Molecular basis for the dialysis disequilibrium syndrome: altered aquaporin and urea transporter expression in the brain

Dialysis disequilibrium syndrome: A case report

The dialysis disequilibrium syndrome is a severe, but rare complication that can occur during or after hemodialysis. It primarily arises from an osmotic gradient, between the plasma and the brain, resulting from the rapidity of the dialysis. This gradient leads to the development of cerebral edema and an increase in intracranial pressure, manifesting as various neurological symptoms. Although this syndrome carries risks of morbidity and mortality, it can be prevented by identifying high-risk patients, implementing preventive measures, and ensuring early detection and prompt management of dialysis disequilibrium syndrome. We present a case of dialysis disequilibrium syndrome in a 59-year-old woman, to raise awareness of this uncommon entity. This review focuses on the discussion of clinical features, and prevention of dialysis disequilibrium syndrome, with a particular emphasis on understanding its pathophysiology, as it significantly influences preventive and management approaches.

Interventions for preventing haemodialysis dysequilibrium syndrome

BACKGROUND

Dialysis dysequilibrium syndrome (DDS) refers to neurological symptoms usually seen during or after new initiation or following reinitiation of haemodialysis (HD) after missing multiple sessions. DDS is associated with death and morbidity. We studied interventions aimed at preventing DDS.

OBJECTIVES

To evaluate the benefits and harms of different types of interventions for preventing DDS.

SEARCH METHODS

We contacted the information specialist and searched the Cochrane Kidney and Transplant Register of Studies up to 8 May 2024 using search terms relevant to this review. Studies in the Register were identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared any intervention against standard care, including individuals initiated on HD, regardless of age.

DATA COLLECTION AND ANALYSIS

Two authors independently determined study eligibility, assessed quality and extracted data. Data were collected on methods, interventions, participants, and outcomes (DDS incidence, severe DDS, death, adverse events). Risk ratios (RR) and confidence intervals (CI) were calculated. Study quality was assessed using the Cochrane Risk of Bias 2 (ROB2) tool. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

We included two RCTs, enrolling 32 adult participants. Interventions included were slow dialysis, sodium modelling, standard sodium dialysate, and high sodium dialysate. The risk of bias was of some concern to high risk of bias in both studies. Slow dialysis compared to sodium modelling (1 study, 15 participants) may result in little to no difference in DDS, severe DDS, and death (low certainty evidence) and has uncertain effects on adverse events (RR 1.33, 95% CI 0.15 to 11.64; very low certainty evidence). Standard sodium dialysate compared to high sodium dialysate (1 study, 17 participants) has uncertain effects on the incidence of DDS (RR 0.07, 95% CI 0.00 to 1.12), severe DDS (RR 0.47, 95% CI 0.02 to 10.32), and adverse events (RR 0.29, 95% CI 0.08 to 1.02) (very low certainty evidence).

AUTHORS' CONCLUSIONS

In HD patients, sodium modelling, compared to slow dialysis, may result in little to no difference in DDS and death (low certainty evidence) and has uncertain effects on adverse events (very low certainty evidence). The evidence is very uncertain for the effect of high-sodium dialysate and standard sodium dialysate on DDS, death and adverse events (very low certainty evidence).

Prevention of dialysis disequilibrium syndrome in children with advanced uremia with a structured hemodialysis protocol: A quality improvement initiative study

BACKGROUND

Dialysis disequilibrium syndrome (DDS) is a rare but significant concern in adult and pediatric patients undergoing dialysis initiation with advanced uremia or if done after an interval. It is imperative to gain insights into the epidemiological patterns, pathophysiological mechanisms, and preventive strategies aimed at averting the onset of this ailment.

DESIGN

Prospective observational quality improvement initiative cohort study.

SETTING AND PARTICIPANTS

A prospective single-center study involving 50 pediatric patients under 18 years recently diagnosed with chronic kidney disease stage V with blood urea ≥200 mg/dL, admitted to our tertiary care center for dialysis initiation from January 2017 to October 2023.

QUALITY IMPROVEMENT PLAN

A standardized protocol was developed and followed for hemodialysis in pediatric patients with advanced uremia. This protocol included measures such as lower urea reduction ratios (targeted at 20%-30%) with shorter dialysis sessions and linear dialysate sodium profiling. Prophylactic administration of mannitol and 25% dextrose was also done to prevent the incidence of dialysis disequilibrium syndrome.

MEASURES

Incidence of dialysis disequilibrium syndrome and severe dialysis disequilibrium syndrome, mortality, urea reduction ratios (URRs), neurological outcome at discharge, and development of complications such as infection and hypotension. Long-term outcomes were assessed at the 1-year follow-up including adherence to dialysis, renal transplantation, death, and loss to follow-up.

RESULTS

The median serum creatinine and urea levels at presentation were 7.93 and 224 mg/dL, respectively. A total of 20% of patients had neurological symptoms attributable to advanced uremia at the time of presentation. The incidence of dialysis disequilibrium syndrome was 4% (n = 2) with severe dialysis disequilibrium syndrome only 2% (n = 1). Overall mortality was 8% (n = 4) but none of the deaths were attributed to dialysis disequilibrium syndrome. The mean urea reduction ratios for the first, second, and third dialysis sessions were 23.45%, 34.56%, and 33.50%, respectively. The patients with dialysis disequilibrium syndrome were discharged with normal neurological status. Long-term outcomes showed 88% adherence to dialysis and 38% renal transplantation.

LIMITATIONS

This study is characterized by a single-center design, nonrandomized approach, and limited sample size.

CONCLUSIONS

Our structured protocol served as a framework for standardizing procedures contributing to low incidence rates of dialysis disequilibrium syndrome.

Connecting the Dots: The Cerebral Lymphatic System as a Bridge Between the Central Nervous System and Peripheral System in Health and Disease

As a recently discovered waste removal system in the brain, cerebral lymphatic system is thought to play an important role in regulating the homeostasis of the central nervous system. Currently, more and more attention is being focused on the cerebral lymphatic system. Further understanding of the structural and functional characteristics of cerebral lymphatic system is essential to better understand the pathogenesis of diseases and to explore therapeutic approaches. In this review, we summarize the structural components and functional characteristics of cerebral lymphatic system. More importantly, it is closely associated with peripheral system diseases in the gastrointestinal tract, liver, and kidney. However, there is still a gap in the study of the cerebral lymphatic system. However, we believe that it is a critical mediator of the interactions between the central nervous system and the peripheral system.

Acute kidney injury in neurocritical care

Approximately 20% of patients with acute brain injury (ABI) also experience acute kidney injury (AKI), which worsens their outcomes. The metabolic and inflammatory changes associated with AKI likely contribute to prolonged brain injury and edema. As a result, recognizing its presence is important for effectively managing ABI and its sequelae. This review discusses the occurrence and effects of AKI in critically ill adults with neurological conditions, outlines potential mechanisms connecting AKI and ABI progression, and highlights AKI management principles. Tailored approaches include optimizing blood pressure, managing intracranial pressure, adjusting medication dosages, and assessing the type of administered fluids. Preventive measures include avoiding nephrotoxic drugs, improving hemodynamic and fluid balance, and addressing coexisting AKI syndromes. ABI patients undergoing renal replacement therapy (RRT) are more susceptible to neurological complications. RRT can negatively impact cerebral blood flow, intracranial pressure, and brain tissue oxygenation, with effects tied to specific RRT methods. Continuous RRT is favored for better hemodynamic stability and lower risk of dialysis disequilibrium syndrome. Potential RRT modifications for ABI patients include adjusted dialysate and blood flow rates, osmotherapy, and alternate anticoagulation methods. Future research should explore whether these strategies enhance outcomes and if using novel AKI biomarkers can mitigate AKI-related complications in ABI patients.

Seizures in patients with kidney diseases: a neglected problem?

Nephrologists may encounter many systemic problems in their patients, including involvement of the neurological system and the development of seizures. Seizures are defined as abnormal neurological functions that cause overstimulation of neurons in the cerebral cortex or limbic system. Seizures may be focal or generalized depending on their origin and may have tonic, clonic, tonic-clonic or myoclonic character depending on the level of involvement of the motor movements. Patients with kidney disease may develop seizures due to etiologies seen in the general population (such as intracranial bleeding, cerebrovascular events, tumors, infections and intoxications) or due to kidney-related etiologies (such as uremic encephalopathy, dialysis disequilibrium syndrome and hyponatremia). Management of seizures in kidney patients is challenging for proper determination of the type and dosage of antiepileptic drugs due to varying renal clearances. This review covers the major causes of new-onset seizures in patients with acute kidney injury, electrolyte imbalances, chronic kidney disease, dialysis, renal transplantation or hypertension, and the available management approaches.

A potential link between AQP3 and SLC14A1 gene expression level and clinical parameters of maintenance hemodialysis patients

Background

The transport of water and urea through the erythrocyte membrane is facilitated by aquaporins such as aquaglyceroporin (AQP3), and type B urea transporters (UT-B). As they may play an important role in osmotic balance of maintenance hemodialysis (HD) patients, the aim of the present study was to determine whether any relationship exists between the expression of their genes and the biochemical / clinical parameters in HD patients.

Methods

AQP3 and UT-B (SLC14A1) gene expression was evaluated using RT-qPCR analysis in 76 HD patients and 35 participants with no kidney failure.

Results

The HD group demonstrated significantly higher median expression of AQP3 and UT-B (Z = 2.16; P = 0.03 and Z = 8.82; p < 0.0001, respectively) than controls. AQP3 negatively correlated with pre-dialysis urea serum concentration (R = -0.22; P = 0.049) and sodium gradient (R = -0.31; P = 0.04); however, no significant UT-B correlations were observed. Regarding the cause of end-stage kidney disease, AQP3 expression positively correlated with erythropoietin dosages in the chronic glomerulonephritis (GN) subgroup (R = 0.6; P = 0.003), but negatively in the diabetic nephropathy subgroup (R = -0.59; P = 0.004). UT-B positively correlated with inter-dialytic weight gain% in the GN subgroup (R = 0.47; P = 0.03).

Conclusion

Maintenance hemodialysis seems significantly modify AQP3 and UT-B expression but their link to clinical and biochemical parameters needs further large-scale evaluation.

Dialysis Disequilibrium: Is Acidosis More Important than Urea?

Dialysis disequilibrium syndrome is a severe complication associated with dialysis treatment. Manifestations may range from mild such as headache to severe such as seizures and coma. Risk factors for development include initial dialysis treatment, uraemia, metabolic acidosis, and extremes of age. We report a case of dialysis disequilibrium in a patient with a failing kidney transplant secondary to the recurrence of IgA nephropathy. Disturbance in cognition and neurologic functioning occurred six hours after the completion of initiation of intermittent haemodialysis. During two sessions of intermittent haemodialysis of 3 and 4 hours, urea was reduced by 21.9 and 17.2 mmol/L and measured serum osmolality was reduced by 25 and 14 mOsm/kg, respectively. Subsequent admission to the intensive care unit and initiation of continuous renal replacement therapy for 48 hours resulted in complete resolution of symptoms. In this case report, we discuss atypical clinical and radiologic features of dialysis disequilibrium occurring with modest reductions in urea and serum osmolality.

Dialysis disequilibrium syndrome (DDS) in pediatric patients on dialysis: systematic review and clinical practice recommendations

BACKGROUND AND OBJECTIVES

Dialysis disequilibrium syndrome (DDS) is a rare neurological complication, most commonly affecting patients undergoing new initiation of hemodialysis (HD), but can also be seen in patients receiving chronic dialysis who miss regular treatments, patients having acute kidney injury (AKI), and in those treated with continuous kidney replacement therapy (CKRT) or peritoneal dialysis (PD). Although the pathogenesis is not well understood, DDS is likely a result of multiple physiological abnormalities. In this systematic review, we provide a synopsis of the data available on DDS that allow for a clear picture of its pathogenesis, preventive measures, and focus on effective management strategies.

METHODS

We conducted a literature search on PubMed/Medline and Embase from January 1960 to January 2021. Studies were included if the patient developed DDS irrespective of age and gender. A summary table was used to summarize the data from individual studies and included study type, population group, age group, sample size, patient characteristics, blood and dialysate flow rate, and overall outcome. A descriptive analysis calculating the frequency of population size, symptoms, and various treatments was performed using R software version 3.1.0.

RESULTS

A total of 49 studies (321 samples) were identified and analyzed. Out of the included 49 studies, a total of 48 studies reported the presence of DSS among patients (1 study reported based on number of dialysis and therefore was not considered for analysis). Among these 48 studies, 74.3% (226/304) patients were reported to have DSS. The most common symptoms were nausea (25.2%), headache (24.8%), vomiting (23.9%), muscle cramps (18.1%), affected level of consciousness (8.8%), confusion (4.4%), and seizure (4.9%) among the 226 DDS patients. Furthermore, 12 studies decided to switch from HD to alternative dialysis modalities including continuous venovenous hemofiltration/hemodiafiltration (CVVH/CVVHDF) or PD which reported no DDS symptoms.

CONCLUSION

Early recognition and timely prevention are crucial for DDS patients. We have provided comprehensive clinical practice points for pediatric, adolescent, and young adult populations. However, it is essential to recognize that DDS was reported more frequently in the early dialysis era, as there was a lack of advanced dialysis technology and limited resources.

Protective Role of Quercetin in Carbon Tetrachloride Induced Toxicity in Rat Brain: Biochemical, Spectrophotometric Assays and Computational Approach

Carbon tetrachloride (CCL4) induces oxidative stress by free radical toxicities, inflammation, and neurotoxicity. Quercetin (Q), on the other hand, has a role as anti-inflammatory, antioxidant, antibacterial, and free radical-scavenging. This study explored protection given by quercetin against CCL4 induced neurotoxicity in rats at given concentrations. Male Wistar rats were divided into four groups Group C: control group; Group CCL4: given a single oral dose of 1 mL/kg bw CCL4; Group Q: given a single i.p injection of 100 mg/kg bw quercetin; and Group Q + CCL4: given a single i.p injection of 100 mg/kg bw quercetin before two hours of a single oral dose of 1 mL/kg bw CCL4. The results from brain-to-body weight ratio, morphology, lipid peroxidation, brain urea, ascorbic acid, reduced glutathione, sodium, and enzyme alterations (aspartate aminotransferase (AST), alanine aminotransferase (ALT), catalase, and superoxide dismutase) suggested alterations by CCL4 and a significant reversal of these parameters by quercetin. In silico analysis of quercetin with various proteins was conducted to understand the molecular mechanism of its protection. The results identified by BzScore4 D showed moderate binding between quercetin and the following receptors: glucocorticoids, estrogen beta, and androgens and weak binding between quercetin and the following proteins: estrogen alpha, Peroxisome proliferator-activated receptors (PPARγ), Herg k+ channel, Liver x, mineralocorticoid, progesterone, Thyroid α, and Thyroid β. Three-dimensional/four-dimensional visualization of binding modes of quercetin with glucocorticoids, estrogen beta, and androgen receptors was performed. Based on the results, a possible mechanism is hypothesized for quercetin protection against CCL4 toxicity in the rat brain.

Uremic encephalopathy

Uremic encephalopathy encompasses a wide range of central nervous system abnormalities associated with poor kidney function occurring with either progressive chronic kidney disease or acute kidney injury. The syndrome is likely caused by retention of uremic solutes, alterations in hormonal metabolism, changes in electrolyte and acid-base homeostasis, as well as changes in vascular reactivity, blood-brain barrier transport, and inflammation. There are no defining clinical, laboratory, or imaging findings, and the diagnosis is often made retrospectively when symptoms improve after dialysis or transplantation. The diagnosis is also made difficult because of the many confounding and overlapping conditions seen in patients with chronic kidney disease and acute kidney injury. Thus, institution of kidney replacement therapy should be considered as a trial to improve symptoms in the right clinical context. Neurological symptoms that do not improve after improvement in clearance should prompt a search for other explanations. Further knowledge linking possible uremic retention solutes with neurological symptoms is needed to better understand this syndrome as well as to develop more tailored treatments that aim to improve cognitive function.

Acute Kidney Injury at the Neurocritical Care Unit

Neurocritical care has advanced substantially in recent decades, allowing doctors to treat patients with more complicated conditions who require a multidisciplinary approach to achieve better clinical outcomes. In neurocritical patients, nonneurological complications such as acute kidney injury (AKI) are independent predictors of worse clinical outcomes. Different research groups have reported an AKI incidence of 11.6% and an incidence of stage 3 AKI, according to the Kidney Disease: Improving Global Outcomes, that requires dialysis of 3% to 12% in neurocritical patients. These patients tend to be younger, have less comorbidity, and have a different risk profile, given the diagnostic and therapeutic procedures they undergo. Trauma-induced AKI, sepsis, sympathetic overstimulation, tubular epitheliopathy, hyperchloremia, use of nephrotoxic drugs, and renal hypoperfusion are some of the causes of AKI in neurocritical patients. AKI is the result of a sum of events, although the mechanisms underlying many of them remain uncertain; however, two important causes that merit mention are direct alteration of the physiological brain-kidney connection and exposure to injury as a result of the specific medical management and well-established therapies that neurocritical patients are subjected to. This review will focus on AKI in neurocritical care patients. Specifically, it will discuss its epidemiology, causes, associated mechanisms, and relationship to the brain-kidney axis. Additionally, the use and risks of extracorporeal therapies in this group of patients will be reviewed.

Renal replacement therapy in cancer patients with acute kidney injury (Review)

Cancer patients are at high risk for developing acute kidney injury (AKI), which is associated with increased morbidity and mortality in these patients. Despite the progress made in understanding the pathogenic mechanisms and etiology of AKI in these patients, the main prevention consists of avoiding medication and nephrotoxic agents such as non-steroidal anti-inflammatory drugs, contrast agents used in medical imaging and modulation of chemotherapy regimens; when prophylactic measures are overcome and renal impairment becomes unresponsive to treatment, renal replacement therapy (RRT) is required. There are several methods of RRT that can be utilized for patients with malignancies and acute renal impairment; the choice of treatment being based on the patient characteristics. The aim of this article is to review the literature data regarding the epidemiology and management of AKI in cancer patients, the extracorporeal techniques used, choice of the appropriate therapy and the optimal time of initiation, and also the dose-prognosis relationship.

Dialysis Disequilibrium Syndrome in a Patient With Acute Kidney Injury on Chronic Kidney Disease

Dialysis disequilibrium syndrome (DDS) is a neurological complication that has been known to occur after hemodialysis (HD). In recent years, the prevalence of DDS has been low as the symptoms are widely recognized; hence, preventive therapies, such as the slow and gentle procedure for HD, are often administered before starting dialysis. However, once DDS occurs, it may cause seizures, coma, and even death in severe cases. Since there has been no established treatment, recognizing risk factors and preventing the syndrome is important.

A 76-year-old man was admitted to our hospital due to exacerbation of chronic heart failure. He also had a history of chronic kidney disease and had consulted with his home doctor about the preparation for HD a month before admission. After treatment with diuretics, the symptoms ameliorated, but he experienced presyncope and malaise. Laboratory tests revealed acute anemia and a decrease in renal function. Upper gastrointestinal endoscopy revealed active bleeding from a gastric ulcer, which was successfully stopped. However, his consciousness deteriorated because of uremia; hence, HD was initiated. We used a cellulose triacetate membrane with a surface area of 1.3 m² and maintained a dialysate flow rate of 500 ml/min with a blood flow rate of 120 ml/min. Four hours after starting HD, he suddenly developed generalized tonic convulsions. The dialysis was immediately stopped, and the patient was transferred to an intensive care unit. A computed tomography scan of the head showed mild edematous change of the brain, and laboratory tests also revealed a rapid decrease of urea nitrogen. We rationalized that he might have developed DDS. After injection of levetiracetam for the treatment of seizures, we initiated continuous hemodiafiltration as renal replacement therapy. Fortunately, his consciousness gradually improved, and he was completely alert on day 18 after admission.

With reference to our current report, DDS can occur even following acute kidney injury, as the progression rate of the injury and accumulation of blood urea may not correlate with the risk of the syndrome.

Inhibition of Urea Transporter (UT)-B Modulates LPS-Induced Inflammatory Responses in BV2 Microglia and N2a Neuroblastoma Cells

Urea is the major nitrogen-containing product of protein metabolism, and the urea cycle is intrinsically linked to nitric oxide (NO) production via the common substrate L-arginine. Urea accumulates in the brain in neurodegenerative states, including Alzheimer's and Huntington's disease. Urea transporter B (UT-B, SLC14A1) is the primary transport protein for urea in the CNS, identified most abundantly in astrocytes. Moreover, enhanced expression of the Slc14a1 gene has been reported under neurodegenerative conditions. While the role of UT-B in disease pathology remains unclear, UT-B-deficient mice display behavioural impairment coupled with urea accumulation, NO disruption and neuronal loss. Recognising the role of inflammation in neurodegenerative disease pathology, the current short study evaluates the role of UT-B in regulating inflammatory responses. Using the specific inhibitor UTBinh-14, we investigated the impact of UT-B inhibition on LPS-induced changes in BV2 microglia and N2a neuroblastoma cells. We found that UTBinh-14 significantly attenuated LPS-induced production of TNFα and IL-6 from BV2 cells, accompanied by reduced release of NO. While we observed a similar reduction in supernatant concentration of IL-6 from N2a cells, the LPS-stimulated NO release was further augmented by UTBinh-14. These changes were accompanied by a small, but significant downregulation in UT-B expression in both cell types following incubation with LPS, which was not restored by UTBinh-14. Taken together, the current evidence implicates UT-B in regulation of inflammatory responses in microglia and neuronal-like cells. Moreover, our findings offer support for the further investigation of UT-B as a novel therapeutic target for neuroinflammatory conditions.

Serum osmolality, cerebrospinal fluid specific gravity and overt hepatic encephalopathy severity in patients with liver failure

BACKGROUND AND AIMS

Hepatic encephalopathy (HE) is a leading contributor to morbidity in liver disease. While hyperammonaemia plays a key role, the mechanisms of cerebral toxicity are unclear. We hypothesized that serum hyperosmolality contributes to HE during acute (ALF) and acute-on-chronic liver failure (ACLF) through mechanisms that affect the water and solute composition of the cerebral environment.

METHODS

We performed a retrospective analysis of serum osmolality, cerebral spinal fluid (CSF) solute density (specific gravity, determined from computed tomography attenuation) and clinical HE severity (Glasgow Coma Score [GCS]) at the time of intensive care admission in a prospectively identified cohort of liver failure patients with overt HE.

RESULTS

Seventy-three patients (39 ALF and 34 ACLF) were included, of whom 28 (38%) were comatose. Serum osmolality (303.9 ± 15.4 mOsm/kg) was elevated despite normal serum sodium (136.6 ± 6.3 mEq/L). Increased osmolality was independently associated with more severe encephalopathy (ordinal adjusted OR 0.26 [95% CI 0.22, 0.31] for higher GCS per standard deviation increase in osmolality) and lower CSF-specific gravity (linear adjusted β = -0.039 [95% CI -0.069, -0.009] Hounsfield unit per 1 mOsm/kg).

CONCLUSIONS

In the context of related research, these data suggest that hyperosmolality increases brain exposure to metabolic toxins by blood-brain barrier alteration and may be a unique therapeutic target.

A vanishing complication of haemodialysis: Dialysis disequilibrium syndrome

Dialysis disequilibrium syndrome (DDS) is a rare syndrome characterised by neurological symptoms related to cerebral oedema. New patients who are started on haemodialysis are at the greatest risk for developing dialysis disequilibrium syndrome. Classical DDS develops during or immediately after haemodialysis. It is a generally self-limiting condition and settles with supportive management. Our case report describes DDS in a patient on chronic haemodialysis. She developed a tonic-clonic seizure shortly after completing 4 h of haemodialysis. This occurred in the context of having missed one session of dialysis, but with no new changes made to her usual dialysis regime. She was managed supportively in the intensive care unit and made a full recovery.

Recurrent reversible neurologic deficits during hemodialysis

Acute neurologic complications in patients receiving dialysis may be secondary to either underlying comorbid diseases, or to the dialysis procedure itself. An incident hemodialysis patient suffered recurrent consecutive episodes of transient ischemic attacks (TIA) that occurred only during hemodialysis and resolved upon discontinuation of the procedure. Eventual work-up demonstrated an almost complete occlusion of left internal carotid artery. It is likely that the decrease in cerebral blood flow that occurs during hemodialysis, in conjunction with the severely stenotic internal carotid artery, explained the patient's symptoms. The stenotic lesion was deemed inoperable. The patient was transferred to peritoneal dialysis and had no further TIA events.

Osmotic Shifts, Cerebral Edema, and Neurologic Deterioration in Severe Hepatic Encephalopathy

OBJECTIVES

We sought to determine the effect of acute electrolyte and osmolar shifts on brain volume and neurologic function in patients with liver failure and severe hepatic encephalopathy.

DESIGN

Retrospective analysis of brain CT scans and clinical data.

SETTING

Tertiary care hospital ICUs.

PATIENTS

Patients with acute or acute-on-chronic liver failure and severe hepatic encephalopathy.

INTERVENTIONS

Clinically indicated CT scans and serum laboratory studies.

MEASUREMENTS AND MAIN RESULTS

Change in intracranial cerebrospinal fluid volume between sequential CT scans was measured as a biomarker of acute brain volume change. Corresponding changes in serum osmolality, chemistry measurements, and Glasgow Coma Scale were determined. Associations with cerebrospinal fluid volume change and Glasgow Coma Scale change for initial volume change assessments were identified by Spearman's correlations (rs) and regression models. Consistency of associations with repeated assessments was evaluated using generalized estimating equations. Forty patients were included. Median baseline osmolality was elevated (310 mOsm/Kg [296-321 mOsm/Kg]) whereas sodium was normal (137 mEq/L [134-142 mEq/L]). Median initial osmolality change was 9 mOsm/kg (5-17 mOsm/kg). Neuroimaging consistent with increased brain volume occurred in 27 initial assessments (68%). Cerebrospinal fluid volume change was more strongly correlated with osmolality (r = 0.70; p = 4 × 10) than sodium (r = 0.28; p = 0.08) change. Osmolality change was independently associated with Glasgow Coma Scale change (p = 1 × 10) and cerebrospinal fluid volume change (p = 2.7 × 10) in initial assessments and in generalized estimating equations using all 103 available assessments.

CONCLUSIONS

Acute decline in osmolality was associated with brain swelling and neurologic deterioration in severe hepatic encephalopathy. Minimizing osmolality decline may avoid neurologic deterioration.

Dialysis disequilibrium syndrome prevention and management

The dialysis disequilibrium syndrome (DDS) is a clinical constellation of neurologic symptoms and signs occurring during or shortly following dialysis, especially when dialysis is first initiated. It is a diagnosis of exclusion occurring in those that are uremic and hyperosmolar, in whom rapid correction with renal replacement therapy leads to cerebral edema and raised intracranial pressure with resultant clinical neurologic manifestations. DDS is most commonly described in association with hemodialysis but can occur in patients with acute kidney injury requiring continuous renal replacement therapy (CRRT). To date, it has not been described in association with peritoneal dialysis. The syndrome is uncommon and becoming rarer, so performing randomized controlled trials to evaluate the effectiveness of potential therapies is almost impossible. This also makes studying the pathophysiology in humans challenging. It is associated with mortality but is also preventable, so identification of patients at risk, preventive measures, early recognition and prompt management of DDS will minimize morbidity and mortality associated with this syndrome. While the focus of this review is the prevention and management of DDS, there will be an emphasis on what is known about the pathophysiology because it strongly impacts the prevention and management strategies.

Therapeutic hypernatremia management during continuous renal replacement therapy with elevated intracranial pressures and respiratory failure

Cerebral edema and elevated intracranial pressure (ICP) are common complications of acute brain injury. Hypertonic solutions are routinely used in acute brain injury as effective osmotic agents to lower ICP by increasing the extracellular fluid tonicity. Acute kidney injury in a patient with traumatic brain injury and elevated ICP requiring renal replacement therapy represents a significant therapeutic challenge due to an increased risk of cerebral edema associated with intermittent conventional hemodialysis. Therefore, continuous renal replacement therapy (CRRT) has emerged as the preferred modality of therapy in this patient population. We present our current treatment approach, with demonstrative case vignette illustrations, utilizing hypertonic saline protocols (3% sodium-chloride or, with coexisting severe combined metabolic and respiratory acidosis, with 4.2% sodium-bicarbonate) in conjunction with the CRRT platform, to induce controlled hypernatremia of approximately 155 mEq/L in hemodynamically unstable patients with acute kidney injury and elevated ICP due to acute brain injury. Rationale, mechanism of activation, benefits and potential pitfalls of the therapy are reviewed. The impact of hypertonic citrate solution during regional citrate anticoagulation is specifically discussed. Maintaining plasma hypertonicity in the setting of increased ICP and acute kidney injury could prevent the worsening of ICP during renal replacement therapy by minimizing the osmotic gradient across the blood-brain barrier and maximizing cardiovascular stability.

Pathogenesis of cerebral edema in patients with acute renal and liver failure and the role of the nephrologist in the management

PURPOSE OF REVIEW

Acute liver failure (ALF) is a severe and complex illness and one of the most daunting conditions managed in the ICU. Because the renal care is intertwined with multiple disciplines, the aim of this review is to examine the multifactorial pathogenesis of cerebral edema in ALF, covering basic established facts as well as recent advances in our understanding of this condition.

RECENT FINDINGS

Acetaminophen remains the most common cause of ALF in the United States and many European countries. The incidence of cerebral edema continues to decline owing to earlier detection and improved management. The pathogenesis of cerebral edema has shifted from a unifactorial hypothesis involving the failed liver to a multifactorial cause. Recent evidence focuses on the role of liver-induced systemic inflammation and its implication in increasing the permeability of the blood-brain barrier. The role of brain aquaporin-4 in mediating water entry into the brain is further clarified. Controversial data regarding the effect of acute kidney injury on the brain emerged. Hyponatremia has been shown to worsen the outcome in acute-on-chronic liver failure patients thus validating findings in animal models. New evidence shed the light on the changes in serum osmolality and potential tissue hypoxia during continuous renal replacement therapy and points to the risks associated with such therapy.

SUMMARY

ALF is a severe systemic illness that is potentially reversible. Understanding the interaction between the multiple failed organs will help the nephrologist provide well tolerated and efficient care.

Association of dialysis with in-hospital disability progression and mortality in community-onset stroke

AIM

End-stage renal disease is associated with increased risk of cerebrovascular disease, but the effect on post-stroke clinical outcomes has not been thoroughly investigated.

METHODS

Using the Japanese Diagnosis Procedure Combination database, which includes administrative claims and discharge abstract data, we examined the association between risk factors including dialysis therapy and in-hospital disability progression or mortality in patients with community-onset stroke. We extracted data of patients aged ≥ 20 years old who were admitted to the hospital within 3 days after onset of stroke between July 2010 and March 2013. The disability level was divided into modified Rankin Scale (mRS) 0-1, 2-3, 4-5, and 6 (death). Disability progression was defined as an increase in disability level. Odds ratios for in-hospital disability progression and mortality were calculated using logistic regression models.

RESULTS

Of 435 403 patients, 7562 (1.7%) received dialysis therapy. The median length of stay was 21 and 20 days for patients with and without dialysis, respectively. During the hospital stay, disability progressed in 100 402 (23.1%) patients and 45 919 (10.5%) died. Patients on dialysis had a higher prevalence of disability progression (26.8%) and mortality (13.1%) compared to those without dialysis (23.0% and 10.5%, respectively). Dialysis was associated with an increased risk of in-hospital disability progression (odds ratio, 1.56; 95% confidence interval, 1.47-1.66) and mortality (odds ratio 1.70; 95% confidence interval, 1.57-1.84). These risks were comparable among subtypes of stroke.

CONCLUSIONS

Dialysis was associated with an increased risk of in-hospital disability progression and mortality among patients with community-onset stroke, regardless of stroke subtype.

The nature, consequences, and management of neurological disorders in chronic kidney disease

Perhaps no other organ in the body is affected as often and in as many ways as the brain is in patients with chronic kidney disease (CKD). Several factors contribute to the neurological disorders in CKD including accumulation of uremic toxins, metabolic and hemodynamic disorders, oxidative stress, inflammation, and impaired blood brain barrier among others. The neurological disorders in CKD involve both peripheral and central nervous system. The peripheral neurological symptoms of CKD are due to somatic and cranial peripheral neuropathies as well as a myopathy. The central neurological symptoms of CKD are due to the cortical predominantly cortical, or subcortical lesions. Cognitive decline, encephalopathy, cortical myoclonus, asterixis and epileptic seizures are distinct features of the cortical disorders of CKD. Diffuse white matter disease due to ischemia and hypoxia may be an important cause of subcortical encephalopathy. A special and more benign form of subcortical disorder caused by brain edema in CKD is termed posterior reversible encephalopathy. Subcortical pathology especially when it affects the basal ganglia causes a number of movement disorders including Parkinsonism, chorea and dystonia. A stimulus-sensitive reflex myoclonus is believed to originate from the medullary structures. Sleep disorder and restless leg syndrome are common in CKD and have both central and peripheral origin. This article provides an overview of the available data on the nature, prevalence, pathophysiology, consequences and treatment of neurological complications of CKD.

Diagnosis, Treatment, and Prevention of Hemodialysis Emergencies

Given the high comorbidity in patients on hemodialysis and the complexity of the dialysis treatment, it is remarkable how rarely a life-threatening complication occurs during dialysis. The low rate of dialysis emergencies can be attributed to numerous safety features in modern dialysis machines; meticulous treatment and testing of the dialysate solution to prevent exposure to trace elements, toxins, and pathogens; adherence to detailed treatment protocols; and extensive training of dialysis staff to handle medical emergencies. Most hemodialysis emergencies can be attributed to human error. A smaller number are due to rare idiosyncratic reactions. In this review, we highlight major emergencies that may occur during hemodialysis treatments, describe their pathogenesis, offer measures to minimize them, and provide specific interventions to prevent catastrophic consequences on the rare occasions when such emergencies arise. These emergencies include dialysis disequilibrium syndrome, venous air embolism, hemolysis, venous needle dislodgement, vascular access hemorrhage, major allergic reactions to the dialyzer or treatment medications, and disruption or contamination of the dialysis water system. Finally, we describe root cause analysis after a dialysis emergency has occurred to prevent a future recurrence.

Generation and phenotypic analysis of mice lacking all urea transporters

Urea transporters (UT) are a family of transmembrane urea-selective channel proteins expressed in multiple tissues and play an important role in the urine concentrating mechanism of the mammalian kidney. UT inhibitors have diuretic activity and could be developed as novel diuretics. To determine if functional deficiency of all UTs in all tissues causes physiological abnormality, we established a novel mouse model in which all UTs were knocked out by deleting an 87 kb of DNA fragment containing most parts of Slc14a1 and Slc14a2 genes. Western blot analysis and immunofluorescence confirmed that there is no expression of urea transporter in these all-UT-knockout mice. Daily urine output was nearly 3.5-fold higher, with significantly lower urine osmolality in all-UT-knockout mice than that in wild-type mice. All-UT-knockout mice were not able to increase urinary urea concentration and osmolality after water deprivation, acute urea loading, or high protein intake. A computational model that simulated UT-knockout mouse models identified the individual contribution of each UT in urine concentrating mechanism. Knocking out all UTs also decreased the blood pressure and promoted the maturation of the male reproductive system. Thus, functional deficiency of all UTs caused a urea-selective urine-concentrating defect with little physiological abnormality in extrarenal organs.

Neurological Complications of Renal Disease

Neurological manifestations related to electrolyte disorders, drug toxicity, and uremia are common in chronic kidney disease (CKD). Seizures and coma are frequent complications of acute renal insufficiency (uremia), whereas peripheral neuropathy and encephalopathy, observed in progressive uremia, are terminal events. Failure to excrete metabolic products causes their accumulation and can lead to severe intoxication. Clinically, the signs and symptoms of uremia can vary widely, depending on the biological characteristics of the patient, the specific type of renal disease, and the time of the uremic intoxication. CKD is an increasing problem worldwide and is now being recognized as a global health burden particularly for cardiovascular and cerebrovascular ischemic events. Despite improvements in the medical management of advanced CKD, including dialysis and transplantation, patients manifest a number of symptoms that neurologists are often confronted with. Appropriate drug dosing, awareness of potential side effects of medications, prompt diagnosis, and treatment are essential in preventing neurological long-term morbidity and mortality.

Cerebral Edema in a Child after Preemptive Kidney Transplantation

Dialysis disequilibrium syndrome (DDS) is characterized by acute neurological manifestations in patients undergoing first dialysis treatment. The mechanisms for the development of DDS include the reverse urea effect, transient intracranial acidosis, and idiogenic osmoles which can increase intracellular osmolality and promote water movement into the brain. We present a case of a 4-year-old child with chronic kidney disease who underwent a preemptive living unrelated donor kidney transplant. He had a 24 mEq/L drop in his sodium concentration, 92% reduction in blood urea nitrogen (BUN) concentration, and a 67 mOsm/kg drop in serum osmolality within 18 hours after transplant, with concurrent development of symptomatic and radiologic cerebral edema, similar to that described in DDS. Mental status rapidly returned to baseline after administration of 3% hypertonic saline. This case highlights the risk of cerebral edema in patients who have a high pretransplant BUN. It emphasizes the need for close monitoring of vital signs, mental status, and electrolytes in children undergoing renal transplant. Hypertonic solutions can be used to prevent or manage cerebral edema in these patients when serum osmolality decreases rapidly. Pretransplant dialysis is another consideration to proactively reduce serum hyperosmolality.

A proposed role for efflux transporters in the pathogenesis of hydrocephalus

Hydrocephalus is a common brain disorder that is treated only with surgery. The basis for surgical treatment rests on the circulation theory. However, clinical and experimental data to substantiate circulation theory have remained inconclusive. In brain tissue and in the ventricles, we see that osmotic gradients drive water diffusion in water-permeable tissue. As the osmolarity of ventricular CSF increases within the cerebral ventricles, water movement into the ventricles increases and causes hydrocephalus. Macromolecular clearance from the ventricles is a mechanism to establish the normal CSF osmolarity, and therefore ventricular volume. Efflux transporters, (p-glycoprotein), are located along the blood brain barrier and play an important role in the clearance of macromolecules (endobiotics and xenobiotics) from the brain to the blood. There is clinical and experimental data to show that macromolecules are cleared out of the brain in normal and hydrocephalic brains. This article summarizes the existing evidence to support the role of efflux transporters in the pathogenesis of hydrocephalus. The location of p-gp along the pathways of macromolecular clearance and the broad substrate specificity of this abundant transporter to a variety of different macromolecules are reviewed. Involvement of p-gp in the transport of amyloid beta in Alzheimer disease and its relation to normal pressure hydrocephalus is reviewed. Finally, individual variability of p-gp expression might explain the variability in the development of hydrocephalus following intraventricular hemorrhage.

Association of Predialysis Calculated Plasma Osmolarity With Intradialytic Blood Pressure Decline

BACKGROUND

The rapid reduction in plasma osmolality during hemodialysis (HD) may induce temporary gradients that promote the movement of water from the extracellular to the intracellular compartment, predisposing to the development of intradialytic hypotension (IDH).

STUDY DESIGN

Observational cohort study.

SETTING & PARTICIPANTS

3,142 prevalent patients receiving thrice-weekly HD from a single dialysis provider organization.

PREDICTOR

Predialysis calculated plasma osmolarity (calculated after the 2-day interval as 2 × serum sodium + serum urea nitrogen/2.8 + serum glucose/18).

OUTCOME

Magnitude of systolic blood pressure (SBP) decline (predialysis SBP - nadir intradialytic SBP) and risk of IDH (SBP decline > 35 or nadir SBP < 90 mm Hg).

MEASUREMENTS

Unadjusted and multivariable-adjusted generalized linear models were fit to estimate the association of calculated osmolarity with intradialytic SBP decline and the odds of developing IDH.

RESULTS

Mean age of participants was 62.6±15.2 (SD) years, 57.1% were men, and 61.0% had diabetes. Mean predialysis calculated osmolarity during follow-up was 306.4 ± 9.5 mOsm/L. After case-mix adjustment, each 10-mOsm/L increase in predialysis calculated osmolarity was associated with 1.48 (95% CI, 0.86-2.09) mm Hg (P < 0.001) greater decline in intradialytic SBP and 10% greater odds of IDH (OR, 1.10; 95% CI, 1.05-1.15). In adjusted models, lower predialysis sodium and higher serum urea nitrogen and serum glucose levels were associated with greater decline in intradialytic SBP.

LIMITATIONS

Measured serum osmolality, timing of changes in intradialytic osmolality, dialysate osmolality, and dialysate temperature were not available.

CONCLUSIONS

Higher predialysis calculated osmolarity is associated with greater decline in intradialytic SBP and greater risk of IDH in maintenance HD patients. Strategies to minimize rapid shifts in osmolality should be tested prospectively to minimize excess SBP decline in susceptible patients.

Development of dialysis disequilibrium-like clinical signs during postobstructive management of feline urethral obstruction

OBJECTIVE

To describe the clinical features, treatment, and outcome of a cat with acute neurologic signs subsequent to relief of urethral obstruction and rapid resolution of severe azotemia, suggesting a process similar to dialysis disequilibrium syndrome.

CASE SUMMARY

A male castrated domestic short-hair cat was presented for weakness and dull mentation. Initial physical examination was consistent with urethral obstruction and laboratory data demonstrated severe azotemia, hyperkalemia, and acidemia. Interventions for hyperkalemia and urethral catheterization were performed without complication. The patient demonstrated a marked postobstructive diuresis and 7 hours after presentation suffered a grand mal seizure and was neurologically inappropriate. These changes corresponded with marked decreases in blood urea nitrogen (from 89.25 mmol/L to 19.99 mmol/L [250 mg/dL to 56 mg/dL]) and calculated serum osmolality (429 mOsm/kg to 359 mOsm/kg) from initial presentation without other apparent cause for seizure activity. The patient was treated with hypertonic saline (bolus and continuous infusion) for presumed osmotic injury (dialysis disequilibrium-like clinical signs) along with other supportive care. All neurologic signs resolved within 48 hours, the urinary catheter was removed, and the patient was discharged after 24 hours of observation of spontaneous urination.

NEW OR UNIQUE INFORMATION PROVIDED

Dialysis disequilibrium syndrome has been documented in small animals, but similar signs have not been reported as a sequelae of treatment of feline urethral obstruction. Urethral obstruction is a common emergency and practitioners should be aware of this potential complication as a cause of delayed neurologic recovery or seizures in the postobstructive period.

New concepts in the pathogenesis of hydrocephalus

Hydrocephalus is a central nervous system disorder characterized by excessive accumulation of cerebrospinal fluid (CSF) in the ventricles of the brain. Cognitive and physical handicap can occur as a result of hydrocephalus. The disorder can present at any age as a result of a wide variety of different diseases. The pathophysiology of hydrocephalus is unclear. While circulation theory is widely accepted as a hypothesis for the development of hydrocephalus, there is a lack of adequate proof in clinical situations and in experimental settings. However, there is growing evidence that osmotic gradients are responsible for the water content of the ventricles of the brain, similar to their presence in other water permeable organs in the body. Therefore, brain disorders that results in excess macromolecules in the ventricular CSF will change the osmotic gradient and result in hydrocephalus. This review encompasses several key findings that have been noted to be important in the genesis of hydrocephalus, including but not limited to the drainage of CSF through the olfactory pathways and cervical lymphatics, the paravascular pathways and the role of venous system. We propose that as osmotic gradients play an important role in the water transport into the ventricles, the transport of osmotically active macromolecules play a critical role in the genesis of hydrocephalus. Therefore, we can view hydrocephalus as a disorder of macromolecular clearance, rather than circulation. Current evidence points to a paravascular and/or lymphatic clearance of these macromolecules out of the ventricles and the brain into the venous system. There is substantial evidence to support this theory, and further studies may help solidify the merit of this hypothesis.

Changing the hemodialysis prescription for hemodialysis patients with subdural and intracranial hemorrhage

Although continuous modalities of renal replacement therapy offer an advantage to the patient with compromised cerebral perfusion and intracranial hypertension, they are generally limited to the intensive care unit setting. Many hemodialysis patients admitted with strokes and subdural hematoma are managed on general wards. As such, these patients are generally treated by intermittent hemodialysis, and their dialysis prescription should be altered to minimize changes in serum osmolality, and fall in blood pressure during dialysis. Such patients require more frequent but shorter dialysis sessions, using minimally bioincompatible small surface area dialyzers with lower blood flows, in combination with higher sodium and cooled dialysate. In patients at risk of intracranial hemorrhage and those with invasive intracranial monitoring, systemic anticoagulants should be avoided, choosing no anticoagulation protocols or regional anticoagulants.

Genes and proteins of urea transporters

A urea transporter protein in the kidney was first proposed in 1987. The first urea transporter cDNA was cloned in 1993. The SLC14a urea transporter family contains two major subgroups: SLC14a1, the UT-B urea transporter originally isolated from erythrocytes; and SLC14a2, the UT-A group originally isolated from kidney inner medulla. Slc14a1, the human UT-B gene, arises from a single locus located on chromosome 18q12.1-q21.1, which is located close to Slc14a2. Slc14a1 includes 11 exons, with the coding region extending from exon 4 to exon 11, and is approximately 30 kb in length. The Slc14a2 gene is a very large gene with 24 exons, is approximately 300 kb in length, and encodes 6 different isoforms. Slc14a2 contains two promoter elements: promoter I is located in the typical position, upstream of exon 1, and drives the transcription of UT-A1, UT-A1b, UT-A3, UT-A3b, and UT-A4; while promoter II is located within intron 12 and drives the transcription of UT-A2 and UT-A2b. UT-A1 and UT-A3 are located in the inner medullary collecting duct, UT-A2 in the thin descending limb and liver, UT-A5 in testis, UT-A6 in colon, UT-B1 primarily in descending vasa recta and erythrocytes, and UT-B2 in rumen.

Expression of urea transporters and their regulation

UT-A and UT-B families of urea transporters consist of multiple isoforms that are subject to regulation of both acutely and by long-term measures. This chapter provides a brief overview of the expression of the urea transporter forms and their locations in the kidney. Rapid regulation of UT-A1 results from the combination of phosphorylation and membrane accumulation. Phosphorylation of UT-A1 has been linked to vasopressin and hyperosmolality, although through different kinases. Other acute influences on urea transporter activity are ubiquitination and glycosylation, both of which influence the membrane association of the urea transporter, again through different mechanisms. Long-term regulation of urea transport is most closely associated with the environment that the kidney experiences. Low-protein diets may influence the amount of urea transporter available. Conditions of osmotic diuresis, where urea concentrations are low, will prompt an increase in urea transporter abundance. Although adrenal steroids affect urea transporter abundance, conflicting reports make conclusions tenuous. Urea transporters are upregulated when P2Y2 purinergic receptors are decreased, suggesting a role for these receptors in UT regulation. Hypercalcemia and hypokalemia both cause urine concentration deficiencies. Urea transporter abundances are reduced in aging animals and animals with angiotensin-converting enzyme deficiencies. This chapter will provide information about both rapid and long-term regulation of urea transporters and provide an introduction into the literature.

Dialysis disequilibrium syndrome induced by neoplastic meningitis in a patient receiving maintenance hemodialysis

BACKGROUND

Dialysis disequilibrium syndrome is characterized by neurological symptoms resulting from cerebral edema, which occurs as a consequence of hemodialysis. Dialysis disequilibrium syndrome most often occurs in patients who have just started hemodialysis, during hemodialysis, or soon after hemodialysis; although it may also occur in patients who are under maintenance hemodialysis with pre-existing neurological disease.

CASE PRESENTATION

A 70-year-old woman, who had been receiving maintenance hemodialysis for one year, was diagnosed with ovarian cancer by ascites cytological examination. Two years later, she reported severe headache and nausea during hemodialysis and was diagnosed with dialysis disequilibrium syndrome. Although brain images revealed mild hydrocephalus without any mass lesions, poorly differentiated adenocarcinoma cells were detected in her cerebrospinal fluid. These findings indicated that DDS was induced by neoplastic meningitis due to ovarian cancer metastasis.

CONCLUSION

Neoplastic meningitis should be considered and excluded in hemodialysis patients with dialysis disequilibrium syndrome and malignancy by cytological examination of the cerebrospinal fluid even if cerebral imaging shows no obvious lesions. This is the first reported case of dialysis disequilibrium syndrome induced by neoplastic meningitis in a patient receiving maintenance hemodialysis.

Dialysis disequilibrium syndrome occurring during continuous renal replacement therapy

The dialysis disequilibrium syndrome (DDS) is characterized by progressive neurological symptoms and signs attributable to cerebral edema that occurs due to fluid shifts into the brain following a relatively rapid decrease in serum osmolality during hemodialysis (HD). Since continuous renal replacement therapy (CRRT) is less efficient at solute clearance than intermittent HD, it seems logical that this mode of therapy is less likely to cause DDS. This entity has not been previously reported to occur with this modality. Here, we report two cases of DDS associated with CRRT that provide insights into its pathophysiological mechanisms and suggest strategies for its prevention.

Dialysis disequilibrium syndrome

The dialysis disequilibrium syndrome is a rare but serious complication of hemodialysis. Despite the fact that maintenance hemodialysis has been a routine procedure for over 50 years, this syndrome remains poorly understood. The signs and symptoms vary widely from restlessness and headache to coma and death. While cerebral edema and increased intracranial pressure are the primary contributing factors to this syndrome and are the target of therapy, the precise mechanisms for their development remain elusive. Treatment of this syndrome once it has developed is rarely successful. Thus, measures to avoid its development are crucial. In this review, we will examine the pathophysiology of this syndrome and discuss the factors to consider in avoiding its development.