Cerebral oedema in minimal hepatic encephalopathy due to extrahepatic portal venous obstruction

Prevalence of hepatic encephalopathy in patients with non-cirrhotic portal hypertension: A systematic review and meta-analysis

BACKGROUND

Hepatic encephalopathy, (HE) although commonly associated with cirrhosis, has also been reported in non-cirrhotic portal hypertension (NCPH). The importance of identifying and treating HE in NCPH lies in the fact that many patients may be wrongly diagnosed as having psychiatric or neurologic disorders. Hence, we aimed to systematically review the prevalence of HE in NCPH.

METHODS

A comprehensive search of three databases (Medline, Embase and Scopus) was conducted from inception to November 2022 for studies reporting on the prevalence of minimal HE (MHE) and overt HE (OHE) in patients with NCPH. Results were presented as pooled proportions with their 95% confidence intervals (CI).

RESULTS

Total 25 studies (n = 1487) were included after screening 551 records. The pooled prevalence of MHE in NPCH was 32.9% (95% CI: 26.7-39.0) without any difference between adult (32.9%, 95% CI: 23.5-42.3) and pediatric patients (32.6%, 95% CI: 26.1-39.1) (p = 0.941). There was no significant difference in the prevalence between patients with NCPH and compensated cirrhosis with odds ratio of 1.06 (95% CI: 0.77-1.44). The pooled event rate for prior history of OHE in NCPH was 1.2% (95% CI: 0.3-2.1).

CONCLUSION

Around one-third of the patients with NCPH have MHE, irrespective of age group. OHE is extremely rare in NCPH and is usually associated with a precipitating factor.

Laboratory Abnormalities of Hepatic Encephalopathy

Currently, there is no gold standard serologic or imaging modality to detect hepatic encephalopathy (HE). It is a clinical diagnosis gathered from the history and physical. Imaging is nonspecific; however, PET and MRI have shown areas of utility, but are not widely available, cost-efficient, or necessary for diagnosis. Electroencephalogram has shown promise as it can be used in conjunction with the Portal Systemic Hepatic Encephalopathy Score test to diagnose minimal HE. Further research on these techniques would need to be performed to identify strict criteria and cutoffs for diagnosing HE as well as associated sensitivities and specificities.

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.

Abnormal spontaneous brain activity in minimal hepatic encephalopathy: resting-state fMRI study

PURPOSE

We aimed to assess the abnormality of baseline spontaneous brain activity in minimal hepatic encephalopathy (MHE) by amplitude of low frequency fluctuation (ALFF) and fraction ALFF (fALFF).

METHODS

A total of 14 MHE patients and 14 healthy controls were included in our study. Both ALFF and fALFF of functional magnetic resonance imaging were calculated for statistical analysis.

RESULTS

Compared with healthy controls, patients with MHE had significantly decreased ALFF in the bilateral medial prefrontal cortex (MPFC), left superior frontal gyrus, right precentral gyrus, left opercular part of inferior frontal gyrus, left gyrus rectus, bilateral precuneus, and the posterior lobe of right cerebellum; and they had significantly decreased fALFF in the bilateral MPFC, right middle frontal gyrus, right superior temporal gyrus, and the posterior lobe of left cerebellum.

CONCLUSION

ALFF and fALFF changes in many brain regions demonstrate abnormality of the spontaneous neuronal activity in MHE. Especially the impairment of right precuneus and left MPFC may play a critical role in manifestation of MHE. Changes of ALFF and fALFF in the precuneus and the MPFC can be used as a potential marker for MHE.

Evaluation of cognitivity, proinflammatory cytokines, and brain magnetic resonance imaging in minimal hepatic encephalopathy induced by cirrhosis and extrahepatic portal vein obstruction

BACKGROUND AND AIMS

Minimal hepatic encephalopathy (MHE) is the mildest form of hepatic encephalopathy (HE) and is characterized by deficits in neurocognitive performance without any clinical symptoms of HE. In the current study, we aim to evaluate and compare the neurocognitive, biochemical, and brain magnetic resonance (MR) imaging changes between patients with cirrhotic MHE and extrahepatic portal vein obstruction (EHPVO) MHE.

METHODS

Thirty-three cirrhotic and 14 EHPVO patients were diagnosed with MHE and were included in the analysis along with 24 normal healthy volunteers. All subjects underwent MR imaging including diffusion tensor imaging and proton MR spectroscopy (¹ H-MRS) followed by cognitive assessments, critical flicker frequency (CFF) measurements, quantification of blood ammonia, and serum proinflammatory cytokine levels.

RESULTS

We observed abnormal neurocognitive functions and CFF measurements in both cirrhotic MHE and EHPVO MHE patients as compared with controls. Significantly increased blood ammonia, serum proinflammatory cytokines (IL-6, TNF-α) level, mean diffusivity in multiple brain sites, ¹ H-MRS derived glutamate/glutamine (Glx)/creatine (Cr), and significantly decreased ¹ H-MRS derived myo-inositol/Cr were observed in both cirrhotic MHE and EHPVO MHE compared with those of controls. Choline/Cr level was significantly decreased in cirrhotic MHE as compared with controls and EHPVO MHE.

CONCLUSIONS

Cirrhotic MHE showed more severe changes on mean diffusivity in multiple brain sites and inflammation as compared with EHPVO MHE. This study confirms that there are significant difference in neurocognitive, biochemical, and MR profile between cirrhotic MHE and EHPVO MHE, which may help to understand the pathophysiologies of these two types of MHE and may contribute to improve their clinical managements.

Brain magnetic resonance in hepatic encephalopathy

The term hepatic encephalopathy (HE) covers a wide spectrum of neuropsychiatric abnormalities caused by portal-systemic shunting. The diagnosis requires demonstration of liver dysfunction or portal-systemic shunts and exclusion of other neurologic disorders. Most patients with this condition have liver dysfunction caused by cirrhosis, but it also occurs in patients with acute liver failure and less commonly, in patients with portal-systemic shunts that are not associated with hepatocellular disease. Various magnetic resonance (MR) techniques have improved our knowledge about the pathophysiology of HE. Proton MR spectroscopy and T1-weighted imaging can detect and quantify accumulations of brain products that are normally metabolized or eliminated such as glutamine and manganese. Other MR techniques such as T2-weighted and diffusion-weighted imaging can identify white matter abnormalities resulting from disturbances in cell volume homeostasis secondary to brain hyperammonemia. Partial or complete recovery of these abnormalities has been observed with normalization of liver function or after successful liver transplantation. MR studies have undoubtedly improved our understanding of the mechanisms involved in the pathogenesis of HE, and some findings can be considered biomarkers for monitoring the effects of therapeutic measures focused on correcting this condition.

Minimal hepatic encephalopathy in children with liver cirrhosis: diffusion-weighted MR imaging and proton MR spectroscopy of the brain

INTRODUCTION

The aim of this work was to detect minimal hepatic encephalopathy (minHE) in children with diffusion-weighted MR imaging (DWI) and proton magnetic resonance spectroscopy (1H-MRS) of the brain.

METHODS

Prospective study conducted upon 30 consecutive children (age range 6-16 years, 21 boys and 9 girls) with liver cirrhosis and 15 age- and sex-matched healthy control children. Patients with minHE (n = 17) and with no minHE (n = 13) groups and control group underwent DWI, 1H-MRS, and neuropsychological tests (NPTs). The glutamate or glutamine (Glx), myoinositol (mI), choline (Cho), and creatine (Cr) at the right ganglionic region were determined at 1H-MRS. The apparent diffusion coefficient (ADC) value and metabolic ratios of Glx/Cr, mI/Cr, and Cho/Cr were calculated.

RESULTS

There was elevated ADC value and Glx/Cr and decreased mI/CI and Ch/Cr in patients with minHE compared to no minHE and control group. There was significant difference between minHE, no minHE, and control group in the ADC value (P = 0.001 for all groups), GLx/Cr (P = 0.001 for all groups), mI/Cr (P = 0.004, 0.001, and 0.001, respectively), Ch/Cr (P = 0.001 for all groups), and full-scale IQ of NPT (P = 0.001, 0.001, and 0.143, respectively). The NPT of minHE had negative correlation with ADC value (r = -0.872, P = 0.001) and GLx/Cr (r = -0.812, P = 0.001) and positive correlation with mI/Cr (r = 0.732, P = 0.001).

CONCLUSION

DWI and 1H-MRS are imaging modalities that can detect minHE in children with liver cirrhosis and correlate well with parameters of NPT.

Meta-analysis: The diagnostic accuracy of critical flicker frequency in minimal hepatic encephalopathy

BACKGROUND

Minimal hepatic encephalopathy (MHE) reduces quality of life, increases the risk of road traffic incidents and predicts progression to overt hepatic encephalopathy and death. Current psychometry-based diagnostic methods are effective, but time-consuming and a universal 'gold standard' test has yet to be agreed upon. Critical Flicker Frequency (CFF) is a proposed language-independent diagnostic tool for MHE, but its accuracy has yet to be confirmed.

AIM

To assess the diagnostic accuracy of CFF for MHE by performing a systematic review and meta-analysis of all studies, which report on the diagnostic accuracy of this test.

METHODS

A systematic literature search was performed to locate all publications reporting on the diagnostic accuracy of CFF for MHE. Data were extracted from 2 × 2 tables or calculated from reported accuracy data. Collated data were meta-analysed for sensitivity, specificity, diagnostic odds ratio (DOR) and summary receiver operator curve (sROC) analysis. Prespecified subgroup analysis and meta-regression were also performed.

RESULTS

Nine studies with data for 622 patients were included. Summary sensitivity was 61% (95% CI: 55-67), specificity 79% (95% CI: 75-83) and DOR 10.9 (95% CI: 4.2-28.3). A symmetrical sROC gave an area under the receiver operator curve of 0.84 (SE = 0.06). The heterogeneity of the DOR was 74%.

CONCLUSIONS

Critical Flicker Frequency has a high specificity and moderate sensitivity for diagnosing minimal hepatic encephalopathy. Given the advantages of language independence and being both simple to perform and interpret, we suggest the use of critical flicker frequency as an adjunct (but not replacement) to psychometric testing.

Advantages of the meso-Rex bypass compared with portosystemic shunts in the management of extrahepatic portal vein obstruction in children

BACKGROUND

Consequences of extrahepatic portal vein obstruction (EHPVO) include variceal bleeding and hypersplenism due to portal hypertension, as well as metabolic abnormalities secondary to impaired portal venous circulation. The purpose of this study was to compare the effectiveness of meso-Rex bypass and portosystemic shunt (PSS) for reversing these symptoms in children with EHPVO.

STUDY DESIGN

All children with idiopathic EHPVO evaluated for potential meso-Rex bypass at a single institution between 1997 and 2010 were reviewed. Portosystemic shunt was performed in patients with refractory portal hypertension when meso-Rex bypass was not technically feasible. Outcomes of meso-Rex bypass and PSS were compared, including resolution of portal hypertensive bleeding and hypersplenism, as well as changes in liver synthetic function, ammonia levels, and somatic growth.

RESULTS

Sixty-five children with EHPVO underwent successful meso-Rex bypass, while 16 required PSS. Nearly all patients experienced complete relief of variceal bleeding after meso-Rex (96%) bypass and PSS (100%). The improvements in platelet count (+82.1 ± 60.0 vs +32.4 ± 56.3 thousand/μL; p=0.004), internal normalized ratio (-0.22 ± 0.27 vs 0.01 ± 0.14; p=0.022), and serum ammonia level (-26.8 ± 36.8 vs +19.4 ± 33.1 μM/L; p=0.002) were greater after meso-Rex bypass than PSS. Among patients with below average (standard deviation z-score<0) preoperative weight for age, the improvement in weight-for-age z-score was greater after meso-Rex bypass (+0.84 ± 0.98) than PSS (+0.17 ± 0.79, p=0.044). Median duration of follow-up was 4.45 years after meso-Rex bypass and 1.8 years after PSS.

CONCLUSIONS

Both meso-Rex bypass and PSS effectively relieve symptoms of portal hypertensive bleeding in children with EHPVO, although the meso-Rex better relieves hypersplenism. By restoring normal portal venous circulation, the meso-Rex bypass has additional metabolic benefits.

Surgical management of portal hypertension in children

The management of children with portal hypertension has dramatically changed during the past decade, with an improvement in outcome. This has been achieved by improved efficiency of endoscopic variceal control and the success of liver transplantation. Emergency surgical shunt procedures are rarely required, with acute bleeding episodes generally controlled endoscopically or, occasionally in adults, by interventional radiological procedures. Portosystemic shunts may be considered as a bridge to transplant in adults but are rarely used in this context in children. Nontransplant surgery or radiological interventions may still be indicated for noncirrhotic portal hypertension when the primary cause can be cured and to allow normalization of portal pressure before liver parenchyma is damaged by chronic secondary changes in some specific diseases. The meso-Rex bypass shunt is used widely but is limited to those with a favorable anatomy and can even be performed preemptively. Elective portosystemic shunt surgery is reserved for failure to respond to conservative management in the absence of alternative therapies.

Structural and functional abnormalities of default mode network in minimal hepatic encephalopathy: a study combining DTI and fMRI

Background and Purpose

Live failure can cause brain edema and aberrant brain function in cirrhotic patients. In particular, decreased functional connectivity within the brain default-mode network (DMN) has been recently reported in overt hepatic encephalopathy (HE) patients. However, so far, little is known about the connectivity among the DMN in the minimal HE (MHE), the mildest form of HE. Here, we combined diffusion tensor imaging (DTI) and resting-state functional MRI (rs-fMRI) to test our hypothesis that both structural and functional connectivity within the DMN were disturbed in MHE.

Materials and Methods

Twenty MHE patients and 20 healthy controls participated in the study. We explored the changes of structural (path length, tracts count, fractional anisotropy [FA] and mean diffusivity [MD] derived from DTI tractography) and functional (temporal correlation coefficient derived from rs-fMRI) connectivity of the DMN in MHE patients. Pearson correlation analysis was performed between the structural/functional indices and venous blood ammonia levels/neuropsychological tests scores of patients. All thresholds were set at P<0.05, Bonferroni corrected.

Results

Compared to the healthy controls, MHE patients showed both decreased FA and increased MD in the tract connecting the posterior cingulate cortex/precuneus (PCC/PCUN) to left parahippocampal gyrus (PHG), and decreased functional connectivity between the PCC/PCUN and left PHG, and medial prefrontal cortex (MPFC). MD values of the tract connecting PCC/PCUN to the left PHG positively correlated to the ammonia levels, the temporal correlation coefficients between the PCC/PCUN and the MPFC showed positive correlation to the digital symbol tests scores of patients.

Conclusion

MHE patients have both disturbed structural and functional connectivity within the DMN. The decreased functional connectivity was also detected between some regions without abnormal structural connectivity, suggesting that the former may be more sensitive in detecting the early abnormalities of MHE. This study extends our understanding of the pathophysiology of MHE.

Brain imaging and hepatic encephalopathy

Novel imaging techniques allow the investigation of structural and functional neuropathology of hepatic encephalopathy in greater detail, but limited techniques are applicable to the clinic. Computed tomography and magnetic resonance imaging (MRI) can rule out other diagnoses and, in MRI, give diagnostic features in widely available sequences. An internationally accepted diagnostic framework that includes an objective imaging test to replace or augment psychometry remains elusive. Quantitative MRI is likely to be the best candidate to become this test. The utility of MR and nuclear medical techniques to the clinic and results from recent research are described in this article.

Reversible cytotoxic edema in TPN-related hepatic encephalopathy

Hepatic encephalopathy (HE) is an uncommon complication of total parenteral nutrition (TPN). Cytotoxic edema has not been reported in children with TPN-related HE. We describe a case of TPN-related HE presenting with diffuse cytotoxic edema which reversed after liver transplantation.

Lactulose for minimal hepatic encephalopathy in patients with extrahepatic portal vein obstruction

BACKGROUND/AIMS

Minimal hepatic encephalopathy (MHE) is common in patients with extrahepatic portal vein obstruction (EHPVO). There is no study on the treatment of MHE using lactulose in patients with EHPVO.

PATIENTS AND METHODS

Consecutive EHPVO patients were assessed by psychometric (number connection test (NCT-A and B), digit symbol test (DST), serial dot test (SDT), line tracing test (LTT)), and critical flicker frequency (CFF) at inclusion. Patients diagnosed as MHE were treated with lactulose and psychometric tests, CFF, and were reassessed after 3 months.

RESULTS

Of the 70 patients screened, the prevalence of abnormal psychometric test was as follows: NCT-A (41%), NCT-B (53%), DST (38%), SDT (40%), and LTT (44%). Thirty patients (43%) had two or more than two abnormal (>2 SD) psychometry tests. Lactulose improved MHE in 16/30 (53%) of patients after 3 months of treatment. Arterial ammonia decreased after lactulose treatment compared to baseline (83.7±19.1 vs. 65.1±19.3 μmol/l, P=0.001). A total of 9 (75%) of 12 patients with large spontaneous shunt and 7 (39%) of 18 patients without spontaneous shunt improved with lactulose (P=0.07). CFF in patients with MHE (n=30) was significantly lower than those without MHE (n=40) (38.1±2.4 vs. 41.5±3.1 Hz, P=0.01). CFF was less than 38 Hz in 21 (70%) of 30 patients before treatment and in 10 (33%) patients after lactulose therapy in MHE patients. All patients could tolerate lactulose without any significant side effects. Four patients (13%) developed transient diarrhea in whom dose needed reduction, 3 (10%) did not like its taste but have continued, and 2 (6%) developed abdominal bloating sensation.

CONCLUSIONS

Lactulose is effective in the treatment of MHE in patients with EHPVO.

Three dimensional cultures of rat liver cells using a natural self-assembling nanoscaffold in a clinically relevant bioreactor for bioartificial liver construction

Till date, no bioartificial liver (BAL) procedure has obtained FDA approval or widespread clinical acceptance, mainly because of multifactorial limitations such as the use of microscale or undefined biomaterials, indirect and lower oxygenation levels in liver cells, short-term undesirable functions, and a lack of 3D interaction of growth factor/cytokine signaling in liver cells. To overcome preclinical limitations, primary rat liver cells were cultured on a naturally self-assembling peptide nanoscaffold (SAPN) in a clinically relevant bioreactor for up to 35 days, under 3D interaction with suitable growth factors and cytokine signaling agents, alone or combination (e.g., Group I: EPO, Group II: Activin A, Group III: IL-6, Group IV: BMP-4, Group V: BMP4 + EPO, Group VI: EPO + IL-6, Group VII: BMP4 + IL-6, Group VIII: Activin A + EPO, Group IX: IL-6 + Activin A, Group X: Activin A + BMP4, Group XI: EPO + Activin A + BMP-4 + IL-6 + HGF, and Group XII: Control). Major liver specific functions such as albumin secretion, urea metabolism, ammonia detoxification, phase contrast microscopy, immunofluorescence of liver specific markers (Albumin and CYP3A1), mitochondrial status, glutamic oxaloacetic transaminase (GOT) activity, glutamic pyruvic transaminase (GPT) activity, and cell membrane stability by the lactate dehydrogenase (LDH) test were also examined and compared with the control over time. In addition, we examined the drug biotransformation potential of a diazepam drug in a two-compartment model (cell matrix phase and supernatant), which is clinically important. This present study demonstrates an optimized 3D signaling/scaffolding in a preclinical BAL model, as well as preclinical drug screening for better drug development.

Pro-inflammatory cytokines are raised in extrahepatic portal venous obstruction, with minimal hepatic encephalopathy

BACKGROUND AND AIMS

Minimal hepatic encephalopathy (MHE) and hyperammonemia are seen in patients with extrahepatic portal venous obstruction (EHPVO). Inflammation has been shown to play an important role in the pathogenesis of hepatic encephalopathy in cirrhotics. This study assessed serum pro-inflammatory cytokines and their correlation with hyperammonemia, (1)H-magnetic resonance (MR) spectroscopy-derived brain glutamine, and diffusion tensor imaging (DTI)-derived metrics in patients with EPHVO, with and without MHE.

METHODS

Neuropsychological tests, DTI, (1)H-MR spectroscopy, and estimation of blood ammonia and pro-inflammatory cytokines (tumor necrosis factor-α[TNF-α] and interleukin-6 [IL-6]) were done in 20 patients with EHPVO and eight healthy controls.

RESULTS

Pro-inflammatory cytokines (TNF-α and IL-6), blood ammonia, brain glutamine, and mean diffusivity were increased in both patient groups, as compared to controls. Patients with MHE (n-12) had significantly higher TNF-α, IL-6, blood ammonia, brain glutamine, and mean diffusivity, signifying brain edema, than controls. A significant, positive correlation was seen between TNF-α and IL-6 and between blood ammonia and TNF-α, IL-6, and brain glutamine. Significant, positive correlations of TNF-α, IL-6, and blood ammonia with mean diffusivity values were seen in various brain regions, including spectroscopy voxel-derived mean diffusivity.

CONCLUSION

Patients with extrahepatic portal vein obstruction have inflammation and hyperammonemia made evident by higher blood TNF-α, IL-6, ammonia, and brain glutamine levels. A significant correlation between hyperammonemia, pro-inflammatory cytokines, and cerebral edema on DTI in various brain regions suggests that both these factors play a role in the pathogenesis of MHE in these patients.