Non-Cirrhotic Hepatic Encephalopathy Presenting as a Spontaneous Intrahepatic Porto-systemic Shunt

Abstract

Hepatic encephalopathy (HE) is a common manifestation of cirrhosis, which is treated medically. Cirrhotic patients who require TIPS may also develop HE. Spontaneous porto-systemic shunts are a rare occurrence. In patients without liver disease they can be either congenital or spontaneous. Many go undetected if patients are asymptomatic. We present a case of a non-cirrhotic patient with a spontaneous intrahepatic porto-systemic shunt presenting with encephalopathy. A 58-year-old female presented with acute onset encephalopathy and concern for seizures. She underwent an EEG which was consistent with complex partial status epilepticus. She had an ammonia level of 56 but ranged as high as 110 mcmol/L. Liver function tests, PT/INR were within normal limits. She had no prior history of liver disease. She was not on any medications to cause hyperammonemia. She was started on AEDs and lactulose but continued to have cognitive deficits, trouble with short-term memory, concentration and balance. An LP was performed and revealed pleocytosis. Neurology felt her presentation and symptomology was consistent with autoimmune/paraneoplastic encephalitis and she was placed on IV steroids. A paraneoplastic antibody panel was unrevealing. She was referred to Hepatology for evaluation of persistent hyperammonemia. Workup revealed a large porto-hepatic shunt on CT scan. Chronic liver disease workup was unremarkable. Symptoms persisted despite medical treatment for hyperammonemia. She was referred to Interventional Radiology for embolization of her spontaneous intrahepatic porto-systemic shunt as there was suspicion that her symptoms and presentation were due to non-cirrhotic hepatic encephalopathy secondary to the intrahepatic shunt. She underwent a successful embolization. Her ammonia levels normalized. She has had an improvement in her symptoms and has been without overt encephalopathy. She also remains seizure free. Further follow up will be needed to assess for concurrent autoimmune/paraneoplastic encephalitis versus symptoms entirely due to her porto-systemic shunt. Spontaneous intrahepatic porto-systemic shunts are rare with many patients being asymptomatic. Mildly symptomatic patients are initially managed conservatively with medications and dietary modifications, however if symptoms persist or are severe enough, they may require intervention such as IR guided embolization to redistribute blood flow within the portal system.Figure: large shunt between the right portal and hepatic veins.Figure: Portal venography demonstrating large portal vein-hepatic vein shunt with poor parenchymal opacification of the liver giving preferential flow through the shunt rather than into native intrahepatic portal veins.Figure: Following embolization there was near complete occlusion of the shunt itself with preferential flow into the intrahepatic portal veins. Following shunt embolization marked improvement in the degree of hepatic parenchymal opacification was noted.