Portosystemic encephalopathy, also known as hepatic encephalopathy (HE), is defined as a neuropsychiatric syndrome that can develop in patients with a portosystemic shunt. A patient with liver dysfunction having neuropsychiatric signs and symptoms should be considered as having hepatic encephalopathy until proven otherwise.
In a portosystemic shunt, blood from the splanchnic venous circulation is shunted to collateral venous drainage instead of passing through hepatic sinusoids. A portosystemic shunt can be congenital or acquired. Congenital portosystemic shunts are rare and could be extrahepatic or intrahepatic. A portosystemic shunt is called congenital when there is no history of cirrhosis, portal hypertension, or portal vein thrombosis. The acquired portosystemic shunt is usually caused by portal hypertension due to cirrhosis of the liver in end-stage liver disease. Acquired and congenital portosystemic shunt both can present with hepatic encephalopathy.
Due to the shunt, ammonia, and other neurotoxins that usually get metabolized in the liver, bypass and cross the blood-brain barrier leading to the accumulation of neurotoxins in the brain, causing cognitive and psychomotor disturbances.
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