Classification of EEG patterns in patients with impaired consciousness.

There is significant variability and controversy regarding the interpretation, nomenclature, and clinical implications of many EEG patterns seen in encephalopathic patients. The American Clinical Neurophysiology Society has attempted to create well-defined, objective rules for naming these patterns in order to allow scientific investigation into their significance. After many revisions, clarifications in definitions, and Web-based training modules, interrater reliability has improved. A perfect system for describing complex wave forms with words will never be perfect; scalp EEG itself has substantial limitations, as intracranial recordings in neurocritical care patients have shown. The latest version of the nomenclature is available at https://www.acns.org.