Intrahepatic portosystemic venous shunt: occurrence in patients with and without liver cirrhosis.

Portosystemic venous shunt within the hepatic parenchyma is rare, and its cause is disputed. Only 12 cases have been reported in the literature. Four new patients are presented here, all of whom had cerebral manifestations due to elevated blood-ammonia levels. One patient, initially misdiagnosed as having a psychiatric disorder, had multiple small portohepatic venous shunts in the peripheral hepatic parenchyma that were believed to be congenital in origin. The other three patients with clinical evidence of cirrhosis and portal hypertension had large tubular shunts between the posterior branch of the portal vein and the inferior vena cava. Shunts of this type were considered to be the collateral pathways developed in the hepatic parenchyma as a result of portal hypertension. The diagnosis of intrahepatic portosystemic venous shunts was established by angiography in all four patients. Sonography and CT failed to show the multiple small shunts, but did provide diagnostic information concerning the large tubular shunts. Intrahepatic portosystemic venous shunt can be the cause of hepatic encephalopathy. One should be familiar with the typical radiographic manifestations of this condition to prevent misdiagnosis as a psychiatric or neurologic disorder.