Diagnosis and management of hepatic encephalopathy

Neurological Wilson's Disease Signs-Hepatic Encephalopathy or Copper Toxicosis?

Wilson's disease (WD) is a rare autosomal recessive (AR) disorder resulting from mutations in the ATP7B gene, which is responsible for the encryption of transmembrane copper transporting ATPase. The symptomatic presentation of the disease is estimated to be about 1 in 30,000. The impairment of ATP7B function results in a copper overload in hepatocytes, which further leads to liver pathology. This copper overload also occurs in other organs, most particularly in the brain. This could then cause the occurrence of neurological and psychiatric disorders. Symptoms differ substantially and most often occur between the ages of 5 and 35 years. Early symptoms are commonly hepatic, neurological, or psychiatric. While disease presentation is most often asymptomatic, it could also range as far as to include fulminant hepatic failure, ataxia, and cognitive disorders. Various treatments are available for Wilson's disease, including chelation therapy and zinc salts, which can reverse copper overload through different mechanisms. In select cases, liver transplantation is recommended. New medications, such as tetrathiomolybdate salts, are currently being investigated in clinical trials. With prompt diagnosis and treatment, prognosis is favorable; however, diagnosing patients before the onset of severe symptoms is a significant concern. Early screening for WD could help in diagnosing patients earlier and improving treatment outcomes.

Nitazoxanide versus rifaximin in preventing the recurrence of hepatic encephalopathy: A randomized double-blind controlled trial

BACKGROUND/PURPOSE

Hepatic encephalopathy (HE) is a neuropsychiatric complication of liver cirrhosis. HE is associated with poor survival and detrimental effects on quality of life (QOL). The drawbacks of the long-term use of rifaximin in HE necessitates searching for alternative therapies. In this context, our study aimed at evaluating the safety and efficacy of nitazoxanide (NTZ) as compared to rifaximin (RFX) in preventing the recurrence of HE and assessing its impact on QOL.

PATIENTS AND METHODS

This prospective, randomized, double-blind controlled study included 60 patients who were randomly assigned to receive either rifaximin 550 mg twice daily (group 1; n = 30) or nitazoxanide 500 mg twice daily (group 2; n = 30) for 24 weeks. During the study period, the patients' neurological symptoms, mental status, and performance were monitored. The serum levels of HE triggers (ammonia, TNF-α, and octopamine) were assessed. The patients' health-related quality of life was also evaluated.

RESULTS

Six months after treatment, patients on NTZ therapy showed a statistically significant improvement in CHESS score and mental status. NTZ provided 136 days of remission vs 67 days of remission for patients on RFX (P₁  = .0001) and significant reduction in Child score (P₁  = .018). Additionally, NTZ showed a statistically significant decrease in serum ammonia, TNF-α, and octopamine levels as compared to rifaximin. Regarding QOL, NTZ group showed an improvement in total Chronic Liver Disease Questionnaire (CLDQ) score. Both groups experienced minor controllable side effects.

CONCLUSION

Nitazoxanide may represent a suitable and safe alternative therapy to rifaximin in preventing the recurrence of hepatic encephalopathy.

The critical role of hippocampal dopamine in the pathogenesis of hepatic encephalopathy

The pathogenesis of hepatic encephalopathy (HE) has been generally linked to blood ammonia, gamma-aminobutyric acid and serotonin. However, the exact mechanism remains unclear. In the present study, we aimed to explore the role of hippocampal dopamine (DA) and its receptors in the pathogenesis of HE through the use of behavioral testing, western blotting, and immunofluorescence staining in normal rats, HE model rats and rats treated with the DA precursor-levodopa (L-DOPA). HE model rats manifested fibrotic livers and showed serious behavioral disorders. They also had significantly lower hippocampal DA content and increased expression of both D1 and D2 receptors relative to normal rats. After treatment with L-DOPA, the HE model rats showed normal behavior and expression of D1 returned to normal levels. Furthermore, pretreatment with the D1 antagonist SCH23390 blocked the therapeutic effect of L-DOPA on behavior in HE model rats. Taken together, these results clarify that the decrease in hippocampal DA plays a role in the pathogenesis of HE and that this effect is mediated by D1. These findings provide new evidence for the pathogenesis of HE.

A model of blood-ammonia homeostasis based on a quantitative analysis of nitrogen metabolism in the multiple organs involved in the production, catabolism, and excretion of ammonia in humans

Increased blood ammonia (NH₃) is an important causative factor in hepatic encephalopathy, and clinical treatment of hepatic encephalopathy is focused on lowering NH₃. Ammonia is a central element in intraorgan nitrogen (N) transport, and modeling the factors that determine blood-NH₃ concentration is complicated by the need to account for a variety of reactions carried out in multiple organs. This review presents a detailed quantitative analysis of the major factors determining blood-NH₃ homeostasis – the N metabolism of urea, NH₃, and amino acids by the liver, gastrointestinal system, muscle, kidney, and brain – with the ultimate goal of creating a model that allows for prediction of blood-NH₃ concentration. Although enormous amounts of NH₃ are produced during normal liver amino-acid metabolism, this NH₃ is completely captured by the urea cycle and does not contribute to blood NH₃. While some systemic NH₃ derives from renal and muscle metabolism, the primary site of blood-NH₃ production is the gastrointestinal tract, as evidenced by portal vein-NH₃ concentrations that are about three times that of systemic blood. Three mechanisms, in order of quantitative importance, release NH₃ in the gut: 1) hydrolysis of urea by bacterial urease, 2) bacterial protein deamination, and 3) intestinal mucosal glutamine metabolism. Although the colon is conventionally assumed to be the major site of gut-NH₃ production, evidence is reviewed that indicates that the stomach (via Helicobacter pylori metabolism) and small intestine and may be of greater importance. In healthy subjects, most of this gut NH₃ is removed by the liver before reaching the systemic circulation. Using a quantitative model, loss of this “first-pass metabolism” due to portal collateral circulation can account for the hyperammonemia observed in chronic liver disease, and there is usually no need to implicate hepatocyte malfunction. In contrast, in acute hepatic necrosis, hyperammonemia results from damaged hepatocytes. Although muscle-NH₃ uptake is normally negligible, it can become important in severe hyperammonemia. The NH₃-lowering actions of intestinal antibiotics (rifaximin) and lactulose are discussed in detail, with particular emphasis on the seeming lack of importance of the frequently emphasized acidifying action of lactulose in the colon.