Neurological complications in renal failure: a review

Severe encephalopathy after ingestion of star fruit juice in a patient with chronic renal failure admitted to the intensive care unit

Star fruit (Averrhoa carambola) is a popular tropical fruit that is usually consumed as fresh fruit or fruit juice. Consumption of star fruit by patients with chronic renal failure can lead to neurologic symptoms. The present report describes the clinical course, management, and outcome of a patient with chronic renal failure admitted to an intensive care unit after ingestion of star fruit juice 2 days before hospital admission. A case of nausea, vomiting, intractable hiccups, and severe encephalopathy along with mental confusion, disorientation, agitation, and seizures in a 53-year-old woman is presented. The patient's ventilatory pattern worsened, with development of dyspnea and tachypnea, which resulted in her transfer to an intensive care unit. Although hemodialysis was performed and the septic shock was adequately treated, the patient died on the fifth day after hospital admission. The susceptibility of patients with chronic renal failure to star fruit and the severity of intoxication are poorly known by intensivists. This case demonstrates that star fruit consumption should be considered as a cause of rapid deterioration in the renal function of patients with underlying chronic renal failure, potentially resulting in a fatal outcome.

Cerebral metabolic changes in neurologically presymptomatic patients undergoing haemodialysis: in vivo proton MR spectroscopic findings

OBJECTIVE

To prospectively investigate and detect early cerebral metabolic changes in patients with end-stage renal disease (ESRD) by using in vivo proton MR spectroscopy (MRS).

METHODS

We enrolled 32 patients with ESRD and 32 healthy controls between the ages of 26 and 50 years. Short echo time single-voxel proton MRS was acquired from volumes of interest (VOIs) located in the frontal grey and white matter, temporal white matter and basal ganglia. The choline/phospatidylcholine (Cho), myo-inositol (mI), N-acetylaspartate (NAA) and total creatine (tCr) peaks were measured and the metabolic ratios with respect to tCr were calculated.

RESULTS

In the ESRD group, significant elevations of the Cho/tCr and mI/tCr ratios were observed for the frontal grey matter, frontal white matter, temporal white matter and basal ganglia as compared with controls. There was no significant difference in the NAA/tCr ratios at all VOIs between the ESRD patients and the healthy controls.

CONCLUSIONS

Proton MRS is a useful and non-invasive imaging tool for the detection of early cerebral metabolic changes in neurologically presymptomatic ESRD patients.

End-stage renal disease: in vivo diffusion-tensor imaging of silent white matter damage

PURPOSE

To characterize and compare regional differences in anisotropy in patients with end-stage renal disease (ESRD) and in control subjects to understand the effect of ESRD and hemodialysis on the microstructures of white matter.

MATERIALS AND METHODS

This study was approved by an institutional review board; written informed consent was obtained. From March 2007 to December 2007, 34 patients (16 men, 18 women; mean age, 40.0 years; range, 26-50 years) with ESRD who were undergoing dialysis and 35 control subjects (16 men, 19 women; mean age, 38.3 years; range, 25-49 years) were enrolled. There was no significant sex or age difference between the ESRD and control groups. By using a 1.5-T imager, fractional anisotropy (FA) data obtained at diffusion-tensor magnetic resonance (MR) imaging (echo-planar imaging, 33 directions; b value, 1000 sec/mm(2)) and at T2-weighted fluid-attenuated inversion recovery (FLAIR) MR imaging of the bilateral parietal, frontal, occipital, and temporal lobe white matter, as well as the genu and splenium of the corpus callosum, were compared. The Cognitive Abilities Screening Instrument (CASI) was administered to all participants at imaging.

RESULTS

The ESRD group had significantly lower FA values in all regions than the control group. FA values were generally lower in older patients and in those who had been undergoing dialysis for a longer duration. Duration of dialysis was more often than age found to be correlated with differences in FA values. In areas in which there was a significant correlation between age, duration, and FA values, the regression coefficients were greater for those who had been undergoing dialysis longer than for those who were older. Patients with ESRD had significantly lower CASI scores than control subjects (P = .03). There were no significant group differences in FLAIR values (P = .25-.89).

CONCLUSION

Changes in FA values may be used to follow-up white matter changes in patients with ESRD who are undergoing maintenance dialysis.

SUPPLEMENTAL MATERIAL

http://radiology.rsnajnls.org/cgi/content/full/2523080484/DC1.

Fatal head injury in children younger than 2 years in New York City and an overview of the shaken baby syndrome

CONTEXT

Shaken baby syndrome is a controversial topic in forensic pathology. Some forensic pathologists state that shaking alone is insufficient to explain death and that an impact must have occurred even if there is no impact site on the head.

OBJECTIVE

To examine a large cohort of fatal, pediatric head injuries for patterns of specific autopsy findings and circumstances that would support or dispute pure shaking as the cause of death.

DESIGN

We retrospectively reviewed 59 deaths due to head injuries in children younger than 2 years certified in our office during a 9 year period (1998-2006). The review included autopsy, toxicology, microscopy, neuropathology, and police and investigators' reports.

RESULTS

There were 46 homicides, 8 accidents, and 1 undetermined death from blunt-impact injury of the head. In 10 (22%) of the homicides, there was no impact injury to the head, and the cause of death was certified as whiplash shaking. In 4 (40%) of these 10 deaths, there was a history of shaking. In 5 (83%) of the other 6, there was no history of any purported accidental or homicidal injury. All 8 accidental deaths had impact sites. Of the 59 deaths, 4 (6.7%) had only remote injuries (chronic subdural hematomas, remote long bone fractures) that were certified as undetermined cause and manner. These 4 deaths were excluded from the study.

CONCLUSIONS

We describe a subset of fatal, nonaccidental head-injury deaths in infants without an impact to the head. The autopsy findings and circumstances are diagnostic of a nonimpact, shaking mechanism as the cause of death. Fatal, accidental head injuries in children younger than 2 years are rare.

Hyponatremia is a risk factor of hepatic encephalopathy in patients with cirrhosis: a prospective study with time-dependent analysis

OBJECTIVES

The aim of this study was to investigate whether hyponatremia is a risk factor of overt hepatic encephalopathy (HE) in cirrhosis.

METHODS

A total of 61 patients with cirrhosis were evaluated prospectively for 1 year and all episodes of overt HE were recorded. Predictive factors of HE were analyzed using a conditional model (Prentice, Williams, and Peterson) for recurrent events to assess the relationship between HE and time-dependent covariates. The effects of hyponatremia on the brain concentration of organic osmolytes were analyzed in 25 patients using 1 H-magnetic resonance spectroscopy.

RESULTS

Twenty-eight of the 61 patients developed 57 episodes of overt HE during follow-up. Among a number of clinical and laboratory variables analyzed, the only independent predictive factors of overt HE were hyponatremia (serum sodium < 130 mEq / l), history of overt HE, serum bilirubin,and serum creatinine. Hyponatremia was associated with low brain concentration of organic osmolytes, particularly myo-inositol (MI). Furthermore, patients with low brain MI levels had a higher probability of development of overt HE compared with that of patients with high brain MI levels.

CONCLUSIONS

In patients with cirrhosis, the existence of hyponatremia is a major risk factor of the development of overt HE. Treatment of hyponatremia may be a novel therapeutic approach to preventing HE in cirrhosis.

Neuromuscular disease in the dialysis patient: an update for the nephrologist

Neuromuscular disease is an extremely common complication of end-stage kidney disease (ESKD), manifesting in almost all dialysis patients, and leading to weakness, reduced exercise capacity, and disability. Recent studies have suggested that hyperkalemia may underlie the development of neuropathy. As such, maintenance of serum K(+) within normal limits between periods of dialysis in ESKD patients manifesting early neuropathic symptoms may reduce neuropathy development and progression. For patients with more severe neuropathic syndromes, increased dialysis frequency or a switch to high-flux dialysis may prevent further deterioration, while ultimately, renal transplantation is required to improve and restore nerve function. Exercise training programs are beneficial for ESKD patients with muscle weakness due to neuropathy or myopathy, and are capable of improving exercise tolerance and quality of life. Specific treatments have recently been evaluated for symptoms of autonomic neuropathy, including sildenafil for impotence and midodrine for intra-dialytic hypotension, and have been shown to be effective and well tolerated. Other important management strategies for neuropathy include attention to foot care to prevent callus and ulceration, vitamin supplementation, and erythropoietin. Treatment with membrane-stabilizing agents, such as amitryptiline and gabapentin, are highly effective in patients with painful neuropathy.

Management of acute renal failure in cats using peritoneal dialysis: a retrospective study of six cases (2003-2007)

Information regarding the use and success of peritoneal dialysis (PD) in the management of acute renal failure (ARF) in cats is lacking. The purpose of this retrospective study is to describe the indications, efficacy, complications and outcome of cats undergoing PD for ARF. Six cats that underwent PD for treatment of ARF of various etiologies were included. PD effectively replaced renal function in all cats and allowed renal recovery in 5/6 cats. Five cats were discharged and one cat died. Complications were reported in all cats and included subcutaneous edema (n=5), hyperglycemia (n=4), dialysate retention (n=3), and hypoalbuminemia (n=3). A novel technique consisting of a Blake surgical drain and an intermittent closed suction system was used, which appears to be a viable option for PD in cats. Although complications are common, PD is an effective renal replacement therapy for ARF in cats and carries a reasonable prognosis in selected cases.

Fatal vitamin C-associated acute renal failure

Although daily ingestion of high-dose vitamin C is generally regarded as largely innocuous, fatal nephrotoxicity can occur in some rare circumstances. We report a case where the patient, who chose to forgo any advanced conventional medical intervention (dialysis and mechanical ventilation), had failed to disclose his use of high-dose vitamin C and subsequently died. Intra-renal oxalate crystal deposition was demonstrated at autopsy. Directed enquiry with the family then revealed his high-dose vitamin C usage. Even though fully-informed discussion was limited by incomplete prospective disclosure, it remains the prerogative of any competent patient to decline any treatment, including those that may be considered life-saving.

[Headache associated with haemodialysis]

INTRODUCTION

Haemodialysis (HD) is one of the most accessible methods for the treatment of the growing number of patients suffering from terminal-stage renal insufficiency. Although headache is the most frequently encountered neurological symptom during HD, there are few studies reporting its prevalence and clinical features.

OBJECTIVE

The objective of this study was to examine the frequency, demographic and clinical features of headache during HD, and to compare these parameters among patients with and without headache.

METHOD

The study involved 126 patients (48 female and 78 male) with chronic renal failure on regular HD for at least six months, at the Dialysis Unit of Nephrology Department, Krusevac. All patients were inquired about their possible problems with headache using the standardized questionnaire designed according to the diagnostic criteria of the International Headache Classification of Headache Disorders, second edition, published in 2004 (ICHD-II). Subsequently, the patients were clinically evaluated and patients with headaches were further subclassified by a neurologist with special interest in headache disorders. Patients with headache were compared to the patients without headache regarding age, sex, duration of HD, causes of end-stage renal disease, arterial diastolic and systolic blood pressure, and serum values of the most important blood parameters such as sodium, potassium, urea and creatinine. In the group of patients with headache we analyzed the characteristics of specific headache type according to ICHD-II classification. We also analyzed the most important clinical features of haemodialysis headache (HDH).

RESULTS

In the group of 126 evaluated patients, 41 (32.5%) patients had headaches. There were no statistically significant differences between the patients with headaches and those without headaches regarding sex, age, BMI, duration of HD, causes of end-stage renal disease, arterial blood pressure, red blood cell count, serum concentration of haemoglobin, blood urea nitrogen, creatinine, glucose, MCHC, total protein, sodium and potassium. Fourteen patients (34% of those with headaches) experienced headache during the HD session and were subclassifled as HDH using diagnostic criteria of the International Headache Society. Tension type headache (41% of those with headaches) and migraine without aura (10%) were most common in the primary headache group and headache due to arterial hypertension (7%) was the most prevalent among the secondary headaches. Although there were some common clinical characteristics, we could not find a unifying clinical pattern in the patients with HDH.

CONCLUSION

Haemodialysis headache is the most common headache in patients undergoing haemodialysis, and despite some common symptoms, it does not appear to be uniform in its clinical characteristics.

A hypothesis on the origin and evolution of the response to inhaled anesthetics

In this article, I present an evolutionary explanation for why organisms respond to inhaled anesthetics. It is conjectured that organisms today respond to inhaled anesthetics owing to the sensitivity of ion channels to inhaled anesthetics, which in turn has arisen by common descent from ancestral, anesthetic-sensitive ion channels in one-celled organisms (i.e., that the response to anesthetics did not arise as an adaptation of the nervous system, but rather of ion channels that preceded the origin of multicellularity). This sensitivity may have been refined by continuing selection at synapses in multicellular organisms. In particular, it is hypothesized that 1) the beneficial trait that was selected for in one-celled organisms was the coordinated response of ion channels to compounds that were present in the environment, which influenced the conformational equilibrium of ion channels; 2) this coordinated response prevented the deleterious consequences of entry of positive charges into the cell, thereby increasing the fitness of the organism; and 3) these compounds (which may have included organic anions, cations, and zwitterions as well as uncharged compounds) mimicked inhaled anesthetics in that they were interfacially active, and modulated ion channel function by altering bilayer properties coupled to channel function. The proposed hypothesis is consistent with known properties of inhaled anesthetics. In addition, it leads to testable experimental predictions of nonvolatile compounds having anesthetic-like modulatory effects on ion channels and in animals, including endogenous compounds that may modulate ion channel function in health and disease. The latter included metabolites that are increased in some types of end-stage organ failure, and genetic metabolic diseases. Several of these predictions have been tested and proved to be correct.

Numerical simulation of the effect of sodium profile on cardiovascular response to hemodialysis

PURPOSE

We developed a numerical model that predicts cardiovascular system response to hemodialysis, focusing on the effect of sodium profile during treatment.

MATERIALS AND METHODS

The model consists of a 2-compartment solute kinetics model, 3-compartment body fluid model, and 12-lumped-parameter representation of the cardiovascular circulation model connected to set-point models of the arterial baroreflexes. The solute kinetics model includes the dynamics of solutes in the intracellular and extracellular pools and a fluid balance model for the intracellular, interstitial, and plasma volumes. Perturbation due to hemodialysis treatment induces a pressure change in the blood vessels and the arterial baroreceptors then trigger control mechanisms (autoregulation system). These in turn alter heart rate, systemic arterial resistance, and cardiac contractility. The model parameters are based largely on the reported values.

RESULTS

We present the results obtained by numerical simulations of cardiovascular response during hemodialysis with 3 different dialysate sodium concentration profiles. In each case, dialysate sodium concentration profile was first calculated using an inverse algorithm according to plasma sodium concentration profiles, and then the percentage changes in each compartment pressure, heart rate, and systolic ventricular compliance and systemic arterial resistance during hemodialysis were determined. A plasma concentration with an upward convex curve profile produced a cardiovascular response more stable than linear or downward convex curves.

CONCLUSION

By conducting numerical tests of dialysis/cardiovascular models for various treatment profiles and creating a database from the results, it should be possible to estimate an optimal sodium profile for each patient.

Acute kidney injury leads to inflammation and functional changes in the brain

Although neurologic sequelae of acute kidney injury (AKI) are well described, the pathogenesis of acute uremic encephalopathy is poorly understood. This study examined the short-term effect of ischemic AKI on inflammatory and functional changes of the brain in mice by inducing bilateral renal ischemia for 60 min and studying the brains 24 h later. Compared with sham mice, mice with AKI had increased neuronal pyknosis and microgliosis in the brain. AKI also led to increased levels of the proinflammatory chemokines keratinocyte-derived chemoattractant and G-CSF in the cerebral cortex and hippocampus and increased expression of glial fibrillary acidic protein in astrocytes in the cortex and corpus callosum. In addition, extravasation of Evans blue dye into the brain suggested that the blood-brain barrier was disrupted in mice with AKI. Because liver failure also leads to encephalopathy, ischemic liver injury was induced in mice with normal renal function; neuronal pyknosis and glial fibrillary acidic protein expression were not increased, suggesting differential effects on the brain depending on the organ injured. For evaluation of the effects of AKI on brain function, locomotor activity was studied using an open field test. Mice subjected to renal ischemia or bilateral nephrectomy had moderate to severe declines in locomotor activity compared with sham-operated mice. These data demonstrate that severe ischemic AKI induces inflammation and functional changes in the brain. Targeting these pathways could reduce morbidity and mortality in critically ill patients with severe AKI.

Stroke in chronic renal failure

Chronic kidney diseases and cardiovascular diseases have several common risk factors like hypertension and diabetes. In chronic renal disease stroke risk is several times higher than in the average population. The combination of classical risk factors and those characteristic of chronic kidney disease might explain this increased risk. Among acute cerebrovascular diseases intracerebral hemorrhages are more frequent than in those with normal kidney function. The outcome of stroke is worse in chronic kidney disease. The treatment of stroke (thrombolysis, antiplatelet and anticoagulant treatment, statins, etc.) is an area of clinical research in this patient group. There are no reliable data on the application of thrombolysis in acute stroke in patients with chronic renal disease. Aspirin might be administered. Carefulness, individual considerations and lower doses might be appropriate when using other treatments. The condition of the kidney as well as other associated diseases should be considered during administration of antihypertensive and lipid lowering medications.

Epileptic fits and epilepsy in the elderly: general reflections, specific issues and therapeutic implications

Seizures and epilepsy are commonly encountered in the elderly. Diagnosis is not always straightforward as reliable history is often difficult to obtain and EEG findings can be non-specific. When to treat and how may be difficult choices as adequate studies in elderly are rather scarce. Treatment should be based on careful assessment and comparison of risk/benefit profiles of various anti-epileptic drugs (AEDs) in this specific elderly population. Since most AEDs are effective in terms of seizure control in the elderly, the choice of treatment is often determined by tolerability, pharmacokinetic profile and drug interactions of AEDs. As recently introduced AEDs have a better safety profile compared to older agents it seems logical to initiate treatment in the frail elderly patient with those more modern AEDs. In this review some distinctive clinical features of epilepsy in the elderly are discussed in three sections (general issues, special issues and selected treatment options with special reference to medicinal treatment).

Stress echocardiography for risk stratification in patients with end-stage renal disease undergoing renal transplantation

BACKGROUND

The predictive accuracy of stress echocardiography (SE) for adverse cardiac events has been variable in the population with end-stage renal disease undergoing renal transplantation (RT).

METHODS

We performed a retrospective study of 149 patients who had pretransplant SE before RT between 1997 and 2003. Patients were followed up for a mean of 2.85 years for major adverse cardiovascular events (MACE).

RESULTS

Of 149 patients studied, 139 had a negative SE, 65% were African American; 12 underwent cardiac catheterization. Only 1 patient required pre-RT revascularization. Sixteen MACE occurred over the follow-up period. SE had 37.5% sensitivity, 95.3% specificity, 33.3% positive predictive value, and 96.1% negative predictive value for MACE in the first year post-RT. First-year posttransplant event rates were 4.0% versus 30% (P < .001) for patients with a negative SE and positive SE, respectively. Multivariate predictors of MACE were positive SE (hazard ratio [HR] 7.64), hemoglobin less than 11 g/dL post-RT (HR 4.44), and calcium channel blocker use posttransplant (HR 2.90).

CONCLUSIONS

A negative SE has low incidence of MACE in this intermediate- to high-risk patient subset. A positive SE predicts a sevenfold higher risk of cardiovascular events regardless of the need for revascularization before the transplant.

Ammonia has anesthetic properties

BACKGROUND

A recent theory of anesthesia predicts that some endogenous compounds should have anesthetic properties. This theory raises the possibility that metabolites that are profoundly elevated in disease may also exert anesthetic effects. Because in pathophysiologic concentrations, ammonia reversibly impairs memory, consciousness, and responsiveness to noxious stimuli in a manner similar to anesthetics, we investigated whether ammonia had anesthetic properties.

METHODS

The effect of ammonia was studied on alpha1beta2 and alpha1beta2gamma2s gamma-amino butyric acid type A, alpha1 glycine, and NR1/NR2A N-methyl-D-aspartate receptors, and the two-pore domain potassium channel TRESK. Channels were expressed in Xenopus laevis oocytes and studied using two-electrode voltage clamping. The immobilizing effect of ammonia in rats was evaluated by determining the reduction in isoflurane minimum alveolar concentration produced by IV infusion of ammonium chloride. The olive oil-water partition coefficient was measured to determine whether free ammonia (NH3) followed the Meyer-Overton relation.

RESULTS

Ammonia positively modulated TRESK channels and glycine receptors. No effect was seen on alpha1beta2 and alpha1beta2gamma2s gamma-amino butyric acid type A receptors or NR1/NR2A N-methyl-d-aspartate receptors. Ammonia reversibly decreased the requirement for isoflurane, with a calculated immobilizing EC50 of 1.6 +/- 0.1 mM NH4Cl. The Ostwald olive oil-water partition coefficient for NH3 was 0.018. At a pH of 7.4, and at the anesthetic EC50, the NH3 concentration in bulk olive oil is 0.42 muM, approximately five orders of magnitude less than observed by anesthetics that follow the Meyer-Overton relation.

CONCLUSIONS

These findings support the hypothesis that ammonia has anesthetic properties. Bulk oil concentration did not predict the potency of ammonia.

Wernicke's encephalopathy: new clinical settings and recent advances in diagnosis and management

Wernicke's encephalopathy is an acute neuropsychiatric syndrome resulting from thiamine deficiency, which is associated with significant morbidity and mortality. According to autopsy-based studies, the disorder is still greatly underdiagnosed in both adults and children. In this review, we provide an update on the factors and clinical settings that predispose to Wernicke's encephalopathy, and discuss the most recent insights into epidemiology, pathophysiology, genetics, diagnosis, and treatment. To facilitate the diagnosis, we classify the common and rare symptoms at presentation and the late-stage symptoms. We emphasise the optimum dose of parenteral thiamine required for prophylaxis and treatment of Wernicke's encephalopathy and prevention of Korsakoff's syndrome associated with alcohol misuse. A systematic approach helps to ensure that patients receive a prompt diagnosis and adequate treatment.

Uremic neuropathy: clinical features and new pathophysiological insights

Neuropathy is a common complication of end-stage kidney disease (ESKD), typically presenting as a distal symmetrical process with greater lower-limb than upper-limb involvement. The condition is of insidious onset, progressing over months. and has been estimated to be present in 60%-100% of patients on dialysis. Neuropathy generally only develops at glomerular filtration rates of less than 12 ml/min. The most frequent clinical features reflect large-fiber involvement, with paresthesias, reduction in deep tendon reflexes, impaired vibration sense, muscle wasting, and weakness. Nerve conduction studies demonstrate findings consistent with a generalized neuropathy of the axonal type. Patients may also develop autonomic features, with postural hypotension, impaired sweating, diarrhea, constipation, or impotence. The development of uremic neuropathy has been related previously to the retention of neurotoxic molecules in the middle molecular range, although this hypothesis lacked formal proof. Studies utilizing novel axonal excitability techniques have recently shed further light on the pathophysiology of this condition. Nerves of uremic patients have been shown to exist in a chronically depolarized state prior to dialysis, with subsequent improvement and normalization of resting membrane potential after dialysis. The degree of depolarization correlates with serum K(+), suggesting that chronic hyperkalemic depolarization plays an important role in the development of nerve dysfunction in ESKD. These recent findings suggest that maintenance of serum K(+) within normal limits between periods of dialysis, rather than simple avoidance of hyperkalemia, is likely to reduce the incidence and severity of uremic neuropathy.

IDENTIFICATION OF BLOOD PRESSURE CONTROL MECHANISMS BY POWER SPECTRAL ANALYSIS

1. Blood pressure and organ perfusion are controlled by a variety of cardiovascular control systems, such as the baroreceptor reflex and the renin-angiotensin system (RAS), and by local vascular mechanisms, such as shear stress-induced release of nitric oxide (NO) from the endothelium and the myogenic vascular response. Deviations in arterial blood pressure from its set point activate these mechanisms in an attempt to restore blood pressure and/or secure organ perfusion. However, the response times at which different cardiovascular mechanisms operate differ considerably (e.g. blood pressure control by the RAS is slower than blood pressure control via the baroreceptor reflex). 2. Owing to these different response times, some cardiovascular control systems affect blood pressure more rapidly and others more slowly. Thus, identifying the frequency components of blood pressure variability (BPV) by power spectral analysis can potentially provide important information on individual blood pressure control mechanisms. 3. Evidence is presented that the RAS, catecholamines, endothelial-derived NO and myogenic vascular function affect BPV at very low frequencies (0.02-0.2 Hz) and that low-frequency (LF) BPV (0.2-0.6 Hz) is affected by sympathetic modulation of vascular tone and endothelial-derived NO in rats. In humans, LF BPV (0.075-0.15 Hz) is affected by sympathetic modulation of vascular tone and myogenic vascular function. The impact of the RAS and endothelial-derived NO on BPV in humans requires further investigation. 4. In conclusion, power spectral analysis is a powerful diagnostic tool that allows identification of pathophysiological mechanisms contributing to cardiovascular diseases, such as hypertension, heart failure and stroke, because it can separate slow from fast cardiovascular control mechanisms. The limitation that some cardiovascular control mechanisms affect the same frequency components of BPV requires the combination of blood pressure spectral analysis with other techniques.

Effect of Atorvastatin on Cognitive Function in Patients from the Lipid Lowering and Onset of Renal Disease (LORD) Trial

STUDY OBJECTIVE

To examine the effect of atorvastatin on cognitive function by testing two hypotheses: that atorvastatin 10 mg/day would impair cognitive function, and that other biochemical and demographic measures would better predict cognitive performance than atorvastatin alone.

DESIGN

Randomized, double-blind, placebo-controlled study.

SETTING

Two primary acute care settings in the north and northwest of Tasmania, Australia.

PATIENTS

Fifty-seven patients from the Lipid Lowering and Onset of Renal Disease (LORD) trial.

INTERVENTION

Participants were randomly assigned to receive either atorvastatin 10 mg/day or matching placebo. Cognitive testing was performed in two sessions occurring 12 weeks apart and involved three repeated measures of attention and concentration.

MEASUREMENTS AND MAIN RESULTS

Performance was measured using three standard neuropsychological tests: Digit Symbol Coding subtest, Trail Making Test, and Stroop Color-Word Reading Test. Patients received atorvastatin for a mean of 72.93 weeks and placebo for a mean of 68.85 weeks. Repeated-measures multivariate analysis of variance failed to identify any significant differences between the two groups on any of the three cognitive measures. Multiple regression analyses identified no single factor or combination of plasma cholesterol levels, renal function, liver function, or age that predicted cognitive performance in either the atorvastatin or placebo group on the three measures at either testing session.

CONCLUSION

Atorvastatin 10 mg/day did not produce decrements to cognitive performance. In addition, biochemical and demographic measures and the receipt of atorvastatin versus placebo did not individually or in combination predict cognitive performance on measures of attention and concentration.

Care of the end-stage renal disease patient on dialysis in the ED

End-stage renal disease is a major public health problem. In the United States, more than 350,000 patients are being treated with either hemodialysis or continuous ambulatory peritoneal dialysis. Given the high burden of comorbidities in these patients, it is imperative that emergency physicians be aware of the complexities of caring for acute illnesses in this population. This article reviews the common medical problems that bring patients with end-stage renal disease to the emergency department, and their evaluation and management.

Neurologic manifestations in Sagliker syndrome: uglifying human face appearance in severe and late secondary hyperparathyroidism in chronic renal failure patients

Patients with chronic renal failure (CRF) often have signs and symptoms related to fluid and electrolyte disturbances, anemia, malnutrition, bone disease, and gastrointestinal problems. Vascular and neurologic impairment in particular remain an important source of morbidity and mortality in this vulnerable patient population. Sagliker syndrome is a novel syndrome that was recently described in 2004 in patients with CRF and severe and late secondary hyperparathyroidism who suffered from severe skull and facial bone changes, particularly from uglifying human face appearances and neuropsychiatric disorders. The goal of this study was to assess neuropsychiatric manifestations occurring in CRF patients with Sagliker syndrome. Four female and 8 male patients with CRF on regular dialysis at the hemodialysis units of the Internal Medicine Departments around southern Turkey participated in the study. All patients underwent a clinical neurologic examination performed by the same neurologist. Neuropsychiatric signs and symptoms were found in all cases. The results showed that the most frequent neurologic manifestations in CRF patients with Sagliker syndrome were headache, polyneuropathy, cranial neuropathy, fatigue, and psychiatric disorders.

Posterior reversible encephalopathy syndrome caused by hypertensive encephalopathy and acute uremia

INTRODUCTION

The posterior reversible encephalopathy syndrome (PRES) is a recently proposed cliniconeuroradiological entity. The most common causes of PRES are hypertensive encephalopathy, eclampsia, cyclosporin A neurotoxicity, and the uremic encephalopathy. On magnetic resonance imaging (MRI) studies, edema has been reported in a relatively symmetrical pattern, typically in the subcortical white matter and occasionally in the cortex of the posterior circulation area of the cerebrum.

METHODS AND RESULTS

A 19-year-old woman undergoing chronic hemodialysis was admitted with encephalopathy. High signal intensity was seen bilaterally in the subcortical and deep white matter areas of the temporal, frontal, parietal, and occipital lobes on cranial MRI.

CONCLUSION

Particular attention needs to be given to PRES because initiation of appropriate intervention can reverse the encephalopathic condition in most cases. Cerebral lesions may be more prominent in the anterior circulation area in some patients.

Biochemical validation of a rat model for polycystic kidney disease: Comparison of guanidino compound profile with the human condition

Polycystic kidney disease (PKD) accounts for 7-10% of all dialyzed renal insufficient patients. Accumulation of specific guanidino compounds (GCs) has been related to neurological, cardiovascular, hematological, and immunological complications of renal failure. In this study, we investigate whether the PKD/Mhm rat model can be used as a biochemical model for human PKD. For the validation of the rat model, we performed the first detailed evaluation of the concentrations of GCs in serum and urine of patients with PKD in addition to the GC patterns in the plasma, urine, and tissues of the PKD/Mhm rat model. The GCs were determined after separation on a cation exchange resin and fluorescence detection. The GC levels and changes observed in blood and urine of patients with PKD are comparable with those found in patients with renal insufficiency due to different etiologies. The PKD/Mhm rat model can be used as a biochemical model for human PKD as the obvious increases of urea, guanidinosuccinic acid, creatinine, guanidine, methylguanidine, and N(G)N(G)-dimethylarginine (symmetrical dimethylarginine) seen in blood of oldest heterozygous and younger homozygous PKD rats were largely within the same range as those found in the studied human PKD population, especially in patients with a glomerular filtration rate below 60 ml/min/1.73 m(2). The decreased levels of plasma guanidinoacetic acid seen at end-stage renal disease in homozygous and oldest heterozygous rats were also observed in serum of patients with a glomerular filtration rate below 20 ml/min/1.73 m(2). The PKD/Mhm rat model has, besides similar disease characteristics with human PKD, comparable GC alterations.

Skeletal muscle dysfunction in chronic renal failure: effects of exercise

A number of chronic illnesses such as renal failure (CRF), obstructive pulmonary disease, and congestive heart failure result in a significant decrease in exercise tolerance. There is an increasing awareness that prescribed exercise, designed to restore some level of physical performance and quality of life, can be beneficial in these conditions. In CRF patients, muscle function can be affected by a number of direct and indirect mechanisms caused by renal disease as well as various treatment modalities. The aims of this review are twofold: first, to briefly discuss the mechanisms by which CRF negatively impacts skeletal muscle and, therefore, exercise capacity, and, second, to discuss the available data on the effects of programmed exercise on muscle function, exercise capacity, and various other parameters in CRF.

Differential symptoms of acute myocardial infarction in patients with kidney disease: a community-wide perspective

BACKGROUND

Patients seeking care for acute myocardial infarction (AMI) present with multiple symptoms. The objectives of our community-wide study are to examine the symptom profile of patients with, as compared with those without, kidney disease who present to the hospital with independently confirmed AMI.

METHODS

The symptom profile of 4,482 patients from the Worcester, MA, metropolitan area hospitalized with independently validated AMI at all 11 area medical centers during the 4 study years of 1997, 1999, 2001, and 2003 was examined. Factor analysis was used to aggregate the relevant symptoms of AMI. Logistic regression analysis was used to examine differences in symptoms of AMI according to the presence of kidney disease while controlling for several potentially confounding demographic and clinical factors.

RESULTS

Patients with kidney disease were less likely to report chest pain (adjusted odds ratio, 0.57; 95% confidence interval, 0.46 to 0.70), arm pain (odds ratio, 0.52; 95% confidence interval, 0.42 to 0.64), shoulder pain (odds ratio, 0.53; 95% confidence interval, 0.40 to 0.72), or neck pain (odds ratio, 0.54; 95% confidence interval, 0.41 to 0.70), while being more likely to report shortness of breath (odds ratio, 1.35; 95% confidence interval, 1.13 to 1.62), in comparison to patients without kidney disease in the setting of AMI.

CONCLUSION

Kidney disease impacts on the manner in which patients present with AMI. Although patients with kidney disease are at known increased risk for several diseases, this study suggests that kidney disease also might change how these patients experience these diseases, including acute coronary disease.

Association between 4G/5G polymorphism of the plasminogen activator inhibitor 1 gene with stroke or encephalopathy after cardiac surgery

OBJECTIVE

To evaluate whether the 4G/5G polymorphism of the plasminogen activator inhibitor 1 gene increases the risk of thromboembolic neurological complications, and, if so, whether these complications lengthen the period of mechanical ventilation and hospital stay.

DESIGN

Prospective, case-control study in a 14 bed surgical intensive care unit of a university hospital.

PATIENTS

260 consecutive patients who underwent cardiac surgery with cardiopulmonary bypass and 111 controls.

INTERVENTIONS

DNA was isolated and 4G/5G polymorphism was typed using RFLP methodology.

MEASUREMENTS AND RESULTS

Genetic analysis revealed 4G/5G in 131 patients (50.4%), 5G/5G genotype in 82 (31.5%), and 4G/4G in only 47 (18.1%). Prevalence of neurological complications was 20.8% (n=54) (stroke 5.4%, n=14; encephalopathy 15.4%, n=40]. A trend towards higher risk of developing stroke (8.5% vs. 4.7%, RR 1.9) and a significant twofold increase in encephalopathy (27.7% vs. 12.7%; RR 2.6) was documented in 4G/4G carriers. Multivariate analysis showed that development of stroke or encephalopathy was independently associated with prolonged mechanical ventilation (OR 20), and that neurological complication (OR 2.4) and 4G/4G genotype (OR 2.6) were independently associated with hospital stay of 2 weeks or longer.

CONCLUSIONS

The 4G/4G genotype can increase the risk of thromboembolic neurological complications after cardiac surgery with cardiopulmonary by-pass. The neurological complications result in longer time on ventilator and longer hospital stay.

Involvement of organic anion transporters in the efflux of uremic toxins across the blood-brain barrier

Renal failure causes multiple physiological changes involving CNS dysfunction. In cases of uremia, there is close correlation between plasma levels of uremic toxins [e.g. 3-carboxy-4-methyl-5-propyl-2-furanpropionate (CMPF), hippurate (HA) and indoleacetate (IA)] and the degree of uremic encephalopathy, suggesting that uremic toxins are involved in uremic encephalopathy. In order to evaluate the relevance of uremic toxins to CNS dysfunction, we investigated directional transport of uremic toxins across the blood-brain barrier (BBB) using in vivo integration plot analysis and the brain efflux index method. We observed saturable efflux transport of [(3)H]CMPF, [(14)C]HA and [(3)H]IA, which was inhibited by probenecid. For all uremic toxins evaluated, apparent efflux clearance across the BBB was greater than apparent influx clearance, suggesting that these toxins are predominantly transported from the brain to blood across the BBB. Saturable efflux transport of [(3)H]CMPF, [(14)C]HA and [(3)H]IA was completely inhibited by benzylpenicillin, which is a substrate of rat organic anion transporter 3 (rOat3). Taurocholate and digoxin, which are common substrates of rat organic anion transporting polypeptide (rOatp), partially inhibited the efflux of [(3)H]CMPF. Transport experiments using a Xenopus laevis oocyte expression system revealed that CMPF, HA and IA are substrates of rOat3, and that CMPF (but not HA or IA) is a substrate of rOap2. These results suggest that rOat3 mediates brain-to-blood transport of uremic toxins, and that rOatp2 is involved in efflux of CMPF. Thus, conditions typical of uremia can cause inhibition of brain-to-blood transport involving rOat3 and/or rOatp2, leading to accumulation of endogenous metabolites and drugs in the brain.

Neurotoxicity induced by beta-lactam antibiotics: from bench to bedside

Central nervous system toxicity following administration of beta-lactam antibiotics, of which penicillin is the prototype, is a potential cause of morbidity and mortality. In recent years, important advances have been made in the pathogenesis of antibiotic-related neurotoxicity. This review focuses on the experimental and clinical aspects of neurotoxicity caused by beta-lactam antibiotics. The purpose is to provide an update on the pathogenesis, mechanism, and clinical manifestations of the neurotoxicity, along with an overview of the relationship between antibiotic structure and convulsive action. In particular, some of the prevailing ideas about pathogenesis are highlighted, including theories of the mechanism of pathogenicity. A better understanding of antibiotic-related neurotoxicity, as derived from animal models and human clinical experience, would be of value in facilitating more efficient and safer use of antimicrobial compounds.

Status epilepticus induced by star fruit intoxication in patients with chronic renal disease

Star fruit has been reported as containing neurotoxins that often cause severe neurological complications in patients with chronic renal disease. We report two patients with chronic renal failure at a pre-dialyzed stage who developed refractory status epilepticus after ingestion of star fruit. In addition, we review 51 cases in the literature. Among 53 patients, 16 patients presented with epileptic seizures (30%). The mortality rate was as high as 75% in patients with seizures. On the other hand, in patients without seizures, the mortality rate was only 0.03%. There is a poor correlation with the degree of underlying renal function and mortality due to intoxication. We propose that epileptic seizure is significantly associated with poor prognosis, and that status epilepticus is an unpredictable and potentially fatal complication in star fruit intoxication. We advise consultant neurologists that star fruit intoxication must be considered when patients with chronic renal disease present with seizures or other unexplained neurological or psychiatric symptoms. Since no effective treatment has been established, star fruit consumption should be avoided in patients with chronic renal disease, especially in the elderly.

GSA: behavioral, histological, electrophysiological and neurochemical effects

Renal insufficient patients suffer from a variety of complications as direct and indirect consequence of accumulation of retention solutes. Guanidinosuccinic acid (GSA) is an important probable uremic toxin, increased in plasma, urine, cerebrospinal fluid and brain of patients with uremia and supposed to play a role in the pathogenesis of some neurological symptoms. GSA, an NMDA-receptor agonist and GABA-receptor antagonist, is suggested to act as an excitotoxin and shown to be convulsive. The effect of hippocampal (i.h.) GSA injection on behavior and hippocampal volume in mice is presented here. In addition, hippocampal cGMP concentration after systemic injection of GSA was measured. The effect of co-application of NMDA-receptor antagonist CGP37849 with GSA was tested, in vivo, after hippocampal GSA injection and, in vitro, on GSA evoked currents in spinal cord neurons. A significant dose-dependent effect of i.h. injection of GSA on cognitive performance, activity and social exploratory behavior was observed. There was a protective effect of CGP37849 on GSA induced behavioral alterations. Volume of hippocampal cornu ammonis region decreased significantly and dose-dependently after GSA injection. Systemic GSA injection increased cGMP concentration in hippocampal formation. It can be concluded that GSA is an important neurotoxin. As GSA is increased in patients with uremia, it probably contributes to their neurological symptoms. Knowledge of neurotoxic effects and mechanisms of action of GSA and other uremic retention solutes could help in the development of more efficient treatment of uremic patients. Animal models like the 'GSA mouse model' are useful tools for research in this context.