Use the background organization, periodicity, and reaction to stimulation to decide whether the tracing suggests a toxic-metabolic encephalopathy or severe structural injury. A prognostic interpretation should never be based on triphasic waves alone.

Triphasic waves are common in hepatic encephalopathy but can also occur in renal failure, hyponatremia, hypoglycemia, drug intoxication, and anoxic injury; Polymorphic delta suggests diffuse cerebral dysfunction; Burst suppression, alpha coma, and periodic epileptiform discharges are unfavorable prognostic signs; Triphasic waves are frontal, bilateral, and have a stereotyped morphology; Clinical context determines whether the pattern is reversible or ominous