Hepatic encephalopathy in non-cirrhotic portal hypertension

Hepatic encephalopathy (HE) is traditionally associated with hepatic parenchymal diseases, such as acute liver failure and cirrhosis. Its prevalence in non-cirrhotic portal hypertension (NCPH) patients, extrahepatic portal vein obstruction (EHPVO), and non-cirrhotic portal fibrosis (NCPF) is less well described. HE in NCPH allows one to study the effect of portosystemic shunting and ammonia without significant hepatic parenchymal injury. The current review narrates the spectrum and management of hepatic encephalopathy in NCPH patients. We synthesized data from various studies on the occurrence and management of HE in NCPH, mainly EHPVO, idiopathic non-cirrhotic portal hypertension (INCPH), and porto-sinusoidal vascular disease (PSVD). The prevalence of minimal hepatic encephalopathy (MHE) in NCPH is reported from 12 to 60%, depending on the condition and diagnostic criteria. MHE was reported in nearly a third of EHPVO patients. Studies show that venous ammonia levels are significantly elevated in patients with MHE and spontaneous shunts (82.4 ± 20.3 vs. 47.1 ± 16.7 µmol/L, P = 0.001). Large portosystemic shunts substantially increase the risk of HE, with 46-71% of patients with persistent or recurrent HE having identifiable shunts. Management of HE in NCPH primarily focuses on reducing ammonia levels through lactulose, which has shown improvement in 53% of patients with MHE after three months (P = 0.001). Shunt occlusion in patients with large portosystemic shunts is helpful in selected cases. HE in NCPH, particularly in EHPVO, is associated with elevated ammonia levels and spontaneous shunts. Despite the high prevalence of HE in NCPH, this is still a neglected aspect in the care of NCPH. A high index of suspicion and the application of appropriate screening tools are crucial for timely diagnosis and management. HE screening tools that are well-studied in cirrhosis, are also valid in NCPH. Effective management strategies include lactulose, rifaximin, dietary modifications, and shunt embolisation in some cases. Future research should focus on the long-term natural history and efficacy of treatment strategies in this population.