Isolated ACTH deficiency presenting with a glucocorticoid-responsive triphasic wave coma

Triphasic Waves: Historical Overview of an Unresolved Mystery

SUMMARY

Triphasic waves are a fascinating and mysterious EEG feature. We now have to accept that, at times, epileptiform discharges may have a blunted "triphasic morphology," and that there may be great difficulty in distinguishing between these often similar forms. The aim of this review was to describe the evolution in our understanding of triphasic waves that has occurred regarding the pathophysiology of triphasic waves, their most frequent causes, and the diagnostic difficulties involved in interpretation and differentiation from nonconvulsive status epilepticus.

Electroencephalography of encephalopathy in patients with endocrine and metabolic disorders

Patients with acute alteration in mental status from encephalopathy because of underlying metabolic-toxic or endocrine abnormalities are frequently seen in the acute hospital setting. A rapid diagnosis and correction of the underlying cause is essential as a prolonged state of encephalopathy portends a poor outcome. Correct diagnosis and management remain challenging because several encephalopathies may present similarly, and further laboratory, imaging, or other testing may not always reveal the underlying cause. EEG provides rapid additional information on the encephalopathic patient. It may help establish the diagnosis and is indispensable for identifying nonconvulsive status epilepticus, an important possible complication in this context. The EEG may assist the clinician in gauging the severity of brain dysfunction and may aid in predicting outcome. This review summarizes the current knowledge on EEG findings in selected metabolic and endocrine causes of encephalopathy and highlights distinct EEG features associated with particular etiologies.