Definition and Classification SINCE the precise etiology of hepatic coma is unknown, any discussion of pathogenesis requires a definition and brief description of the clinical entity, a listing of the predisposing and precipitating factors, and a careful review of the biochemical and physiological alterations taking place.1 Hepatic coma is a disorder of consciousness occurring in patients with severe liver disease; a neuropsychiatric disturbance with no striking anatomic basis. The manifestations may be extreme, yet are entirely reversible, and the brain does not show pathologic changes that will account for the symptoms.2 Episodes of hepatic coma may be classified as spontaneous or induced, or alternatively as endogenous or exogenous in origin. The clinical manifestations of both types are similar, a fact that often makes their differentiation difficult. The spontaneous cases have no evident precipitating factor, being simply the final consequence of practically complete liver cell destruction. The induced cases