Impact of preoperative overt hepatic encephalopathy on neurocognitive function after liver transplantation

Neuropathological changes in the brain of pigs with acute liver failure

OBJECTIVE

Cerebral edema is a serious complication of acute liver failure (ALF), which may lead to intracranial hypertension and death. An accepted tenet has been that the blood-brain barrier is intact and that brain edema is primarily caused by a cytotoxic etiology due to hyperammonemia. However, the neuropathological changes in ALF have been poorly studied. Using a well characterized porcine model we aimed to investigate ultrastructural changes in the brain from pigs suffering from ALF.

MATERIALS AND METHODS

Sixteen female Norwegian Landrace pigs weighing 27-35 kg were randomised into two groups: ALF (n = 8) and sham operated controls (n = 8). ALF was induced with an end-to-side portacaval shunt followed by ligation of the hepatic arteries. Biopsies were harvested from three different areas of the brain (frontal lobe, cerebellum, and brain stem) following eight hours of ALF and analyzed using electron microscopy.

RESULTS

Profound perivascular and interstitial edema were found in all three areas. Disruption of pericytic and astrocytic processes were seen, reflecting breakdown/lesion of the blood-brain barrier in animals suffering from ALF. Furthermore, neurons and axons were edematous and surrounded by vesicles. Severe damage to Purkinje neuron (necrosis) and damaged myelin were seen in the cerebellum and brain stem, respectively. Biopsies from sham operated animals were normal.

CONCLUSIONS

Our data support the concept that vasogenic brain edema plays an important role in the development of intracranial hypertension in pigs with ALF.

Persistence of cognitive impairment after resolution of overt hepatic encephalopathy

BACKGROUND & AIMS

In patients with cirrhosis, hepatic encephalopathy (HE) has acute but reversible as well as chronic components. We investigated the extent of residual cognitive impairment following clinical resolution of overt HE (OHE).

METHODS

Cognitive function of cirrhotic patients was evaluated using psychometric tests (digit symbol, block design, and number connection [NCT-A and B]) and the inhibitory control test (ICT). Improvement (reduction) in ICT lures and first minus second halves (DeltaL(1-2)) were used to determine learning of response inhibition. Two cross-sectional studies (A and B) compared data from stable cirrhotic patients with or without prior OHE. We then prospectively assessed cognitive performance, before and after the first episode of OHE.

RESULTS

In study A (226 cirrhotic patients), 54 had experienced OHE, 120 had minimal HE, and 52 with no minimal HE. Despite normal mental status on lactulose after OHE, cirrhotic patients were cognitively impaired, based on results from all tests. Learning of response inhibition (DeltaL(1-2) > or =1) was evident in patients with minimal HE and no minimal HE but was lost after OHE. In study B (50 additional patients who developed > or =1 documented OHE episode during follow-up), the number of OHE hospitalizations correlated with severity of residual impairment, indicated by ICT lures (r = 0.5, P = .0001), digit symbol test (r = -0.39, P = .002), and number connection test-B (r = 0.33, P = .04). In the prospective study (59 cirrhotic patients without OHE), 15 developed OHE; ICT lure response worsened significantly after OHE (12 before vs 18 after, P = .0003), and learning of response inhibition was lost. The 44 patients who did not experience OHE did not have deteriorations in cognitive function in serial testing.

CONCLUSIONS

In cirrhosis, episodes of OHE are associated with persistent and cumulative deficits in working memory, response inhibition, and learning.

Persistence of cognitive impairment after resolution of overt hepatic encephalopathy

BACKGROUND & AIMS

In patients with cirrhosis, hepatic encephalopathy (HE) has acute but reversible as well as chronic components. We investigated the extent of residual cognitive impairment following clinical resolution of overt HE (OHE).

METHODS

Cognitive function of cirrhotic patients was evaluated using psychometric tests (digit symbol, block design, and number connection [NCT-A and B]) and the inhibitory control test (ICT). Improvement (reduction) in ICT lures and first minus second halves (DeltaL(1-2)) were used to determine learning of response inhibition. Two cross-sectional studies (A and B) compared data from stable cirrhotic patients with or without prior OHE. We then prospectively assessed cognitive performance, before and after the first episode of OHE.

RESULTS

In study A (226 cirrhotic patients), 54 had experienced OHE, 120 had minimal HE, and 52 with no minimal HE. Despite normal mental status on lactulose after OHE, cirrhotic patients were cognitively impaired, based on results from all tests. Learning of response inhibition (DeltaL(1-2) > or =1) was evident in patients with minimal HE and no minimal HE but was lost after OHE. In study B (50 additional patients who developed > or =1 documented OHE episode during follow-up), the number of OHE hospitalizations correlated with severity of residual impairment, indicated by ICT lures (r = 0.5, P = .0001), digit symbol test (r = -0.39, P = .002), and number connection test-B (r = 0.33, P = .04). In the prospective study (59 cirrhotic patients without OHE), 15 developed OHE; ICT lure response worsened significantly after OHE (12 before vs 18 after, P = .0003), and learning of response inhibition was lost. The 44 patients who did not experience OHE did not have deteriorations in cognitive function in serial testing.

CONCLUSIONS

In cirrhosis, episodes of OHE are associated with persistent and cumulative deficits in working memory, response inhibition, and learning.

Neurocognitive-neurological complications of liver transplantation: a review

Neurological complications are common after liver transplantation (LT) and they are associated with a significant morbidity. Long-term effects of LT on cognitive and psychological outcomes are not clear. The objective of this study was to summarize the present knowledge on the neurological and cognitive complications of LT, resulting from a systematic review of the literature in the last 10 years. Several studies have investigated the incidence and the pathophysiology of neurological complications; in contrast, the knowledge of cognitive and psychological status after LT is poor. Currently, the effect of LT on mental performance is debated. Some studies have shown an improvement of cognitive function after OLTX and, at the same time, a persistence of different cognitive deficits. In addition, the quality of life (QoL) and the psychological status after LT seem to improve but LT recipients have significant deficiencies in most QoL domains. Consequently, future studies are necessary in order to investigate cognitive alterations and QoL in LT recipients.

Review article: the modern management of hepatic encephalopathy

BACKGROUND; Hepatic encephalopathy, both overt and minimal, forms a continuum of cognitive change in cirrhosis. Strategies to diagnose and treat hepatic encephalopathy have evolved considerably.

AIM

To examine the updated diagnostic and treatment strategies for hepatic encephalopathy.

METHODS

Techniques for the clinical, psychometric and neurophysiological evaluation of hepatic encephalopathy are reviewed. The methods reviewed include pure clinical scales (West-Haven), psychometric tests (PSE-syndrome test), neurophysiological tests (EEG, Critical flicker frequency, CFF) and computerized tests (Inhibitory control test, ICT).

RESULTS

Clinical scales are limited, whereas psychometric tests (specifically PSE-syndrome test), CFF and ICT can be used to diagnose minimal hepatic encephalopathy. However, there is no single test that can capture the entire spectrum of cognitive impairment. Treatment options and goals depend on the acuity of hepatic encephalopathy. In-patient management should concentrate on supportive care, precipitating factor reversal and lactulose and/or rifaximin therapy. Out-patient therapy should aim to prevent recurrences, and both lactulose and rifaximin have evidence to support their use.

CONCLUSIONS

Diagnostic techniques for hepatic encephalopathy range from simple scales to sophisticated tools. Treatment options depend on the stage of hepatic encephalopathy. The future challenge is to evaluate cognitive function as a continuum with clinically relevant outcomes and to develop well-tolerated and inexpensive treatments for hepatic encephalopathy.

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.