Critical flicker frequency: it is time to break down barriers surrounding minimal hepatic encephalopathy

Current vision on diagnosis and comprehensive care in hepatic encephalopathy

The first clinical guidelines on hepatic encephalopathy were published in 2009. Almost 14 years since that first publication, numerous advances in the field of diagnosis, treatment, and special condition care have been made. Therefore, as an initiative of the Asociación Mexicana de Gastroenterología A.C., we present a current view of those aspects. The manuscript described herein was formulated by 24 experts that participated in six working groups, analyzing, discussing, and summarizing the following topics: Definition of hepatic encephalopathy; recommended classifications; epidemiologic panorama, worldwide and in Mexico; diagnostic tools; conditions that merit a differential diagnosis; treatment; and primary and secondary prophylaxis. Likewise, these guidelines emphasize the management of certain special conditions, such as hepatic encephalopathy in acute liver failure and acute-on-chronic liver failure, as well as specific care in patients with hepatic encephalopathy, such as the use of medications and types of sedation, describing those that are permitted or recommended, and those that are not.

Hepatic encephalopathy

Hepatic encephalopathy (HE) is a prognostically relevant neuropsychiatric syndrome that occurs in the course of acute or chronic liver disease. Besides ascites and variceal bleeding, it is the most serious complication of decompensated liver cirrhosis. Ammonia and inflammation are major triggers for the appearance of HE, which in patients with liver cirrhosis involves pathophysiologically low-grade cerebral oedema with oxidative/nitrosative stress, inflammation and disturbances of oscillatory networks in the brain. Severity classification and diagnostic approaches regarding mild forms of HE are still a matter of debate. Current medical treatment predominantly involves lactulose and rifaximin following rigorous treatment of so-called known HE precipitating factors. New treatments based on an improved pathophysiological understanding are emerging.

Impact of sustained viral response in the evolution of minimal hepatic encephalopathy: A prospective pilot study

INTRODUCTION AND AIMS

To determine the prevalence of minimal hepatic encephalopathy(MHE) in patients with liver cirrhosis (LC) due to hepatitis C virus (HCV) infection and to evaluate the impact of sustained viral response (SVR) on MHE.

MATERIALS AND METHODS

We performed a prospective study using MHE screening and follow-up on patients with HCV and LC. The patients were evaluated at the beginning of treatment and 24 weeks after treatment.

RESULTS

64 patients were included. 51.6% were male, the median age was 62 years, Child-Pugh classification A/B/C 93.8%/4.7%/1.6% and median MELD was 8.3. Prior hydropic decompensation was present in 11 patients. Median values of liver stiffness, as measured by transient elastography (TE) were 22.8kPa. Indirect signs of portal hypertension (PH) were present in 53.1% of patients, with a mean of 11.9mmHg among the ones with a measurement of the hepatic venous pressure gradient. The prevalence of MHE before treatment was 26.6%. After treatment, 98.4% of patients achieved SVR. The presence of MHE at 24 weeks post-treatment had an statistically significant association with the presence of pre-treatment MHE (80% vs. 21.6%; p<0.01), higher MELD scores at 24-weeks post-treatment (9.8 vs. 8; p=0.02), higher Child-Pugh scores at 24-weeks post-treatment (p=0.04), higher baseline INR levels (1.4 vs. 1.1; p<0.001) and with the presence of indirect signs of PH (100% vs. 47.1%; p=0.02). During follow-up, those patients without MHE at 24 weeks post-treatment had a higher probability of experiencing an improvement in post-treatment TE (80.9% vs. 40%, p=0.04).

CONCLUSION

We found that SVR may lead to MHE resolution in a considerable proportion of patients, which has potential implications for disease prognosis.

Minimal Hepatic Encephalopathy: Effect of H. pylori infection and small intestinal bacterial overgrowth treatment on clinical outcomes

The effect Helicobacter pylori (Hp) infection and small intestinal bacterial over growth (SIBO) in minimal hepatic encephalopathy (MHE) is not well understood. The aim of the study was to determine the effect of eradication of Hp infection and SIBO treatment on MHE in patients with cirrhosis. Patients with cirrhosis were enrolled and MHE was determined by psychometric tests and critical flicker frequency analysis. Hp infection and SIBO were assessed by urea breath and Hydrogen breath tests respectively in patients with cirrhosis and in healthy volunteers. Patients with Hp infection and SIBO were given appropriate treatment. At six weeks follow-up, presence of Hp infection, SIBO and MHE status was reassessed. Ninety patients with cirrhosis and equal number of healthy controls were included. 55 (61.1%) patients in the cirrhotic group were diagnosed to have underlying MHE. Among cirrhotic group, Hp infection was present in 28 with MHE (50.9%) vs. in 15 without MHE (42.8%) (p = 0.45). Similarly, SIBO was present in 17 (30.9%) vs. 11 (31.4%) (p = 0.95) in patients with and without MHE respectively. In comparison with healthy controls, patients with cirrhosis were more frequently harboring Hp and SIBO (47.7% vs. 17.7% (p < 0.001) and 31.1% vs. 4.4% (p < 0.001) respectively. On follow-up, all patients showed evidence of eradication of Hp and SIBO infection. Treatment of SIBO significantly improved the state of MHE in cirrhotics, however eradication of Hp infection did not improve MHE significantly. Additionally, patients with low Model for End-Stage Liver Disease (MELD) score and belonging to Child class B had significantly better improvement in MHE. A large number of patients with cirrhosis had either active Hp infection or SIBO with or without MHE, compared to healthy controls. Treatment of SIBO significantly improved MHE in patients with cirrhosis, whereas eradication of Hp did not affect the outcome of MHE in these patients.

Hepatic encephalopathy 2018: A clinical practice guideline by the Italian Association for the Study of the Liver (AISF)

Hepatic encephalopathy (HE) is a common, worrisome and sometimes difficult to manage complication of end-stage liver disease. HE is often recurrent, requiring multiple hospital admissions. It can have serious implications in terms of a patient's ability to perform complex tasks (for example driving), their earning capacity, their social and family roles. This guideline reviews current knowledge on HE definition, pathophysiology, diagnosis and treatment, both by general principles and by way of a summary of available drugs and treatment strategies. The quality of the published, pertinent evidence is graded, and practical recommendations are made. Where possible, these are placed within the Italian health service context, with reference to local diagnosis and management experience.

Impact of Sustained Viral Response in the Evolution of Minimal Hepatic Encephalopathy: a Prospective Pilot Study

INTRODUCTION AND AIMS

To determine the prevalence of minimal hepatic encephalopathy (MHE) in patients with liver cirrhosis (LC) due to hepatitis C virus (HCV) infection and to evaluate the impact of sustained viral response (SVR) on MHE.

MATERIAL AND METHODS

We performed a prospective study using MHE screening and follow-up on patients with HCV and LC. The patients were evaluated at the beginning of treatment and 24 weeks after treatment.

RESULTS

64 patients were included. 51.6% were male, the median age was 62years, Child-Pugh classification A/B/C 93.8%/4.7%/1.6% and median MELD was 8.3. Prior hydropic decompensation was present in 11 patients. Median values of liver stiffness, as measured by transient elastography (TE) were 22.8 KPa. Indirect signs of portal hypertension (PH) were present in 53.1% of patients, with a mean of 11.9 mmHg among the ones with a measurement of the hepatic venous pressure gradient. The prevalence of MHE before treatment was 26.6%. After treatment, 98.4% of patients achieved SVR. The presence of MHE at 24weeks post-treatment had an statistically significant association with the presence of pre-treatment MHE (80% vs. 21.6%; p < 0.01), higher MELD scores at 24-weeks post-treatment (9.8 vs. 8; p = 0.02), higher Child-Pugh scores at 24-weeks post-treatment (p = 0.04), higher baseline INR levels (1.4 vs. 1.1; p < 0.001) and with the presence of indirect signs of PH (100% vs. 47.1%; p = 0.02). During follow-up, those patients without MHE at 24weeks post-treatment had a higher probability of experiencing an improvement in post-treatment TE (80.9% vs. 40%, p = 0.04).

CONCLUSION

We found that SVR may lead to MHE resolution in a considerable proportion of patients, which has potential implications for disease prognosis.

Minimal hepatic encephalopathy: A review

Minimal hepatic encephalopathy (MHE) is the earliest form of hepatic encephalopathy and can affect up to 80% of patients with liver cirrhosis. By definition, MHE is characterized by cognitive function impairment in the domains of attention, vigilance and integrative function, but obvious clinical manifestation are lacking. MHE has been shown to affect daily functioning, quality of life, driving and overall mortality. The diagnosis can be achieved through neuropsychological testing, recently developed computerized psychometric tests, such as the critical flicker frequency and the inhibitory control tests, as well as neurophysiological procedures. Event related potentials can reveal subtle changes in patients with normal neuropsychological performances. Spectral analysis of electroencephalography (EEG) and quantitative analysis of sleep EEG provide early markers of cerebral dysfunction in cirrhotic patients with MHE. Neuroimaging, in particular MRI, also increasingly reveals diffuse abnormalities in intrinsic brain activity and altered organization of functional connectivity networks. Medical treatment for MHE to date has been focused on reducing serum ammonia levels and includes non-absorbable disaccharides, probiotics or rifaximin. Liver transplantation may not reverse the cognitive deficits associated with MHE. We performed here an updated review on epidemiology, burden and quality of life, neuropsychological testing, neuroimaging, neurophysiology and therapy in subjects with MHE.

The effects of intra-dorsal hippocampus infusion of pregnenolone sulfate on memory function and hippocampal BDNF mRNA expression of biliary cirrhosis-induced memory impairment in rats

Learning and memory impairment is one of the most challenging complications of cirrhosis and present treatments are unsatisfactory. The exact mechanism of cirrhosis cognitive dysfunction is unknown. Pregnenolone sulfate (PREGS) is an excitatory neurosteroid that acts as a N-methyl-D-aspartate (NMDA) receptor agonist and GABAA receptor antagonist. In this study we evaluated the effect of intra CA1 infusion of PREGS on cirrhotic rats' memory function using the Y-maze test. Hippocampal brain-derived neurotrophic factor (BDNF) mRNA expression was also evaluated. Three weeks after bile duct ligation (BDL) surgery, rats were under stereotaxic surgery for insertion of two guide cannulas in the CA1 region of the hippocampus. After 1-week of recovery, PREGS was administered through CA1 cannulas in cirrhotic rats, while control or sham groups received vehicle. For evaluation of NMDA receptor role in memory-enhancing effects of PREGS, DL-2-Amino-5-phosphonopentanoic acid (AP5) which is a potent and competitive antagonist of NMDA receptor, co-administered with PREGS and for assessment of hippocampal BDNF mRNA expression, quantitative Real-time reverse transcriptase-PCR (RT-PCR) was used. Results showed that 28 days after BDL, cirrhotic animals' memory significantly decreased in comparison with control and sham groups, while PREGS infusion could restore memory impairment (P<0.05). PREGS effects on memory of cirrhotic rats were antagonized by DAP5. RT-PCR findings have shown that hippocampal relative BDNF mRNA expression was up-regulated in PREGS-treated groups in comparison with the BDL group (P<0.001). Our findings suggest that PREGS has a memory-enhancing effect in cirrhosis memory deficit in acute therapy and this effect may be through NMDA (glutamate) receptor involvement and BDNF mRNA expression.

Minimal hepatic encephalopathy

Minimal hepatic encephalopathy (MHE) is the earliest form of hepatic encephalopathy and can affect up to 80% of cirrhotic patients. By definition, it has no obvious clinical manifestation and is characterized by neurocognitive impairment in attention, vigilance and integrative function. Although often not considered to be clinically relevant and, therefore, not diagnosed or treated, MHE has been shown to affect daily functioning, quality of life, driving and overall mortality. The diagnosis of MHE has traditionally been achieved through neuropsychological examination, psychometric tests or the newer critical flicker frequency test. A new smartphone application (EncephalApp Stroop Test) may serve to function as a screening tool for patients requiring further testing. In addition to physician reporting and driving restrictions, medical treatment for MHE includes non-absorbable disaccharides (eg, lactulose), probiotics or rifaximin. Liver transplantation may not result in reversal of the cognitive deficits associated with MHE.

Psychometric hepatic encephalopathy score for diagnosis of minimal hepatic encephalopathy in China

AIM: To construct normal values for the tests of the psychometric hepatic encephalopathy score (PHES) and to evaluate its usefulness in the diagnosis of minimal hepatic encephalopathy (MHE) among Chinese individuals with cirrhosis.

METHODS: The five tests of PHES, number connection test-A (NCT-A), number connection test-B, serial dotting test, line tracing test and digit symbol test (DST), were administered to all enrolled subjects in a quiet room with sufficient light. Cirrhotic subjects with overt HE were excluded by the West-Haven criteria and a detailed neurological examination. Based on the nomograms of healthy volunteers, the patients were classified as having MHE when their PHES was less than -4.

RESULTS: In total, 146 healthy volunteers completed all the PHES tests. Age and education years were confirmed to be predictors of all five tests. In total, 53 patients with liver cirrhosis completed the PHES. Of the patients with liver cirrhosis, 24 (45.3%), 22(41.5%) and 7(13.2%) had Child-Pugh grades A, B and C, respectively. MHE was diagnosed in 26 patients (49.1%). Compared with compensated cirrhotic patients (Child A), decompensated cirrhotic patients (Child B and C) had a higher proportion of MHE (65.5% vs 29.2%). No differences in age and education years were found between the MHE and non-MHE groups. NCT-A and DST were able to diagnose MHE with a sensitivity of 76.9% and a specificity of 96.3% (AUC = 0.866, K = 0.735).

CONCLUSION: The proportion of MHE is associated with liver function. NCT-A and DST are simple tools that can be used for the diagnosis of MHE in China.

Multi-dimensional MR spectroscopy: towards a better understanding of hepatic encephalopathy

Hepatic encephalopathy (HE) is normally diagnosed by neuropsychological (NP) tests. The goals of this study were to quantify cerebral metabolites, separate glutamate (Glu) from glutamine (Gln) in patients with minimal hepatic encephalopathy (MHE) as well as healthy subjects using the prior-knowledge fitting (ProFit) algorithm on data acquired by two-dimensional (2D) localized correlated spectroscopy (L-COSY) on two different MR scanners, and to correlate the metabolite changes with neuropsychological (NP) tests. We studied 14 MHE patients and 18 healthy controls using a GE 1.5 T Signa MR scanner. Another group of 16 MHE patients and 18 healthy controls were studied using a Siemens 1.5 T Avanto MR scanner. The following parameters were used for L-COSY: TR/TE = 2 s/30 ms, 3 × 3 × 3 cm(3) voxel size, 96 Δt(1) increments with 8 averages per Δt(1). Using the ProFit algorithm, we were able to differentiate Gln from Glu on the GE 1.5 T data in the medial frontal white/gray matter. The ratios of myo-inositol (mI), Glu, total choline, scyllo-inositol (sI), phosphoethanolamine (PE), and total N-acetyl aspartate (NAA) showed statistically significant decline in HE patients compared to healthy controls, while the ratio of Gln was significantly increased. Similar trend was seen in the ProFit quantified Siemens 1.5 T data in the frontal and occipito-parietal white/gray regions. Among the NP domain scores, motor function, cognitive speed, executive function and the global scores showed significant differences. Excellent correlations between various NP domains and metabolite ratios were also observed. ProFit based cerebral metabolite quantitation enhances the understanding and basis of the current hypothesis of MHE.

Critical flicker frequency fails to disclose brain dysfunction in patients with primary biliary cirrhosis

BACKGROUND

Recent studies suggest that stage-independent symptoms of primary biliary cirrhosis (PBC) such as chronic fatigue are a consequence of structural and functional abnormalities of the brain. Critical flicker frequency (CFF) is a psychophysiological modality analysing function of cerebral cortex.

AIM

To analyse the usefulness of CFF in detection of brain dysfunction in patients with PBC.

METHODS

Fifty-one (37 non-cirrhotic/14 cirrhotic) patients with PBC were included. Control group consisted of 31 matched healthy individuals. Fatigue and health-related quality of life (HRQoL) were assessed using Fatigue Impact Scale (FIS) and questionnaire PBC-40. CFF was analysed with HEPAtonorm Analyzer(®).

RESULTS

When compared to healthy controls all patients with PBC showed significantly impaired HRQoL in majority of PBC-40 domains and increased fatigue level in physical domain of FIS. No differences in HRQoL and PBC-40 domains were seen, when patients with and without cirrhosis where compared. CFF analysis showed no difference between healthy controls and patients with PBC. CFF did not correlate with PBC-40 and FIS domains.

CONCLUSION

CFF fails to determine brain dysfunction in non-encephalopatic patients with PBC, suggesting that functional efficiency of their cerebral cortex remains unaffected and other central mechanisms are responsible for chronic fatigue in these patients.

Improving the inhibitory control task to detect minimal hepatic encephalopathy

BACKGROUND & AIMS

Quantification of the number of noninhibited responses (lures) in the inhibitory control task (ICT) has been proposed for the diagnosis of minimal hepatic encephalopathy (MHE). We assessed the efficacy of ICT compared with recommended diagnostic standards.

METHODS

We studied patients with cirrhosis and healthy individuals (controls) who underwent the ICT at 2 centers (center A: n=51 patients and 41 controls, center B: n=24 patients and 14 controls). Subjects were evaluated for MHE by psychometric hepatic encephalopathy score (PHES). Patients from center B also were assessed for MHE by critical flicker frequency and spectral electroencephalogram analyses.

RESULTS

Patients with cirrhosis had higher ICT lures (23.2+/-12.8 vs 12.9+/-5.8, respectively, P<.01) and lower ICT target accuracy (0.88+/-0.17 vs 0.96+/-0.03, respectively, P<.01) compared with controls. However, lures were comparable (25.2+/-12.5 vs 21.4+/-13.9, respectively, P=.32) among patients with/without altered PHES (center A). There was a reverse, U-shaped relationship between ICT lure and target accuracy; a variable adjusting lures was devised based on target accuracy (weighted lures at center B). This variable differed between patients with and without MHE. The variable weighted lures was then validated from data collected at center A by receiver operator characteristic curve analysis; it discriminated between patients with and without PHES alterations (area under the curve=0.71+/-0.07). However, target accuracy alone was as effective as a stand-alone variable (area under the curve=0.81+/-0.06).

CONCLUSIONS

The ICT is not useful for the diagnosis of MHE, unless adjusted by target accuracy. Testing inhibition (lures) does not seem to be superior to testing attention (target accuracy) for the detection of MHE.

Pharmacotherapy of hepatic encephalopathy in cirrhosis

IMPORTANCE OF THE FIELD

Hepatic encephalopathy (HE) is a major complication encountered in nearly half of the patients with liver cirrhosis.

AREAS COVERED IN THIS REVIEW

A review of the safety and efficacy of current therapies for HE that seek to pre-empt ammonia production and/or to increase its elimination, reducing inflammation, blocking benzodiazepine-like compound production, and supporting systemic hemodynamics.

WHAT THE READER WILL GAIN

Insight into some recent advances in the management of HE that could modify our therapeutic approach to end-stage liver disease. Cirrhotic individuals during an overt HE episode require careful management, focusing on precipitant factors as well as metabolic and hemodynamic derangements.

TAKE HOME MESSAGE

Intestinal ammoniagenesis requires flora modification by antibiotics, prebiotics and probiotics; glutaminase inhibition as well as antibiotics to pre-empt systemic inflammation. Hemodynamic/fluid support is essential. Nutritional support is crucial and hypoproteinemic diets should be avoided. Blocking benzodiazepine-like compounds by the use of flumazenil could be useful in patients with severe, benzodiazepine-induced HE. Long-term rifaximin is well tolerated, does not promote resistance and could decrease overt HE bouts in patients with previous episodes of overt HE. Lactulose is better than no treatment in improving quality of life in patients with minimal HE; it also acts as secondary prophylaxis following overt HE.