L-ornithine-L-aspartate in experimental portal-systemic encephalopathy: therapeutic efficacy and mechanism of action

Strategies aimed at the lowering of blood ammonia remain the treatment of choice in portal-systemic encephalopathy (PSE). L-ornithine-L-aspartate (OA) has recently been shown to be effective in the prevention of ammonia-precipitated coma in humans with PSE. These findings prompted the study of mechanisms of the protective effect of OA in portacaval-shunted rats in which reversible coma was precipitated by ammonium acetate administration (3.85 mmol/kg i.p.). OA infusions (300 mg/kg/h, i.v) offered complete protection in 12/12 animals compared to 0/12 saline-infused controls. This protective effect was accompanied by significant reductions of blood ammonia, concomitant increases of urea production and significant increases in blood and cerebrospinal fluid (CSF) glutamate and glutamine. Increased CSF concentrations of leucine and alanine also accompanied the protective effect of OA. These findings demonstrate the therapeutic efficacy of OA in the prevention of ammonia-precipitated coma in portacaval-shunted rats and suggest that this protective effect is both peripherally-mediated (increased urea and glutamine synthesis) and centrally-mediated (increased glutamine synthesis)

Evaluation of acoustic radiation force impulse imaging for determination of liver stiffness using transient elastography as a reference

AIM: To evaluate cut-off values and performance of acoustic radiation force impulse imaging (ARFI) using transient elastography [FibroScan© (FS)] as a reference

Voxel-based analyses of magnetization transfer imaging of the brain in hepatic encephalopathy

AIM: To evaluate the spatial distribution of cerebral abnormalities in cirrhotic subjects with and without hepatic encephalopathy (HE) found with magnetization transfer imaging (MTI)

Paired associative stimulation demonstrates alterations in motor cortical synaptic plasticity in patients with hepatic encephalopathy

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. Conclusion: 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.Comment: number of pages: 33; number of tables: 1; number of figures: 5; References: 9

How to diagnose and manage hepatic encephalopathy: a consensus statement on roles and responsibilities beyond the liver specialist

INTRODUCTION: Hepatic encephalopathy is defined as brain dysfunction caused by liver insufficiency and/or portosystemic shunting. Symptoms include nonspecific cognitive impairment, personality changes and changes in consciousness. Overt (symptomatic) hepatic encephalopathy is a common complication of cirrhosis that is associated with a poor prognosis. Patients with hepatic encephalopathy may present to healthcare providers who do not have primary responsibility for management of patients with cirrhosis. Therefore, we developed a series of 'consensus points' to provide some guidance on management. METHODS: Using a modified 'Delphi' process, consensus statements were developed that summarize our recommendations for the diagnosis and management of patients with hepatic encephalopathy. Points on which full consensus could not be reached are also discussed. RESULTS: Our recommendations emphasize the role of all healthcare providers in the identification of cognitive impairment in patients with cirrhosis and provide guidance on steps that might be considered to make a diagnosis of overt hepatic encephalopathy. In addition, treatment recommendations are summarized. Minimal hepatic encephalopathy can have a significant impact on patients; however, in most circumstances identification and management of minimal hepatic encephalopathy remains the responsibility of specialists in liver diseases. CONCLUSION: Our opinion statements aim to define the roles and responsibilities of all healthcare providers who at times care for patients with cirrhosis and hepatic encephalopathy. We suggest that these recommendations be considered further by colleagues in other disciplines and hope that future guidelines consider the management of patients with cirrhosis and with a 'suspicion' of cognitive impairment through to a formal diagnosis of hepatic encephalopathy.status: publishe