Congenital Portal Systemic Encephalopathy Misdiagnosed as Senile Dementia

Congenital portal systemic encephalopathy without liver cirrhosis and/or portal hypertension is rare. An 86-year-old man with senile dementia was admitted due to disturbance of consciousness. His serum ammonia level was high, but there was no evidence of liver cirrhosis or portal hypertension on laboratory tests and upper abdominal enhanced computed tomography (CT). However, on lower abdominal enhanced CT, a meso-caval shunt was found in the right lower abdomen. Superior mesenteric arteriography revealed a shunt flowing into the inferior vena cava via the right gonadal vein. The shunt was closed by balloon occluded retrograde transvenous obliteration, and dementia-like symptoms improved.