Cerebral 1H MR spectroscopy and neuropsychologic status of patients with hepatic encephalopathy

[WITHDRAWN] Serum biomarkers of liver fibrosis identify changes in striatal metabolite levels

The full text of this preprint has been withdrawn by the authors due to author disagreement with the posting of the preprint. Therefore, the authors do not wish this work to be cited as a reference. Questions should be directed to the corresponding author.

Hepatic Encephalopathy and Liver Transplantation: The Past, Present, and Future Toward Equitable Access

Cirrhosis is a debilitating chronic disease with high morbidity and mortality, with the only real cure being liver transplantation (LT). Currently, we allocate organs for transplantation based on the Model for End-Stage Liver Disease-Sodium (MELD-Na) score that does not account for hepatic encephalopathy (HE). HE affects patients, families, and the health care system because of high rates of recurrence and major readmission burden. Moreover, HE casts a long shadow even after LT. Accounting for HE and incorporating it into the current allocation system has many proponents, but the framework to do this is currently lacking because of differences in consensus or in operationalization parameters. We review the latest evidence of the burden of HE, management of HE before and after LT, and evaluate pros and cons of several methods of diagnosing HE objectively to ensure early and equitable access to LT in this underserved population.

Meta-analysis of magnetic resonance spectroscopy in the diagnosis of hepatic encephalopathy

Objective

Various imaging modalities have been used to explore pathogenic mechanisms and stratify the severity of hepatic encephalopathy (HE). The hypothesis of this meta-analysis was that there is a progressive identifiable derangement of imaging measures using magnetic resonance spectroscopy (MRS) related to the severity of the HE.

Methods

Studies with more than 10 cases and HE diagnosis were identified from the electronic databases PubMed, EMBASE, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Literatura Latino Americana em Ciências da Saúde (LILACS), and Cochrane Central Register of Controlled Trials (CENTRAL) through July 25, 2018. Participants were stratified into healthy controls and patients with non-HE (NHE) (cirrhosis without HE), minimal HE (MHE), and overt HE (OHE). Analyses were organized by metabolite studied and brain region examined. Statistical meta-analysis was performed using the metafor package in R (v3.4.1). Pooled standardized mean differences between patient groups were calculated using a random effects model.

Results

We identified 31 studies (1,481 patients) that included data for cirrhosis-related HE. We found the parietal region to be the most reliable in differentiating between patients with and without MHE, with standard mean differences of +0.82 (95% confidence interval [CI] +0.49 to +1.15, p < 0.0001, I2 = 37.45%) for glutamine/glutamate, −0.36 (95% CI −0.61 to −0.10, p = 0.007, I2 = 20.00%) for choline, and−0.77 (95% CI −1.19 to −0.34, p = 0.0004, I2 = 67.48%) for myo-inositol. We also found that glutamine/glutamate was the metabolite that reliably correlated with HE grade in all brain regions.

Conclusions

The meta-analysis reveals that MRS changes in glutamine/glutamate, choline, and myo-inositol, particularly in the parietal lobe, correlate with the severity of HE. MRS may be of value in the assessment of HE.

The influence of HE history, HE status and neuropsychological test type on learning ability in patients with cirrhosis

BACKGROUND & AIMS

Learning ability may be impaired in patients with a history of overt hepatic encephalopathy (OHE). The aim of this study was to compare performance on the first/second attempt at a series of tests.

METHODS

Two hundred and fourteen patients with cirrhosis were enrolled. On the day of study, 41% were classed as unimpaired, 38% as having minimal HE and 21% as having mild OHE; 58% had a history of OHE. Performance was compared between two versions of the trail-making test A (TMT-A), and between the first/second half of a simple/choice reaction time (sRT and cRT), and a working memory test (ScanRT).

RESULTS

Both patients with and without OHE history improved in TMT-A, sRT and ScanRT. Only patients with no OHE history improved in cRT. All patients, regardless of their HE status on the day of study, improved in TMT-A and sRT. Only patients with mild OHE on the day of study improved in cRT. Only unimpaired patients improved in ScanRT. When OHE history and HE status on the day of study were tested together, only HE status had an effect. The same held true when age, the Model for End Stage Liver Disease (MELD) and educational attainment were adjusted for.

CONCLUSIONS

HE status on the day of study and the type of neuropsychological test had an effect on learning ability in a well-characterized group of patients with cirrhosis.

Neuroimaging in alcohol use disorder: From mouse to man

This article provides an overview of recent advances in understanding the effects of alcohol use disorders (AUD) on the brain from the perspective of magnetic resonance imaging (MRI) research in preclinical models and clinical studies. As a noninvasive investigational tool permitting assessment of morphological, metabolic, and hemodynamic changes over time, MRI offers insight into the dynamic course of alcoholism beginning with initial exposure through periods of binge drinking and escalation, sobriety, and relapse and has been useful in differential diagnosis of neurological diseases associated with AUD. Structural MRI has revealed acute and chronic effects of alcohol on both white and gray matter volumes. MR Spectroscopy, able to quantify brain metabolites in vivo, has shed light on biochemical alterations associated with alcoholism. Diffusion tensor imaging permits microstructural characterization of white matter fiber tracts. Functional MRI has allowed for elucidation of hemodynamic responses at rest and during task engagement. Positron emission tomography, a non-MRI imaging tool, has led to a deeper understanding of alcohol-induced receptor and neurotransmitter changes during various stages of drinking and abstinence. Together, such in vivo imaging tools have expanded our understanding of the dynamic course of alcoholism including evidence for regional specificity of the effects of AUD, hints at mechanisms underlying the shift from casual to compulsive use of alcohol, and profound recovery with sustained abstinence.

Learning and Memory Impairments in Patients with Minimal Hepatic Encephalopathy are Associated with Structural and Functional Connectivity Alterations in Hippocampus

Patients with minimal hepatic encephalopathy (MHE) show mild cognitive impairment associated with alterations in attentional and executive networks. There are no studies evaluating the relationship between memory in MHE and structural and functional connectivity (FC) changes in the hippocampal system. This study aimed to evaluate verbal learning and long-term memory in cirrhotic patients with (C-MHE) and without MHE (C-NMHE) and healthy controls. We assessed the relationship between alterations in memory and the structural integrity and FC of the hippocampal system. C-MHE patients showed impairments in learning, long-term memory, and recognition, compared to C-NMHE patients and controls. Cirrhotic patients showed reduced fimbria volume compared to controls. Larger volumes in hippocampus subfields were related to better memory performance in C-NMHE patients and controls. C-MHE patients presented lower FC between the L-presubiculum and L-precuneus than C-NMHE patients. Compared to controls, C-MHE patients had reduced FC between L-presubiculum and subiculum seeds and bilateral precuneus, which correlated with cognitive impairment and memory performance. Alterations in the FC of the hippocampal system could contribute to learning and long-term memory impairments in C-MHE patients. This study demonstrates the association between alterations in learning and long-term memory and structural and FC disturbances in hippocampal structures in cirrhotic patients.

Low visual cortex GABA levels in hepatic encephalopathy: links to blood ammonia, critical flicker frequency, and brain osmolytes

The pathogenesis of hepatic encephalopathy (HE) is not fully understood yet. Hyperammonemia due to liver failure and subsequent disturbance of cerebral osmolytic balance is thought to play a pivotal role in the emergence of HE. The aim of this in-vivo MR spectroscopy study was to investigate the levels of γ-aminobutyric acid (GABA) and its correlations with clinical symptoms of HE, blood ammonia, critical flicker frequency, and osmolytic levels. Thirty patients with minimal HE or HE1 and 16 age-matched healthy controls underwent graduation of HE according to the West-Haven criteria and including the critical flicker frequency (CFF), neuropsychometric testing and blood testing. Edited proton magnetic resonance spectroscopy ((1)H MRS) was used to non-invasively measure the concentrations of GABA, glutamate (Glu), glutamine (Gln), and myo-inositol (mI) - all normalized to creatine (Cr) - in visual and sensorimotor cortex. GABA/Cr in the visual area was significantly decreased in mHE and HE1 patients and correlated both to the CFF (r = 0.401, P = 0.013) and blood ammonia levels (r = -0.434, P = 0.006). Visual GABA/Cr was also strongly linked to mI/Cr (r = 0.720, P < 0.001) and Gln/Cr (r = -0.699, P < 0.001). No group differences or correlations were found for GABA/Cr in the sensorimotor area. Hepatic encephalopathy is associated with a regional specific decrease of GABA levels in the visual cortex, while no changes were revealed for the sensorimotor cortex. Correlations of visual GABA/Cr with CFF, blood ammonia, and osmolytic regulators mI and Gln indicate that decreased visual GABA levels might contribute to HE symptoms, most likely as a consequence of hyperammonemia.

New Methods of Testing and Brain Imaging in Hepatic Encephalopathy: A Review

The diagnosis of hepatic encephalopathy is predominantly clinical, and the tests available assist in the diagnosis only by excluding other causes. Covert hepatic encephalopathy, which is defined as abnormal performance on psychometric tests when standard neurologic examination is completely normal, has gained widespread attention in recent years due to its effect on quality of life. This review focuses on the tests available to aid in the diagnosis of this significant complication of liver disease, and discusses the complex pathophysiologic mechanisms identified through new imaging techniques and their significance toward development of new therapeutic targets for this condition.

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.

Glutamate and glutamine: a review of in vivo MRS in the human brain

Our understanding of the roles that the amino acids glutamate (Glu) and glutamine (Gln) play in the mammalian central nervous system has increased rapidly in recent times. Many conditions are known to exhibit a disturbance in Glu-Gln equilibrium, and the exact relationships between these changed conditions and these amino acids are not fully understood. This has led to increased interest in Glu/Gln quantitation in the human brain in an array of conditions (e.g. mental illness, tumor, neuro-degeneration) as well as in normal brain function. Accordingly, this review has been undertaken to describe the increasing number of in vivo techniques available to study Glu and Gln separately, or pooled as 'Glx'. The present MRS methods used to assess Glu and Gln vary in approach, complexity, and outcome, thus the focus of this review is on a description of MRS acquisition approaches, and an indication of relative utility of each technique rather than brain pathologies associated with Glu and/or Gln perturbation. Consequently, this review focuses particularly on (1) one-dimensional (1)H MRS, (2) two-dimensional (1)H MRS, and (3) one-dimensional (13)C MRS techniques.

Two-dimensional MR spectroscopy of minimal hepatic encephalopathy and neuropsychological correlates in vivo

PURPOSE

To evaluate regional cerebral metabolic and structural changes in patients with minimal hepatic encephalopathy (MHE) using two-dimensional (2D) MR spectroscopy (MRS) and T( (1) )-weighted MRI, to correlate the observed MR changes with neuropsychological (NP) test scores, and to compare the diagnostic accuracy of MRI, 2D MRS, and NP tests in discriminating between patients and healthy subjects.

MATERIALS AND METHODS

Thirty-three MHE patients and 30 healthy controls were investigated. The 2D localized correlated spectroscopy (L-COSY) was performed in the frontal and occipital brain on a 1.5 Tesla (T) MR scanner. The NP test battery included 15 tests, grouped into 6 cognitive domains. Globus pallidus signal intensities were calculated from T(1)-weighted images.

RESULTS

The 2D MRS showed significant differences in ratios of the following metabolite(s) peaks with respect to creatine (Cr): decreased myo-inositol (mI), choline (Ch), mICh, and increased (glutamate plus glutamine) (Glx) in patients compared with healthy subjects in both occipital and frontal lobes. Frontal lobe taurine also showed a decline in patients. The NP test results revealed declines in cognitive speed, motor function, executive function, and global cognitive status. Significant correlations were found between the altered metabolites and NP tests. Alteration in the mICh/Cr ratio was noted as a powerful discriminant between healthy subjects and the patients.

CONCLUSION

The study demonstrates that relative metabolite levels determined by 2D MRS, in particular mICh/Cr, provide the best diagnostic prediction for MHE. The results suggest that depletions of myo-inositol, choline and taurine with respect to creatine correlate with measures of neuropsychological impairment.

Reversibility of hepatic encephalopathy after liver transplantation

Until the advent of Liver transplantation, it was widely believed that Hepatic Encephalopathy (HE) was usually reversible. The exceptions were the so called "Acquired Hepatocerebral Degeneration cases" which were considered irreversible. Paradoxically, it seems, with liver transplantation, we have seen cases that contradict these rules. Whether the "residual effects" of HE, degenerative brain injury or independent neurological insults are causing post transplant neurological deficits is not easy to discern. As more emphasis is being put on maintaining brain 'status' after liver transplantation, we are finding confirmation of the largely reversible nature of HE. But, enough important exceptions to this rule are occurring to make further research on this topic mandatory.

Minimal hepatic encephalopathy in children: evaluation with proton MR spectroscopy

BACKGROUND AND PURPOSE

Minimal hepatic encephalopathy (MHE) in children is difficult to evaluate because of lack of standardized neuropsychological tests for all age ranges. The purpose of this retrospective study of children with clinically suspected MHE was to investigate relationships between brain MR spectroscopy metabolites and biochemical markers of encephalopathy as well as measures of liver disease severity.

MATERIALS AND METHODS

A total of 12 children (age range, 9-19 years; 8 female) with clinically suspected MHE were studied by short TE brain MR spectroscopy on a 1.5T magnet. We estimated gray matter (GM) and white matter (WM) metabolite concentrations using "LCModel" software. Regional metabolite concentrations were examined for correlation with various parameters, including plasma ammonia, the ratio of branched-chain to aromatic amino acids (BCAA/AAA), model for end stage liver disease/pediatric end stage liver disease (MELD/PELD) and Child-Pugh scores, bilirubin, albumin, and platelet counts.

RESULTS

Myo-inositol (mIns) levels correlated with BCAA/AAA ratios (r = 0.86; P = .002 for GM and r = 0.77; P = .01 for WM). WM choline (Cho) levels and GM mIns levels showed significant negative correlation with ammonia levels (r = -0.58; P = .04 and r = -0.65; P = .02, respectively). A positive significant correlation trend was present for GM glutamine/glutamate (Glx) and ammonia levels (r = 0.66; P = .05). There was no correlation of brain MR spectroscopy parameters and severity of liver disease.

CONCLUSIONS

Brain MR spectroscopy metabolites in children with suspected MHE show significant correlations with plasma ammonia levels and BCAA/AAA. As in adults, brain MR spectroscopy in children may be helpful in establishing a diagnosis of MHE.

Minimal hepatic encephalopathy in children: evaluation with proton MR spectroscopy

BACKGROUND AND PURPOSE

Minimal hepatic encephalopathy (MHE) in children is difficult to evaluate because of lack of standardized neuropsychological tests for all age ranges. The purpose of this retrospective study of children with clinically suspected MHE was to investigate relationships between brain MR spectroscopy metabolites and biochemical markers of encephalopathy as well as measures of liver disease severity.

MATERIALS AND METHODS

A total of 12 children (age range, 9-19 years; 8 female) with clinically suspected MHE were studied by short TE brain MR spectroscopy on a 1.5T magnet. We estimated gray matter (GM) and white matter (WM) metabolite concentrations using "LCModel" software. Regional metabolite concentrations were examined for correlation with various parameters, including plasma ammonia, the ratio of branched-chain to aromatic amino acids (BCAA/AAA), model for end stage liver disease/pediatric end stage liver disease (MELD/PELD) and Child-Pugh scores, bilirubin, albumin, and platelet counts.

RESULTS

Myo-inositol (mIns) levels correlated with BCAA/AAA ratios (r = 0.86; P = .002 for GM and r = 0.77; P = .01 for WM). WM choline (Cho) levels and GM mIns levels showed significant negative correlation with ammonia levels (r = -0.58; P = .04 and r = -0.65; P = .02, respectively). A positive significant correlation trend was present for GM glutamine/glutamate (Glx) and ammonia levels (r = 0.66; P = .05). There was no correlation of brain MR spectroscopy parameters and severity of liver disease.

CONCLUSIONS

Brain MR spectroscopy metabolites in children with suspected MHE show significant correlations with plasma ammonia levels and BCAA/AAA. As in adults, brain MR spectroscopy in children may be helpful in establishing a diagnosis of MHE.

Evaluation of mannitol effect in patients with acute hepatic failure and acute-on-chronic liver failure using conventional MRI, diffusion tensor imaging and in-vivo proton MR spectroscopy

AIM: To evaluate the effect of an intravenous bolus of mannitol in altering brain metabolites, brain water content, brain parenchyma volume, cerebrospinal fluid (CSF) volume and clinical signs in controls and in patients with acute liver failure (ALF) and acute-on-chronic liver failure (ACLF), by comparing changes in conventional magnetic resonance imaging (MRI), in vivo proton magnetic resonance spectroscopy (PMRS) and diffusion tensor imaging (DTI) before and after its infusion.

METHODS: Five patients each with ALF and ACLF in grade 3 or 4 hepatic encephalopathy and with clinical signs of raised intracranial pressure were studied along with five healthy volunteers. After baseline MRI, an intravenous bolus of 20% mannitol solution was given over 10 min in controls as well as in patients with ALF and ACLF. Repeat MRI for the same position was acquired 30 min after completing the mannitol injection.

RESULTS: No statistically significant difference was observed between controls and patients with ALF and ACLF in metabolite ratios, DTI metrics and brain volume or CSF volume following 45 min of mannitol infusion. There was no change in clinical status at the end of post-mannitol imaging.

CONCLUSION: The osmotic effect of mannitol did not result in significant reduction of brain water content, alteration in metabolite ratios or any change in the clinical status of these patients during or within 45 min of mannitol infusion.

Cerebral diffusion tensor imaging and in vivo proton magnetic resonance spectroscopy in patients with fulminant hepatic failure

BACKGROUND AND AIM

Cerebral edema is a major complication in patients with fulminant hepatic failure (FHF). The aim of this study was to evaluate the metabolite alterations and cerebral edema in patients with FHF using in vivo proton magnetic resonance spectroscopy (MRS) and diffusion tensor imaging, and to look for its reversibility in survivors.

METHODS

Ten FHF patients along with 10 controls were studied. Five of the 10 patients who recovered had a repeat imaging after three weeks. N-acetylaspartate, choline (Cho), glutamine (Gln), glutamine/glutamate (Glx), and myoinositol ratios were calculated with respect to creatine (Cr). Mean diffusivity (MD) and fractional anisotropy (FA) were calculated in different brain regions.

RESULTS

Patients exhibited significantly increased Gln/Cr and Glx/Cr, and reduced Cho/Cr ratios, compared to controls. In the follow-up study, all metabolite ratios were normalized except Glx/Cr. Significantly decreased Cho/Cr were observed in deceased patients compared to controls. In patients, significantly decreased MD and FA values were observed in most topographical locations of the brain compared to controls. MD and FA values showed insignificant increase in the follow-up study compared to their first study.

CONCLUSIONS

We conclude that the Cho/Cr ratio appears to be an in vivo marker of prognosis in FHF. Decreased MD values suggest predominant cytotoxic edema may be present. Persistence of imaging and MRS abnormalities at three weeks' clinical recovery suggests that metabolic recovery may take longer than clinical recovery in FHF patients.

MR imaging findings in hepatic encephalopathy

The term hepatic encephalopathy (HE) includes a spectrum of neuropsychiatric abnormalities occurring in patients with liver dysfunction. Most cases are associated with cirrhosis and portal hypertension or portal-systemic shunts, but the condition can also be seen in patients with acute liver failure and, rarely, with portal-systemic bypass and no associated intrinsic hepatocellular disease. Although HE is a clinical condition, several neuroimaging techniques, particularly MR imaging, may eventually be useful for the diagnosis because they can identify and measure the consequences of central nervous system (CNS) increase in substances that under normal circumstances, are efficiently metabolized by the liver. Classic MR imaging abnormalities include high signal intensity in the globus pallidum on T1-weighted images, likely a reflection of increased tissue concentrations of manganese, and an elevated glutamine/glutamate peak coupled with decreased myo-inositol and choline signals on proton MR spectroscopy, representing disturbances in cell-volume homeostasis secondary to brain hyperammonemia. Recent data have shown that white matter abnormalities, also related to increased CNS ammonia concentration, can also be detected with several MR imaging techniques such as magnetization transfer ratio measurements, fast fluid-attenuated inversion recovery sequences, and diffusion-weighted images. All these MR imaging abnormalities, which return to normal with restoration of liver function, probably reflect the presence of mild diffuse brain edema, which seems to play an essential role in the pathogenesis of HE. It is likely that MR imaging will be increasingly used to evaluate the mechanisms involved in the pathogenesis of HE and to assess the effects of therapeutic measures focused on correcting brain edema in these patients.

Role of Magnetic Resonance in Understanding the Pathogenesis of Hepatic Encephalopathy

A spectrum of neuropsychiatric abnormalities caused by portosystemic venous shunting occurs in hepatic encephalopathy (HE) patients with or without liver dysfunction. It is not completely clear how the astrocyte swelling leads to glial-neuronal dysfunction, and how the symptoms are manifested in HE. A major goal of this work is to review the current status of information available from the existing magnetic resonance (MR) modalities including MR imaging (MRI) and MR Spectroscopy (MRS) as well as other modalities in the understanding the pathogenesis of HE. First, we discuss briefly neuron-histopathology, neurotoxins, neuropsychological and neurophysiological tests. A short review on the progress with single-photon emission computed tomography (SPECT) and positron emission tomography (PET) is then presented. In the remaining part of the manuscript, the following topics pertinent to understanding the pathogenesis of HE are discussed: MRI, diffusion tensor imaging (DTI), one-dimensional MRS based single- and multi-voxel based spectroscopic imaging techniques and two-dimensional MRS.

Hepatic encephalopathy: a neurochemical, neuroanatomical, and neuropsychological study

Hepatic encephalopathy (HE) is normally diagnosed by neuropsychological (NP) tests, which are not very specific and do not reveal the underlying pathology. Magnetic resonance imaging (MRI) and spectroscopy (MRS) of the brain offer alternative and possibly more specific markers for HE. These methods were applied in conjunction with NP testing in order to determine their usefulness in the identification of HE and to understand the pathogenesis of HE more clearly. MR imaging and spectroscopy examinations, in addition to a battery of 15 NP tests, were administered to investigate 31 patients awaiting liver transplantation and 23 healthy controls. MR image intensities from the globus pallidus region were calculated and normalized to those of the thalamus. Absolute concentrations and ratios with respect to creatine (Cr) of several metabolites were computed from MR spectra. The MR data were correlated with the results of NP tests. The patients showed impairment in NP tests of attention and visuospatial and verbal fluency. In T1-weighted MRI, the relative intensity of the globus pallidus with respect to that of the thalamus region was significantly elevated in patients and correlated(negatively) with three NP tests (Hooper, FAS, and Trails B). The absolute concentrations of myo-inositol (mI) and choline (Ch) were significantly reduced in three brain regions. In addition, the absolute concentrations of glutamine (Gln) and combined glutamate and glutamine (Glx) were increased in all three locations, with Gln increase being significant in all areas while that of Glx only in the occipital white matter. In summary, this study partially confirms a hypothesized mechanism of HE pathogenesis, an increased synthesis of glutamine by brain glutamate in astrocytes due to excessive blood ammonia, followed by a compensatory loss of myo-inositol to maintain astrocyte volume homeostasis. It also indicates that the hyperintensity observed in globus pallidus could be used as complementary to the NP test scores in evaluating the mental health of HE patients.

Motor dysfunction in patients with liver cirrhosis: impairment of handwriting

Motor dysfunction is an important clinical finding in patients with liver cirrhosis and mild forms of hepatic encephalopathy. The mechanisms and clinical appearance of motor impairment in patients with liver cirrhosis are not completely understood. We studied fine motor control in forty four patients with advanced liver cirrhosis (excluding those with hepatic encephalopathy grade II) and 48 healthy controls using a kinematic analysis of standardized handwriting tests. We analysed parameters of velocity, the ability to coordinate and the level of automatisation of handwriting movements. Furthermore, we studied the association between impairment of handwriting and clinical neuro-psychiatric symptoms. As compared with control subjects, patients showed a statistically significant reduction of movement peak velocity in all handwriting tasks as well as a substantial increase of number of velocity inversions per stroke. Using a z-score based assessment we found impairment of handwriting in fourteen out of forty four patients (31.8 %). The deterioration of handwriting was associated with clinical symptoms of motor dysfunction, such as bradykinesia, adiadochokinesia, dysmetria of upper extremities and gait ataxia. This is the first study that quantitatively investigates impairment of handwriting in patients with liver cirrhosis. Our findings suggest the application of kinematic analysis of handwriting for diagnostics of motor dysfunction in patients with mild forms of hepatic encephalopathy.

Multidimensional assessment of neuro-psychiatric symptoms in patients with low-grade hepatic encephalopathy: A clinical rating scale

AIM: To evaluate the feasibility of a new clinical rating scale for a standardized assessment of cirrhosis-associated neuro-psychiatric symptoms.

METHODS: Forty patients with liver cirrhosis (LC, with or without low-grade hepatic encephalopathy) were invest-igated using a clinical neuro-psychiatric rating scale based on a comprehensive list of neurological, psychomotor, cognitive, affective, behavioral symptoms, and symptoms of disturbed bioregulation.

RESULTS: The analysis revealed that the majority of cirrhotic patients showed, besides characteristic neurological symptoms of hepatic encephalopathy, various psychomotor, affective and bioregulatory symptoms (disturbed sleep and sexual dysfunction). Patients were impaired in the following subscales: sleep and biorhythm disorder (75.0% of patients), Parkinsonoid symptoms (25.0%), affective symptoms (17.5%), and psychomotor retardation (12.5%). The increase of total neuro-psychiatric clinical score was significantly associated with the degree of hepatic enceph-alopathy.

CONCLUSION: This study suggests that a substantial number of patients with LC and low-grade hepatic encephalopathy manifest various clinical neuro-psychiatric symptoms. The use of a rating scale, which explores clinical dimensions of hepatic encephalopathy, would improve the management of patients with LC.

Cognitive Abilities in Children after Liver Transplantation

BACKGROUND

The authors investigated the cognitive status during the late postoperative phase in children who had undergone liver transplantation (LTx).

METHODS

The authors examined 44 children who had undergone liver transplantation at their center. The children were 8.9+/-2.3 (mean+/-SD) years of age and had received the transplant 6.1+/-2.6 years previously. In 24 of the 44 children, a living-related transplantation had been carried out. Cognitive abilities were assessed with the three subscales of the Kaufman Assessment Battery for Children (K-ABC): the sequential processing scale (SES), the simultaneous processing scale (SIS), and the achievement scale (AS).

RESULTS

The children scored below the population mean but within the normal range on all subscales of the K-ABC. In the SIS and the AS, age at transplantation influenced the cognitive outcome, as the children who were younger at transplantation scored significantly better than the older children and their results were within the normal range. However, for the SES, no such differences were found. A multiple regression analysis revealed that duration of illness and height at transplantation predicts the performance in the SIS and the AS. To a lesser degree, type of transplantation (cadaveric vs. living-related) predicts performance in the AS. Performance in the SES was not predicted by any of these variables. Time since LTx and type of immunosuppressive regimen were not associated with the cognitive status after transplantation.

CONCLUSIONS

Children who are younger, with a shorter duration of illness, and who are more physically developed before LTx have a better prognosis regarding their mental development. However, this result does not hold for sequential processing functions, which showed no relationship with any of these variables. This could indicate differential effects of liver disease and consecutive metabolic derangements on brain development during the preoperative phase.

Adding another spectral dimension to1H magnetic resonance spectroscopy of hepatic encephalopathy

PURPOSE

To evaluate a localized two-dimensional correlated magnetic resonance spectroscopic (L-COSY) technique in patients with hepatic encephalopathy (HE) and healthy subjects, and to correlate the cerebral metabolite changes with neuropsychological (NP) test scores.

MATERIALS AND METHODS

Eighteen minimal hepatic encephalopathy (MHE) patients and 21 healthy controls have been investigated. A GE 1.5-T magnetic resonance (MR) scanner was used in combination with a body MR coil for transmission and a 3-inch surface coil for reception. A 27-mL voxel was localized by three slice-selective radio frequency (RF) pulses (90 degrees-180 degrees-90 degrees) in the anterior cingulate region. The total duration of each two-dimensional L-COSY spectrum was approximately 25 minutes. The NP battery included a total of 15 tests, which were grouped into six domains.

RESULTS

MR spectroscopic results showed a statistically significant decrease in myo-inositol (mI) and choline (Ch) and an increase in glutamate/glutamine (Glx) in patients when compared to healthy controls. There was also an increase in taurine (Tau) in patients. The NP results indicated a significant correlation between motor function assessed by NP tests and mI ratios recorded using two-dimensional L-COSY.

CONCLUSION

The study demonstrated the feasibility of evaluating the two-dimensional L-COSY sequence in a clinical environment. The results showed additional cerebral metabolites that can be measured with the technique in comparison to one-dimensional study.

Incomplete improvement of visuo-motor deficits in patients with minimal hepatic encephalopathy after liver transplantation

Previous studies have suggested reversibility of minimal hepatic encephalopathy in patients with liver cirrhosis after liver transplantation (LT), however, this topic is controversially discussed. We investigated this issue in a prospective study on liver cirrhotic patients listed for LT. Patients were investigated before and after liver transplantation (on average 21 months later) using a neuropsychological test battery which measured visuo-constructive and visuo-motor ability, verbal fluency, and memory function. To assess visuo-motor and visuo-constructive functions, we performed 4 tests: Rey Complex Figure Test copy, trail making tests A and B, and digital symbol test. The average percentile score of the tests, arbitrarily named the visuo-motor and visuo-constructive performance score (VMCP), was calculated. After LT, the patients did not demonstrate a significant increase of VMCP (P =.29) and additionally showed significantly lower VMCP score (P =.041) compared to control group. Analysis of individual responses showed that only 7 of 14 patients improved their VMCP values after LT. These data indicate that the cirrhosis-associated visuo-motor deficits subside or disappear only in some of the patients after LT, whereas a significant number of patients show no improvement of the visuo-motor and visuo-constructive function. We concluded that monitoring of cognitive and visuo-motor functioning is important for the post-transplant rehabilitation of patients with liver cirrhosis.

Memory function in early hepatic encephalopathy

BACKGROUND

Early hepatic encephalopathy (HE) is characterized by deficits in motor performance, visual perception, visuo-constructive abilities and attention. Whether defective memory is a feature of early HE is controversial.

AIMS

To analyze memory function in patients with early HE.

METHODS

Memory tests were applied to cirrhotic patients with grade 0 HE, minimal HE and grade I HE (n=45) and controls (n=52). The battery included short and long term memory tests requiring free recall or recognition. Minimal HE was diagnosed by assessing the psychometric hepatic encephalopathy score using the PSE-Syndrom-Test and by carrying out a neurological examination. Group differences of the test results were analyzed using analysis of covariance.

RESULTS

HE 0 patients achieved test results similar to the controls in all but two tests. Patients with early HE (minimal and grade I HE) scored lower than the controls in all tests applied. A detailed analysis of test performance showed that the patients' deficits were in attention and visual perception, rather than memory.

CONCLUSIONS

Patients with early HE score lower than controls in memory tasks predominantly because of deficits in attention and visual perception.

Neurocognitive outcome in pediatric liver transplant recipients

Studies have shown that children with liver transplants demonstrate deficits on intellectual, academic, and language measures. However, limited information is known about the long-term cognitive development of these children. In this study, 15 children who were at least 2 yr post-liver transplantation (LT) were compared on cognitive measures to an equated group of 15 children with cystic fibrosis (CF). Children with CF were selected as a clinical control given similarities in disease onset and chronicity, as well as physical growth and development. Results indicated that children with LT tended to have lower verbal intelligence quotient scores and performed significantly lower than CF children on language measures, particularly on receptive language tasks. No significant differences were obtained on measures of academic achievement or visual-spatial performance. In the LT group, days in the intensive care unit, total number of days spent in the hospital during the first year following the transplant, and elevated pretransplant bilirubin levels significantly predicted the speech and language delays.

Clinical significance of basal ganglia alterations at brain MRI and 1H MRS in cirrhosis and role in the pathogenesis of hepatic encephalopathy

In hepatic encephalopathy, a progressive and diffuse impairment in brain function is associated with gradual alterations that can be detected by magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy (1H MRS). In some patients, a variety of movement disorders suggestive of extrapyramidal impairment points toward basal ganglia (BG) alterations. Accordingly, (i) hyperintensities at MRI predominant in the pallidum, an important region of BG involved in the motor control, (ii) redistribution of cerebral blood flow from cortical areas to BG structures observed using positron emission tomography studies, and (iii) the preferential pallidal location of Alzheimer astrocytosis, all support this hypothesis. In most clinical studies, little if any correlations have been found between cerebral hyperintensities and neurological manifestations. The application of a test designed to evaluate patients with Parkinson's disease (where extrapyramidal signs are typical) showed significant clinical correlations both with pallidal hyperintensity and with choline/creatine ratio at 1H MRS in BG structures. Because of complex neuronal connections between BG and many cortical areas, BG dysfunction may influence the neurocognitive manifestations of hepatic encephalopathy. Similarities between chronic Mn intoxication and cirrhosis suggest common pathophysiological mechanisms including altered dopaminergic neurotransmission, although information in chronic liver failure is limited. Clinical observations are presented regarding the evolution of parkinsonian signs in various situations.

1H magnetic resonance in the study of hepatic encephalopathy in humans

1H magnetic resonance (1H MR) studies of the brain in patients with liver diseases have shown several abnormalities that may be relevant for the pathogenesis of hepatic encephalopathy. 1H magnetic resonance imaging shows a typical pallidal hyperintensity on T1-weighted images. This abnormality appears to be secondary to the accumulation of manganese in basal ganglia because of portal-systemic shunting. No direct correlation between the magnitude of pallidal hyperintensity and the grade of hepatic encephalopathy has been found, but some studies have related pallidal hyperintensity to parkinsonism. 1H magnetic resonance spectroscopy shows relative to creatine an increase in glutamine/glutamate (Glx) signal and a decrease of choline containing compounds (Cho) and myo-inositol. Abnormalities in the Glx signal have been interpreted as an increase in brain glutamine secondary to the metabolism of ammonia in astrocytes. Disturbances of Cho and myo-inositol have been interpreted as a compensatory response to the increase in intracellular osmolality caused by the accumulation of glutamine in astrocytes. In addition, magnetization transfer imaging shows signs compatible with low-grade cerebral edema. Altogether, 1H MR studies suggest the accumulation of manganese and the development of osmotic abnormalities in the brain of patients with cirrhosis. These abnormalities appear to participate in some of the neurological manifestations of hepatic encephalopathy.

Follow-up by one- and two-dimensional NMR of plasma from pigs with ischemia-induced acute liver failure treated with a bioartificial liver

Hepatic encephalopathy may occur following acute hepatic failure (AHF), which results in the release of toxic compounds from the injured liver. These compounds, which induce cerebral edema, are not well characterized, yet. The aim of this study was to evaluate the potential interest of NMR spectroscopy in the follow-up of different plasma compounds in pigs with ischemia-induced fulminant hepatic failure treated or not with a bioartificial liver (BAL), which has been previously shown to improve the neurological status of the animals. Qualitative analysis of pig plasma was achieved by one-dimensional-(1)H CPMG, two-dimensional homonuclear (1)H-(1)H TOCSY CPMG and heteronuclear (1)H-(13)C HSQC sequences. Semi-quantitative analysis of selected plasma metabolites along the disease evolution was carried out on pigs with ischemia-induced AHF treated with the BAL containing alginate beads with or without hepatocytes. A quantitative longitudinal follow-up was performed on characteristic metabolites via a one-dimensional CPMG sequence, including choline, glutamine, N-acetyl-glucosamine (NAG), pyruvate and trimethylamine-N-oxide (TMAO). The concentrations of choline and TMAO increased from the beginning to the end in animals treated with the BAL containing alginate beads without hepatocytes. Treatment of pigs with BAL containing hepatocytes resulted in an improvement of survival, the plasma concentrations of choline and TMAO being decreased in three out of five animals. Thus, NMR spectroscopy is a useful approach for the identification of toxic compounds which are involved in hepatic encephalopathy associated with AHF. These compounds can be cleared by a BAL resulting in the improvement of survival and neurological parameters of the animals.

Distinctly abnormal brain metabolism in late-onset ornithine transcarbamylase deficiency

OBJECTIVE

To assess alterations in brain metabolites in patients with late-onset ornithine transcarbamylase deficiency (OTCD).

METHODS

Six unrelated, asymptomatic Japanese late-onset OTCD patients were analyzed by proton MRS ((1)HMRS) using a point-resolved spectroscopy technique (repetition and echo times, 5000 and 30 ms). Localized spectra for the centrum semiovale were acquired and absolute metabolite concentrations were calculated using an LCModel.

RESULTS

Compared with age-matched controls, N-acetylaspartate and creatine concentrations were normal in all patients. The glutamine (Gln) plus glutamate concentration was increased in four patients, which progressed in proportion to the clinical stage. myo-inositol (mI) could not be detected in five symptomatic patients. A decreased choline (Cho) concentration was detected in two clinically severe patients. (1)HMRS after liver transplantation in one patient revealed the normalization of all metabolites.

CONCLUSION

These findings suggest progression of neurochemical events in OTCD, i.e., mI depletion and Gln accumulation followed by Cho depletion, which is reverse of that in hepatic encephalopathy, i.e., Cho depletion followed by mI depletion and Gln accumulation.

Localized two-dimensional shift correlated MR spectroscopy of human brain

A two-dimensional (2D) chemical shift correlated MR spectroscopic (COSY) sequence integrated into a new volume localization technique (90 degrees -180 degrees -90 degrees ) is proposed for whole-body MR spectroscopy (MRS). Using the product operator formalism, a theoretical calculation of the volume localization as well as the coherence transfer efficiencies in 2D MRS is presented. Phantom model solutions were used to test and optimize the efficiency of the proposed sequence. A combination of different MRI transmit/receive RF coils was used: a head MRI coil and a 3" surface coil receive combined with a body coil transmit. The J cross-peaks due to N-acetyl aspartate (NAA), glutamate/glutamine (Glx), myo-inositol (mI), creatine (Cr), choline (Ch), aspartate (Asp), gamma-aminobutyrate (GABA), taurine (Tau), glutathione (GSH), threonine (Thr), and macromolecules (MM) were identified. The cross-peak intensities excited by the proposed 2D sequence were asymmetric with respect to the diagonal peaks. Localized COSY (L-COSY) spectra of cerebral prefrontal and occipital gray/white matter regions in 15 healthy controls are presented. Magn Reson Med 46:58-67, 2001.

Hepatic encephalopathy

In the last decade, a significant amount of research has been devoted to the pathogenesis and treatment of hepatic encephalopathy (HE). Non-invasive neuroimaging techniques such as magnetic resonance imaging and spectroscopy have become important research tools. The search for a suitable animal model of HE associated with cirrhosis is still ongoing. Moreover, consensus terminology and diagnostic criteria for HE in humans are badly needed.

Magnetic resonance spectroscopy in toxic encephalopathy and neurodegeneration

Magnetic resonance spectroscopy allows neurochemistry to be probed noninvasively in vivo. Recent advances in our understanding of the biochemical significance of the various neurochemicals that are observable allow a variety of pathologic states of relevance to encephalopathies and neurodegenerative disorders to be observed. Measurements of brain glutamate and glutamine allow observation of neuronal/glial substrate cycling and ammonia detoxification. Myo-inositol allows changes in cerebral osmolarity and gliosis to be observed. N-acetylaspartate is a marker of neuronal health and number. Lactate allows nonoxidative glycolysis to be observed. These molecules are now being used to ask etiologic questions that are of relevance to encephalopathies and neurodegeneration, as well to probe longitudinally both natural history and therapeutic interventions in these conditions. Combined with recent advances in anatomic magnetic resonance imaging as well as perfusion magnetic resonance imaging, magnetic resonance spectroscopy has the potential to aid greatly in our understanding of neuronal dysfunction in a wide variety of neurologic pathologies, even in single patients.