Neurological complications in renal failure: a review

Nerve cross-sectional area in advanced uremic neuropathy: A nerve ultrasound pilot study

BACKGROUND AND PURPOSE

Uremic neuropathy (UN) is a disabling neuropathy in end-stage kidney disease (ESKD) affecting the majority of patients receiving long-term hemodialysis (HD). One previous nerve ultrasound study reported an increased cross-sectional area (CSA) of the median nerve in moderate UN, while another study found enlarged sural nerves in small-fiber polyneuropathy associated with ESKD. The present cohort study aims to analyze bilateral CSA of multiple nerves in UN.

METHODS

Ten nondiabetic ESKD patients with UN on HD for at least 2 years and 10 healthy age-matched controls underwent bilateral ultrasound examinations with CSA measurements in 13 arm and leg nerve sites. Nerve conduction studies (NCS) and the total neuropathy score (TNS) were recorded. Pearson's coefficient and the Mann-Whitney U-test were used to analyze correlations and compare groups.

RESULTS

ESKD patients presented advanced neuropathic symptoms (mean TNS 15.9). NCS showed significantly reduced motor and sensory amplitudes in the UN group compared to the control group, and a slightly reduced nerve CSA was observed in 5 of 13 nerve sites (p < .05); the other nerve sites were not enlarged. Sural nerve CSA (p < .05) and sensory amplitude (p < .01) were negatively correlated with the TNS.

CONCLUSIONS

Nerve enlargement was not observed in the present study in advanced UN. A reduced nerve CSA observed in the sural nerve suggests an axonal loss associated with long-term HD in ESKD. During clinical workup of an acute disease of the peripheral nervous system in ESKD patients, nerve enlargement might be attributable to other causes than chronic UN.

Sleep disorders in chronic kidney disease

Sleep disorders are highly prevalent in chronic kidney disease (CKD) but are often under-recognized. Restless legs syndrome, which is common in CKD owing to issues with dopamine metabolism and is exacerbated by iron deficiency and uraemia, can lead to poor sleep quality and increased daytime fatigue. Insomnia is also prevalent in CKD, particularly in patients requiring dialysis, with increased sleep latency and sleep fragmentation being reported. The cause of insomnia in CKD is multifactorial - poor sleep habits and frequent napping during dialysis, uraemia, medications and mood disorders have all been suggested as potential contributing factors. Sleep apnoea and CKD are also now recognized as having a bi-directional relationship. Sleep apnoea is a risk factor for accelerated progression of CKD, and fluid overload, which is associated with kidney failure, can lead to both obstructive and central sleep apnoea. The presence of obstructive sleep apnoea in CKD can exacerbate the already heightened cardiovascular morbidity and mortality in these patients, as well as leading to daytime fatigue and reduced quality of life. Increased awareness, timely diagnosis and appropriate therapeutic interventions are essential to reduce the negative impact of sleep disorders in patients with kidney disease.

Peripheral Neuropathy Associated with Higher Mortality in Population with Chronic Kidney Disease: National Health and Nutrition Examination Surveys

Introduction

Peripheral neuropathy (PN), one of the commonest neurological complications of chronic kidney disease (CKD), was associated with physical limitation. Studies showed that a decrease in physical capability in patients with CKD is related with an increased risk of mortality. The objective of our research was to directly explore the relationship between PN and risk of mortality in patients with CKD.

Method

1,836 participants with CKD and 6,036 participants without CKD, which were classified by PN based on monofilament examination in National Health and Nutrition Examination Survey (NHANES), were collected from the 1999 to 2004 National Health and Nutrition Examination Surveys. Multivariable Cox proportional hazard models were conducted to assess the relationships of PN and deaths in patients with CKD and non-CKD.

Results

During 14 years of a median follow-up from 1999 to 2015 and 2004 to 2015, 1,072 (58.4%) and 1,389 (23.0%) deaths were recorded in participants with CKD and without CKD, respectively. PN was related with increased all-cause mortality even after adjusting possible confounding factors in population with CKD (hazard ratio [HR] 1.34, 95% confidence interval [CI] 1.17-1.53) and without CKD (HR 1.27, 95% CI 1.12-1.43). And the adjusted HRs (95% CI) for cardiovascular mortality of the people with CKD and without CKD who suffered from PN were 1.42 (1.07, 1.90) and 1.23 (0.91, 1.67), respectively, versus those without PN.

Conclusion

PN was related with a higher risk of all-cause and cardiovascular death in people with CKD, which clinically suggests that the adverse prognostic impact of PN in the CKD population deserves attention and is an important target for intervention.

Association of obstructive sleep apnea and diurnal variation of cystatin C

PURPOSE

Obstructive sleep apnea is a known risk factor for the progression of chronic kidney disease. To find early signs of the progression in subjects with obstructive sleep apnea., we assessed the diurnal variation of kidney biomarkers.

METHODS

A prospective observational study was conducted at Kangwon National University Hospital, Chuncheon, South Korea. All participants underwent in-laboratory polysomnography and phlebotomy in the evening before the polysomnography and in the morning after the polysomnography. Kidney biomarkers, including serum creatinine, blood urea nitrogen, and serum cystatin C, were measured. Delta kidney biomarkers were calculated by subtracting the evening level of the biomarkers from the morning level.

RESULTS

Twenty-six of 50 participants had severe obstructive sleep apnea. Delta cystatin C was significantly correlated with apnea-hypopnea index, oxygen desaturation index, and total arousal index with coefficients of -0.314, -0.323, and -0.289, respectively. In participants without severe obstructive sleep apnea, the morning cystatin C level (0.84 ± 0.11 mg/L) was significantly higher than the evening cystatin C level (0.81 ± 0.11 mg/L) (P = 0.005). With severe obstructive sleep apnea, the cystatin C levels were not different between the morning (0.85 ± 0.11 mg/L) and the evening (0.85 ± 0.10 mg/L).

CONCLUSIONS

Cystatin C level was increased in the morning in participants without severe obstructive sleep apnea, but not in participants with severe obstructive sleep apnea.

Electrochemical Skin Conductance by Sudoscan in Non-Dialysis Chronic Kidney Disease Patients

BACKGROUND

Peripheral neuropathy is prevalent among patients with chronic kidney disease (CKD). Sudoscan non-invasively detects polyneuropathy by measuring electrochemical skin conductance (ESC). We conducted a study on sudomotor function in CKD patients across various stages based on their estimated glomerular filtration rate (eGFR).

METHODS

In this cross-sectional study of 700 CKD patients, all underwent Sudoscan. Pathological ESC was defined as hands < 40 μS or feet < 50 μS. Clinical neuropathy scores including Michigan Neuropathy Screening Instrument (MNSI) and Douleur Neuropathique en 4 questionnaire (DN4) were obtained.

RESULTS

Among participants, 344 had diabetes and 356 did not. Hands and feet ESC decreased with CKD progression (median (IQR) in stage 1-2, 3, 4-5: 54.0 (39.0-68.0), 45.5 (30.0-63.0), 41.8 (26.5-60.5), p trend < 0.001; 64.5 (53.5-74.0), 60.5 (43.0-72.5), 55.0 (39.0-69.8), p trend < 0.001). Pathological hands and feet ESC increased in later CKD stages (stage 1-2, 3, 4-5: 26.6%, 40.9%, 45.7%, p trend < 0.001; 21.7%, 34.0%, 40.6%, p trend < 0.001). Positive hands and feet ESC-eGFR correlation existed irrespective of diabetes. Diabetic patients had lower hands and feet ESC than non-diabetics as CKD progressed. However, multivariate regression found no significant ESC-eGFR association. Sudoscan correlated with clinical neuropathy scores.

CONCLUSION

Pathological sudomotor function was common in non-dialysis CKD stages 4-5. Diabetic patients had worse function. Sudomotor dysfunction progressed with renal disease but eGFR was not an independent risk factor.

Characterizing Topological Properties of Brain Functional Networks Using Multi-Threshold Derivative for End-Stage Renal Disease with Mild Cognitive Impairment

Patients with end-stage renal disease (ESRD) experience changes in both the structure and function of their brain networks. In the past, cognitive impairment was often classified based on connectivity features, which only reflected the characteristics of the binary brain network or weighted brain network. It exhibited limited interpretability and stability. This study aims to quantitatively characterize the topological properties of brain functional networks (BFNs) using multi-threshold derivative (MTD), and to establish a new classification framework for end-stage renal disease with mild cognitive impairment (ESRDaMCI). The dynamic BFNs (DBFNs) were constructed and binarized with multiple thresholds, and then their topological properties were extracted from each binary brain network. These properties were then quantified by calculating their derivative curves and expressing them as multi-threshold derivative (MTD) features. The classification results of MTD features were compared with several commonly used DBFN features, and the effectiveness of MTD features in the classification of ESRDaMCI was evaluated based on the classification performance test. The results indicated that the linear fusion of MTD features improved classification performance and outperformed individual MTD features. Its accuracy, sensitivity, and specificity were 85.98 ± 2.92%, 86.10 ± 4.11%, and 81.54 ± 4.27%, respectively. Finally, the feature weights of MTD were analyzed, and MTD-cc had the highest weight percentage of 28.32% in the fused features. The MTD features effectively supplemented traditional feature quantification by addressing the issue of indistinct classification differentiation. It improved the quantification of topological properties and provided more detailed features for diagnosing cognitive disorders.

Restless Legs Syndrome in Chronic Kidney Disease- a Systematic Review

Objectives

The objective of this review is to provide updated information on the epidemiology, correlating factors and treatment of chronic kidney disease associated restless legs syndrome (CKD-A-RLS) in both adult and pediatric population.

Materials and Methods

We have reviewed the Medline search and Google Scholar search up to May 2022, using key words restless legs syndrome, chronic kidney disease and hemodialysis and kidney transplant. The reviewed articles were studied for epidemiology, correlating factors, as well as pharmacologic and non-pharmacologic treatment options.

Results

Our search revealed 175 articles, 111 were clinical trials or cross- sectional studies and 64 were review articles. All 111 articles were retrieved and studied in detail. Of these, 105 focused on adults and 6 on children. A majority of studies on dialysis patients reported a prevalence between 15-30%, which is notably higher than prevalence of RLS in general population (5-10%). The correlation between presence of CKD-A-RLS with age, gender, abnormalities of hemogram, iron, ferritin, serum lipids, electrolytes and parathyroid hormones were also reviewed. The results were inconsistent and controversial. Limited studies have reported on the treatment of CKD-A-RLS. Non-pharmacological treatment focused on the effect(s) of exercise, acupuncture, massage with different oils and infra-red light whereas, pharmacologic treatment options include the effects of dopaminergic drugs, Alpha2-Delta ligands (gabapentin and pregabalin), vitamins E and C, and intravenous iron infusion.

Conclusion

This updated review showed that RLS is two to three times more common in patients with CKD compared to the general population. More patients with CKD-A-RLS demonstrated increased mortality, increased incidence of cardiovascular accident, depression, insomnia and impaired quality of life than those with CKD without RLS. Dopaminergic drugs such as levodopa, ropinirole, pramipexole and rotigotine as well as calcium channel blockers (gabapentin and pregabalin) are helpful for treatment of RLS. High quality studies with these agents are currently underway and hopefully confirm the efficacy and practicality of using these drugs in CKD-A-RLS. Some studies have shown that aerobic exercise and massage with lavender oil can improve symptoms of CKD-A- RLS suggesting that these measures can be useful as adjunct therapy.

The applicability research of the diagnostic criteria for 10.2 Heamodialysis-related headache in the international classification of headache disorders-3rd edition

BACKGROUND

Headache during hemodialysis (HDH) is prevalent but not negligible. Despite the high prevalence of dialysis headaches, they have rarely been studied. Therefore, this study aimed to evaluate the prevalence, risk factors, and clinical characteristics of HDH and reappraise the HDH diagnostic criteria in the International Classification of Headache Disorders 3 (ICHD-3).

METHODS

One hundred and fifty-four patients completed this randomized cross-sectional study. Consecutive patients who underwent haemodialysis were assessed using a semi-structured questionnaire. The patients were administered face-to-face questionnaires while undergoing dialysis.

RESULTS

This study included 154 patients. Before commencing dialysis, 3.24% (5/154) of the patients had migraine without aura, 1.29% (2/154) had menstrual-related migraine, 0.6% (1/154) had tension-type headaches, and 0.6% (1/154) had an unclassifiable headache. One case (0.6%) of headache resolved after dialysis treatment. HDH was diagnosed in 9.09% (14/154) of the patients. Headache after haemodialysis (HAH) was reported in 6.49% (10/154) of patients. The most prevalent features of HDH were frontal or temporal location, bilateral headaches, dull and throbbing nature, and moderate severity. HDH started at a mean of 2.33 ± 0.79 h after dialysis commenced. The average headache duration was 6.56 ± 1.57 h (median = 3.0 h), with 66.67% of the patients reporting a duration of ≤4 h. HDH was more prevalent in females than males (P = 0.01, P < 0.05). Female sex was a risk factor for HDH (P = 0.01，P < 0.05).

CONCLUSIONS

The diagnostic criteria for 10.2 HDH in ICHD-3 may miss several HAH. Therefore, ICHD-3 should be revised according to the literature and further studies.

Static and Dynamic Characteristics of Functional Network Connectivity in Neurologically Asymptomatic Patients Undergoing Maintenance Hemodialysis: A Resting-State Functional MRI Study

BACKGROUND

The characteristics of static functional network connectivity (sFNC) and dynamic FNC (dFNC) in neurologically asymptomatic patients undergoing maintenance hemodialysis are unknown. Elucidating these characteristics may improve our understanding of the mechanisms of neuropathological damage in these patients.

PURPOSE

To explore the static and dynamic characteristics of FNC in neurologically asymptomatic patients undergoing maintenance hemodialysis and the relationship between FNC-related parameters with the neuropsychological scores and blood biomarkers.

STUDY TYPE

Retrospective.

POPULATION

A total of 23 neurologically asymptomatic patients undergoing maintenance hemodialysis and 25 healthy controls matched for age, sex, and years of education.

FIELD STRENGTH/SEQUENCE

A 3.0 T MRI/functional MRI and three-dimensional-T1 structural imaging ASSESSMENT: Independent components; spatial map intensity; sFNC and dFNC strengths; and time attribute parameters (mean dwell time, fractional window, and number of transitions) were determined. Neuropsychological tests were performed. Blood biochemical tests were performed for the patients but not healthy controls.

STATISTICAL TESTS

Chi-squared test, one-sample t-test, two-sample t-test, partial correlation analysis, and family-wise error and false discovery rate correction. P < 0.05 denoted statistical significance.

RESULTS

Significant group differences in the strengths of sFNC and dFNC between networks were found. The sFNC strength between the visual and sensorimotor networks was significantly associated with the global cognitive function score (i.e. the Montreal Cognitive Assessment [MoCA]) (r = 0.606). The sFNC strength between the salience and default mode networks was significantly associated with anxiety scores (r = 0.458). In state 1, positive correlations were found between the mean dwell time and backward digital span task score (r = 0.562), fractional window and MoCA score (r = 0.576), and fractional window and backward digital span task score (r = 0.592).

DATA CONCLUSION

Neurologically asymptomatic patients undergoing maintenance hemodialysis had defective sFNC and dFNC. Our results provide a new perspective on the mechanism of neuropathological damage in patients undergoing maintenance hemodialysis.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 1.

Association between acute kidney injury and brain injury on term-equivalent age brain magnetic resonance imaging in very preterm infants

BACKGROUND

This study aimed to investigate the relationship between acute kidney injury (AKI) in the first 2 weeks of life and brain injury on term-equivalent age magnetic resonance imaging in very preterm infants.

METHODS

We included 116 infants with a birth weight of < 1500 g who were born at the King Saud Medical City at ≤ 32 gestational weeks. They were admitted to the neonatal intensive care unit and underwent term-equivalent age and pre-discharge brain magnetic resonance imaging. A negative binomial with generalized linear models and a robust variance estimator (Huber-White) was applied for univariate relative risk analysis. The Kidokoro score was then used to determine the effect of AKI on brain morphology and growth at term-equivalent age.

RESULTS

Sixty-eight (64.2%) infants had developed an AKI in the first 2 weeks of life. AKI was significantly associated with cerebellum signal abnormalities, cerebellar volume reduction, and a high total cerebellum score (P = 0.04, P < 0.001, P < 0.001, respectively).

CONCLUSIONS

AKI in the first 2 weeks of life is associated with brain insult, especially in the cerebellum. More well-designed studies are required to investigate the association and impact of AKI on the central nervous system. A higher resolution version of the Graphical abstract is available as Supplementary information.

Effect of Renal Ischemia Reperfusion on Brain Neuroinflammation

Acute kidney injury (AKI) is an inflammatory sequence. It can lead to distant organ injury, including damage to the central nervous system (CNS), mediated by increased circulating cytokines and other inflammatory mediators. It can also lead to increased blood-brain barrier (BBB) permeability. However, the effect of AKI on the inflammatory response of the brain has not yet been investigated. Therefore, we observed the effect of AKI on BBB permeability, microglia and astrocyte activation, and neuronal toxicity in the brain. The striatum and ventral midbrain, known to control overall movement, secrete the neurotransmitter dopamine. The activation of microglia and astrocytes present in this area causes neuro-degenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease (PD). The activation of astrocytes and microglia in the hippocampus and cerebral cortex, which are responsible for important functions, including memory, learning, concentration, and language, can trigger nerve cell apoptosis. The activation of astrocytes and microglia at this site is also involved in the inflammatory response associated with the accumulation of beta-amyloid. In the situation of kidney ischemia reperfusion (IR)-induced AKI, activation of microglia and astrocytes were observed in the striatum, ventral midbrain, hippocampus, and cortex. However, neuronal cell death was not observed until 48 h.

Acute kidney injury-associated delirium: a review of clinical and pathophysiological mechanisms

Acute kidney injury is a known clinical risk factor for delirium, an acute cognitive dysfunction that is commonly encountered in the critically ill population. In this comprehensive review of clinical and basic research studies, we detail the epidemiology, clinical implications, pathogenesis, and management strategies of patients with acute kidney injury-associated delirium. Specifically addressed are the pathological roles of endogenous toxin or drug accumulation, acute kidney injury-mediated neuroinflammation, and acute kidney injury-associated volume overload as discrete potential biological mechanisms of the condition. The optimization of clinical contributors and normalization of renal function are reviewed as pragmatic management strategies in addition to potential and emerging therapeutic approaches.

Communicating Hydrocephalus as a Consequence of Chronic Kidney Disease on Maintenance Hemodialysis: An Uncommon Complication of a Common Disease

While many etiologies of hydrocephalus for different age groups have been studied in detail, chronic kidney disease remains rare. We report a case of a 42-year-old male who was a known case of chronic kidney disease on maintenance hemodialysis since seven years. He was brought to the emergency department with a history of altered sensorium and irrelevant talk since the last 4-5 hours and was found to be a case of communicating hydrocephalus with periventricular ooze, as revealed by a computed tomography (CT) of the brain. A ventriculoperitoneal shunt surgery was performed, and the patient ultimately recovered and was discharged.

Prazosin Treatment Protects Brain and Heart by Diminishing Oxidative Stress and Apoptotic Pathways After Renal Ischemia Reperfusion

Acute kidney injury (AKI) is a major medical challenge caused from renal ischemia-reperfusion (IR) injury connected with different cellular events in other distant organs. Renal IR-related oxidative stress and inflammation followed by cell apoptosis play a crucial role in IR-induced distant organ pathological damages. Prazosin has shown protective effects against IR-injuries. Thus, the current study intended to investigate the possible protective role of prazosin against the consequents of renal IR in the heart and brain tissues. To reach this goal, rats were randomly divided into 3 groups (n=7): Sham, IR and prazosin pretreatment-IR animals (1 mg/kg intraperitoneally injection of prazosin 45 min before IR induction). After 6 h reperfusion, lipid peroxidation and antioxidant markers levels were evaluated in the both, brain and heart tissue. Moreover, apoptotic pathway in the heart and brain tissues were assessed by western blotting. Accordingly, prazosin pretreatment in IR model rats could significantly increase the antioxidant capacity and attenuate apoptotic pathways by increasing the bcl-2 levels and decreasing the expression of Bax and caspase 3 enzymes (P<0.05). Thus, prazosin suppressed cellular damages of heart and brain tissues post kidney IR by anti-oxidative and anti-apoptotic effects, which suggests the plausible use of prazosin in improving the clinical outcomes during AKI after further investigations.

Transcranial sonography depicts a larger substantia nigra echogenic area in renal transplant patients on calcineurin inhibitors than on rapamycin

BACKGROUND

After kidney transplantation neurologic manifestations may develop, including Parkinson's disease (PD). An enlarged substantia nigra (SN) by transcranial sonography has been recognized as a marker of PD.

METHODS

In renal transplant recipients (RTRs = 95) and controls (n = 20), measurement of mesencephalon, SN, third ventricle, spleen and carotid intima-media thickness (cIMT) and middle cerebral artery (MCA), kidney and spleen arteries Doppler resistive index (RI) were performed.

RESULTS

RTRs had larger SN, third ventricle and cIMT and higher renal RI than controls. The SN was larger in the CNIs group than in controls and rapamycin group, while the third ventricle was similar between patients but larger than in controls. In RTRs, SN showed a direct linear correlation with spleen and the third ventricle with age, cIMT and RI of the MCA, kidney and spleen. In CNIs group the SN correlated positively with age and cIMT, while the third ventricle reproduced RTRs correlations. Rapamycin group showed a direct linear relationship between the third ventricle and age and RI of the MCA, kidney and spleen; SN showed no correlations.

CONCLUSION

RTRs on CNIs present a larger SN area than on rapamycin, probably due to the antiproliferative effect of rapamycin. This finding might be relevant when interpreting TCS in RTRs.

The association between olfactory and gustatory dysfunction and chronic kidney disease

BACKGROUND

Olfactory and gustatory changes may contribute to poor appetite and food aversion in chronic kidney disease (CKD), though the prevalence of olfactory and gustatory dysfunction is not known in the CKD population.

METHODS

We conducted a cross-sectional study among 3527 US adults aged ≥40 years old in the National Health and Nutrition Examination Survey (NHANES) between 2013 and 2014. We measured the prevalence of olfactory and gustatory dysfunction among patients with CKD defined as eGFR < 60 ml/min/1.73m² using the "scratch and sniff" NHANES Pocket Smell Test and quinine whole-mouth test. We also examined the association between CKD and olfactory/gustatory dysfunction, and nutritional markers.

RESULTS

The prevalence of olfactory dysfunction was 30% among CKD and 15% among non-CKD (p < 0.001). The prevalence of gustatory dysfunction was 13% among CKD and 17% among non-CKD (p = 0.10). After adjusting for confounders, CKD was significantly associated with olfactory dysfunction (OR = 1.47, 95% CI [1.07, 2.01]; p = 0.02) but not gustatory dysfunction (OR = 1.76, 95%CI [0.99, 3.11]; p = 0.05). Among the CKD population, the odds of olfactory dysfunction was 72% higher for every 10 kg decrease in grip strength (OR = 1.72, 95% CI [1.39, 2.13]; adjusted p = 0.005).

CONCLUSION

CKD was associated with higher odds of olfactory but not gustatory dysfunction. Olfactory dysfunction was associated with lower grip strength among those with CKD. Screening and early intervening on olfactory dysfunction among CKD may preserve muscle strength and improve nutritional status in this vulnerable population.

Visual evoked potentials as a method for the prospective assessment of tacrolimus neurotoxicity in patients after kidney transplantation

INTRODUCTION

Neurotoxicity, including optic nerve injury, is one of the most common adverse effects of tacrolimus, the principal calcineurin inhibitor used after kidney transplantation (KTx). The electrophysiologic measurements of both pattern visual evoked potentials (PVEP) and flash visual evoked potentials (FVEP) are valuable when drug-induced optic neuropathy is suspected.

OBJECTIVES

To determine whether VEP measurement is a sensitive and repeatable method for monitoring tacrolimus neurotoxicity.

MATERIAL AND METHODS

This prospective study focused on 35 patients (20 M, 15F, 69 eyes, mean age 43 ± 11 years) who were at a median of 3.0 (IQR, 2.2-3.7) months after KTx at the time of the initial VEP evaluation and were treated with tacrolimus since KTx. The follow-up VEP examination was done after a median of 24 (22-27) months (both VEP measurements followed the ISCEV standards). The P100 wave latency and amplitude for the 1° and 15' PVEP simulations, and the P2 wave latency and amplitude for the FVEP were analyzed.

RESULTS

For the 1° checks, the P100 wave latency and amplitude values were significantly worse in the follow-up examination compared to the early post-transplant time-point. Independent associations between FVEP parameters and the tacrolimus blood trough level were observed in the follow-up examination but not at the early post-transplant period. The P2 wave latency correlated with the tacrolimus trough level only in patients treated with the twice-daily, but not the once-daily, tacrolimus formulation. The brain derived neurotrophic factor (BDNF) level correlated with the P100 (15') latency (R = 0.499; p = 0.005) and the P2 latency (R = 0.409; p = 0.025) only in patients treated with the once-daily, but not the twice-daily, tacrolimus formulation.

CONCLUSION

The observations in this study may support the rationale for the use of VEP measurements as non-invasive monitoring of subclinical tacrolimus neurotoxicity.

Long-term hemodialysis may affect enlarged perivascular spaces in maintenance hemodialysis patients: evidence from a pilot MRI study

BACKGROUND

Hemodialysis (HD) causes various nervous system abnormalities. Alterations in white matter (WM) microstructure after long-term HD have been reported in a few previous studies; however, no studies have been performed to investigate enlarged perivascular spaces (PVS) in WM regions. We measured cerebral blood flow (CBF) and white matter volume (WMV) in HD patients to assess enlarged PVS severity in the WM across the whole brain and suggest possible explanations for this.

METHODS

Fifty-one HD patients and 51 age-, sex-, and education-matched healthy controls (HCs) were recruited. The number of enlarged PVS in the centrum semiovale (CS), cerebral watershed (CW), and basal ganglia (BG) regions were assessed by T2-weighted MRI. CBF was estimated by arterial spin labeling (ASL), which is a non-invasive perfusion imaging technique. WMV was assessed by the computational anatomy toolbox (CAT12), which is a statistical analysis package. Differences in descriptive variables (two-tailed t-tests, χ² tests, Mann-Whitney U tests, and Friedman M tests), an intra-class correlation between radiologists, the relationship between enlarged PVS number and HD duration, normalized CBF and WMV (multiple regression), and group differences in CBF and WMV {voxel-wise t-tests with age and sex as covariates [cluster size >50 voxels, false discovery rate (FDR) corrected, P<0.05]} were assessed.

RESULTS

HD patients displayed a more significant number of CS-PVS and CW-PVS in WM regions compared with the HCs, but there was no significant difference in the number of BG-PVS. The number of CS-PVS and CW-PVS were positively associated with HD duration. The number of CW-PVS was positively associated with CBF changes and WMV alteration in HD patients. Meanwhile, significant differences in the blood pressure (BP) readings pre-HD, intra-HD, and post-HD were observed in HD patients. Compared with the HCs, the HD patients showed higher CBF in the CS, CW, and BG regions (P<0.05). Hence, decreased WMV in the CS, CW, and BG regions were shown in the HD patients compared with the HCs (P<0.05).

CONCLUSIONS

Enlarged CS-PVS and CW-PVS on MRI might be a feature of long-term HD patients. Enlarged CW-PVS number is associated with higher CBF in the CW region and lower WMV in the CW region in HD patients.

Associations of the Disrupted Functional Brain Network and Cognitive Function in End-Stage Renal Disease Patients on Maintenance Hemodialysis: A Graph Theory-Based Study of Resting-State Functional Magnetic Resonance Imaging

Objective: Cognitive impairment (CI) is a common neurological complication in patients with end-stage renal disease undergoing maintenance hemodialysis (MHD). Brain network analysis based on graph theory is a promising tool for studying CI. Therefore, the purpose of this study was to analyze the changes of functional brain networks in patients on MHD with and without CI by using graph theory and further explore the underlying neuropathological mechanism of CI in these patients. Methods: A total of 39 patients on MHD (19 cases with CI and 20 without) and 25 healthy controls (HCs) matched for age, sex, and years of education were enrolled in the study. Resting-state functional magnetic resonance imaging (rs-fMRI) and T1-weighted high-resolution anatomical data were obtained, and functional brain networks for each subject were constructed. The brain network parameters at the global and regional levels were calculated, and a one-way analysis of covariance was used to compare the differences across the three groups. The associations between the changed graph-theory parameters and cognitive function scores in patients on MHD were evaluated using Spearman correlation analysis. Results: Compared with HCs, the global parameters [sigma, gamma, and local efficiency (Eloc)] in both patient groups decreased significantly (p < 0.05, Bonferroni corrected). The clustering coefficient (Cp) in patients with CI was significantly lower than that in the other two groups (p < 0.05, Bonferroni corrected). The regional parameters were significantly lower in the right superior frontal gyrus, dorsolateral (SFGdor) and gyrus rectus (REC) of patients with CI than those of patients without CI; however the nodal local efficiency in the left amygdala was significantly increased (all p < 0.05, Bonferroni corrected). The global Cp and regional parameters in the three brain regions (right SFGdor, REC, and left amygdala) were significantly correlated with the cognitive function scores (all FDR q < 0.05). Conclusion: This study confirmed that the topology of the functional brain network was disrupted in patients on MHD with and without CI and the disruption of brain network was more severe in patients with CI. The abnormal brain network parameters are closely related to cognitive function in patients on MHD.

Chronic kidney disease and neurological disorders: are uraemic toxins the missing piece of the puzzle?

Chronic kidney disease (CKD) perturbs the crosstalk with others organs, with the interaction between the kidneys and the heart having been studied most intensively. However, a growing body of data indicates that there is an association between kidney dysfunction and disorders of the central nervous system. In epidemiological studies, CKD is associated with a high prevalence of neurological complications, such as cerebrovascular disorders, movement disorders, cognitive impairment and depression. Along with traditional cardiovascular risk factors (such as diabetes, inflammation, hypertension and dyslipidaemia), non-traditional risk factors related to kidney damage (such as uraemic toxins) may predispose patients with CKD to neurological disorders. There is increasing evidence to show that uraemic toxins, for example indoxyl sulphate, have a neurotoxic effect. A better understanding of factors responsible for the elevated prevalence of neurological disorders among patients with CKD might facilitate the development of novel treatments. Here, we review (i) the potential clinical impact of CKD on cerebrovascular and neurological complications, (ii) the mechanisms underlying the uraemic toxins' putative action (based on pre-clinical and clinical research) and (iii) the potential impact of these findings on patient care.

Acute Acquired Metabolic Encephalopathy Based on Diffusion MRI

Metabolic encephalopathy is a critical condition that can be challenging to diagnose. Imaging provides early clues to confirm clinical suspicions and plays an important role in the diagnosis, assessment of the response to therapy, and prognosis prediction. Diffusion-weighted imaging is a sensitive technique used to evaluate metabolic encephalopathy at an early stage. Metabolic encephalopathies often involve the deep regions of the gray matter because they have high energy requirements and are susceptible to metabolic disturbances. Understanding the imaging patterns of various metabolic encephalopathies can help narrow the differential diagnosis and improve the prognosis of patients by initiating proper treatment regimen early.

[Self-reported sleep and wake disorders in patients with ostheoarthrosis and end-stage renal disease]

OBJECTIVE

This study aimed to assess subjective sleep and wake disorders (SWD) in patients with osteoarthritis and comorbid end-stage renal disease (ESRD) receiving hemodialysis (ESRD-HD) compared to patients with osteoarthritis and without chronic kidney disease (CKD) as well as to clarify of the association of subjective sleep characteristics with the levels of anxiety and depression and pain, general health score and laboratory parameters in these cohorts.

MATERIAL AND METHODS

This pilot case-control study included the patients with stage III hip osteoarthritis with ESRD-HD (n=19) and without CKD (n=19) aged 18-85 years. The patients received the consultations of orthopedic surgeon and internal medicine specialist with anthropometry and clinical and biochemical blood tests. Subjective SWD were assessed with Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), Fatigue Severity Scale (FSS), Insomnia Severity Index (ISI), diagnostic criteria for restless legs syndrome (RLS) and Berlin questionnaire. Anxiety and depression were assessed with Hospital Anxiety and Depression Scale (HADS) and Beck Depression Inventory (BDI). Subjective general health and osteoarthritis-related pain were assessed with visual analog scales (VAS).

RESULTS

Compared to the patients with osteoarthritis and without CKD, the patients with osteoarthritis and ESRD-HD had a lower VAS score for general health (50.00 (40.00-75.00) points and 80.00 (70.00-80.00) points, p=0.014), a higher PSQI (12.0 (8.5-14.5) points and 8.0 (6.0-11.0) points, p=0.046), a higher incidence of RLS (59% and 16.8%, p=0.017) and a lower level of anxiety according to HADS (0.0 (0.0-3.0) points and 3.0 (2.0-5.5) points, p=0.025). The correlation and regression analysis showed the association of PSQI score with VAS score for general health (b= -1.7 points, p=0.002 with adjustment for age, sex and ESRD-HD), as well as the association of SWD with laboratory markers (PSQI score with creatinine level, FSS with eosinophil count, RLS with creatinine, urea and potassium levels).

CONCLUSION

The results of our study demonstrated the high incidence of SWD in patients with osteoarthritis. These SWD have complex pathogenesis and require specific approach in patients with osteoarthritis and ESRD-HD.

No evidence of improvement in neuropathy after renal transplantation in patients with end stage kidney disease

To assess the impact of renal transplantation on peripheral nerve damage in patients with chronic kidney disease (CKD). Fifteen patients with CKD (eGFR <15 mL/min/1.73 m² ) underwent longitudinal assessment after renal transplantation (age: 56.88 ± 2.53 years, eGFR: 46.82 ± 4.86) and were compared with 15 age-matched controls (age: 58.25 ± 2.18 years, eGFR: 86.0 ± 2.0). The neuropathy symptom profile (NSP), neuropathy disability score (NDS), vibration perception threshold (VPT), cold and warm sensation threshold (CST and WST), cold and heat induced pain (CIP and HIP), deep breathing heart rate variability (DB-HRV), nerve conduction studies and corneal confocal microscopy (CCM) to quantify small nerve fibre pathology, were undertaken within 1-month of renal transplantation (baseline) and at 6, 12 and 24 months of follow up. There was no significant difference in NSP (P = .1), NDS (P = .3), VPT (P = .6), CST (P = .2), CIP (P = .08), HIP (P = .1), DB-HRV (P = .9) and sural (P = .4) and peroneal (P = .1) nerve amplitude between patients with CKD and controls at baseline. However, sural (P = .04), peroneal (P = .002) and tibial (P = .007) nerve conduction velocity and tibial nerve amplitude (P = .03) were significantly lower, WST (P = .02) was significantly higher and corneal nerve fibre density (P = .004) was significantly lower in patients with CKD compared with controls. There was no significant change in NSP, NDS, quantitative sensory testing, DB-HRV, nerve conduction or CCM parameters 24 months after renal transplantation. There is evidence of small and large fibre neuropathy in patients with CKD, but no change up to 24 months after successful renal transplantation.

CENTRAL NERVOUS SYSTEM RESPONSE TO CHRONIC KIDNEY DISEASE

Due to the aging of the human population, the prevalence of chronic diseases such as chronic kidney disease (CKD) is increasing every year. Chronic kidney disease is a general term that refers to heterogeneous disorders that affect kidney structure and function. Decrease in glomerular filtration can be defined as chronic and progressive deterioration in fluid-solute balance, metabolic and endocrine functions of the kidney. CKD often affects the elderly. With the advancement of age, some structural and functional changes occur in the kidneys. Therefore, the number of patients suffering from mild and moderate CKD is expected to increase in the future.CKD leads to the deep metabolic and hemodynamic changes that damage other organs, such as the heart and brain. CNS abnormalities and cognitive deficits progress with the severity of CBS and occurs mostly among hemodialysis patients. It also has great socio-economic effects on individuals. Since symptoms of CKD are not often found in patients, early recognition of risk factors is the main point. For this reason, it is necessary to identify possible protective and preventive treatments to be applied in at-risk groups and to examine these mechanisms for the treatment of the disease. This review provides available information on the relevant mechanisms.

Altered resting-state functional networks in patients with hemodialysis: a graph-theoretical based study

Recent studies have demonstrated that hemodialysis patients exhibit disruptions in functional networks with invisible cerebral alterations. We explored the alterations of functional connectivity in hemodialysis patients using the graph-theory method. A total of 46 hemodialysis patients (53.11 ± 1.58 years, 28 males) and 47 healthy controls (55.57 ± 0.86 years, 22 males) were scanned by using resting-state functional magnetic resonance imaging. The brains of these patients were divided into 90 regions and functional connectivity was constructed with the automatic anatomical labeling atlas. In the defined threshold range, the graph-theory analysis was performed to compare the topological properties including global, regional and edge parameters between the hemodialysis and the healthy control groups. Both hemodialysis patients and healthy control subjects demonstrated common small-world property of the brain functional connections. At the global level, the parameters normalized clustering coefficients and small-worldness were significantly decreased in hemodialysis patients compared with those noted in healthy controls. At the regional level, abnormal nodal metrics (increased or decreased nodal degree, betweenness centrality and efficiency) were widely found in hemodialysis patients compared with those of healthy controls. The network-based statistical method was employed and two disrupted neural circuits with 18 nodes and 19 edges (P = 0.0139, corrected) and 10 nodes and 11 edges (P = 0.0399, corrected) were detected. Of note, the edge-increased functional connectivity was associated with the salience network and the frontal-temporal-basal ganglia connection, whereas the edge-decreased functional connectivity was associated with the frontoparietal network. The graph-theory method may be one of the potential tools to detect disruptions of cerebral functional connectivity and provide important evidence for understanding the neuropathology of hemodialysis patients from the disrupted network organization perspective.

Chronic and End-Stage Kidney Disease in the Neurological Intensive Care Unit

Patients with renal disease have increased rates of admission to the neurological intensive care unit related to overlapping risk factors for renal and cerebrovascular disease as well as unique risks associated with renal dysfunction alone. Management of acute neurological injury in these patients requires individualized attention to diagnostic and management factors as they relate to coagulopathy, disorders of immune function, encephalopathy and renal replacement modalities. Careful consideration of these brain-kidney interactions is necessary to optimize care for this special patient population and improve neurological and renal outcomes.

Structural and Functional Brain Changes in Hemodialysis Patients with End-Stage Renal Disease: DTI Analysis Results and ALFF Analysis Results

Introduction

The current study aimed to depict intrinsic structural changes and the spontaneous brain activity patterns in voxel level in patients with end-stage renal disease (ESRD) undergoing hemodialysis (HD) by using diffusion-tensor imaging and resting-state functional magnetic resonance (MR) imaging with an amplitude of low-frequency fluctuations (ALFF) algorithm and their clinical relevance.

Materials and Methods

In the study, the diffusion-tensor imaging and resting-state functional MR imaging were performed in forty-two hemodialysis patients with ESRD and 42 healthy control subjects. Neuropsychological and laboratory tests were performed in all subjects. ALFF, fraction anisotropy (FA), and mean diffusivity (MD) values were compared between the two groups. Correlations between ALFF, FA or MD values, and clinical markers were analyzed.

Results

We found that ESRD patients exhibited significantly lower ALFF values in multiple areas, including medial frontal gyrus, limbic lobe, superior frontal gyrus, bilateral lingual gyri, occipital lobe, parahippocampal gyrus, precuneus, while increased ALFF values in medial frontal gyrus than healthy controls. FA values were decreased in medial frontal gyrus, parietal lobe, and left precuneus regions in the ESRD group compared with controls. Importantly, FA for the frontal and parietal lobes was negatively associated with the dialysis duration of ESRD patients, ALFF z-scores for the medial prefrontal cortex (MPFC) were positively correlated with the dialysis duration of ESRD patients and Serum calcium of ESRD patients negatively correlated with FA values in the frontal and parietal lobes (p<0.05).

Conclusion

Our study revealed that both impaired brain structure and function in ESRD patients with routine hemodialysis distributed mainly in the parietal, temporal, and frontal lobes. ESRD patients have cognitive impairment and declined memory ability. Serum calcium and dialysis duration might be associated with the impairment of brain structure and function in patients with ESRD.

Electrophysiological and inflammatory changes of CA1 area in male rats exposed to acute kidney injury: Neuroprotective effects of erythropoietin

The high mortality rate associated with acute kidney injury (AKI) is commonly due to progressive, inflammatory multiple organ dysfunction, which often involves neurological complications. The AKI-stimulated mechanisms leading to brain dysfunction are not well understood, which hinders development of new therapeutic avenues to minimize AKI-mediated neural effects. The hippocampal CA1 area is a particularly vulnerable region during AKI but the electrophysiological and inflammatory mechanisms involved in this vulnerability remain largely unknown. Here, we used immunohistochemistry to quantitatively investigate the number of astrocytes expressing glial fibrillary acidic protein (GFAP) as an indicator of inflammation, and whole cell patch clamp to evaluate electrophysiological changes in CA1 at different time points following induction of bilateral renal ischemia (BRI) in male Wistar rats. Further we evaluated the effectiveness of erythropoietin (EPO, 1000 U/kg i.p.) in mitigating BRI-associated changes. Plasma concentrations of blood urea nitrogen (BUN) were significantly enhanced at 24 h, 72 h and 1 week, and creatinine (Cr) was increased at 24 h after reperfusion, which were changes reduced by EPO. BRI led to an increase in CA1 GFAP-positive cells 24 h and 72 h, but not 1 week, after reperfusion, and EPO reversed this effect of BRI at 24 h. Additionally, BRI caused an increase in the peak amplitude and coefficient of variation of CA1 pyramidal neuronal action potentials, which were changes not seen in presence of EPO. When taken together, altered neuronal electrophysiological properties and astrogliosis could contribute to the neurological complications induced by AKI, and EPO offers hope as a potential neuroprotective agent.

Kidney Disease and Epilepsy

Chronic kidney disease and seizures often co-exist. When seizures are provoked in patients with kidney disease, their treatment poses a particular challenge. Seizures may be provoked in the context of uremia, and toxic substances associated with uremic encephalopathy. In that case, the mainstay of therapy is to treat the uremia before consideration for anticonvulsant therapy. Treatment of seizures in the setting of chronic kidney disease requires special attention to selection of anticonvulsant medications and knowledge of the altered pharmacokinetics of these medications, which may require special titration schedule in that setting. The purpose of this review is to summarize the current knowledge about inter-relation of seizures and kidney disease. The review will also help practitioners who treat patients with renal failure and coexisting seizures in choosing the best treatment options.

Functional Imaging Using Fluorine (19F) MR Methods: Basic Concepts

Kidney-associated pathologies would greatly benefit from noninvasive and robust methods that can objectively quantify changes in renal function. In the past years there has been a growing incentive to develop new applications for fluorine (¹⁹F) MRI in biomedical research to study functional changes during disease states. ¹⁹F MRI represents an instrumental tool for the quantification of exogenous ¹⁹F substances in vivo. One of the major benefits of ¹⁹F MRI is that fluorine in its organic form is absent in eukaryotic cells. Therefore, the introduction of exogenous ¹⁹F signals in vivo will yield background-free images, thus providing highly selective detection with absolute specificity in vivo. Here we introduce the concept of ¹⁹F MRI, describe existing challenges, especially those pertaining to signal sensitivity, and give an overview of preclinical applications to illustrate the utility and applicability of this technique for measuring renal function in animal models.This chapter is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers. This introduction chapter is complemented by two separate chapters describing the experimental procedure and data analysis.

Review of the structural and functional brain changes associated with chronic kidney disease

Chronic kidney disease (CKD) leads to profound metabolic and hemodynamic changes, which damage other organs, such as heart and brain. The brain abnormalities and cognitive deficit progress with the severity of the CKD and are mostly expressed among hemodialysis patients. They have great socio-economic impact. In this review, we present the current knowledge of involved mechanisms.

Acute nephrotoxicity and neurotoxicity associated with concentrated star fruit juice consumption

Star fruit toxicity has been hugely described in patients with chronic kidney disease, either on conservative or renal replacement therapy. This is a case report of a man, without prior kidney or neurological dysfunction, who appeared to develop nephrotoxicity and neurotoxicity less than 12 hours after drinking concentrated star fruit juice (approximately 20 units of the fruit). He received timely renal replacement therapy and renal function fully recovered after discharge.

Abnormal rich club organization in end-stage renal disease patients before dialysis initiation and undergoing maintenance hemodialysis

Background

End-stage renal disease (ESRD) patients are at a substantially higher risk for developing cognitive impairment compared with the healthy population. Dialysis is an essential way to maintain the life of ESRD patients. Based on previous research, there isn’t an uncontested result whether cognition was improved or worsened during dialysis.

Methods

To explore the impact of dialysis treatment on cognitive performance, we recruited healthy controls (HCs), predialysis ESRD patients (predialysis group), and maintenance hemodialysis ESRD patients (HD group). All ESRD patients performed six blood biochemistry tests (hemoglobin, urea, cystatin C, Na+, K+, and parathyroid hormone). Neuropsychological tests were used to measure cognitive function. By using diffusion tensor imaging and graph-theory approaches, the topological organization of the whole-brain structural network was investigated. Generalized linear models (GLMs) were performed to investigate blood biochemistry predictors of the neuropsychological tests and the results of graph analyses in the HD group and predialysis group.

Results

Neuropsychological analysis showed the HD group exhibited better cognitive function than the predialysis group, but both were worse than HCs. Whole-brain graph analyses revealed that increased global efficiency and normalized shortest path length remained in the predialysis group and HD group than the HCs. Besides, a lower normalized clustering coefficient was found in the predialysis group relative to the HCs and HD group. For the GLM analysis, only the Cystatin C level was significantly associated with the average fiber length of rich club connections in the predialysis group.

Conclusions

Our study revealed that dialysis had a limited effect on cognitive improvement.

Neurophysiological and Neuroradiological Changes in Children With Chronic Kidney Disease

Background: Patients with chronic kidney disease (CKD) on maintenance hemodialysis frequently present with neurological complications. These complications include peripheral neuropathy, encephalopathy, and stroke. Objectives: To detect the prevalence of neurological manifestations and complications in children with CKD through neurophysiological and neuro-radiological findings. Methods: The study included 50 patients with CKD admitted to a pediatric nephrology unit. Their history and complete physical and neurological examination findings had been recorded. All patients underwent nerve conduction, electromyography, electroencephalography, and magnetic resonance imaging of the brain. Results: Fifty children of both sexes (23 males and 27 females) with a mean age of (12.08 ± 3.46 year) were studied. Eleven (22%) patients with CKD developed polyneuropathy, mostly of an axonal polyneuropathy pattern, while 39 (78%) of them showed normal electrophysiological studies. No myopathy was detected. Abnormal electroencephalography findings were detected in 18% of patients, mostly generalized and focal (temporal, occipital, and frontal) epileptogenic activity. Abnormal MRI brain findings were detected in 16% of patients, mostly of encephalomalacia. Conclusion: Uremic neuropathy was highly prevalent in children with CKD on maintenance hemodialysis. They developed polyneuropathy, mostly of an axonal polyneuropathy pattern. EEG is a useful method for early recognition of subclinical uremic encephalopathy and/or epileptogenic activity. Early demonstration and management of uremic neurological conditions may decrease the physical disability of CKD patients.

Symptom Clusters in Patients with End-Stage Renal Disease Undergoing Hemodialysis

Background

End-stage renal disease (ESRD) patients undergoing hemodialysis have to face many symptoms from disease progression and treatment. These symptoms cause suffering and affect physical, psychological, emotional, social, and spiritual of the patients, resulting in decreased quality of life and might increase the death rate of these patients. Therefore, the study of symptoms in ESRD patients undergoing hemodialysis will lead to effective symptom management and maximize benefits for the patients. The purpose of this study was to explore the symptom clusters of ESRD patients undergoing hemodialysis.

Materials and Methods

The sample of this descriptive study consisted of 150 ESRD patients undergoing hemodialysis from two dialysis centre of the university hospital and specialized kidney hospital in Bangkok. The instruments consisted of Personal Information Questionnaire (PIQ) and Dialysis Symptom Index-THAI (DSI-THAI). The data were analyzed by exploratory factor analysis.

Results

The 8 clusters of symptoms were found: 1) gastrointestinal, 2) musculoskeletal and fluid volume 3) neurological 4) irritation of the mucous membranes and skin 5) depression 6) sleep disturbance 7) sexual 8) anemic.

Conclusion

The results of this study can be raised awareness and used as the information for the health-care provider to develop the intervention to manage unpleasant symptoms which lead to improving the quality of life.

Uraemic Encephalopathy in a Persian Cat with Chronic Kidney Disease

Uraemic encephalopathy (UE) is rarely associated with acute kidney injury or chronic kidney disease in domestic animals, and we now report the first case in a cat. The animal presented with hypothermia, apathy, lethargy, depression, severe dehydration, uraemic breath, elevated serum urea nitrogen and creatine concentrations, and eventual seizures and coma prior to death. Gross necropsy findings included severe bilateral renal scarring, ulcerative stomatitis and glossitis, and uraemic gastropathy. Microscopic lesions of diffuse interstitial fibrosis, multifocal mineralization and lymphoplasmacytic interstitial nephritis were seen in the kidneys. There was symmetrical, bilateral spongy vacuolation of the white matter of the basal nuclei and cerebellum and Alzheimer type II astrocytes in the cerebral cortex and hippocampus. Glial fibrillary acid protein immunolabelling was absent or faint in astrocytes of the cerebral grey matter. UE should be included in the differential diagnosis in animals with chronic kidney disease and neurological signs.

Cerebro-renal interaction and stroke

Stroke is an event causing a disturbance in cerebral function leading to death and disability worldwide. Both acute kidney injury and chronic kidney disease (CKD) are associated with an increased risk of stroke and cerebrovascular events. The underlying mechanistic approach between impaired renal function and stroke is limitedly explored and has attracted researchers to learn more for developing therapeutic intervention. Common risk factors such as hypertension, hyperphosphatemia, atrial fibrillation, arteriosclerosis, hyperhomocysteinemia, blood-brain barrier disruption, inflammation, etc. are observed in the general population, but are high in renal failure patients. Also, risk factors like bone mineral metabolism, uremic toxins, and anemia, along with the process of dialysis in CKD patients, eventually increases the risk of stroke. Therefore, early detection of risks associated with stroke in CKD is imperative, which may decrease the mortality associated with it. This review highlights mechanisms by which kidney dysfunction can lead to cerebrovascular events and increase the risk of stroke in renal impairment.

Toxicosis with grapes or raisins causing acute kidney injury and neurological signs in dogs

Background

The ingestion of grapes or raisins has been reported to cause acute kidney injury (AKI) in dogs, with a clinical picture dominated by early gastrointestinal signs and rapidly developing uremia. Ataxia is mentioned in a few reports, but not further characterized.

Objectives

To evaluate the clinical, laboratory, and pathological features of dogs diagnosed with grape or raisin toxicosis (GRT) with emphasis on renal and neurological manifestations, compared to a control group of dogs with AKI from other causes.

Animals

Fifteen client‐owned dogs with GRT and 74 control dogs.

Methods

Retrospective study over 17 months.

Results

All dogs with GRT were presented with severe AKI (grade 4, n = 5; grade 5, n = 10). Eleven dogs (73%) had marked forebrain, cerebellar, or vestibular signs. These manifestations dominated the clinical picture in some dogs, but were not associated with the severity of azotemia or the presence of systemic hypertension. Eight dogs (53%) survived, and 5 dogs experienced a complete neurological recovery. Causes of death were unrelated to the neurological manifestations. Neuropathological examination of 4 dogs did not identify any structural central nervous system abnormality. Only 2 control dogs (3%) displayed neurological signs with seizures unrelated to the AKI; 42 control dogs (57%) survived.

Conclusions and Clinical Importance

Severe forebrain, cerebellar, or vestibular signs may be an important feature of GRT and dominate the early clinical picture. The described features suggest a reversible functional brain injury specific to GRT and unrelated to uremia.

Delirium risk prediction models for intensive care unit patients: A systematic review

OBJECTIVE

To systematically review the delirium risk prediction models for intensive care unit (ICU) patients.

METHODS

A systematic review was conducted. The Cochrane Library, PubMed, Ovid and Web of Science were searched to collect studies on delirium risk prediction models for ICU patients from database establishment to 31 March 2019. Two reviewers independently screened the literature according to the pre-determined inclusion and exclusion criteria, extracted the data and evaluated the risk of bias of the included studies using the CHARMS (CHecklist for critical Appraisal and data extraction for systematic Reviews of prediction Modelling Studies) checklist. A descriptive analysis was used to describe and summarise the data.

RESULTS

A total of six models were included. All studies reported the area under the receiver operating characteristic curve (AUROC) of the prediction models in the derivation and (or) validation datasets as over 0.7 (from 0.75 to 0.9). Five models reported calibration metrics. Decreased cognitive reserve and the Acute Physiology and Chronic Health Evaluation II (APACHE-II) score were the most commonly reported predisposing and precipitating factors, respectively, of ICU delirium among all models. The small sample size, lack of external validation and the absence of or unreported blinding method increased the risk of bias.

CONCLUSION

According to the discrimination and calibration statistics reported in the original studies, six prediction models may have moderate power in predicting ICU delirium. However, this finding should be interpreted with caution due to the risk of bias in the included studies. More clinical studies should be carried out to validate whether these tools have satisfactory predictive performance in delirium risk prediction for ICU patients.

Renal transplant recipient seizure practical management

Seizures are not uncommon in renal transplant patients. The common aetiologies are metabolic disturbance associated with renal failure, immunosuppression and associated complications and infections. Their management can be challenging because of altered pharmacokinetics of antiepileptic drugs (AEDs) and their removal by dialysis. A practical approach to the management of seizure in renal transplant patients is discussed. This review highlights the guidelines for use of various AEDs in renal transplants.

The role of urea in neuronal degeneration and sensitization: An in vitro model of uremic neuropathy

Background

Uremic neuropathy commonly affects patients with chronic kidney disease, with painful sensations in the feet, followed by numbness and weakness in the legs and hands. The symptoms usually resolve following kidney transplantation, but the mechanisms of uremic neuropathy and associated pain symptoms remain unknown. As blood urea levels are elevated in patients with chronic kidney disease, we examined the morphological and functional effects of clinically observed levels of urea on sensory neurons.

Methods

Rat dorsal root ganglion neurons were treated with 10 or 50 mmol/L urea for 48 h, fixed and immunostained for PGP9.5 and βIII tubulin immunofluorescence. Neurons were also immunostained for TRPV1, TRPM8 and Gap43 expression, and the capsaicin sensitivity of urea- or vehicle-treated neurons was determined.

Results

Urea-treated neurons had degenerating neurites with diminished PGP9.5 immunofluorescence, and swollen, retracted growth cones. βIII tubulin appeared clumped after urea treatment. After 48 hours urea treatment, neurite lengths were significantly reduced to 60 ± 2.6% (10 mmol/L, **P < 0.01), and to 56.2 ± 3.3% (50 mmol/L, **P < 0.01), compared with control neurons. Fewer neurons survived urea treatment, with 70.08 ± 13.3% remaining after 10 mmol/L (*P < 0.05) and 61.49 ± 7.4% after 50 mmol/L urea treatment (**P < 0.01), compared with controls. The proportion of neurons expressing TRPV1 was reduced after urea treatment, but not TRPM8 expressing neurons. In functional studies, treatment with urea resulted in dose-dependent neuronal sensitization. Capsaicin responses were significantly increased to 115.29 ± 3.4% (10 mmol/L, **P < 0.01) and 125.3 ± 4.2% (50 mmol/L, **P < 0.01), compared with controls. Sensitization due to urea was eliminated in the presence of the TRPV1 inhibitor SB705498, the mitogen-activated protein kinase kinase inhibitor PD98059, the PI3 kinase inhibitor LY294002 and the TRPM8 inhibitor N-(3-Aminopropyl)-2-[(3-methylphenyl)methoxy]-N-(2-thienylmethyl)benzamide (AMTB hydrochloride).

Conclusion

Neurite degeneration and sensitization are consistent with uremic neuropathy and provide a disease-relevant model to test new treatments.

Disturbed neurovascular coupling in hemodialysis patients

Background

Altered cerebral blood flow (CBF) and amplitude of low-frequency fluctuation (ALFF) have been reported in hemodialysis patients. However, neurovascular coupling impairments, which provide a novel insight into the human brain, have not been reported in hemodialysis patients.

Methods

We combined arterial spin labeling (ASL) and blood oxygen level dependent (BOLD) techniques to investigate neurovascular coupling alterations and its relationships with demographic and clinical data in 46 hemodialysis patients and 47 healthy controls. To explore regional neuronal activity, ALFF was obtained from resting-state functional MRI. To measure cerebral vascular response, CBF was calculated from ASL. The across-voxel CBF-ALFF correlations for global neurovascular coupling and CBF/ALFF ratio for regional neurovascular coupling were compared between hemodialysis patients and healthy controls. Two-sample t-tests were used to compare the intergroup differences in CBF and ALFF. Multiple comparisons were corrected using a voxel-wise false discovery rate (FDR) method (P < 0.05).

Results

All hemodialysis patients and healthy controls showed significant across-voxel correlations between CBF and ALFF. Hemodialysis patients showed a significantly reduced global CBF-ALFF coupling (P = 0.0011) compared to healthy controls at the voxel-level. Of note, decreased CBF/ALFF ratio was exclusively located in the bilateral amygdala involved in emotional regulation and cognitive processing in hemodialysis patients. In hemodialysis patients, the decreased CBF (right olfactory cortex, anterior cingulate gyrus and bilateral insula) and ALFF (bilateral precuneus and superior frontal gyrus) were mainly located in the default mode network and salience network-related regions as well as increased CBF in the bilateral thalamus.

Conclusions

These novel findings reveal that disrupted neurovascular coupling may be a potential neural mechanism in hemodialysis patients.

Structural and Functional Alterations in Hemodialysis Patients: A Voxel-Based Morphometry and Functional Connectivity Study

Structural and functional brain alterations have been always observed in end-stage renal disease (ESRD) patients undergoing hemodialysis. The present study aimed to investigate the gray matter volume (GMV) changes in hemodialysis patients compared with those noted in healthy subjects, as well as explore the associated functional connectivity alterations based on the abnormal GMV regions. The experiments revealed the effects of regional morphometry aberrance on the brain functional integrity. A total of 46 hemodialysis patients (53.11 ± 1.58 years, 28 males) and 47 healthy subjects (55.57 ± 0.86 years, 22 males) were enrolled in the present study. All subjects underwent high-resolution T1-weighted imaging, resting-state functional MR imaging, and laboratory examinations were performed in hemodialysis patients. The GMV deficits were analyzed using voxel-based morphometry (VBM) and regions with GMV alteration were defined as seeds for functional connectivity analysis. Correlation analyses between significantly different regions and the results of the blood examination were further performed. We found that bilateral thalamus exhibited significantly increased volumes in the hemodialysis patients compared with those of the healthy subjects. However, the bilateral rectus, bilateral caudate, and bilateral temporal gyrus demonstrated significantly decreased volumes. When the regions with GMV alterations were defined as seeds, the hemodialysis patients exhibited decreased integrations in the thalamo-cortical network and within the basal-ganglia connection. The present study revealed the presence of different types of structural and functional brain impairments in hemodialysis patients.