LAUSR

Approximately 30% of patients seen in specialized epilepsy clinics or admitted for EEG-video monitoring for “refractory seizures” do not have epileptic seizures and hence have been misdiagnosed. Often the history is not particularly suggestive of an epileptic seizure, and the diagnosis had been predicated mainly or solely on the finding of an “abnormal” EEG. This is why many have concluded that a “routine interictal EEG recording is one of the most abused investigations in clinical medicine and is unquestionably responsible for great human suffering.”1 There is no doubt that a poorly interpreted EEG can be bad for you.2,3 The consequences of being misdiagnosed with epilepsy are obvious and serious. Once an “abnormal” EEG (“showing epilepsy”) is a part of the patient’s medical record, there is no way for subsequent EEGs to cancel the effect of the abnormal interpretation. Unlike a CT or MRI scan that is misread, repeating the test and obtaining a normal result in a subsequent EEG will not cancel the effects of the “abnormal” one, because the test represents a sample of brain activity at a given time and may alternate between being abnormal and normal in the same patient. Only rereview of the actual abnormal sample can cancel the misdiagnosis and undo the harmful result; this can be challenging. Thus, the problem of EEG misinterpretation and specifically that of “over-reading” an artifact or a physiological normal variant as representing an abnormal EEG is a very common scenario encountered at referral epilepsy centers. This is likely related to the little-known fact that EEG training is not required during neurology training.2,3 This supplement will provide a review of the EEG findings that can be misleading and over-read: