Hepatic Encephalopathy

Overview
  • Hepatic Encephalopathy refers to a characteristic neurological syndrome associated with advanced hepatic failure.
Pathogenesis
  • Alimentary tract bacteria produce a wide variety of neurotoxic compounds that are normally metabolized by the liver. In the context of advanced failure the liver may have a reduced functional capacity to metabolize these compounds. Additionally, development of extensive portosystemic shunts in advanced liver disease allows neurotoxin-laden blood from the gut to completely bypass the liver and enter the systemic circulation. Originally, it was thought that the neurological symptoms of hepatic encephalopathy were due to hyperammonemia caused by an inability of the failing liver to metabolize blood ammonia. However, in recent years doubt has been cast upon the connection between high blood ammonia levels and the neurologic deficits associated with hepatic failure.
Clinical Consequences
  • Hepatic encephalopathy manifests as a characteristic neurological syndrome in patients with advanced liver failure. The syndrome typically manifests with altered mental status and behavioral changes such as excitability, confusion, somnolence, or if untreated ultimately coma. A classic sign of hepatic encephalopathy is "asterxis" which refers to a a characteristic flapping tremor in the hand elicited when the wrist is extended (dorsiflexed). Over time, significant brain edema can occur which without rapid management can lead to cerebral herniation.