Normal Variants Are Commonly Overread as Interictal Epileptiform Abnormalities

Abstract

Summary: 

Electroencephalographers may misclassify benign variant EEG patterns as epileptiform discharges, resulting in delays in the diagnosis and appropriate treatment of other paroxysmal disorders, such as psychogenic nonepileptic seizures, anxiety/panic disorders, and near syncope. These benign variant patterns include wicket spikes, small sharp spikes, and rhythmic mid-temporal theta of drowsiness. Cautious interpretations of semi-rhythmic sharp transients, usually gradually rising from the EEG background in drowsiness, can help avoid misdiagnosing patients as having seizures. Viewing the EEG as confirmatory for a clear clinical diagnosis is also helpful—elderly patients with syncope, for example, often have microvascular disease and EEG wicket rhythms in drowsiness—a careful review of the clinical history and the paroxysmal EEG pattern usually help distinguish normal variant patterns from interictal sharp waves and spikes and avoid misdiagnosing epilepsy.