Description

• Reversible altered mental and neuromotor functioning associated with acute or chronic liver disease and/or portal systemic shunting of blood
• The prominent features are confusion, impaired arousability, and a “flapping tremor” (asterixis).
• System(s) affected: Gastrointestinal; Nervous
• Synonym(s): Portosystemic encephalopathy; Hepatic coma; Liver coma

Epidemiology

Predominant sex: Male = Female (reflecting underlying liver disease)

• Occurs in 1/3 of cirrhosis cases
• Occurs in all cases of fulminant hepatic failure
• Present in nearly 1/2 of patients who require transplantation
• Parallels the age predominance of fulminant liver disease: Peaks in the 40s; cirrhosis peaks in the late 50s; may occur at any age

Risk Factors

• Infection (overt or occult, including spontaneous bacterial peritonitis)
• GI hemorrhage
• Use of sedative or opiate drugs
• Fluid or electrolyte disturbance (Na⁺, K⁺, Mg²⁺, or other electrolyte depletion)
• Transjugular intrahepatic portosystemic shunt (TIPS)

• Unknown
• Conditions such as cystic fibrosis, α-1-antitrypsin deficiency, and Wilson disease can contribute to hepatic encephalopathy (HE).

General Prevention

• Recognize early signs and seek prompt treatment.
• Avoid nonessential medications, particularly opiates and sedatives.

Pathophysiology

• Failure of liver to detoxify agents noxious to the CNS (e.g., ammonia, mercaptans, fatty acids)
• Increased aromatic and reduced branched-chain amino acids in blood
• These act as false neurotransmitters, possibly inter-acting with the γ-aminobutyric acid (GABA) receptor

Etiology

• Shunting of intestinal blood through the severely diseased liver without the intervention of viable liver cells
• Most common in long-standing cirrhosis of the liver with spontaneous shunting of intestinal blood through collateral vessels
• Shunting of such blood through collateral circulation or surgically constructed portacaval shunts
• TIPS, a widely used radiologically inserted shunt to lower portal pressure, produces HE.
• Acute onset of HE: Search for risk factors.

Commonly Associated Conditions

• Occurs rarely with portacaval shunt with normal liver function
• May occur as a complication of acute fatty liver of pregnancy