Recent developments in the pathophysiology and treatment of hepatic encephalopathy

Update on the Therapeutic Management of Hepatic Encephalopathy

PURPOSE OF REVIEW

Hepatic encephalopathy (HE) is a common and devastating complication to chronic liver disease. In this paper, we summarize the latest research and evidence of both conventional and up-coming treatments.

RECENT FINDINGS

Meta-analyses report beneficial effects of lactulose, branched-chain amino acids, rifaximin, and to some degree L-ornithine L-aspartate on the manifestations of HE in patients with cirrhosis, and generally the numbers needed to treat are low. Recent studies on newer HE treatments including ornithine phenylacetate, spherical carbon, and fecal microbiota transplant also report potentially beneficial effects on HE manifestations. The conventional treatments benefit patients with HE. Newer treatments are under study and more research is needed for their validation.

Differential regional responsiveness of astroglia in mild hepatic encephalopathy: An Immunohistochemical approach in bile duct ligated rat

Hepatic encephalopathy (HE) is a neuropsychiatric disorder that occurs in both acute and chronic liver failure. However, the pathomechanisms of the disease remains obscure. Neuropathological studies have demonstrated a primary gliopathy in humans as well as in animal models of chronic and acute liver failure. Here, we have investigated in an animal model of mild HE: the bile duct ligated rat (BDL) at the cirrhotic stage (4 weeks after surgery), the expression of the key marker of mature astrocytes; the glial fibrillary acidic protein (GFAP) in different brain areas such as: Substantia nigra pars compacta (SNc), Ventral tegmental area (VTA), hippocampus, dorsal striatum and brain cortex by means of immunohistochemistry. The immunohistochemical study showed, in BDL compared to the operated controls (shams), a diminished astrocyte reactivity corresponding to a loss of GFAP expression within SNc, VTA, hippocampus and dorsal striatum (p<0.05),whereas in the brain cortex astrocytes appeared strongly immunoreactive with increased GFAP expression (p<0.05) as compared to shams. Our finding demonstrated differential astroglial responses which depend to the specificity of the area investigated and its particular neuronal neighboring environment, and could have possible outcomes on the diverse neuronal functions especially those observed during the different episodes of hepatic encephalopathy.

Helicobacter pylori infection in hepatic encephalopathy: Relationship to plasma endotoxins and blood ammonia

BACKGROUND/AIM

Hepatic encephalopathy (HE) is frequently observed in patients with advanced liver disease and manifests a wide variety of neuropsychiatric signs and symptoms. Ammonia toxicity and bacterial endotoxins have been suggested as key determinants of HE onset whereas a role for Helicobacter pylori infection has not been established. We investigated the correlation between H. pylori infection and HE severity (evaluated through functional tests) in 60 outpatients with established liver cirrhosis and 20 non-cirrhotic controls.

METHODS

Fasting arterial blood ammonia, plasma endotoxins, and H. pylori infection status were investigated in all subjects.

RESULTS

H. pylori infection was documented in 35/60 (58%) patients and in 6/20 (30%) controls (P = 0.039). Significant differences were observed between patients with and withoutHE for age, presence of ascites, fasting arterial blood ammonia, plasma endotoxin, and H. pylori infection. Further, a significant increase in fasting arterial blood ammonia and plasma endotoxin was associated with H. pylori infection in cirrhotic patients. Last, medical treatment of H. pylori infection led to a significant decrease in HE severity and fasting arterial blood ammonia levels.

CONCLUSION

In conclusion, we submit that H. pylori infection might, in fact, play a role in increasing the circulating levels of ammonia and endotoxins in cirrhotic patients, thus facilitating the onset of HE.

Portosystemic shunts versus endoscopic therapy for variceal rebleeding in patients with cirrhosis

BACKGROUND

Randomised clinical trials have compared portosystemic shunting procedures with endoscopic therapy for variceal haemorrhage, but there is no consensus as to which approach is preferable.

OBJECTIVES

To compare the effects of shunts (total surgical shunt (TS); distal spleno-renal shunts (DSRS) or transjugular intrahepatic porto-systemic shunts (TIPS) with endoscopic therapy (ET, sclerotherapy and/or banding) for prevention of variceal rebleeding in patients with cirrhosis.

SEARCH STRATEGY

The Cochrane Hepato-Biliary Group Controlled Trials Register, The Cochrane Library, MEDLINE, EMBASE, conference proceedings, and the references of identified trials were searched (last search February 2004). Researchers in the field and in industry were contacted.

SELECTION CRITERIA

Randomised clinical trials comparing TS, DSRS or TIPS with ET in patients who had recovered from a variceal haemorrhage and were known to be cirrhotic.

DATA COLLECTION AND ANALYSIS

Data were collected to allow intention-to-treat analysis where possible. For each outcome, a pooled estimate of treatment effect (log hazard ratio for time to outcome, Peto odds ratio for binary outcomes, and differences in means for continuous outcomes) across trials was calculated.

MAIN RESULTS

Twenty-two trials evaluating 1409 patients were included. All trials had problems of method. Shunt therapy compared with ET demonstrated significantly less rebleeding (OR 0.24, 95% CI 0.18 to 0.30) at the cost of significantly increased acute hepatic encephalopathy (OR 2.07, 95% CI 1.59 to 2.69) and chronic encephalopathy (OR 2.09, 95% CI 1.20 to 3.62). There were no significant differences regarding mortality (hazard ratio 1.00, 95% CI 0.82 to 1.21) and duration of in-patient stay (weighed mean difference 0.78 day, 95% CI -1.48 to 3.05). The proportion of patients with shunt occlusion or dysfunction was 3.1% (95% CI 0.4 to 10.7%) following TS (two trials), 7.8% (95% CI 3.8 to 13.9%) following DSRS (four trials), and 59% (range 18% to 72%) following TIPS (14 trials).

AUTHORS' CONCLUSIONS

All shunts resulted in a significantly lower rebleeding rate at the expense of a higher incidence of encephalopathy. TIPS was complicated by a high incidence of shunt dysfunction. No survival advantage was demonstrated with any shunt.

Portosystemic shunts versus endoscopic therapy for variceal rebleeding in patients with cirrhosis

BACKGROUND

Randomised clinical trials have compared portosystemic shunting procedures with endoscopic therapy for variceal haemorrhage, but there is no consensus as to which approach is preferable.

OBJECTIVES

To compare the effects of shunts (total surgical shunt (TS); distal spleno-renal shunts (DSRS) or transjugular intrahepatic porto-systemic shunts (TIPS) with endoscopic therapy (ET, sclerotherapy and/or banding) for prevention of variceal rebleeding in patients with cirrhosis.

SEARCH STRATEGY

The Cochrane Hepato-Biliary Group Controlled Trials Register, The Cochrane Library, MEDLINE, EMBASE, conference proceedings, and the references of identified trials were searched (last search February 2004). Researchers in the field and in industry were contacted.

SELECTION CRITERIA

Randomised clinical trials comparing TS, DSRS or TIPS with ET in patients who had recovered from a variceal haemorrhage and were known to be cirrhotic.

DATA COLLECTION AND ANALYSIS

Data were collected to allow intention-to-treat analysis where possible. For each outcome, a pooled estimate of treatment effect (log hazard ratio for time to outcome, Peto odds ratio for binary outcomes, and differences in means for continuous outcomes) across trials was calculated.

MAIN RESULTS

Twenty-two trials evaluating 1409 patients were included. All trials had problems of method. Shunt therapy compared with ET demonstrated significantly less rebleeding (OR 0.24, 95% CI 0.18 to 0.30) at the cost of significantly increased acute hepatic encephalopathy (OR 2.07, 95% CI 1.59 to 2.69) and chronic encephalopathy (OR 2.09, 95% CI 1.20 to 3.62). There were no significant differences regarding mortality (hazard ratio 1.00, 95% CI 0.82 to 1.21) and duration of in-patient stay (weighed mean difference 0.78 day, 95% CI -1.48 to 3.05). The proportion of patients with shunt occlusion or dysfunction was 3.1% (95% CI 0.4 to 10.7%) following TS (two trials), 7.8% (95% CI 3.8 to 13.9%) following DSRS (four trials), and 59% (range 18% to 72%) following TIPS (14 trials).

AUTHORS' CONCLUSIONS

All shunts resulted in a significantly lower rebleeding rate at the expense of a higher incidence of encephalopathy. TIPS was complicated by a high incidence of shunt dysfunction. No survival advantage was demonstrated with any shunt.

Non-absorbable disaccharides for hepatic encephalopathy: systematic review of randomised trials

OBJECTIVE

To assess the effects of non-absorbable disaccharides (lactulose and lactitol) in patients with hepatic encephalopathy.

DATA SOURCES

Cochrane Hepato-Biliary Group controlled trials register, Cochrane Library, Medline, and Embase until March 2003; reference lists of relevant articles; authors and pharmaceutical companies.

REVIEW METHODS

Randomised trials that compared non-absorbable disaccharides with placebo, no intervention, or antibiotics for hepatic encephalopathy were included. The primary outcome measures were no improvement of hepatic encephalopathy and all cause mortality.

RESULTS

22 trials were included. Compared with placebo or no intervention, non-absorbable disaccharides seemed to reduce the risk of no improvement in patients with hepatic encephalopathy (relative risk 0.62, 95% confidence interval 0.46 to 0.84, six trials). However, high quality trials found no significant effect (0.92, 0.42 to 2.04, two trials). Compared with placebo or no intervention, non-absorbable disaccharides had no significant effect on mortality (0.41, 0.02 to 8.68, four trials). Non-absorbable disaccharides were inferior to antibiotics in reducing the risk of no improvement (1.24, 1.02 to 1.50, 10 trials) and lowering blood ammonia concentration (weighted mean difference 2.35 micromol/l, 0.06 micromol/l to 13.45 micromol/l, 10 trials). There was no significant difference in mortality (0.90, 0.48 to 1.67, five trials).

CONCLUSIONS

There is insufficient evidence to support or refute the use of non-absorbable disaccharides for hepatic encephalopathy. Antibiotics were superior to non-absorbable disaccharides in improving hepatic encephalopathy, but it is unclear whether this difference is clinically important. Non-absorbable disaccharides should not serve as comparator in randomised trials on hepatic encephalopathy.

Nonabsorbable disaccharides for hepatic encephalopathy

BACKGROUND

Nonabsorbable disaccharides (lactulose or lactitol) are considered the treatment of choice for hepatic encephalopathy.

OBJECTIVES

To assess the beneficial and harmful effects of nonabsorbable disaccharides for patients with hepatic encephalopathy.

SEARCH STRATEGY

Trials were identified through The Cochrane Hepato-Biliary Group Controlled Trials Register (March 2003), The Cochrane Central Register of Controlled Trials (Issue 1, 2003), MEDLINE (1966 to 2003/03), EMBASE (1980 to 2003/03), manual searches of bibliographies and journals, authors of trials, and pharmaceutical companies.

SELECTION CRITERIA

Randomised trials comparing lactulose or lactitol versus no intervention, placebo, or antibiotics and trials comparing lactulose versus lactitol for hepatic encephalopathy.

DATA COLLECTION AND ANALYSIS

The primary outcome measures included no improvement of hepatic encephalopathy and all-cause mortality. Binary outcomes are reported as relative risks (RR) based on a random effects model. Subgroup analyses were performed with regard to methodological quality and form of hepatic encephalopathy.

MAIN RESULTS

Thirty trials assessed nonabsorbable disaccharides versus placebo, no intervention, or antibiotics or assessed lactulose versus lactitol. We could not extract data from all trials. Compared with placebo or no intervention, nonabsorbable disaccharides had no statistically significant effect on mortality (RR 0.41, 95% CI 0.02 to 8.68, four trials), but appeared to reduce the risk of no improvement of hepatic encephalopathy (RR 0.62, 95% CI 0.46 to 0.84, six trials). However, this result may reflect bias due to low methodological quality of the majority of included trials. Trials of high methodological quality found no significant effect of nonabsorbable disaccharides on the risk of no improvement (RR 0.92, 95% CI 0.42 to 2.04, two trials). We found no statistically significant difference between lactulose and lactitol on mortality (two trials) or risk of no improvement (four trials). However, our meta-analyses were underpowered to establish whether these treatments have comparable effect. Nonabsorbable disaccharides appeared to be inferior to antibiotics on reducing the risk of no improvement (RR 1.24, 95% CI 1.02 to 1.50, 10 trials).

REVIEWERS' CONCLUSIONS

This systematic review questions the beneficial effects of nonabsorbable disaccharides and highlights that there is insufficient high-quality evidence to support this treatment. We found that antibiotics appeared to be superior to nonabsorbable disaccharides in improving hepatic encephalopathy, but it is unclear whether this difference in treatment effect is clinically important to patients. Nonabsorbable disaccharides should not serve as comparator in randomised trials on hepatic encephalopathy.

Pathophysiology of Hepatitis C and HIV Coinfection

Hepatitis C infection is the most common cause of chronic hepatitis that can lead to cirrhosis and hepatocellular cancer. Hepatitis C virus infects approximately 70 million people worldwide. Hepatitis C is usually transmitted by injection drug use and blood transfusion. Hepatitis C is prevalent in HIV-infected individuals. Coinfection complicates the treatment of these two distinct viral infections. Understanding the normal functions of the liver and the pathophysiological effects of coinfection enables health care professionals to provide the highest level of care for these individuals.

Brain histamine levels and neocortical slow-wave activity in rats with portacaval anastomosis

To determine whether the increased histamine levels in the brain of rats with portacaval anastomosis (PCA) are associated with the development of sleep disturbances during the light phase, the neocortical slow-wave activity of PCA-operated rats was examined with electroencephalography (EEG) 1 month and 6 months after the surgery. The tissue levels of histamine, tele-methylhistamine, 5-hydroxytryptamine (5-HT) (serotonin), and 5-hydroxyindole-3-acetic acid (5-HIAA) in frontal cortex were assayed by high-performance liquid chromatography 6 months after the surgery. PCA surgery led to changes in the synchronized, low-frequency, high-amplitude frontal cortex EEG activity recorded during the light phase. Delta-wave amplitude but not delta time was significantly decreased, whereas both spindle amplitude and spindling time were significantly decreased. There were also significant age-related changes, presented as increases in the duration of spindles and the amplitude of both delta waves and spindles. PCA-operated rats showed a change in the pattern of EEG activity with increasing age similar to sham-operated rats. This suggests that once established, the resetting of the systems regulating the sleep-waking behavior is being maintained with time. The tissue levels of both histamine and metabolite in the frontal cortex were increased, whereas the serotonin system showed only an increase in the level of the metabolite. There was a significant negative correlation between the spindling time and the tissue histamine levels. We suggest that histamine, which participates in the control of vigilance, sleep, and wakefulness, as well as in the modulation of circadian rhythmicity, may play a role in the development of sleep disturbances in rats with PCA.