurology, Mayo Clinic College of Medicine & Health Sciences, Jacksonville, Florida, U.S.A.

Address correspondence and reprint requests to William O. Tatum, DO, FAAN, FACNS, Department of Neurology, Mayo Clinic Mangurian Building, 4500 San Pablo Rd, Jacksonville, Florida 32224; e-mail:

The authors have no funding or conflicts of interest to disclose.

© 2019 by the American Clinical Neurophysiology Society