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

Abstract

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

Unusual Case of Hyperammonemic Encephalopathy in Elderly Patient Without Liver Disease

“…In this case and in support of imaging, the electroencephalography (EEG) showed triphasic nonepileptiform wave patterns, that we defined as generalized, bilaterally synchronous, bifrontal periodic waves, such as dyssynchronization of fast activity, with increased dysrhythmicity, and slower delta activity followed by mixtures of slow-with-fast frequencies. These are an expression of metabolic brain distress and are seen more often in patients with encephalopathy and subcortical brain atrophy, as with our patient, than in patients with encephalopathy and no subcortical atrophy, as has already reported by several works in the literature [10,11]. The traditional treatment of hepatic encephalopathy first aims to identify and resolve the impacting agents/etiologies such as infection, gastro-intestinal bleeding, dehydration, and electrolyte disturbance.…”

Unexplained hyperammonemia and encephalopathy in the emergency department: Abernethy malformation in elderly patients

“…Unlike in children or young adults, encephalopathy is a cardinal clinical presentation in elderly people. Patients in previous studies presented with encephalopathy and had intermittent ataxia, [7,8,12] asterixis, [8,13] altered mental status, [13,14] discrepant conversation, [10] dysarthria, [12] or stupor. [7,8,12,15] Other cases are usually discovered incidentally or during work-up for liver nodules or dysfunction.…”

Extrahepatic portosystemic shunts as an unusual but treatable cause of hyperammonemic encephalopathy in a noncirrhotic patient – a case report

“…For this rare but important differential diagnosis of noncirrhotic hyperammonemic encephalopathy, special attention should be given to patients with a history of abdominal surgery or trauma, although congenital types and shunts of uncertain etiology have been described. 19 , 20 Noncirrhotic hyperammonemic encephalopathy due to portosystemic shunting has also been observed in patients with portal vein thrombosis. 21 In the reported case, postoperative shunt formation after pancreaticoduodenectomy was the most likely cause, an etiology that has been described elsewhere.…”