Normal variant EEG patterns

Abstract

The object of this chapter is to familiarize the reader with a number of commonly encountered normal variants of brain-derived EEG activity. The term normal variant pattern refers to those rhythms or waveforms that have features reminiscent of either interictal or ictal EEG abnormalities. However, these patterns have been found in a substantial proportion of tracings from healthy subjects and, therefore, are not currently thought to represent pathological entities. It is, therefore, vital that such patterns be appropriately recognized by the EEG reader as normal variants and not erroneously confused for pathological patterns. This chapter addresses four main categories of variant EEG activity: 1. Rhythmic patterns. 2. Epileptiform patterns. 3. Lambda and lambdoids. 4. Age-related variants. © 2007 Humana Press Inc.