RESUMEN
An 84-year-old woman was hospitalized due to consciousness disorder as hyperammonemia. She had no etiology of liver disease. Twelve months before the current admission, she had been diagnosed with dementia based on her low level of daily perception and physical activity. Abdominal computed tomography revealed a large portosystemic shunt between the medial branch of the portal vein and middle hepatic vein. After the improvement of her consciousness disturbance by medical treatment, percutaneous shunt embolization was electively performed. The patient showed a remarkable clinical improvement. Consciousness disturbance caused by hyper-ammonemia might be underlying in dementia patients. Increase of hepatopetal portal blood flow might have contributed to the improvement of her consciousness disturbance. Embolization of the portosystemic shunt might be more effective for patients without liver disease as in the present case.