Clinical significance of extrapyramidal signs in patients with cirrhosis

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

SIGNIFICANCE

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

Important Unresolved Questions in the Management of Hepatic Encephalopathy: An ISHEN Consensus

Management of hepatic encephalopathy (HE) remains challenging from a medical and psychosocial perspective. Members of the International Society for Hepatic Encephalopathy and Nitrogen Metabolism recognized 5 key unresolved questions in HE management focused on (i) driving, (ii) ammonia levels in clinical practice, (iii) testing strategies for covert or minimal HE, (iv) therapeutic options, and (v) nutrition and patient-reported outcomes. The consensus document addresses these topical issues with a succinct review of the literature and statements that critically evaluate the current science and practice, laying the groundwork for future investigations.

Targeted upregulation of uncoupling protein 2 within the basal ganglia output structure ameliorates dyskinesia after severe liver failure

Impaired motor function, due to the dysfunction of the basal ganglia, is the most common syndrome of hepatic encephalopathy (HE), and its etiology remains poorly understood. Neural oxidative stress is shown to be the major cellular defects contributing to HE pathogenesis. Mitochondrial uncoupling protein 2 (UCP2) has been implicated in neuroprotection in several neurological disorders. We explored the neuroprotective role of UCP2 within the substantia nigra pars reticulate (SNr), the output structure of the basal ganglia, in HE. The toxin thioacetamide (TAA) induced HE mice showed hypolocomotion, which was associated with decreased ATP levels and loss of antioxidant substances SOD and GSH within the SNr. Stable overexpression of UCP2 via AAV-UCP2 under the control of the UCP2 promoter in bilateral SNr preserved local ATP level, increased antioxidant substances, and ameliorated locomotion defects after severe liver failure. Contrary to UCP2 overexpression, targeted knockdown of UCP2 within bilateral SNr via AAV-UCP2 shRNA exacerbated the impaired mitochondrial dysfunction and hypokinesia in HE mice. The modulatory effects of UCP2 was due to mediation of K⁺-Cl^- cotransporter-2 (KCC2) expression on GABAergic neurons of SNr. Taken together, our results demonstrate that UCP2 exerts a neural protective role at the subcortical level by increasing the resistance of neurons to oxidative stress, which may offer a novel therapeutic target for the treatment of motor dysfunction diseases.

Falls in Patients With Liver Cirrhosis

Health-related quality of life (HRQOL) has become an important outcome for patients with liver cirrhosis as the number of transplantation candidates increases by the progression of treatment strategies. Falls and fall-related injuries are common in patients with liver cirrhosis and negatively affect HRQOL. Many factors increase the risk for falls such as minimal hepatic encephalopathy, psychoactive drugs, muscle strength, autonomic dysfunction, hyponatremia, and sleep problems. It is important to understand the underlying mechanisms for falls in cirrhotic patients to prevent severe injuries such as fractures, decrease healthcare costs, and improve HRQOL. Healthcare professionals, including physiotherapists and nurses, should be aware of the higher risk for falls in this population and therapeutic interventions must be designed for patients, especially those waiting on the transplant list.

Neuropsychological assessment without upper limb involvement: a systematic review of oral versions of the Trail Making Test and Symbol-Digit Modalities Test

The Trail Making Test (TMT) and written version of the Symbol Digit Modalities Test (SDMT) assess attention, processing speed, and executive functions but their utility is limited in populations with upper limb dysfunction. Oral versions of the TMT and SDMT exist, but a systematic review of their psychometric properties and clinical utility has not been conducted, which was the goal of this study. Searches were conducted in PubMed and PsycINFO, test manuals, and the reference lists of included articles. Four measures were identified: the SDMT-oral, oral TMT-A, oral TMT-B, and the Mental Alternation Test (MAT). Two investigators independently reviewed abstracts to identify peer-reviewed articles that reported on these measures in adult populations. From each article, one investigator extracted information on reliability, validity, responsiveness, minimum detectable change, normative data, and demographic influences. A second investigator verified the accuracy of the data in a random selection of 10% of papers. The quality of the evidence for each psychometric property was rated on a 4-point scale (unknown, poor, adequate, excellent). Results showed excellent evidence for the SDMT-oral, adequate evidence for the oral TMT-B and MAT, and adequate to poor evidence for the oral TMT-A. These findings inform the clinical assessment of attention, processing speed, and executive functions in individuals with upper limb disability.

Alterations in cerebral white matter and neuropsychology in patients with cirrhosis and falls

Background & Aim

Falls are frequent in patients with cirrhosis but underlying mechanisms are unknown. The aim was to determine the neuropsychological, neurological and brain alterations using magnetic resonance-diffusion tensor imaging (MR-DTI) in cirrhotic patients with falls.

Patients and methods

Twelve patients with cirrhosis and falls in the previous year were compared to 9 cirrhotic patients without falls. A comprehensive neuropsychological and neurological evaluation of variables that may predispose to falls included: the Mini-Mental State Examination, Psychometric Hepatic Encephalopathy Score (PHES), Parkinson’s Disease-Cognitive Rating Scale, specific tests to explore various cognitive domains, Unified Parkinson’s Disease Rating Scale to evaluate parkinsonism, scales for ataxia and muscular strength, and electroneurography. High-field MR (3T) including DTI and structural sequences was performed in all patients.

Results

The main neuropsychological findings were impairment in PHES (p = 0.03), Parkinson’s Disease-Cognitive Rating Scale (p = 0.04) and in executive (p<0.05) and visuospatial-visuoconstructive functions (p<0.05) in patients with falls compared to those without. There were no statistical differences between the two groups in the neurological evaluation or in the visual assessment of MRI. MR-DTI showed alterations in white matter integrity in patients with falls compared to those without falls (p<0.05), with local maxima in the superior longitudinal fasciculus and corticospinal tract. These alterations were independent of PHES as a covariate and correlated with executive dysfunction (p<0.05).

Conclusions

With the limitation of the small sample size, our results suggest that patients with cirrhosis and falls present alterations in brain white matter tracts related to executive dysfunction. These alterations are independent of PHES impairment.

Abnormal chloride homeostasis in the substancia nigra pars reticulata contributes to locomotor deficiency in a model of acute liver injury

BACKGROUND

Altered chloride homeostasis has been thought to be a risk factor for several brain disorders, while less attention has been paid to its role in liver disease. We aimed to analyze the involvement and possible mechanisms of altered chloride homeostasis of GABAergic neurons within the substantia nigra pars reticulata (SNr) in the motor deficit observed in a model of encephalopathy caused by acute liver failure, by using glutamic acid decarboxylase 67 - green fluorescent protein knock-in transgenic mice.

METHODS

Alterations in intracellular chloride concentration in GABAergic neurons within the SNr and changes in the expression of two dominant chloride homeostasis-regulating genes, KCC2 and NKCC1, were evaluated in mice with hypolocomotion due to hepatic encephalopathy (HE). The effects of pharmacological blockade and/or activation of KCC2 and NKCC1 functions with their specific inhibitors and/or activators on the motor activity were assessed.

RESULTS

In our mouse model of acute liver injury, chloride imaging indicated an increase in local intracellular chloride concentration in SNr GABAergic neurons. In addition, the mRNA and protein levels of KCC2 were reduced, particularly on neuronal cell membranes; in contrast, NKCC1 expression remained unaffected. Furthermore, blockage of KCC2 reduced motor activity in the normal mice and led to a further deteriorated hypolocomotion in HE mice. Blockade of NKCC1 was not able to normalize motor activity in mice with liver failure.

CONCLUSION

Our data suggest that altered chloride homeostasis is likely involved in the pathophysiology of hypolocomotion following HE. Drugs aimed at restoring normal chloride homeostasis would be a potential treatment for hepatic failure.

Cognitive dysfunction in cirrhosis is associated with falls: a prospective study

Falls are frequent among patients with debilitating disorders and can have a serious effect on health status. Mild cognitive disturbances associated with cirrhosis may increase the risk for falls. Identifying subjects at risk may allow the implementation of preventive measures. Our aim was to assess the predictive value of the Psychometric Hepatic Encephalopathy Score (PHES) in identifying patients likely to sustain falls. One hundred and twenty-two outpatients with cirrhosis were assessed using the PHES and were followed at specified intervals. One third of them exhibited cognitive dysfunction (CD) according to the PHES (<-4). Seventeen of the forty-two patients (40.4%) with CD had at least one fall during follow-up. In comparison, only 5 of 80 (6.2%) without CD had falls (P < 0.001). Fractures occurred in 4 patients (9.5%) with CD, but in no patients without CD (P = 0.01). Patients with CD needed more healthcare (23.8% versus 2.5%; P < 0.001), more emergency room care (14.2% versus 2.5%; P = 0.02), and more hospitalization (9.5% versus 0%; P = 0.01) as a result of falls than patients without CD. Patients taking psychoactive treatment (n = 21) had a higher frequency of falls, and this was related to an abnormal PHES. In patients without psychoactive treatment (n = 101), the incidence of falls was 32.4% in patients with CD versus 7.5% in those without CD (P = 0.003). In the multivariate analysis, CD was the only independent predictive factor of falls (odds ratio, 10.2; 95% confidence interval, 3.4-30.4; P < 0.001). The 1-year probability of falling was 52.3% in patients with CD and 6.5% in those without (P < 0.001).

CONCLUSION

An abnormal PHES identifies patients with cirrhosis who are at risk for falls. This psychometric test may be useful to promote awareness of falls and identify patients who may benefit from preventive strategies.

Impairment of the organization of locomotor and exploratory behaviors in bile duct-ligated rats

Hepatic encephalopathy (HE) arises from acute or chronic liver diseases and leads to several problems, including motor impairment. Animal models of chronic liver disease have extensively investigated the mechanisms of this disease. Impairment of locomotor activity has been described in different rat models. However, these studies are controversial and the majority has primarily analyzed activity parameters. Therefore, the aim of the present study was to evaluate locomotor and exploratory behavior in bile duct-ligated (BDL) rats to explore the spatial and temporal structure of behavior. Adult female Wistar rats underwent common bile duct ligation (BDL rats) or the manipulation of common bile duct without ligation (control rats). Six weeks after surgery, control and BDL rats underwent open-field, plus-maze and foot-fault behavioral tasks. The BDL rats developed chronic liver failure and exhibited a decrease in total distance traveled, increased total immobility time, smaller number of rearings, longer periods in the home base area and decreased percentage of time in the center zone of the arena, when compared to the control rats. Moreover, the performance of the BDL rats was not different from the control rats for the elevated plus-maze and foot-fault tasks. Therefore, the BDL rats demonstrated disturbed spontaneous locomotor and exploratory activities as a consequence of altered spatio-temporal organization of behavior.

Significant volume reduction and shape abnormalities of the basal ganglia in cases of chronic liver cirrhosis

BACKGROUND AND PURPOSE

Chronic liver disease frequently includes cognitive and movement disorders, suggesting an alteration of the striatum. With the exception of hyperintensities evident on T1-weighted images indicative of Mn deposition, radiographic findings of the BG are nonspecific. Volumetric and morphometric analysis of DGM is limited. Whether DGM undergoes degeneration and whether this change is associated with pallidal hyperintensity and cognitive performance are currently unknown in patients with cirrhosis.

MATERIALS AND METHODS

The DGM volumes of 28 patients with chronic cirrhosis and 28 control patients were compared. Using 3D high-resolution MR images, the volume and shape of each structure were automatically analyzed by the FSL. Correlations between the DGM volume and other clinical variables, including the pallidal signal intensity, were assessed by multiple regression analysis.

RESULTS

Patients with Child B and Child C liver disease had significantly smaller bilateral putaminal volumes than control patients, and patients with Child C also demonstrated smaller left caudate nucleus and left amygdala volumes than control patients. Pallidal hyperintensity correlated with smaller striatum volume, which was linearly related to worse cognitive performance. The nonuniform distributed shape abnormalities in the striatum further support the ascending spiral interconnecting theory of the striatum.

CONCLUSIONS

These findings strongly suggest lower DGM volume develops according to the severity of the liver cirrhosis. The Mn deposition might contribute the striatum deficit. These findings support the value of additional psychomotor research associated with liver cirrhosis.

PROMIS computerised adaptive tests are dynamic instruments to measure health-related quality of life in patients with cirrhosis

BACKGROUND

Cirrhotic patients have an impaired health-related quality of life (HRQOL), which is usually analysed using static paper-pencil questionnaires. The Patient Reported Outcomes Measurement Information System (PROMIS) computerised adaptive testing (CAT) are flexible, freely available, noncopyrighted, HRQOL instruments with US-based norms across 11 domains. CAT presents five to seven questions/domain depending on the patient's response, from large validated question banks. This provides brevity and precision equivalent to the entire question bank.

AIM

To evaluate PROMIS CAT tools against 'legacy instruments' for cirrhotics and their informal caregivers.

METHODS

A total of 200 subjects: 100 cirrhotics (70 men, 53% decompensated) and 100 caregivers were administered the PROMIS and legacy instruments [Sickness Impact Profile (SIP), Beck depression/anxiety inventories, Pittsburgh Sleep-Quality Index (PSQI) and Epworth Sleepiness scale (ESS)] concurrently. Both legacy and PROMIS results for patients were compared with caregivers and US norms. These were also compared between compensated and decompensated patients. Preference for SIP or PROMIS was inquired of a selected group (n = 70, 50% patients). Test - retest reliability was assessed in another group of 20 patients.

RESULTS

Patients had significant impairment on all PROMIS domains apart from anger and anxiety compared with caregivers and US norms (P < 0.02 to <0.0001). Decompensated patients had significantly worse sleep, pain, social and physical function scores compared with compensated ones, similar to legacy instruments. There was a statistically significant correlation between PROMIS and their corresponding legacy instruments. The majority (71%) preferred PROMIS over SIP. PROMIS tools had significant test - retest reliability (ICC range 0.759-0.985) when administered 12 ± 6 days apart.

CONCLUSION

PROMIS computerised adaptive testing tools had significant concurrent and discriminant validity, test - retest reliability and subject preference for assessing HRQOL in cirrhotic patients.

Acquired hepatocerebral degeneration: clinical characteristics and MRI findings

OBJECTIVE

To determine the prevalence of acquired hepatocerebral degeneration (AHD), its clinical and neuroimaging characteristics and response to treatments.

BACKGROUND

Acquired hepatocerebral degeneration is a chronic encephalopathy with predominant motor signs in the context of severe liver disease. Its clinical picture is not well defined, and its prevalence and risk factors are not well known.

METHODS

Review of a database of 1000 patients with cirrhosis to identify cases of AHD. Clinical and neuroimaging data, follow-up and response to treatments, including liver transplantation, were recorded.

RESULTS

Eight patients with AHD were identified. Its prevalence was 0.8% of patients with cirrhosis. The main risk factor for AHD was the presence of portosystemic shunts. Movement disorders, especially a combination of parkinsonism and cerebellar signs were observed in all patients. All AHD cases showed on MRI T1-weighted images hyperintensities in the globus pallidus, and 75% had extrapallidal involvement as well. Antiparkisonian drugs and treatments to prevent acute encephalopathies were ineffective. Three patients who underwent liver transplantation did not experience neurological improvement. Persistence of portosystemic shunts was demonstrated in two cases.

CONCLUSIONS

Acquired hepatocerebral degeneration is a chronic encephalopathy which occurs in ∼1% of patients with liver cirrhosis and seems related to portosystemic shunts. Its is characterized by a combination of parkinsonism and cerebellar signs. MRI pallidal and extrapallidal lesions are seen in most patients, probably reflecting intracerebral deposits of manganese. Liver transplant did not improve the neurological signs in our patients, perhaps because of the persistence of portosystemic shunts.

Extrapyramidal signs predict the development of overt hepatic encephalopathy in patients with liver cirrhosis

BACKGROUND/AIMS

The long-term evolution of cirrhotic patients with extrapyramidal signs has not yet been studied. We have investigated the influence of extrapyramidal signs on the prognosis, evolution, and quality of life of patients with liver cirrhosis.

METHODS

Forty-six patients with cirrhosis were followed up and 18 of them were reevaluated, a mean of 45 months later. Cognitive impairment was measured with psychometric tests (Trail-Making Test part A, Grooved-Pegboard, Block-Design, Oral Symbol Digit and Stroop Test). Extrapyramidal signs were evaluated using the Unified Parkinson's Disease Rating Scale (UPDRS). Health-related quality of life was measured using the SF-36 scale and the Chronic Liver Disease Questionnaire.

RESULTS

Eleven of the 46 patients who were followed up developed overt hepatic encephalopathy (HE) during the follow-up. The presence of extrapyramidal signs was the unique factor that predicted overt HE and patients with basal higher score in the part 3 of the UPDRS developed overt HE more frequently [hazard ratio=1.29; 95% confidence interval (1.04-1.60) P=0.023]. In the 18 reevaluated patients, there was an increase in the score of the UPDRS part 3 after follow-up. There was a worsening in the score values of the block design and the Number Connection Test. In health-related quality of life scales, patients scored better in the area of mental health of the SF-36 scale. Patients with extrapyramidal signs persisted with worse scores in several items of the SF-36 scale and the Chronic Liver Disease Questionnaire.

CONCLUSION

The presence of extrapyramidal signs in patients with liver cirrhosis predicts the development of overt HE. These signs increased along the follow-up, and remain a bad influence on quality of life.

Effect of the class I metabotropic glutamate receptor antagonist AIDA on certain behaviours in rats with experimental chronic hyperammonemia

PURPOSE

This study examines possible interactions between behavioral effects and mGluR1 (class I metabotropic glutamate receptor) by injecting AIDA [(RS)-1-aminoindan-1,5-dicarboxylic acid] in rats with experimental chronic hyperammonemia (chHA).

MATERIAL/METHODS

The effects of mGluR1 antagonist on some behaviors were tested in control groups of rats and in rats with chHA. Experimental chHA was induced by intraperitoneal injection of ammonium acetate (12 mmol/kg) for five consecutive days. We used the following behavioural tests: the open field test, the passive avoidance test and the elevated "plus" maze.

RESULTS

In control rats AIDA administered intracerebroventricularly (i.c.v.) at the dose 100 nmol decreased the number of crossings and bar approaches in the open field test and impaired acquisition and recall in the passive avoidance situation. ChHA significantly inhibited locomotor and exploratory activity and profoundly impaired acquisition and recall processes in the passive avoidance test and significantly increased acute stress responses. AIDA increased locomotor activity in chHA rats (especially number of crossed fields and rearings) and produced anxiety enhancement in rats with chHA. AIDA used in rats with chHA significantly improved acquisition and retrieval processes.

CONCLUSIONS

The obtained results suggest that AIDA, the antagonist of mGluR1, had beneficial effects on learning and memory in rats with experimental chronic hyperammonemia.

Deep sedation with propofol does not precipitate hepatic encephalopathy during elective upper endoscopy

BACKGROUND

The risk of hepatic encephalopathy (HE) precipitated by propofol has not been established.

OBJECTIVE

To know whether the use of propofol for endoscopy in patients with cirrhosis induces minimal or overt HE.

DESIGN

A cohort study.

SETTING

A tertiary-referral university hospital endoscopy unit.

PATIENTS

Patients with cirrhosis who received an endoscopy with propofol sedation. We excluded patients with clinical HE. A group of patients without liver disease was included to compare the incidence of adverse effects.

INTERVENTIONS

Minimal HE (MHE) was diagnosed by using the psychometric hepatic encephalopathy score (PHES) battery of psychometric tests. Cognitive status before and 1 hour after the endoscopy was evaluated by measuring the critical flicker frequency (CFF).

MAIN OUTCOME MEASUREMENTS

Overt and minimal HE.

RESULTS

Twenty patients with cirrhosis and 20 patients without cirrhosis were included. There were no differences between groups in the incidence of adverse effects. Thirteen patients (65%) had MHE before the endoscopy. No patient developed overt HE after sedation. We did not observe differences in CFF before and after sedation in patients without MHE: median (25th-75th percentile), 40.8 Hz (37.1-46.0 Hz) versus 41.1 Hz (36.0-44.3 Hz), P = .8). None of the patients who were without MHE showed a decrease in the CFF under the cutoff of 39 Hz after sedation. There were not significant changes in CFF before and after propofol sedation in patients previously diagnosed of MHE: median (25th-75th percentile), 40.6 Hz (36.8-49.1 Hz) versus 42.7 Hz (36.8-52.4 Hz), P = .08.

LIMITATION

A small number of patients were included in the study.

CONCLUSIONS

The use of propofol in the sedation of patients with cirrhosis during endoscopic procedures does not precipitate minimal or overt HE.

Neuroinflammation contributes to hypokinesia in rats with hepatic encephalopathy: ibuprofen restores its motor activity

Patients with hepatic encephalopathy show altered motor function, psychomotor slowing, and hypokinesia, which are reproduced in rats with portacaval shunts (PCS). Increased extracellular glutamate in substantia nigra pars reticulata (SNr) is responsible for hypokinesia in PCS rats. The mechanisms by which liver failure leads to increased extracellular glutamate in SNr remain unclear. Inflammation seems to act synergistically with hyperammonemia to induce neurological alterations in hepatic encephalopathy. It is therefore possible that inflammation-associated alterations may contribute to motor alterations in hepatic encephalopathy. The aim of this work was to assess whether treatment with an antiinflammatory, ibuprofen, is able to normalize extracellular glutamate in SNr and/or to improve hypokinesia in PCS rats. The amounts of the glutamate transporters GLT-1 and EAAC-1 are reduced by 26% and 32%, respectively, in SNr of PCS rats. This reduction is associated with a tenfold increase in extracellular glutamate in SNr and a reduction in motor activity. Chronic treatment with 30 mg/kg ibuprofen completely normalizes the amount of GLT-1 and EAAC-1 and significantly reduces (by 53%) extracellular glutamate in SNr of PCS rats. Moreover, ibuprofen, at 15 or 30 (but not at 5) mg/kg/day, completely eliminates hypokinesia, restoring normal motor activity. This supports the idea that inflammation is a main contributor to the induction of hypokinesia in hepatic encephalopathy. Moreover, these data point to the possible therapeutic utility of decreasing inflammation, by safe procedures, in the treatment of the motor deficits in patients with hepatic encephalopathy.

Glutamatergic and gabaergic neurotransmission and neuronal circuits in hepatic encephalopathy

Patients with hepatic encephalopathy (HE) may present different neurological alterations including impaired cognitive function and altered motor activity and coordination. HE may lead to coma and death. Many of these neurological alterations are the consequence of altered neurotransmission. Hyperammonemia is a main contributor to the alterations in neurotransmission and in neurological functions in HE. Both glutamatergic and GABAergic neurotransmission are altered in animal models of HE. We review some of these alterations, especially those alterations in glutamatergic neurotransmission responsible for some specific neurological alterations in hyperammonemia and HE: the role 1) of excessive NMDA receptors activation in death induced by acute hyperammonemia; 2) of impaired function of the glutamate-nitric oxide-cGMP pathway, associated to NMDA receptors, in cognitive impairment in chronic HE; 3) of increased extracellular glutamate and activation of metabotropic glutamate receptors in substantia nigra in hypokinesia in chronic HE. The therapeutic implications are discussed. We also review the alterations in the function of the neuronal circuits between basal ganglia-thalamus-cortex modulating motor activity and the role of sequential alterations in glutamatergic and GABAergic neurotransmission in these alterations. HE would be a consequence of altered neuronal communication due to alterations in general neurotransmission involving different neurotransmitter systems in different neurons.

Acquired hepatocerebral degeneration

Cirrhosis and its co-morbidities may cause a variety of neurological complications, the most common being bouts of toxic metabolic encephalopathy. A proportion of patients with chronic liver disease develop acquired hepatocerebral degeneration (AHD), a chronic progressive neurological syndrome characterized by parkinsonism, ataxia and other movement disorders. This article reviews the clinical spectrum, pathophysiology, neuroimaging features and differential diagnosis of AHD along with emerging treatment options.

Motor activity is modulated via different neuronal circuits in rats with chronic liver failure than in normal rats

The mechanisms by which liver failure alters motor function remain unclear. It has been suggested that liver disease alters the neuronal circuit between basal ganglia and cortex that modulates motor function. Activation of group I metabotropic glutamate receptors in the nucleus accumbens (NAcc) by injecting (S)-3,5-dihydroxyphenylglycine (DHPG) activates this circuit and induces locomotion We analysed by in vivo brain microdialysis the function of the circuits that modulate motor function in rats with liver failure due to portacaval shunt (PCS). We inserted cannulae in the NAcc and microdialysis probes in the NAcc, ventral pallidum (VP), substantia nigra pars reticulata (SNr), medio-dorsal thalamus (MDT), ventro-medial thalamus (VMT) or prefrontal cortex (PFCx). We injected DHPG in the NAcc and analysed extracellular neurotransmitters concentration in these areas. The results indicate that in control rats DHPG induces locomotion by activating the 'normal' neuronal circuit: NAcc --> VP --> MDT --> PFCx. In PCS rats this circuit is not activated. In PCS rats, DHPG injection activates an 'alternative' circuit: NAcc --> SNr --> VMT --> PFCx. This circuit is not activated in control rats. DHPG injection increases dopamine in the NAcc of control but not of PCS rats, and glutamate in PCS but not in control rats. DHPG-induced increase in dopamine would activate the 'normal' neuronal circuit, while an increase in glutamate would activate the 'alternative' circuit. The identification of the mechanisms responsible for altered motor function and coordination in liver disease would allow designing treatments to improve motor function in patients with hepatic encephalopathy.

Value of the critical flicker frequency in patients with minimal hepatic encephalopathy

Minimal hepatic encephalopathy (MHE) is mainly diagnosed using psychometric tests such as the psychometric hepatic encephalopathy score (PHES). Despite the clinical and social relevance of MHE, psychometric testing is not widespread in routine clinical care. We assessed the usefulness of the critical flicker frequency (CFF), for the diagnosis of MHE and for the prediction of the development of overt episodes of HE. The normal range of PHES in the Spanish population was evaluated in a control group. Subsequently, 114 patients with cirrhosis and 103 healthy controls underwent both PHES and CFF tests. A diagnosis of MHE was made when the PHES was lower than -4 points. Patients were followed-up every 6 months for a total of 1 year. CFF did not correlate with age, education, or sex in the control group. The mean CFF was significantly lower in patients with MHE versus non-MHE or controls. Mean CFF correlated with individual psychometric tests as well as PHES (r = 0.54; P < 0.001). CFF <38 Hz was predictive of further bouts of overt HE (log-rank: 14.2; P < 0.001). There was a weak correlation between mean CFF and Child-Pugh score but not with model for end-stage liver disease score. In multivariate analysis using Cox regression, CFF together with Child-Pugh score was independently associated with the development of overt HE.

CONCLUSION

CFF is a simple, reliable, and accurate method for the diagnosis of MHE. It is not influenced by age or education and could predict the development of overt HE.

Contribution of altered signal transduction associated to glutamate receptors in brain to the neurological alterations of hepatic encephalopathy

Patients with liver disease may present hepatic enceph-alopathy (HE), a complex neuropsychiatric syndrome covering a wide range of neurological alterations, including cognitive and motor disturbances. HE reduces the quality of life of the patients and is associated with poor prognosis. In the worse cases HE may lead to coma or death.

The mechanisms leading to HE which are not well known are being studied using animal models. The neurological alterations in HE are a consequence of impaired cerebral function mainly due to alterations in neurotransmission. We review here some studies indicating that alterations in neurotransmission associated to different types of glutamate receptors are responsible for some of the cognitive and motor alterations present in HE.

These studies show that the function of the signal transduction pathway glutamate-nitric oxide-cGMP associated to the NMDA type of glutamate receptors is impaired in brain in vivo in HE animal models as well as in brain of patients died of HE. Activation of NMDA receptors in brain activates this pathway and increases cGMP. In animal models of HE this increase in cGMP induced by activation of NMDA receptors is reduced, which is responsible for the impairment in learning ability in these animal models. Increasing cGMP by pharmacological means restores learning ability in rats with HE and may be a new therapeutic approach to improve cognitive function in patients with HE. However, it is necessary to previously assess the possible secondary effects.

Patients with HE may present psychomotor slowing, hypokinesia and bradykinesia. Animal models of HE also show hypolocomotion. It has been shown in rats with HE that hypolocomotion is due to excessive activation of metabotropic glutamate receptors (mGluRs) in substantia nigra pars reticulata. Blocking mGluR1 in this brain area normalizes motor activity in the rats, suggesting that a similar treatment for patients with HE could be useful to treat psychomotor slowing and hypokinesia. However, the possible secondary effects of mGluR1 antagonists should be previously evaluated.

These studies are setting the basis for designing therapeutic procedures to specifically treat the individual neurological alterations in patients with HE.

Hypolocomotion in rats with chronic liver failure is due to increased glutamate and activation of metabotropic glutamate receptors in substantia nigra

BACKGROUND/AIMS

Patients with hepatic encephalopathy show altered motor function, psychomotor slowing and hypokinesia. The underlying mechanisms remain unclear. This work's aims were: (1) to analyse in rats with chronic liver failure due to portacaval shunt (PCS) the neurochemical alterations in the basal ganglia-thalamus-cortex circuits; (2) to correlate these alterations with those in motor function and (3) to normalize motor activity of PCS rats by pharmacological means.

METHODS

Extracellular neurotransmitters levels were analysed by in vivo brain microdialysis. Motor activity was determined by counting crossings in open field.

RESULTS

Extracellular glutamate is increased in substantia nigra pars reticulata (SNr) of PCS rats. Blocking metabotropic receptor 1 (mGluR1) in SNr normalizes motor activity in PCS rats. In ventro-medial thalamus of PCS rats GABA is increased and it is normalized by blocking mGluR1 in SNr. Blocking mGluR1 in SNr increases and mGluR1 activation reduces glutamate in motor cortex and motor activity.

CONCLUSIONS

Increased extracellular glutamate and activation of mGluR1 in SNr are responsible for reduced motor activity in rats with chronic liver failure. Blocking mGluR1 in SNr normalizes motor activity in PCS rats, suggesting that, under appropriate conditions, similar treatments could be useful to treat the psychomotor slowing and hypokinesia in patients with hepatic encephalopathy.