Modification in CSF specific gravity in acutely decompensated cirrhosis and acute on chronic liver failure independent of encephalopathy, evidences for an early blood-CSF barrier dysfunction in cirrhosis

Protein-S-100-beta is increased in patients with decompensated cirrhosis admitted to ICU

Background

Hepatic encephalopathy (HE) is highly prevalent in patients with liver diseases. The pathophysiology of HE is centered on the synergic role of hyperammonemia and systemic inflammation. However, some data suggest altered functioning of the blood-brain barrier (BBB). Assessing BBB function is challenging in clinical practice and at the bedside. Protein-S-100 Beta (PS100-Beta) could be a useful peripheral marker of BBB permeability in HE. This study aimed to assess plasmatic PS100-Beta levels in a prospective cohort of patients admitted to the intensive care unit (ICU) with decompensated cirrhosis with and without overt HE.

Methods

We retrospectively evaluated a prospective cohort of cirrhotic patients admitted to the ICU from October 2013 to September 2015 that had an available plasmatic PS100-Beta measurement. Patients with previous neurological impairment or limitation of intensive or resuscitative measures were excluded. Overt HE was defined as West-Haven grades 2 to 4. The patients were compared to a control cohort of outpatient clinic cirrhotic and non-cirrhotic patients explored for isolated elevation of liver enzymes. After ICU discharge, the patients were followed for at least 3 months for the occurrence of overt HE. Adverse outcomes (liver transplantation or death) were collected. The ability of PS100-Beta - in combination with other factors - to predict overt HE was evaluated in a multivariate analysis using logistic regression. Likelihood ratios were used to determine the effects and calculate odds ratios (OR). Survival analysis was performed by using the Kaplan-Meier method and survival between groups was compared using a Log-rank test.

Results

A total of 194 ICU patients and 207 outpatients were included in the study. Increased levels of plasmatic PS100-Beta were detected in the ICU decompensated cirrhotic patients compared with the outpatients ([0.15±0.01] mg/L vs. [0.08±0] mg/L, P <0.001). ICU patients with overt HE had higher levels of PS100-Beta ([0.19±0.03] mg/L) compared with the ICU patients without overt HE ([0.13±0.01] mg/L) (P=0.003). PS100-Beta levels did not differ in outpatients with F 0-3 compared to F 4 fibrosis (P=0.670). PS100-Beta values were correlated with Child-Pugh score (P <0.001), Model for End-Stage Liver Disease (MELD) score (P=0.004), C-reactive protein (P <0.001), ammonemia (P <0.001), and chronic liver failure consortium (CLIF-C) organ failure (P <0.001) and CLIF-C acute-on-chronic (P=0.038) scores, but not with leukocytes (P=0.053), procalcitonin (PCT) (P=0.107), or the lymphocyte-to-neutrophil ratio in ICU patients (P=0.522). In a multivariate model including age, ammonemia, PS100-Beta, PCT, MELD, presence of transjugular portosystemic shunt, and sodium level, the diagnostic performance was 0.765 for the diagnosis of overt HE. Patients with a PS100-Beta level <0.12 mg/L had a better overall survival (P=0.019) and a better survival without liver transplantation (P=0.013).

Conclusions

Serum levels of PS100-Beta are elevated in ICU patients with decompensated cirrhosis, and even more so in those displaying overt HE, and the levels are correlated with outcome. This suggests an increase in the permeability of the BBB in these patients.

Tacrolimus-associated neurotoxicity isolated to the brainstem: two illustrative cases and a systematic review of the literature

INTRODUCTION

Tacrolimus-associated neurotoxicity (TAN) manifests with wide clinical spectrum, ranging from mild tremors to severe encephalopathy. The isolated involvement of the brainstem is a rarely documented presentation of TAN, and its clinical and diagnostic characteristics are unclear.

METHODS

We report two cases of brainstem-isolated TAN (bi-TAN). Moreover, we performed a systematic review of the literature on bi-TAN and extracted data concerning demographics, clinical characteristics, radiological features, and management. The systematic literature search followed PRISMA guidelines and a pre-defined protocol.

RESULTS

Eleven patients, including our two, were identified (mean age: 41.3 years, ± 18.8; five males, 45%). Speech disturbance was the most common clinical presentation (45%). The mean latency from Tacrolimus initiation to bi-TAN onset was 26 days (± 30.8). Tacrolimus serum level tested above the reference range in three patients (mean: 26.83 ± 5.48). Brain MRI showed T2-FLAIR hyperintensities; three showed restricted diffusion on ADC maps. Neurological symptoms resolved completely in seven patients (63%) after Tacrolimus withdrawal or dose reduction.

CONCLUSIONS

Our findings suggest that bi-TAN could represent a brainstem variant of posterior reversible encephalopathy syndrome. Recognition of bi-TAN as a potential cause of isolated brainstem lesions is crucial to disentangle the diagnostic work-up and ensure prompt withdrawal or reduction of the offending agent.

Blood-brain barrier dysfunction in intensive care unit

The central nervous system is characterized by a peculiar vascularization termed blood-brain barrier (BBB), which regulates the exchange of cells and molecules between the cerebral tissue and the whole body. BBB dysfunction is a life-threatening condition since its presence corresponds to a marker of severity in most diseases encountered in the intensive care unit (ICU). During critical illness, inflammatory response, cytokine release, and other phenomena activating the brain endothelium contribute to alterations in the BBB and increase its permeability to solutes, cells, nutrients, and xenobiotics. Moreover, patients in the ICU are often old, with underlying acute or chronic diseases, and overly medicated due to their critical condition; these factors could also contribute to the development of BBB dysfunction. An accurate diagnostic approach is critical for the identification of the mechanisms underlying BBB alterations, which should be rapidly managed by intensivists. Several methods were developed to investigate the BBB and assess its permeability. Nevertheless, in humans, exploration of the BBB requires the use of indirect methods. Imaging and biochemical methods can be used to study the abnormal passage of molecules through the BBB. In this review, we describe the structural and functional characteristics of the BBB, present tools and methods for probing this interface, and provide examples of the main diseases managed in the ICU that are related to BBB dysfunction.

EASL Clinical Practice Guidelines on the management of hepatic encephalopathy

The EASL Clinical Practice Guidelines (CPGs) on the management of hepatic encephalopathy (HE) present evidence-based answers to a set of relevant questions (where possible, formulated in PICO [patient/population, intervention, comparison and outcomes] format) on the definition, diagnosis, differential diagnosis and treatment of HE. The document does not cover the pathophysiology of HE and does not cover all available treatment options. The methods through which it was developed and any information relevant to its interpretation are also provided.

A critical review of bile acids and their receptors in hepatic encephalopathy

Hepatic encephalopathy describes an array of neurological complications that arise due to liver insufficiency. The pathogenesis of hepatic encephalopathy shares a longstanding association with hyperammonemia and inflammation, and recently, aberrant bile acid signaling has been implicated in the development of key features of hepatic encephalopathy. These key features include neuronal dysfunction, neuroinflammation and blood-brain barrier permeability. This review summarizes the findings of recent studies demonstrating a role for bile acids in the pathogenesis of hepatic encephalopathy via one of three main bile acid receptors and speculates on the possible downstream consequences of aberrant bile acid signaling.

A systemic mechanism of increased transendothelial migration of leukocytes through the blood-brain barrier in hepatic encephalopathy

BACKGROUND

Hepatic encephalopathy (HE) is a frequent neurological complication of cirrhosis. Evidence suggests a synergic pathophysiological implication of hyperammonemia and systemic inflammation. In addition, the blood-brain barrier (BBB) permeability can be impaired in cirrhotic patients, notably in those displaying HE. We hypothesized that systemic inflammation could trigger leukocytes transendothelial migration (TEM) through the BBB in cirrhotic patients and especially those with HE.

METHODS

We studied the effects of patients' plasma on the TEM of the leukocyte U937 cell line in vitro, using a validated BBB model (hCMEC/D3 cell line). We compared TEM of U937 leukocytes across hCMEC/D3 monolayer incubated with the plasma of i) patients with cirrhosis without HE, ii) patients with cirrhosis and HE, iii) healthy controls.

RESULTS

We show that the plasma of cirrhotic patients with HE enhances TEM of U937 leukocytes across hCMEC/D3 BBB model. We found a correlation between U937 TEM on the one hand, the West-Haven score and ammonemia on the other one. A trend towards a correlation between U937 TEM and PS-100Beta in plasma, a marker of BBB solute's permeability increase, was also found.

CONCLUSION

These findings suggest that circulating factors could increase leukocytes TEM in cirrhotic patients and contribute to the increased BBB permeability that has been described in cirrhotic patients with HE.

Toxic-metabolic encephalopathy in adults: Critical discussion and pragmatical diagnostic approach

Toxic-metabolic encephalopathy (TME) results from an acute cerebral dysfunction due to different metabolic disturbances including medications or illicit-drugs. It can lead to altered consciousness, going from delirium to coma, which may require intensive care and invasive mechanical ventilation. Even if it is a life-threatening condition, TME might have an excellent prognosis if its etiology is rapidly identified and treated adequately. This review summarizes the main etiologies, their differential diagnosis, and diagnostic strategy and management of TME with a critical discussion on the definition of TME.

Metabolomics in the understanding and management of hepatic encephalopathy

Metabolomics refers to the study of biological components below 1000 Daltons (Da) involved in metabolic pathways as substrates, products or effectors. According to the interconnected metabolic disturbances that have been described in the pathophysiology of hepatic encephalopathy (HE), this technique appears to be well adapted to study and better delineate the disease. This review will focus on recent advances in metabolomics in the field of HE. Thus, after a brief overview of the general principles of metabolomics, we will discuss metabolomics as a potentially efficient tool for unraveling new HE pathophysiological insights, biomarkers identification, or as a predicting tool for treatment response or outcome prognosis. Finally, we will give our vision on the prospects offered by metabolomics for improving care of HE patients.

Serum osmolality, cerebrospinal fluid specific gravity and overt hepatic encephalopathy severity in patients with liver failure

BACKGROUND AND AIMS

Hepatic encephalopathy (HE) is a leading contributor to morbidity in liver disease. While hyperammonaemia plays a key role, the mechanisms of cerebral toxicity are unclear. We hypothesized that serum hyperosmolality contributes to HE during acute (ALF) and acute-on-chronic liver failure (ACLF) through mechanisms that affect the water and solute composition of the cerebral environment.

METHODS

We performed a retrospective analysis of serum osmolality, cerebral spinal fluid (CSF) solute density (specific gravity, determined from computed tomography attenuation) and clinical HE severity (Glasgow Coma Score [GCS]) at the time of intensive care admission in a prospectively identified cohort of liver failure patients with overt HE.

RESULTS

Seventy-three patients (39 ALF and 34 ACLF) were included, of whom 28 (38%) were comatose. Serum osmolality (303.9 ± 15.4 mOsm/kg) was elevated despite normal serum sodium (136.6 ± 6.3 mEq/L). Increased osmolality was independently associated with more severe encephalopathy (ordinal adjusted OR 0.26 [95% CI 0.22, 0.31] for higher GCS per standard deviation increase in osmolality) and lower CSF-specific gravity (linear adjusted β = -0.039 [95% CI -0.069, -0.009] Hounsfield unit per 1 mOsm/kg).

CONCLUSIONS

In the context of related research, these data suggest that hyperosmolality increases brain exposure to metabolic toxins by blood-brain barrier alteration and may be a unique therapeutic target.

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.

Bile Acids in Hepatic Encephalopathy

Hepatic encephalopathy describes the array of neurological complications that arise due to liver insufficiency and/or portal-systemic shunt. The pathogenesis of hepatic encephalopathy shares a longstanding association with hyperammonemia and inflammation. Recently, aberrant bile acid signaling has been implicated in the development of key features of hepatic encephalopathy due to acute liver failure including neuronal dysfunction, neuroinflammation and blood-brain barrier permeability. This review summarizes the findings of recent studies demonstrating a role for bile acids in hepatic encephalopathy and speculates on the possible downstream consequences of bile acid signaling.

Hepatic encephalopathy: Diagnosis and management

Hepatic encephalopathy (HE) is a peculiar kind of brain dysfunction caused by liver insufficiency and/or portal-systemic shunting. It is related to gut-derived substances. It is a relevant cause of morbidity and hospitalisation for patients with cirrhosis. The prognosis of HE is important in terms of survival and re-hospitalisation. It is related to impaired quality of life, falls and poor driving; presents a relevant burden for caregivers and health services; and may negatively impact on patient's job and income. Proper diagnosis and classification are expected to improve HE management. Once diagnosed, the management and therapeutic options for HE are generally clear. The improvement of knowledge in recent years has also clarified which are the further aims of research in this field of medicine. Prophylaxis of overt HE should always be performed, and this is generally secondary prophylaxis. Primary prophylaxis should be done immediately after upper gastrointestinal bleeding. Great advances in the detection and treatment of mild forms of HE are expected to lead to further improvement in patient management.

Neuropsychiatric performance and treatment of hepatitis C with direct-acting antivirals: a prospective study

BACKGROUND

Since direct-acting antivirals (DAAs) have been approved for the treatment of hepatitis C virus (HCV) infection, a small series of patients with new-onset neuropsychiatric alterations have been referred to us. We therefore set out to study neuropsychiatric function in relation to DAAs prospectively.

METHODS

Ten patients with cirrhosis and 12 post-liver transplant (post-LT) patients were enrolled. All underwent wake electroencephalography (EEG) and a neuropsychological evaluation (paper and pencil battery, simple/choice reaction times, working memory task) at baseline, at the end of treatment with DAAs and after 6 months. At the same time points, full blood count, liver/kidney function tests, quantitative HCV RNA, ammonia and immunosuppressant drug levels were obtained, as appropriate.

RESULTS

Patients with cirrhosis were significantly older than post-LT patients (65±12 vs 55±7 years; P<0.05). Neuropsychological performance and wake EEG were comparable in the two groups at baseline. At the end of a course of treatment with DAAs, a significant slowing in choice reaction times and in the EEG (increased relative delta power) was observed in patients with cirrhosis, which resolved after 6 months. In contrast, no significant changes over time were observed in the neuropsychiatric performance of post-LT patients. No significant associations were observed between neuropsychiatric performance and stand-alone/combined laboratory variables.

CONCLUSION

Some degree of neuropsychiatric impairment was observed in relation to treatment with DAAs in patients with cirrhosis, but not in post-LT patients, suggesting that the former may be sensitive to mild DAA neurotoxicity.

Recent advances in hepatic encephalopathy

Hepatic encephalopathy describes the array of neurological alterations that occur during acute liver failure or chronic liver injury. While key players in the pathogenesis of hepatic encephalopathy, such as increases in brain ammonia, alterations in neurosteroid levels, and neuroinflammation, have been identified, there is still a paucity in our knowledge of the precise pathogenic mechanism. This review gives a brief overview of our understanding of the pathogenesis of hepatic encephalopathy and then summarizes the significant recent advances made in clinical and basic research contributing to our understanding, diagnosis, and possible treatment of hepatic encephalopathy. A literature search using the PubMed database was conducted in May 2017 using "hepatic encephalopathy" as a keyword, and selected manuscripts were limited to those research articles published since May 2014. While the authors acknowledge that many significant advances have been made in the understanding of hepatic encephalopathy prior to May 2014, we have limited the scope of this review to the previous three years only.

Transport across the choroid plexus epithelium

The choroid plexus epithelium is a secretory epithelium par excellence. However, this is perhaps not the most prominent reason for the massive interest in this modest-sized tissue residing inside the brain ventricles. Most likely, the dominant reason for extensive studies of the choroid plexus is the identification of this epithelium as the source of the majority of intraventricular cerebrospinal fluid. This finding has direct relevance for studies of diseases and conditions with deranged central fluid volume or ionic balance. While the concept is supported by the vast majority of the literature, the implication of the choroid plexus in secretion of the cerebrospinal fluid was recently challenged once again. Three newer and promising areas of current choroid plexus-related investigations are as follows: 1) the choroid plexus epithelium as the source of mediators necessary for central nervous system development, 2) the choroid plexus as a route for microorganisms and immune cells into the central nervous system, and 3) the choroid plexus as a potential route for drug delivery into the central nervous system, bypassing the blood-brain barrier. Thus, the purpose of this review is to highlight current active areas of research in the choroid plexus physiology and a few matters of continuous controversy.