Triphasic waves: a reassessment of their significance.
Electroencephalograms and case histories of 50 patients with triphasic waves were reviewed. EEGs were studied for slowed dominant activity, anteriorly dominant triphasic waves, anterior-posterior lag time and bursts of triphasic waves. Etiologies of triphasic waves were: hepatic (28), azotemia (10), anoxia (10) and hyperosmolarity (2). Sixteen hepatic and two azotemic patients showed all of these characteristic EEG features. Triphasic waves demonstrating all of these features are highly characteristic of but are not pathognomonic for hepatic encephalopathy. Prognosis correlated best with the type of hepatic injury and deteriorating renal function. We postulate that triphasic waves are generated by the same thalamocortical volleys which normally induce spindles.
D001921:Brain / Q000503:physiopathology; D004569:Electroencephalography; D006501:Hepatic Encephalopathy / Q000503:physiopathology*; D006801:Humans; D009460:Neurologic Examination