Critical flicker frequency test predicts overt hepatic encephalopathy and survival in patients with liver cirrhosis

Portal hypertension: recommendations for diagnosis and treatment. Consensus document sponsored by the Spanish Association for the Study of the Liver (AEEH) and the Biomedical Research Network Centre for Liver and Digestive Diseases (CIBERehd)

Portal hypertension is a hemodynamic abnormality that complicates the course of cirrhosis, as well as other diseases that affect the portal venous circulation. The development of portal hypertension compromises prognosis, especially when it rises above a certain threshold known as clinically significant portal hypertension (CSPH). In the consensus conference on Portal Hypertension promoted by the Spanish Association for the Study of the Liver and the Hepatic and Digestive diseases area of the Biomedical Research Networking Center (CIBERehd), different aspects of the diagnosis and treatment of portal hypertension caused by cirrhosis or other diseases were discussed. The outcome of this discussion was a set of recommendations that achieved varying degrees of consensus among panelists and are reflected in this consensus document. The six areas under discussion were: the relevance of CSPH and the non-invasive methods used for its diagnosis and that of cirrhosis, the prevention of the first episode of decompensation and its recurrence, the treatment of acute variceal bleeding and other complications of portal hypertension, the indications for the use of TIPS, and finally, the diagnosis and treatment of liver vascular diseases.

Portal hypertension: recommendations for diagnosis and treatment. Consensus document sponsored by the Spanish Association for the Study of the Liver (AEEH) and the Biomedical Research Network Center for Liver and Digestive Diseases (CIBERehd)

Portal hypertension is a hemodynamic abnormality that complicates the course of cirrhosis, as well as other diseases that affect the portal venous circulation. The development of portal hypertension compromises prognosis, especially when it rises above a certain threshold known as clinically significant portal hypertension (CSPH). In the consensus conference on Portal Hypertension promoted by the Spanish Association for the Study of the Liver and the Hepatic and Digestive diseases area of the Biomedical Research Networking Center (CIBERehd), different aspects of the diagnosis and treatment of portal hypertension caused by cirrhosis or other diseases were discussed. The outcome of this discussion was a set of recommendations that achieved varying degrees of consensus among panelists and are reflected in this consensus document. The six areas under discussion were: the relevance of clinically significant portal hypertension and the non-invasive methods used for its diagnosis and that of cirrhosis, the prevention of the first episode of decompensation and its recurrence, the treatment of acute variceal bleeding and other complications of portal hypertension, the indications for the use of TIPS, and finally, the diagnosis and treatment of liver vascular diseases.

Evaluating a Novel, Portable, Self-Administrable Device ("Beacon") That Measures Critical Flicker Frequency as a Test for Hepatic Encephalopathy

INTRODUCTION

We compared critical flicker frequency (CFF) thresholds obtained using a novel portable device "Beacon" with thresholds from the commercially available Lafayette Flicker Fusion System (Lafayette-FFS) in patients with cirrhosis.

METHODS

One hundred fifty-three participants with chronic liver disease underwent CFF testing using Beacon and Lafayette-FFS with a method-of-limits and/or forced-choice protocol.

RESULTS

Beacon demonstrated excellent test-retest reliability (intraclass correlation 0.91-0.97) and good correlation with the Lafayette-FFS values (intraclass correlation 0.77-0.84). Forced-choice CFF were on average 4.1 Hz higher than method-of-limits descending CFFs.

DISCUSSION

Beacon can be self-administered by patients with chronic liver disease and cirrhosis to measure CFF, a validated screening test for minimal hepatic encephalopathy.

Prediction and prevention of the first episode of overt hepatic encephalopathy in patients with cirrhosis

Hepatic encephalopathy (HE) is one of the most important complications of patients with liver cirrhosis. In addition, HE is associated with a dismal prognosis and has detrimental effects on patients' quality of life. Thus, it is of pivotal importance to identify patients at high risk for overt HE (OHE) in whom primary prophylaxis may be justified. In this narrative review, we aim to provide insight into predictors and prediction tools for a first-time episode of OHE and to scrutinize the current level of evidence of primary prophylaxis. In recent decades, several cognitive tests, composite scores, and blood-based biomarkers have been demonstrated to be predictive of a first-time episode of OHE. Among the best validated are the established tests for minimal HE, such as the Psychometric Hepatic Encephalopathy Score, determination of the critical flicker frequency, Stroop EncephalApp, or the Animal Naming Test. Individualized risk stratification using blood-based biomarkers and cross-sectional imaging (sarcopenia and spontaneous portosystemic shunts) is coming to the fore, but validation in larger multicenter cohorts is often lacking. On the basis of current evidence, a recommendation for primary prophylaxis of a first episode of OHE cannot be made in general. Only 2 studies have investigated the prevention of a first-time OHE episode as the primary endpoint. In this narrative review, we provide a concise overview of the current evidence levels on prediction tools and pharmacological prevention of a first episode of OHE. In addition, we give an outlook on future research targets to improve knowledge on this important topic.

Risk factors for hepatic encephalopathy and mortality in cirrhosis: The role of cognitive impairment, muscle alterations and shunts

INTRODUCTION/AIM

Muscle alterations, portosystemic shunts (SPSS) and minimal hepatic encephalopathy (MHE) are related to hepatic encephalopathy (HE), however no studies have investigated the relative role of all these risk factors detected in the same patients. The aim of the study was to assess the prognostic impact of muscle alterations, MHE and SPSS on hepatic encephalopathy and transplant free survival.

PATIENTS/METHODS

114 cirrhotics were submitted to Psychometric Hepatic Encephalopathy Score (PHES) and Animal Naming Test (ANT) to detect MHE. CT scan was used to analyze the skeletal muscle index (SMI), muscle attenuation and SPSS. The incidence of the first episode of HE and survival were estimated.

RESULTS

Previous HE was present in 47 patients (41%). The variables independently associated to previous HE were: sarcopenia, MHE and SPSS. 44 patients (39%) developed overt HE during 14±11 months; MHE and SPSS were the only variables significantly asociated to overt HE. During the same follow-up, 42 patients died (37%); MELD and sarcopenia were the only variables significantly asociated to transplant free survival.

CONCLUSIONS

MHE, sarcopenia and SPSS are clinically relevant and should be sought for in cirrhotics. In particular, MHE and SPSS are the only risk factors significantly associated to the development of HE while MELD and sarcopenia are independently associated to overall mortality.

Psychometric methods for diagnosing and monitoring minimal hepatic encephalopathy -current validation level and practical use

Hepatic encephalopathy (HE) is cerebral dysfunction caused by liver failure and inflicts 30-40% of patients with liver cirrhosis during their disease course. Clinically manifest HE is often preceded by minimal HE (MHE) - a clinically undetectable cognitive disturbance closely associated with loss of quality of life. Accordingly, detecting and treating MHE improve the patients' daily functioning and prevent HE-related hospital admissions. The scope of this review article is to create an overview of the validation level and usage of psychometric tests used to detect MHE: Portosystemic hepatic encephalopathy test, continuous reaction time test, Stroop EncephalApp, animal naming test, critical flicker frequency test, and inhibitory control test. Our work is aimed at the clinician or scientist who is about to decide on which psychometric test would fit best in their clinic, cohort, or study. First, we outline psychometric test validation obstacles and requirements. Then, we systematically approach the literature on each test and select well-conducted studies to answer the following questions:• Which percentage of patients with cirrhosis does the test deem as having MHE?• Is the test able to predict clinically manifest HE?• Is there a well-known test-retest variation and inter-observer variation?• Is the test able to detect a treatment response?• Is the test result affected by age, educational level, gender, or comorbidities?

Altered motor cortical plasticity in patients with hepatic encephalopathy: A paired associative stimulation study

OBJECTIVE

Hepatic encephalopathy (HE) is a potentially reversible brain dysfunction caused by liver failure. Altered synaptic plasticity is supposed to play a major role in the pathophysiology of HE. Here, we used paired associative stimulation with an inter-stimulus interval of 25 ms (PAS25), a transcranial magnetic stimulation (TMS) protocol, to test synaptic plasticity of the motor cortex in patients with manifest HE.

METHODS

23 HE-patients and 23 healthy controls were enrolled in the study. Motor evoked potential (MEP) amplitudes were assessed as measure for cortical excitability. Time courses of MEP amplitude changes after the PAS25 intervention were compared between both groups.

RESULTS

MEP-amplitudes increased after PAS25 in the control group, indicating PAS25-induced synaptic plasticity in healthy controls, as expected. In contrast, MEP-amplitudes within the HE group did not change and were lower than in the control group, indicating no induction of plasticity.

CONCLUSIONS

Our study revealed reduced synaptic plasticity of the primary motor cortex in HE.

SIGNIFICANCE

Reduced synaptic plasticity in HE provides a link between pathological changes on the molecular level and early clinical symptoms of the disease. This decrease may be caused by disturbances in the glutamatergic neurotransmission due to the known hyperammonemia in HE patients.

Assessment of Alertness and Cognitive Performance of Closed Circuit Rebreather Divers With the Critical Flicker Fusion Frequency Test in Arctic Diving Conditions

Introduction: Cold water imposes many risks to the diver. These risks include decompression illness, physical and cognitive impairment, and hypothermia. Cognitive impairment can be estimated using a critical flicker fusion frequency (CFFF) test, but this method has only been used in a few studies conducted in an open water environment. We studied the effect of the cold and a helium-containing mixed breathing gas on the cognition of closed circuit rebreather (CCR) divers.

Materials and Methods: Twenty-three divers performed an identical dive with controlled trimix gas with a CCR device in an ice-covered quarry. They assessed their thermal comfort at four time points during the dive. In addition, their skin temperature was measured at 5-min intervals throughout the dive. The divers performed the CFFF test before the dive, at target depth, and after the dive.

Results: A statistically significant increase of 111.7% in CFFF values was recorded during the dive compared to the pre-dive values (p < 0.0001). The values returned to the baseline after surfacing. There was a significant drop in the divers’ skin temperature of 0.48°C every 10 min during the dive (p < 0.001). The divers’ subjectively assessed thermal comfort also decreased during the dive (p = 0.01).

Conclusion: Our findings showed that neither extreme cold water nor helium-containing mixed breathing gas had any influence on the general CFFF profile described in the previous studies from warmer water and where divers used other breathing gases. We hypothesize that cold-water diving and helium-containing breathing gases do not in these diving conditions cause clinically relevant cerebral impairment. Therefore, we conclude that CCR diving in these conditions is safe from the perspective of alertness and cognitive performance.

Minimal portosystemic encephalopathy: A new nosological entity in patients with hereditary haemorrhagic telangiectasia

BACKGROUND

Portosystemic shunts in Hereditary Haemorrhagic Telangiectasia (HHT) are often overlooked by conventional imaging although they could reduce hepatic clearance of gut-derived toxins.

AIMS

To evaluate, the presence of subclinical neurological alterations (SNAs), that we named "minimal portosystemic encephalopathy" (mPSE) in HHT patients without advanced liver disease (ALD).

METHODS

In this cross sectional study, consecutive HHT outpatients were firstly screened by critical flicker frequency (CFF) test (abnormal ≤39Hz), and the simplified animal naming test (S-ANT₁) (abnormal <15) was used to confirm the diagnosis of mPSE. Furthermore, we evaluated the effect of lactulose administration on mPSE. Multi-slice CT, cerebral dynamic magnetic resonance, laboratory analyses and transient elastography were also used.

RESULTS

None of the 37 enrolled patients showed portosystemic shunts at imaging techniques. However, 33 patients had normal CFF values (CFF-) and 4 displayed CFF alterations (37.0±0.7Hz, CFF+). The S-ANT₁ confirmed an impaired neurological performance (10.2±2.8) in CFF+ patients thus confirming the presence of mPSE. Noteworthy, lactulose administration determined a CFF increase (39.1±0.4Hz) and S-ANT₁ normalization in these patients. Neither mPSE- nor mPSE+ patients had ALD and showed similar demographic, clinical and laboratory parameters. Finally, no mPSE+ patient showed radiologically-detectable brain vascular malformations or other brain abnormalities at imaging.

CONCLUSIONS

HHT patients represent a human model of mPSE secondary to portosystemic shunts escaping radiological detection. mPSE evaluation should be incorporated in HHT surveillance protocols since it can affect both health-related/social aspects and pharmacokinetics of orally administered drugs with a narrow therapeutic index and high hepatic first-pass uptake.

Minimal Hepatic Encephalopathy and Biejia-Ruangan Are Associated with First Hospital Readmission in Nonalcoholic Cirrhosis Patients

Introductionand Aim. Patients with cirrhosis are often hospitalized repeatedly for a variety of complications. This retrospective study aimed to assess the effects of minimal hepatic encephalopathy (MHE) and Biejia-Ruangan (BR) on first hospital readmission in nonalcoholic cirrhosis patients without previous overt hepatic encephalopathy (OHE) or hepatocellular carcinoma (HCC). Materials and Methods. A total of 176 hospitalized patients with nonalcoholic cirrhosis were included in this retrospective study. Patients who were first admitted to Beijing Ditan Hospital of Capital Medical University from January 2017 to September 2019 were enrolled. The primary endpoint was their first liver-related hospital readmission. The risk factors for readmission were analyzed by Cox proportional hazard regression analysis. Results. A total of 176 nonalcoholic cirrhosis patients without previous OHE or HCC were included; 57 patients (32.4%) were diagnosed with MHE, and 63 patients (35.8%) were administered BR (2 g, three times a day). Multivariate analysis revealed that nonalcoholic cirrhosis patients with MHE (HR, 5.805; 95% CI, 3.007-11.206; x, P < 0.001) and a higher Model for End-Stage Liver Disease (MELD) score (HR, 1.145; 95% CI, 1.068-1.227; P < 0.001) had an increased risk of first hospital readmission, and patients treated with BR (HR, 0.318; 95% CI, 0.151-0.670; P=0.003) had a decreased risk of first hospital readmission. Conclusion. MHE increased the risk of hospital readmission in nonalcoholic cirrhosis patients without previous OHE or HCC, and this risk was decreased by BR administration.

Outcome Prediction of Covert Hepatic Encephalopathy in Liver Cirrhosis: Comparison of Four Testing Strategies

Despite the negative impact of covert hepatic encephalopathy on the outcome of patients with liver cirrhosis, data regarding the ability of different testing strategies to predict overt hepatic encephalopathy (OHE) development and mortality are limited. This study aimed to compare the ability of Psychometric Hepatic Encephalopathy Score (PHES), critical flicker frequency (CFF), simplified animal naming test (S-ANT1), and clinical covert hepatic encephalopathy (CCHE) score to predict OHE development and mortality.

Clinical, neuropsychological and neurophysiological indices and predictors of hepatic encephalopathy (HE)

BACKGROUND AND AIMS

The occurrence of overt hepatic encephalopathy (HE) marks a significant progression in the natural history of liver disease. The aims of the present study were to: 1) describe a large cohort of patients with cirrhosis in terms of neuropsychological or neurophysiological HE indices, and 2) test if the severity of liver disease and/or any such indices [Psychometric Hepatic Encephalopathy Score (PHES), Scan test, electroencephalography (EEG)] predicted mortality/HE risk in a subgroup of such cohort.

METHOD

Four hundred and sixty-one patients with cirrhosis (59 ± 10 years; 345 males) were included; information on previous overt HE episodes was available in 407. Follow-up information on mortality/HE-related hospitalization in 134/127 respectively. Information on previous overt HE episodes and both mortality and HE-related hospitalization over the follow-up in 124.

RESULTS

Patients with a history of overt HE (60%) had poorer liver function, worse neuropsychiatric indices, higher ammonia levels and higher prevalence of portal-systemic shunt. The risk of HE-related hospitalization over the follow-up was higher in patients with higher MELD score and worse Scan performance. Mortality was higher in those with higher MELD. Among patients without a history of overt HE, those with worse PHES had higher HE risk. Among patients with a history, those with higher MELD, better PHES and worse Scan performance had higher HE risk.

CONCLUSIONS

In patients without previous overt HE episodes, neuropsychological and neurophysiological tests predict HE, while in those with previous overt HE episodes, HE development largely depends on the severity of liver dysfunction.

Evaluation of cerebral dysfunction in patients with chronic kidney disease using neuropsychometric and neurophysiological tests

Background

Uremic encephalopathy is defined as cerebral dysfunction due to toxin accumulation in patients with chronic kidney disease (CKD). This condition is characterized by subtle to florid symptoms, and its clinical course is always progressive when untreated but partially reversible with renal replacement therapy. While no test exists to measure subclinical uremic encephalopathy, two tests have been validated to measure minimal hepatic encephalopathy: the critical flicker frequency (CFF) test and the psychometric hepatic encephalopathy score (PHES).

Objective

To use CFF and PHES to measure the prevalence of cerebral dysfunction in individuals with CKD.

Methods

This cross-sectional study included a total of 69 patients with stage-5 CKD. Cutoff points for minimal encephalopathy were established using existing clinical guidelines: ≤39 Hz for CFF and < −4 for PHES. All participants were also screened for cognitive function and depression.

Results

Eighteen cases (26.1%) of cerebral dysfunction linked to uremic encephalopathy were detected with CFF, while twelve (17.4%) were detected by PHES; only six cases (8.7%) were diagnosed by both methods. Half of the cases (50%) had diabetes, and 61% were on hemodialysis. Cognitive function scores did not differ significantly between those receiving dialysis, hemodialysis, or no renal replacement therapy.

Conclusions

It is essential to identify cerebral dysfunction when uremic encephalopathy is in early subclinical stages to reduce preventable events as traffic and work accidents.

Brain-derived neurotrophic factor as a potential diagnostic marker in minimal hepatic encephalopathy

Introduction

Minimal hepatic encephalopathy (MHE) is a common complication of liver cirrhosis not only leading to a decrease in the quality of life, but also predicting development of overt encephalopathy. The diagnosis of MHE usually relies on a combination of neuropsychological tests, while robust serum biomarkers are lacking. We aimed to assess serum concentrations of brain-derived neurotrophic factor (BDNF) in MHE patients.

Material and methods

Serum BDNF was assessed in 78 patients with liver cirrhosis (53 male, median age 55 years) and 40 healthy individuals. 43 subjects underwent extensive evaluation for MHE by psychometric hepatic encephalopathy score (PHES) and inhibitory control test (ICT) or critical flicker frequency (CFF).

Results

Serum BDNF was twofold lower in liver cirrhosis compared to healthy subjects [13.6 (7.8-22.6) vs. 33.0 (24.1-40.7) ng/ml, p < 0.001] and its decrease reflected a degree of liver insufficiency assessed by model for end-stage liver disease (MELD). BDNF showed a negative correlation with bilirubin (R = –0.35, p = 0.005) and international normalized ratio (INR) (R = –0.37, p = 0.003), and positive with platelets (PLT) (R = 0.36, p = 0.004), while no associations with age, sex, body mass index (BMI), waist-hip ratio (WHR), creatinine and ammonia were noted. Importantly, subjects with a diagnosis of MHE by at least two modalities showed the lowest levels of BDNF [10.9 (2.5-14.4) vs. 19.9 (9.3-29.4) ng/ml, p < 0.01]. Patients with self-reported sleep disturbances had significantly lower serum BDNF [13.0 (2.5-23.4) vs. 20.0 (8.4-31.3) ng/ml, p = 0.04].

Conclusions

The lowest serum BDNF concentration was noted in patients with MHE and sleep disturbances, which suggests a role in pathophysiology of hepatic encephalopathy but also as a potential biomarker.

Cognition-tracking-based strategies for diagnosis and treatment of minimal hepatic encephalopathy

Minimal hepatic encephalopathy (MHE), which shows mild cognitive impairment, is a subtle complication of cirrhosis that has been shown to affect daily functioning and quality of life. However, until 2014, relevant guidelines do not give much attention to the diagnosis and treatment of MHE, resulting in patients being ignored and denied the benefits of treatment. In this review, we summarize recent cognition-based research about (1) alteration of nerve cells, including astrocytes, microglial cells and neurons, in mild cognitive impairment in MHE; (2) comparison of methods in detecting cognitive impairment in MHE; and (3) comparison of methods for therapy of cognitive impairment in MHE. We hope to provide information about diagnosis and treatment of cognitive impairment in patients with MHE.

The Influence of Small Intestinal Bacterial Overgrowth in Digestive and Extra-Intestinal Disorders

Small intestinal bacterial overgrowth (SIBO) is a condition hallmarked by an increase in the concentration of colonic-type bacteria in the small bowel. Watery diarrhea, bloating, abdominal pain and distension are the most common clinical manifestations. Additionally, malnutrition and vitamin (B12, D, A, and E) as well as minerals (iron and calcium) deficiency may be present. SIBO may mask or worsen the history of some diseases (celiac disease, irritable bowel disease), may be more common in some extra-intestinal disorders (scleroderma, obesity), or could even represent a pathogenetic link with some diseases, in which a perturbation of intestinal microbiota may be involved. On these bases, we performed a review to explore the multiple links between SIBO and digestive and extra-intestinal diseases.

Advances in psychometric tests for screening minimal hepatic encephalopathy: From paper-and-pencil to computer-aided assessment

Minimal hepatic encephalopathy (MHE) is a major neuropsychiatric complication of liver cirrhosis and portosystemic shunting. Although MHE produces a spectrum of cognitive impairments in the domains of short-term attention, working memory, and executive function, it generally does not present with obvious clinical manifestation on conventional assessments. Paper-and-pencil psychometric tests, such as the psychometric hepatic encephalopathy score and the repeatable battery for the assessment of neuropsychological status, are recommended to diagnose MHE. However, these tests are neither rapid nor convenient to use in practice. To facilitate repeated testing in clinic and follow-up, computer-aided psychometric tests, such as the scan test, Cognitive Drug Research assessment battery, inhibitory control test, EncephalApp Stroop App, and critical flicker frequency, have been used to screen for MHE among patients with liver cirrhosis. The aim of this review was to describe the progression from the utility of paper-and-pencil to computer-aided psychometric tests for MHE screening in clinical practice.

Prognostic significance of minimal hepatic encephalopathy in patients with liver cirrhosis in Japan: A propensity score-matching analysis

BACKGROUND AND AIM

Minimal hepatic encephalopathy (MHE) represents the mildest form of the hepatic encephalopathy spectrum. This study aimed to clarify the prognostic significance of MHE in cirrhotic patients.

METHODS

This retrospective study evaluated 357 consecutive patients with liver cirrhosis. MHE was diagnosed using a neuropsychiatric test. A propensity score-matching analysis was employed to adjust significant differences in the baseline characteristics between patients with and without MHE.

RESULTS

Of 269 eligible patients, 56 patients (21%) were diagnosed as having MHE. The Child-Pugh score, model for end-stage liver disease score, and serum ammonia levels were significantly increased, while serum albumin levels were reduced in patients with MHE. By contrast, no significant difference was found between the two groups in matched patients. During the median follow-up period of 13.4 months, 67 patients (24.9%) died. Overall survival rates were significantly lower in patients with MHE (median, 25.4 vs 48.8 months; P < 0.001). Multivariate analysis revealed that male sex (hazard ratio [HR], 1.78; 95% confidence interval [CI], 1.03-3.18; P = 0.038), stage III/IV hepatocellular carcinoma (HR, 6.32; 95% CI, 3.30-12.79; P < 0.001), the Child-Pugh score (HR, 1.35; 95% CI, 1.12-1.62; P = 0.002), and MHE (HR, 1.92; 95% CI, 1.09-3.29; P = 0.024) were independently associated with mortality in all patients as well as in matched patients.

CONCLUSION

Minimal hepatic encephalopathy is associated with an increased risk of mortality in patients with liver cirrhosis, independent of hepatocellular carcinoma stage or Child-Pugh score.

Critical flickering frequency test: a diagnostic tool for minimal hepatic encephalopathy

BACKGROUND

Minimal hepatic encephalopathy (MHE) is underestimated. It affects 30-55% of patients with liver cirrhosis and can change their daily functions. Psychometric tests are sensitive in diagnosing MHE, but interpretation is difficult. Availability of a simpler diagnostic tool for MHE is mandatory. Critical flicker frequency (CFF) is a simple diagnostic test.

AIM

The aim of this study was to assess the diagnostic accuracy of CFF test for MHE.

PATIENTS AND METHODS

A total of 86 patients with cirrhosis with negative history of overt hepatic encephalopathy were included. History, clinical examination, laboratory investigations, and abdominal ultrasonography data were collected. Arabic version of number connection test, serial dotting test, and line tracing test were done. Total psychometric hepatic encephalopathy score (PHES) was used to diagnose MHE. CFF was done for all patients with MHE diagnosis at 39 Hz.

RESULTS

Of the 86 patients, 45 (52.3%) had MHE with PHES. Patients with MHE had significantly older age, presentation with jaundice, ascites, lower hemoglobin level, lower serum albumin, prolonged INR, higher Child class and score (P≤0.001), and higher model of end stage liver disease score (P=0.001) than patients without MHE. In comparison with PHES, CFF has a sensitivity of 91.1±8.32%, specificity of 92.7±7.96%, positive predictive value of 93.2±7.44%, and negative predictive value of 90.4±8.91%. In receiver operating characteristic curve, CFF is excellent in diagnosis of MHE, with area under the curve 0.937 (P<0.001).

CONCLUSION

MHE is common among patients with liver cirrhosis. CFF is a simple, rapid, noninvasive test for diagnosis of MHE, with a very good accuracy at 39 Hz.

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.

Impaired Tactile Temporal Discrimination in Patients With Hepatic Encephalopathy

The sensory system constantly receives stimuli from the external world. To discriminate two stimuli correctly as two temporally distinct events, the temporal distance or stimulus onset asynchrony (SOA) between the two stimuli has to exceed a specific threshold. If the SOA between two stimuli is shorter than this specific threshold, the two stimuli will be perceptually fused and perceived as one single stimulus. Patients with hepatic encephalopathy (HE) are known to show manifold perceptual impairments, including slowed visual temporal discrimination abilities as measured by the critical flicker frequency (CFF). Here, we hypothesized that HE patients are also impaired in their tactile temporal discrimination abilities and, thus, require a longer SOA between two tactile stimuli to perceive the stimuli as two temporally distinct events. To test this hypothesis, patients with varying grades of HE and age-matched healthy individuals performed a tactile temporal discrimination task. All participants received two tactile stimuli with varying SOA applied to their left index finger and reported how many distinct stimuli they perceived ("1" vs. "2"). HE patients needed a significantly longer SOA (138.0 ± 11.3 ms) between two tactile stimuli to perceive the stimuli as two temporally distinct events than healthy controls (78.6 ± 13.1 ms; p < 0.01). In addition, we found that the temporal discrimination ability in the tactile modality correlated positively with the temporal discrimination ability in the visual domain across all participants (i.e., negative correlation between tactile SOA and visual CFF: r = -0.37, p = 0.033). Our findings provide evidence that temporal tactile perception is substantially impaired in HE patients. In addition, the results suggest that tactile and visual discrimination abilities are affected in HE in parallel. This finding might argue for a common underlying pathophysiological mechanism. We argue that the known global slowing of neuronal oscillations in HE might represent such a common mechanism.