A 73-Year-Old Woman With Hyperammonemic Encephalopathy Caused by Noncirrhotic Congenital Portosystemic Shunts

A 73-year-old woman with hyperammonemic encephalopathy presented with recurrent, transient episodes of diminished memory and confusion that lasted for 2–3 days. Except for ammonia levels of 208.7 μ mol/L (normal range 10.71–32.13 µmol/L), the laboratory tests, including all liver tests, were normal. Neuropsychological assessment showed cognitive decline (4/30 on Mini-Mental State Examination and 1/30 on Montreal Cognitive Assessment). EEG showed triphasic waves, which disappeared along with clinical remission. MRI showed bilateral symmetrical lesions in cortex, cingulate, lentiform nucleus, and insular (figure 1).1 Abdominal CT angiography found congenital portosystemic shunts connecting the superior mesenteric vein and the inferior vena cava, without liver cirrhosis signs (figure 2).2