Demonstration of interstitial cerebral edema with diffusion tensor MR imaging in type C hepatic encephalopathy

Decrease in the volume of white matter lesions with improvement of hepatic encephalopathy

MR imaging has found abnormalities compatible with low-grade edema in the brain of patients with cirrhosis that have been related to hepatic encephalopathy. We present 3 patients with hepatic encephalopathy who exhibit supratentorial focal or diffuse white matter lesions compatible with small-vessel brain disease. The volume and number of white matter lesions reduced with the improvement of hepatic encephalopathy, suggesting the participation of the blood-brain barrier in the pathogenesis of brain edema in hepatic encephalopathy.

Portal hypertension and its complications

PURPOSE OF REVIEW

Portal hypertension is responsible for most of the complications associated with cirrhosis, specifically variceal hemorrhage, ascites and hepatic encephalopathy. Progress in understanding the pathophysiology of portal hypertension and improvements in the diagnosis and management of its complications that have occurred over the last year are discussed.

RECENT FINDINGS

Endothelial dysfunction contributes to the pathogenesis of portal hypertension and may represent a novel therapeutic target. Hepatic venous pressure gradient measurements, when properly performed, are useful in the management of patients with cirrhosis. Hyponatremia in cirrhosis has prognostic value and novel aquaretic and other agents may provide alternative approaches to the management of chronic liver disease. The mechanisms for bacterial translocation in cirrhosis that predisposes patients to infectious complications, such as spontaneous bacterial peritionitis, are being explored. Adrenal insufficiency is common in septic patients with advanced cirrhosis and corticosteroids may provide a survival benefit. Pulmonary disease complicates the management of patients with advanced liver disease.

SUMMARY

Significant advances continue to be made in the diagnosis and management of the complications of portal hypertension in the face of an increasing burden of chronic liver disease.

Use of diffusion tensor imaging to predict myocardial viability after warm global ischemia: possible avenue for use of non-beating donor hearts

BACKGROUND

The assessment of myocardial viability after global warm ischemia (WI) but before reperfusion is challenging. We hypothesized that fractional anisotropy (FA), a magnetic resonance imaging (MRI) parameter of water diffusion that characterizes cellular integrity within tissues, provides a rapid and useful method for evaluating the viability of hearts after WI.

METHODS

Dog hearts were exposed to 60 minutes of WI after exanguination, explanted and preserved in a cold, non-beating state for 6 hours, using continuous perfusion (CP) or static cold storage (CS). Toward the end of preservation, a global FA assessment, acquired using MRI, was compared with analyses obtained from myocardial biopsies that included adenosine triphosphate (ATP), endothelin-1 (ET-1) and caspase-3 levels, light microscopy and tetrazolium staining. Functional recovery was analyzed after restoration of blood flow on a non-working Langendorff preparation.

RESULTS

FA measured at the end of CP showed strong correlations with all parameters of functional recovery (developed pressure, R = 0.60; dP/dt, R = 0.96; -dP/dt, R = 0.96). Although FA also correlated with tissue levels of ATP, ET-1 and caspase-3 (R = 0.77, -0.84, -0.64), recovery of myocardial function did not correlate with these markers or any other conventional analyses of myocardial injury (troponin I, changes on light microscopy or tetrazolium staining).

CONCLUSIONS

FA, an MRI-based parameter that indicates cellular integrity, was found to reflect better myocardial ATP stores, less induction of ET-1 and caspase-3 and improved functional recovery of hearts after global WI. As a clinically applicable tool capable of rapidly differentiating reversible from lethal injury, diffusion tensor imaging may prove useful in the eventual adoption of non-beating donor hearts for transplantation.

Lactulose improves cognitive functions and health-related quality of life in patients with cirrhosis who have minimal hepatic encephalopathy

Minimal hepatic encephalopathy (MHE) has a negative effect on patients' daily functioning. Thus far, no study has investigated the effect of treatment-related improvement in cognitive functions on health-related quality of life (HRQOL). We measured psychometric performance by number and figure connection tests parts A and B, picture completion, and block design tests and HRQOL by the Sickness Impact Profile (SIP) of 90 patients with cirrhosis on inclusion into the study and 3 months later. A Z score less than -2 on the neuropsychological (NP) tests was considered abnormal. Sixty-one (67.7%) patients had MHE. They were randomly assigned in a 1:1 ratio to receive treatment (lactulose) for 3 months (n=31) or no treatment (n=30) in a nonblinded design. The mean number of abnormal NP tests decreased significantly in patients in the treated group (baseline, 2.74 [95% CI 2.40-3.08]; after 3 months, .75 [95% CI .36-1.16]) compared with patients in the untreated group (baseline, 2.47 [95% CI 2.19-2.74]; after 3 months, 2.55 [95% CI 2.16-2.94]); multivariate analysis of variance (MANOVA) for time and treatment, P=0.001. The mean total SIP score improved among patients in the treated group (baseline, 10.39 [95% CI 9.36-11.43]; after 3 months, 3.77 [95% CI 2.52-5.02]) compared with patients in the untreated group (baseline, 10.36 [95% CI 8.98-11.73]; after 3 months, 10.39 [95% CI 8.36-12.42]); MANOVA for time and treatment, P=0.002. Improvement in HRQOL was related to the improvement in psychometry.

CONCLUSION

Treatment with lactulose improves both cognitive function and HRQOL in patients with cirrhosis who have MHE.

Pathogenetic interplay between osmotic and oxidative stress: the hepatic encephalopathy paradigm

Hepatic encephalopathy (HE) defines a primary gliopathy associated with acute and chronic liver disease. Astrocyte swelling triggered by ammonia in synergism with different precipitating factors, including hyponatremia, tumor necrosis factor (TNF)-alpha, glutamate and ligands of the peripheral benzodiazepine receptor (PBR), is an early pathogenetic event in HE. On the other hand, reactive nitrogen and oxygen species (RNOS) including nitric oxide are considered to play a major role in HE. There is growing evidence that osmotic and oxidative stresses are closely interrelated. Astrocyte swelling produces RNOS and vice versa. Based on recent investigations, this review proposes a working model that integrates the pathogenetic action of osmotic and oxidative stresses in HE. Under participation of the N-methyl-D-aspartate (NMDA) receptor, Ca(2+), the PBR and organic osmolyte depletion, astrocyte swelling and RNOS production may constitute an autoamplificatory signaling loop that integrates at least some of the signals released by HE-precipitating factors.