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Query: UMLS:C0085584 (encephalopathy)
 18,178 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We report here a 1-year-old boy with human herpesvirus 6 (HHV 6) -associated encephalopathy. On the 3rd day of fever, he had a generalized tonic seizure followed by mild disturbance of consciousness, which recovered completely the next day. Two days later, he had skin rash of exanthema subitum, and his consciousness declined frequently. EEG demonstrated rhythmic wave bursts originating from central areas bilaterally, followed by a generalized spike-and-wave complex which was associated with disturbed consciousness. We made the diagnosis of a status of complex partial seizures. Because the focal discharge on ictal EEG, MRI was performed. In the subcortical white matter of the frontal-parietal lobes, there were high signals on diffusion-weighted MRI, the apparent diffusion coefficient of which was much lower than that of normal controls. The affected areas soon disappeared with improvement of clinical symptoms. The transient MRI findings may indicate reversible cytotoxic brain edema. He showed no neurological sequelae as yet.
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PMID:[Identification of ictal foci by EEG and MR apparent diffusion coefficient map in a case of human herpesvirus 6-associated encephalopathy]. 1546 Oct 26

The development of encephalopathy in patients with acute liver injury defines the occurrence of liver failure. The encephalopathy of acute liver failure is characterized by brain edema which manifests clinically as increased intracranial pressure. Despite the best available medical therapies a significant proportion of patients with acute liver failure die due to brain herniation. The present review explores the experimental and clinical data to define the role of hypothermia as a treatment modality for increased intracranial pressure in patients with acute liver failure.
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PMID:Hypothermia in acute liver failure. 1555 17

A 9-year-old boy was admitted to our hospital with daytime urinary incontinence for the past one year. MRI showed craniopharyngioma occupying the third ventricle. The tumor was excised by interhemispheric approach. Because hyponatremia and polyuria with high renal loss of sodium were observed on postoperative day 3, hydrocortisone and DDAVP were replaced. On postoperative day 24, successive general convulsions and hyponatremia recurred, and MRI FLAIR imaging showed marked brain edema in the bilateral parieto-occipital lobes. This finding disappeared late in the course of treatment, and the case was diagnosed as posterior reversible encephalopathy syndrome. The pathophysiology of cerebral salt wasting and posterior reversible encephalopathy syndrome in a craniopharyngioma patient are also discussed in the article.
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PMID:[Prolonged cerebral salt wasting following craniopharyngioma surgery and posterior reversible encephalopathy syndrome: a case report]. 1578 2

Ammonia is a neurotoxin that is implicated in the pathogenesis of hepatic encephalopathy due to acute and chronic liver failure. However, its relation to neurological damage and brain edema is poorly understood. During the last decades, it has been the prevailing hypothesis that an osmotic disturbance induced by the astrocytic accumulation of glutamine leads to brain edema. However, various findings are at variance with this hypothesis. The present review will discuss: (a) correlation of ammonia with encephalopathy and brain edema in HE; (b) glutamine synthesis and astrocyte swelling; (c) glutamine synthesis and the glutamine-cycle: relation to brain energy metabolism; (d) glutamine synthesis and the glutamate-glutamine cycle and its relation to anaplerotic activity; (e) evidence favouring the "glutamine hypothesis"; (f) evidence contradicting the "glutamine hypothesis"; (g) glutamine synthesis and osmoregulation; (h) glutamine synthesis in chronic liver failure; (i) impaired brain energy metabolism in acute liver failure (ALF) and its relation to astrocytic glutamine synthesis. Taken together, the precise role of glutamine in the development of brain edema in ALF remains unclear. Astrocytic changes due to glutamine accumulation may lead secondarily to effects on brain energy metabolism. However, the relation between impaired energy metabolism and glutamine accumulation has not been well established. It is noteworthy that no single biochemical factor appears to be responsible for the many symptoms of HE. For example, brain glutamine accumulation and low-grade brain edema occur in chronic liver failure (CLF) suggesting common mechanisms are responsible for the neurological dysfunction in CLF and ALF. Recent NMR spectroscopic studies have provided considerably new information in this area. Future NMR studies using the stable isotope 13C may be useful in the study of the dynamics of brain metabolism in patients with ALF so as to better elucidate the precise role of glutamine accumulation and of glutamine-independent components to brain edema in ALF.
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PMID:An update on the role of brain glutamine synthesis and its relation to cell-specific energy metabolism in the hyperammonemic brain: further studies using NMR spectroscopy. 1591 33

1. The interplay of four factors determines the outcome in Acute Liver Failure (ALF). Current criteria used for prognosis address each of these factors. a. Hepatic regeneration: Age, poor prognostic etiologies (drug, idiopathic ALF), b. Hepatocellular failure: INR, Bilirubin, c. Encephalopathy and brain edema: Stage III/IV, hyperacute vs acute/subacute, d. Multiorgan failure (MOF): pH. 2. In hyperacute liver failure, exemplified by acetaminophen-induced injury, prognostic criteria have focused on the course of encephalopathy and of multiorgan failure. In non-acetaminophen induced ALF, prognostic criteria reflect a greater role of hepatic regeneration in outcome. 3. Prognostic indices combine features of these four factors. The Kings College criteria (KCC) have been shown to have a better performance than the Clichy criteria. The KCC appear to have a higher specificity than sensitivity for acetaminophen-induced ALF, while its negative predictive value for non-acetaminophen induced ALF is unfortunately low. 4. Newer prognostic markers have been proposed, including serum phosphate and alpha fetoprotein as markers of regeneration and blood lactate, a reflection of MOF and hepatocellular failure. They are likely to complement the KCC rather than replace them. 5. Clinical judgement is still needed to weigh management options in this disease.
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PMID:Selection for acute liver failure: have we got it right? 1623 84

Encephalopathy, brain edema and intracranial hypertension are neurological complications responsible for substantial morbidity/mortality in patients with acute liver failure (ALF), where, aside from liver transplantation, there is currently a paucity of effective therapies. Mirroring its cerebro-protective effects in other clinical conditions, the induction of mild hypothermia may provide a potential therapeutic approach to the management of ALF. A solid mechanistic rationale for the use of mild hypothermia is provided by clinical and experimental studies showing its beneficial effects in relation to many of the key factors that determine the development of brain edema and intracranial hypertension in ALF, namely the delivery of ammonia to the brain, the disturbances of brain organic osmolytes and brain extracellular amino acids, cerebro-vascular haemodynamics, brain glucose metabolism, inflammation, subclinical seizure activity and alterations of gene expression. Initial uncontrolled clinical studies of mild hypothermia in patients with ALF suggest that it is an effective, feasible and safe approach. Randomized controlled clinical trials are now needed to adequately assess its efficacy, safety, clinical impact on global outcomes and to provide the guidelines for its use in ALF.
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PMID:Keeping cool in acute liver failure: rationale for the use of mild hypothermia. 1624 52

Acute liver failure (ALF) is consistently accompanied by alterations in brain energy metabolites and recent nuclear magnetic resonance (NMR) studies suggest disturbances in brain oxidative metabolism in experimental ALF. Glucose transport across the blood-brain barrier is essential to sustain brain energy metabolism and is accomplished by the facilitative glucose transporter GLUT1. To investigate alterations in brain glucose uptake in acute liver failure further, GLUT1 expression and [14C]-2-deoxy-D-glucose uptake were measured in the brains of rats with hepatic devascularization. RT-PCR and Western blot analyses showed significant increases in steady-state levels of GLUT1 mRNA and protein in frontal cortex as early as 6 h following hepatic devascularization, (prior to the onset of brain edema and encephalopathy) which remained elevated at coma stages of encephalopathy. Expression of the astrocytic (45-kDa) and endothelial (55-kDa) forms of GLUT1 was increased as a result of hepatic devascularization. Exposure of cultured astrocytes to pathophysiologically relevant concentrations of ammonia resulted in increased GLUT1 expression, suggesting that elevated ammonia levels are responsible for GLUT1 upregulation in ALF. Increased GLUT1 expression in ALF was selective, since expression of the neuronal glucose transporter GLUT3 and other glucose-regulated proteins (GRP-78 and GRP-94) was unaltered. [14C]-2-deoxy-D-glucose autoradiography revealed increases in cerebral glucose uptake following the induction of GLUT1 in ALF. These results suggest that ammonia-induced increases of GLUT1 expression resulting in increased cerebral glucose uptake occur in ALF and could contribute to the pathophysiological mechanisms responsible for the neurological complications of this condition.
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PMID:Selectively increased expression of the astrocytic/endothelial glucose transporter protein GLUT1 in acute liver failure. 1637 80

The management of children with end-stage chronic liver disease and acute liver failure mandates a multidisciplinary approach and intense monitoring. In recent years, considerable progress has been made in developing specific and supportive medical measures, but studies and publications have mainly concerned adult patients. Therapeutic approaches to complications of end-stage chronic liver disease and acute liver failure (e.g. refractory ascites, hepatorenal syndrome, encephalopathy, and cerebral edema) that may be applied to children are reviewed in this article.Mild-to-moderate ascites should be managed by modest salt restriction and oral diuretic therapy in the first instance. Large volume paracentesis associated with colloid volume expansion and diuretic therapy may be effective for acute relief. Treatment of hepatorenal syndrome type 1 with vasopressin analogs (terlipressin) is recommended prior to liver transplantation in order to improve renal function. Prevention and treatment of chronic hepatic encephalopathy are directed primarily at controlling the events that may precipitate hepatic encephalopathy and at reducing ammonia generation and increasing its detoxification or removal. In addition to reduction of gut ammonia production using non-absorbable disaccharides such as lactulose and/or antibacterials such as neomycin, sodium benzoate may be used on a long-term basis to prevent, stabilize, or improve hepatic encephalopathy. The management of hepatic encephalopathy in acute liver failure is considerably more unsatisfactory; treatment is aimed at preventing brain edema and intracranial hypertension. Extracorporeal liver support devices are now used commonly in critically ill children with acute renal failure, advanced hepatic encephalopathy, cerebral edema, intracranial hypertension, and severe coagulopathy. Continuous renal replacement therapy could potentially help support patients until liver transplantation is performed or liver regeneration occurs. The Molecular Adsorbent Recirculating System (MARS or albumin dialysis) is the liver support system most frequently used worldwide in adults and appears to offer distinct advantages over hepatocyte-based systems. There are no specific medical therapies or devices that can correct all of the functions of the liver. Apart from a few metabolic diseases presenting with severe liver dysfunction for which specific medical therapies may preclude the need for liver transplantation, liver transplantation still remains the only definitive therapy in most instances of end-stage chronic liver disease and acute liver failure. Future research should focus on gaining a better understanding of the mechanisms responsible for liver cell death and liver regeneration, as well as developments in hepatocyte transplantation and liver-directed gene therapy.
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PMID:New management options for end-stage chronic liver disease and acute liver failure: potential for pediatric patients. 1649 8

Molecular biological approaches continue to lead to the identification of alterations in expression of genes coding for key central nervous system proteins involved in water homeostasis, energy metabolism and neurotransmitter regulation in acute liver failure (ALF). However, studies aimed at elucidating the pathophysiological consequences of these changes in gene expression are impeded by the lack of a suitable mouse model of ALF. A previous report described hepatic pathology characteristic of ALF resulting from the administration of azoxymethane (AOM) in mice [Matkowskyj, K.A., Marrero, J.A., Carroll, R.E., Danilkovich, A.V., Green, R.M., Benya, R.V., 1999. Azoxymethane-induced fulminant hepatic failure in C57BL/6J mice: characterization of a new animal model. Am. J. Physiol. 277, G455-G462]. In a series of experiments to further assess this treatment as an effective model of ALF, the effects of administration of AOM to male C57BL mice on hepatic and cerebral function were studied. With maintenance of body temperature at 37 degrees C and control of hypoglycemia, mice developed signs of encephalopathy (decreased locomotor activity followed by loss of righting and corneal reflexes) within 16 h of AOM treatment. AOM-treated mice were hyperammonemic, developed spontaneous hypothermia and brain edema. Brain ammonia concentrations were increased to 0.98+/-0.12 mM at coma stages of encephalopathy. Brain amino acid profiles determined by HPLC were typical of ALF in other species including humans. Mild hypothermia (35 degrees C) led to significant attenuation of brain edema, ammonia, and amino acid changes. These findings demonstrate that AOM treatment affords a simple, reproducible mouse model of ALF which may be suitable for the study of the effects of gene manipulation on the cerebral complications of ALF.
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PMID:Neurobiological characterization of an azoxymethane mouse model of acute liver failure. 1656 65

Over the past 20 years it has become increasingly apparent that hyponatremic encephalopathy is a major cause of inhospital morbidity and mortality, particularly in postoperative patients. The factors that may lead to death or permanent brain damage and the susceptible patient groups have been gradually elucidated. Hyponatremic encephalopathy most commonly leads to brain damage in young women and in prepubescent children. The causes of brain damage include brain edema, cerebral hypoxemia, decreased brain blood flow, increased intracranial pressure, and improper therapy. Cerebral hypoxia occurs through a combination of impaired brain adaptation and cerebral vasoconstriction. Brain adaptation consists largely of brain cell loss of sodium and potassium by means of the Na-K adenosine triphosphatase (ATPase) system. There is also loss of organic osmolytes. The brain Na-K ATPase system is impaired by a combination of vasopressin plus estrogen and is stimulated by testosterone. Similarly, vasopressin plus estrogen leads to cerebral vasoconstriction, resulting in a decrement of brain oxygen utilization and cerebral blood flow. Vasopressin also directly decreases brain production of ATP. The combination leads to hypoxic brain damage, which appears to be the major cause of brain damage associated with hyponatremic encephalopathy. Measurement of arterial PO2 in patients with symptomatic hyponatremia usually demonstrates a PO2 <50 mm Hg. Improper therapy is another possible cause of brain damage in patients with hyponatremic encephalopathy. The type and distribution of such lesions are similar to those found in patients with hyponatremic encephalopathy who have severe hypoxia. Current scientific knowledge indicates that patient survival can be improved through aggressive treatment of hypoxia associated with hyponatremic encephalopathy, particularly in young women.
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PMID:Influence of hypoxia and sex on hyponatremic encephalopathy. 1684 87


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