Serum and CSF levels of neuron-specific enolase (NSE) in cardiac surgery with cardiopulmonary bypass: a marker of brain injury?

Serum tau protein and myelin basic protein in pediatric patients with congenital heart defects undergoing cardiac surgery: preliminary assessment as novel neuromarkers of brain injury

INTRODUCTION

Neurological impairment is a big concern in the development of patients with congenital heart defects (CHD). A number of neuromarkers have been studied in search of a diagnostic or prognostic marker for brain injury during the vulnerable perioperative period. Our aim was to assess two novel neuromarkers, myelin basic protein (MBP) and protein Tau (pTau), as diagnostic markers for brain injury in perioperative period in children with CHD.

METHODS

Forty patients were enrolled and dichotomized based on peripheric oxygen saturation in cyanotic and non-cyanotic group. Blood samples were collected preoperative, after the induction of anesthesia, and in postoperative day 1. Neuromarker concentrations were measured using commercially available ELISA kits.

RESULTS

Neuromarkers' values were increased postoperative, with statistical significance reached only in non-cyanotic group (p < 0.0001). A significant positive correlation was observed between preoperatory MBP and albumin level, hemoglobin level, height, and weight of patients. Association with cerebral saturations were analyzed by a coefficient defined as ≥ 20% reduction in cerebral saturation measured by near-infrared spectroscopy during perioperative period. An acceptable predicting model was observed with pTau in cyanotic group (AUC = 0.7).

CONCLUSION

We evaluated MBP and pTau as potential biomarkers of brain injury in children with CHD undergoing cardiac surgery. Elevated postoperative pTau and MBP concentrations were observed in both groups. Elevated pTau values were associated with perioperative hypoxemia.

Post-Operative Delirium and Cognitive Dysfunction in Aged Patients Undergoing Cardiac Surgery: A Randomized Comparison between Two Blood Oxygenators

In elderly patients undergoing cardiac surgery, extracorporeal circulation affects the incidence of post-operative delirium and cognitive impairment with an impact on quality of life and mortality. In this study, a new oxygenator system (RemoweLL 2) was tested against a conventional system to assess its efficacy in reducing the onset of postoperative delirium and cognitive dysfunction and the levels of serum inflammatory markers. A total of 154 patients (>65 y.o.) undergoing cardiopulmonary bypass (CPB) were enrolled and randomly assigned to oxygenator RemoweLL 2 (n = 81) or to gold standard device Inspire (n = 73) between September 2019 and March 2022. The aims of the study were to assess the incidence of delirium and the cognitive decline by neuropsychiatric tests and the MoCa test intra-hospital and at 6 months after CPB. Inflammation biomarkers in both groups were also evaluated. Before the CPB, the experimental groups were comparable for all variables. After CPB, the incidence of severe post-operative delirium showed a better trend (p = 0.093) in patients assigned to RemoweLL 2 (16.0%) versus Inspire (26.0%). Differences in enolase levels (p = 0.049), white blood cells (p = 0.006), and neutrophils (p = 0.003) in favor of RemoweLL 2 were also found. The use of novel and better construction technologies in CPB oxygenator devices results in measurable better neurocognitive and neurological outcomes in the elderly population undergoing CPB.

Utility of Brain Injury Biomarkers in Children With Congenital Heart Disease Undergoing Cardiac Surgery

BACKGROUND

Congenital heart disease (CHD) affects roughly 40,000 children annually. Despite advancements, children undergoing surgery for CHD are at an increased risk for adverse neurological outcomes. At present, there is no gold standard for the diagnosis of cerebral injury during the perioperative period.

OBJECTIVE

To determine the utility of brain injury biomarkers in children undergoing cardiac surgery.

METHODS

We searched PUBMED, EMBASE, LILACS, EBSCO, ClinicalTrials.gov, Cochrane Databases, and OVID interface to search MEDLINE through July 2021 and assessed the literature following the snowball method. The search terms used were "congenital heart disease," "cardiopulmonary bypass," "biomarkers," "diagnosis," "prognosis," and "children." No language or publication date restrictions were used. Papers studying inflammatory and imaging biomarkers were excluded. The risk of bias, strengths, and limitations of the study were reported. Study was registered in PROSPERO ID: CRD42021258385.

RESULTS

A total of 1449 articles were retrieved, and 27 were included. Eight neurological biomarkers were examined. Outcomes assessed included prognosis of poor neurological outcome, mortality, readmission, and diagnosis of brain injury. Results from these studies support that significant perioperative elevations in brain injury biomarkers in cerebrospinal fluid and serum, including S100B, GFAP, NSE, and activin A, may be diagnostic of real-time brain injury and serve as an independent predictor of adverse neurological outcomes in patients with CHD undergoing cardiopulmonary bypass.

CONCLUSIONS

There are limited homogeneous data in the field, limiting the generalizability and comparability of the results. Further large-scale longitudinal studies addressing neurological biomarkers in children undergoing CHD corrective surgery are required to support the routine use of neuronal biomarkers in this population.

Evaluation of the brain cellular damage during liver transplantations

Background

Neuroinflammation in patients undergoing major surgery can lead to neuronal damage, and neuronal damage can be detected through the measurement of biochemical markers of brain damage. S100 beta (S100 β), neuron-specific enolase (NSE), and glial fibrillary acidic protein (GFAP) levels are considered good biomarkers to detect brain damage that emerged with neurotoxicity.

Aim

To evaluate neuronal damage during liver transplantations.

Materials and Methods

After approval of the ethics committee and patient consents, preoperative and postoperative cognitive functions of 33 patients undergoing liver transplantation were measured using the Mini Mental State Examination (MMSE), whereas simultaneous neuronal damage was evaluated through the measurement of S100β, NSE, and GFAP levels.

Results

There was no statistically significant difference between preoperative and postoperative MMSE. There was a statistically significant decrease in postoperative GFAP (P < 0.05) and a statistically significant increase in NSE (P < 0.05) compared to preoperative values. The decrease in S100β (P > 0.05) level was statistically insignificant.

Conclusions

Neuroprotective approaches in anesthesia protocol protect patients from brain damage during liver transplantation and prevent the development of postoperative cognitive dysfunction. Since the significant increase in NSE levels during liver transplantations was deemed to have been associated with causes other than neuronal damage, NSE should not be evaluated as a marker of brain damage in these operations.

Neuromarkers which can predict neurodevelopmental impairment among children with congenital heart defects after cardiac surgery: A systematic literature review

The aim of this systematic literature review was to assess the data regarding neuromarkers used to evaluate the impact of cardiovascular surgery on neurodevelopmental pattern of children with congenital heart defects. A systematic search was performed on PubMed and Google Scholar databases. Out of 713 publications screened, 10 studies (471 patients) met the inclusion criteria. The included studies were coded on several variables: number and heterogeneity of patients (age, congenital heart defects), exclusion of patients with conditions that predispose to neurological impairment, neuroimaging workup pre- and post-surgery, neurodevelopmental assessment, interventions (part of a different study), and follow-up period. Results were reported according to PRISMA guidelines. Findings include: neuron-specific enolase and brain-derived neurotrophic factor are not reliable neuromarkers, for protein S100B different results were reported, for activin A there is lack of evidence, and glial fibrillary acidic protein could represent a reliable neuromarker for acute brain-injury. Directions for future research are discussed.

Pediatric delirium is associated with increased brain injury marker levels in cardiac surgery patients

Despite global consensus on the importance of screening pediatric delirium, correlations between pediatric delirium during acute brain injury and adult delirium are unclear. Therefore, we hypothesized that similar pediatric biomarkers reflect acute brain injury as in adult delirium. We observed pediatric cardiac surgery patients from neonatal age to 18 years, who were admitted to our pediatric intensive care unit after cardiovascular operations between October 2019 to June 2020, up to post-operative day 3 (4 days total). We recorded age, sex, risk score (Risk Adjustment in Congenital Heart Surgery [RACHS-1]), midazolam/dexmedetomidine/fentanyl dosage, and pediatric Sequential Organ Failure Assessment (pSOFA). Richmond Agitation-Sedation Scale (RASS), Cornell Assessment of Pediatric Delirium (CAPD), Face, Leg, Activity, Consolability (FLACC) behavioral scale, and Withdrawal Assessment Tool (WAT-1) scales were used and serum sampling for neuron specific enolase (NSE) was conducted. Consciousness status was considered hierarchical (coma > delirium > normal) and associations between conscious status and NSE were conducted by hierarchical Bayesian modeling. We analyzed 134 data points from 40 patients (median age 12 months). In the multi-regression model, NSE was positively associated with coma [posterior odds ratio (OR) = 1.1, 95% credible interval (CrI) 1.01-1.19] while pSOFA [posterior OR = 1.63, 95% CrI 1.17-2.5], midazolam [posterior OR = 1.02, 95% CrI 1.01-1.04], and dexmedetomidine [posterior OR = 9.52, 95% CrI 1.02-108.85] were also associated. We also evaluated consciousness state probability at each NSE concentration and confirmed both that consciousness was hierarchically sorted and CAPD scores were also associated with NSE [posterior OR = 1.32, 95% CrI 1.09-1.58]. "Eye contact" (r = 0.55) was the most correlated component with NSE within the pain, withdrawal syndrome, and PD items. PD within the hierarchy of consciousness (coma, delirium, normal) and CAPD scores are associated with brain injury marker levels. Using pediatric delirium assessment tools for monitoring brain injury, especially eye contact, is a reliable method for observing PD.

Changes in NSE and S-100β during the perioperative period and effects on brain injury in infants with biliary atresia undergoing parent donor liver transplantation

The present study aimed to investigate the effects of parental donor liver transplantation on the perioperative changes of serum calcium-binding protein β (S-100β) and neuron-specific enolase (NSE) levels, two markers of brain injury, and on postoperative cognitive function. The present study was a prospective observational study of infants with congenital biliary atresia who underwent selective liver transplantation in 2017 at Tianjin First Central Hospital (Tianjin, China). Blood samples were collected prior to, during and following surgery, and S-100β and NSE levels were measured using ELISA. The pediatric patients were assessed using the Bayley Scales of Infant Development 1 day prior to and 3 months after surgery. Additionally, the pediatric anesthesia emergence delirium scores were evaluated. The results demonstrated that serum NSE and S100β were increased during and after surgery compared with prior to surgery (P<0.05). Furthermore, serum S-100β and NSE levels peaked 1 h after the neohepatic phase compared with prior to surgery (P<0.05). Compared with 1 day before surgery, mental development index (MDI) and psychomotor development index (PDI) were decreased 3 months after surgery (MDI, 87.7±8.4 vs. 84.5±8.5, P=0.015; PDI, 82.9±8.7 vs. 79.6±8.8, P=0.016). In conclusion, parental donor liver transplantation may cause a certain degree of brain injury in pediatric patients with end-stage liver disease, as revealed by increased serum NSE and S100β levels.

Can we delineate brain injury in full-term neonates using serum biomarkers?

OBJECTIVE: Early identification of neonates at risk of neurological impairment is particularly important for the bedside clinician. Clinical value of S100b and neuron-specific enolase in neonates has not been yet established. We investigated their kinetics and possible early clinical utility in neonatal encephalopathy (NE).STUDY DESIGN: 36 full-term neonates (13 with moderate/severe encephalopathy, 11 with mild encephalopathy, 12 controls) were enrolled and studied prospectively. Serum S100b and neuron-specific enolase (NSE) were measured serially on days(d) 1, 3, 9 and 18 of life. Brain MRI and long-term neurodevelopmental outcome were also assessed.RESULT: Neonates with moderate/severe encephalopathy had significantly increased S100b (d1) and NSE levels (d1, d3, d9) compared to controls. Neuron-specific enolase significantly correlated with the degree of encephalopathy, and a cutoff of 38.8 μg/l (d1) accurately predicted moderate/severe encephalopathy. S100b (d1) cutoff points of 1.6 μg/l and 11.4 μg/l prognosticated severe encephalopathy and death/cerebral palsy, respectively. Both biomarkers correlated well with neuroimaging and Bayley-III scores.CONCLUSION: Combined clinical, laboratory, imaging and neurodevelopmental data indicate that serum S100b and NSE can be useful biomarkers for the diagnosis and prognosis of neonatal brain injury, providing useful information to the bedside clinician.

Cardiopulmonary-Bypass Glial Fibrillary Acidic Protein Correlates With Neurocognitive Skills

BACKGROUND

Neurocognitive deficits at school starting age may affect as many as 50% of children who underwent cardiac surgery for complex congenital heart disease (CHD). The aim of this study was to identify which phases of cardiopulmonary bypass (CPB) are associated with an increased risk of impaired neurodevelopmental skills in children with complex CHD. This was assessed by means of glial fibrillary acidic protein (GFAP) plasma levels during CPB for CHD surgery, as a marker of neurologic insult. We correlated GFAP levels with clinical parameters and neurodevelopmental outcome.

METHODS

We studied 45 children undergoing surgery for complex CHD. We measured plasma GFAP levels by enzyme-linked immunosorbent assay at the following steps: anesthesia induction, CPB start, end of hypothermia, end of rewarming, and end of CPB. Neurologic assessment and Vineland Adaptive Behavior Scales (VABS-I) were administered to patients at least 18 months after surgery.

RESULTS

GFAP was undetectable before surgery and it peaked at the end of hypothermia or rewarming. Multiple regression analyses showed that GFAP peak level and preoperative neurologic comorbidity were significant independent predictors of neurologic impairment, as showed by VABS-I communication domain intelligence quotient (IQ). Receiver operating characteristic curve showed that the model was highly significant.

CONCLUSIONS

Impaired neurodevelopment was associated with increase of GFAP plasma levels during cardiac surgery in infants. The identification of the neurologic high-risk phases of CPB run could support the application of new neuroprotective strategies for CHD repair.

Glial fibrillary acidic protein plasma levels are correlated with degree of hypothermia during cardiopulmonary bypass in congenital heart disease surgery

Objectives

Improved congenital heart defect (CHD) operations have reduced operative mortality to 3%. The major concern is now long-term neurological outcomes. We measured plasma glial fibrillary acidic protein (GFAP), an early marker of brain injury, during different phases of cardiopulmonary bypass (CPB), to correlate the increase of GFAP to clinical parameters or specific operative phases.

Methods

We performed a prospective, single-centre, observational study in children undergoing cardiac operations. We studied 69 children with CHD and biventricular heart physiology: 26 had tetralogy of Fallot; 17 transposition of the great arteries; and 26 ventricular/atrial septal defects with or without associated arch defects. GFAP levels were measured by ELISA at different stages of CPB. We recorded clinical and surgical parameters and applied multivariable and logistic regressions to assess which parameters were independent predictors of variations in plasma GFAP.

Results

GFAP increased during CPB and peaked at the end of rewarming. Multivariable regression showed degree of hypothermia as the only significant independent predictor of GFAP increase, adjusted for age, prematurity, type of CHD, cyanosis, aortic cross-clamp time, haemodilution, neurological risk time interval and rewarming rate. Temperature nadir and neurological risk time interval were significant independent predictors of a GFAP value  > 0.46 ng/ml.

Conclusions

Hypothermia degree during CPB is correlated with GFAP plasma increase in children with biventricular heart defects undergoing surgical repair. Rewarming is the most critical CPB phase for GFAP increase. The implication of high plasma GFAP is still under evaluation. Follow-up studies are ongoing to assess the reliability of GFAP as a marker of brain injury and/or as a predictor of neurodevelopmental abnormalities.

Serum Neuronal Biomarkers in Neonates With Congenital Heart Disease Undergoing Cardiac Surgery

BACKGROUND

Newborns with congenital heart disease have associated brain damage that affects short-and long-term neurodevelopment. Several neuronal biomarkers exist that could predict brain damage. We investigated the pattern of neuron-specific enolase (NSE) and s100B levels after cardiopulmonary bypass surgery in neonates with congenital heart disease.

METHODS

We completed a prospective observational study of neonates with congenital heart disease who were undergoing cardiopulmonary bypass surgery. NSE and s100B levels were measured from serum samples obtained preoperatively, immediately postoperatively, and once daily on postoperative days one to seven. Cranial ultrasounds were obtained preoperatively and postoperatively and findings were scored using an internally developed scoring system.

RESULTS

Eighteen neonates were included. Immediate postoperative and peak levels of both NSE (58.0 [21.6] and 68.1 [55.7] μg/L) and s100B (0.14 [0.3] and 0.14 [0.3] μg/L) were significantly increased when compared with preoperative levels (34.0 [21.6] μg/L; P < 0.01 and 0.08 [0.1] μg/L; P < 0.02). By postoperative day seven, NSE and s100B levels were lower than preoperative levels: NSE (18 [5.7]; P = 0.09) and s100B (0.03 [0.05]; P < 0.01). Postoperative s100B levels were negatively correlated with age at surgery and positively correlated with circulatory arrest time. Although there was no significant correlation between either NSE or s100B levels and intensive care unit length of stay, hospital length of stay, and pediatric cerebral performance category score, there was a negative correlation between postoperative levels of NSE and ventriculomegaly.

CONCLUSIONS

NSE and s100B levels increase after bypass surgery and return below preoperative baseline levels by postoperative day seven. The levels of s100B were positively correlated with circulatory arrest time and negatively correlated with age at time of surgery. This finding may be supportive of pre-existing prenatal brain injury that could be enhanced by longer surgical times but also of some brain protection effect associated with longer wait until surgery.

Brain injury with systemic inflammation in newborns with congenital heart disease undergoing heart surgery

The potential role of systemic inflammation on brain injury in newborns with congenital heart disease (CHD) was assessed by measuring levels of central nervous system (CNS)-derived proteins in serum prior to and following cardiac surgery. A total of 23 newborns (gestational age, 39±1 weeks) with a diagnosis of CHD that required cardiac surgery with cardiopulmonary bypass (CPB) were enrolled in the current study. Serum samples were collected immediately prior to surgery and 2, 24 and 48 h following CPB, and serum levels of phosphorylated neurofilament-heavy subunit (pNF-H), neuron-specific enolase (NSE) and S100B were analyzed. Systemic inflammation was assessed by measuring serum concentrations of complement C5a and complement sC5b9, and the following cytokines: Interleukin (IL)-1β, IL-6, IL-8, IL-10, IL12p70, interferon γ and tumor necrosis factor (TNF)-α. Analysis of cord blood from normal term deliveries (n=26) provided surrogate normative values for newborns. pNF-H and S100B were 2.4- to 2.8-fold higher (P<0.0001) in patient sera than in cord blood prior to surgery and remained elevated following CPB. Pre-surgical serum pNF-H and S100B levels directly correlated with interleukin (IL)-12p70 (ρ=0.442, P<0.05). pNF-H was inversely correlated with arterial pO₂ prior to surgery (ρ=−0.493, P=0.01) and directly correlated with arterial pCO₂ post-CPB (ρ=0.426, P<0.05), suggesting that tissue hypoxia and inflammation contribute to blood brain barrier (BBB) dysfunction and neuronal injury. Serum IL12p70, IL-6, IL-8, IL-10 and TNF-α levels were significantly higher in patients than in normal cord blood and levels of these cytokines increased following CPB (P<0.001). Activation of complement was observed in all patients prior to surgery, and serum C5a and sC5b9 remained elevated up to 48 h post-surgery. Furthermore, they were correlated (P<0.05) with low arterial pO₂, high pCO₂ and elevated arterial pressure in the postoperative period. Length of mechanical ventilation was associated directly with post-surgery serum IL-12p70 and IL-8 concentrations (P<0.05). Elevated serum concentrations of pNF-H and S100B in neonates with CHD suggest BBB dysfunction and CNS injury, with concurrent hypoxemia and an activated inflammatory response potentiating this effect.

Effects of two differently heparin-coated extracorporeal circuits on markers for brain and myocardial dysfunction

Objective: The two most commonly used heparin-coated systems for cardiopulmonary bypass (CPB) are the Carmeda Bio-Active Surface (CBAS) (Medtronic, Minneapolis, MN, USA) and the Duraflo II coating (Baxter Healthcare, Irvine, CA, USA). The two surfaces are technically unequal and previous experimental studies have demonstrated disparities in effects on the immune system and blood cells. However, little is known concerning the influence of the two surfaces on markers for brain and myocardial dysfunction.

Methods: Forty patients undergoing elective, primary coronary bypass grafting with CPB were prospectively randomized to either the CBAS system or the Duraflo II circuit. During and after CPB, biological markers for brain dysfunction and myocardial injury were analysed.

Results: Both markers for brain dysfunction S-100B and neuron-specific enolase (NSE) increased significantly during CPB ( p =0.01). The elevation during bypass correlated significantly with the duration of CPB ( r = 0.39 and r= 0.38, respectively, both p< 0.02). NSE was somewhat more elevated in the Duraflo II group at the end of CPB ( p =0.01) and 5 h after CPB ( p= 0.02); for S-100B, there were no intergroup differences. Also, the markers related to myocardial injury, myoglobin and creatine kinase (CK-MB) mass increased during CPB ( p= 0.01), while elevation of troponin-I occurred 5 h after CPB ( p= 0.01). There were no statistically significant intergroup differences. No significant correlation was seen between the release of cardiac markers and the duration of CPB. The clinical course was similar in both groups.

Conclusions: Except for a slightly higher elevation of NSE at the end of CPB and 5 h after CPB in the Duraflo II group, there were no significant differences between the CBAS group and the Duraflo II group concerning markers for brain and myocardial dysfunction.

Serum biomarkers to evaluate the integrity of the neurovascular unit

Biomarkers have the potential to enable the clinicians to screen infants for brain injury, monitor progression of disease, identify injured brain regions, assess efficacy of neuroprotective therapies, and offer hope to identify the timing of the injury, thus shedding light on the potential pathophysiology and the most effective therapy. Currently, clinicians do not routinely use biomarkers to care for neonates with Neonatal Encephalopathy (NE) and brain injury due to prenatal hypoxia-asphyxia. This review will cover potential biomarkers of the neurovascular unit in the setting of NE that (i) can help assess the degree or severity of encephalopathy at birth; (ii) can help monitor progression of disease process and efficacy of neuroprotective therapy; (iii) can help assess neurodevelopmental outcome. These biomarkers will be summarized in two categories: 1) Specific biomarkers targeting the neurovascular unit such as glial fibrillary acidic protein (GFAP), ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1), S100B, and neuron specific enolase (NSE) and 2) general inflammatory cytokines, such as interleukin-6 (IL-6), interleukin-1b (IL-1b), and pNF-H, among others.

Glial fibrillary acidic protein in children with congenital heart disease undergoing cardiopulmonary bypass

OBJECTIVE

To determine whether blood levels of the brain-specific biomarker glial fibrillary acidic protein rise during cardiopulmonary bypass for repair of congenital heart disease.

METHODS

This is a prospective observational pilot study to characterise the blood levels of glial fibrillary acidic protein during bypass. Children <21 years of age undergoing bypass for congenital heart disease at Johns Hopkins Hospital and Texas Children's Hospital were enrolled. Blood samples were collected during four phases: pre-bypass, cooling, re-warming, and post-bypass.

RESULTS

A total of 85 patients were enrolled between October, 2010 and May, 2011. The median age was 0.73 years (range 0.01-17). The median weight was 7.14 kilograms (range 2.2-86.5). Single ventricle anatomy was present in 18 patients (22%). Median glial fibrillary acidic protein values by phase were: pre-bypass: 0 ng/ml (range 0-0.35); cooling: 0.039 (0-0.68); re-warming: 0.165 (0-2.29); and post-bypass: 0.112 (0-0.97). There were significant elevations from pre-bypass to all subsequent stages, with the greatest increase during re-warming (p = 0.0001). Maximal levels were significantly related to younger age (p = 0.03), bypass time (p = 0.03), cross-clamp time (p = 0.047), and temperature nadir (0.04). Peak levels did not vary significantly in those with single ventricle anatomy versus two ventricle repairs.

CONCLUSION

There are significant increases in glial fibrillary acidic protein levels in children undergoing cardiopulmonary bypass for repair of congenital heart disease. The highest values were seen during the re-warming phase. Elevations are significantly associated with younger age, bypass and cross-clamp times, and temperature nadir. Owing to the fact that glial fibrillary acidic protein is the most brain-specific biomarker identified to date, it may act as a rapid diagnostic marker of brain injury during cardiac surgery.

Time-dependent changes of protein biomarker levels in the cerebrospinal fluid after blast traumatic brain injury

Time-dependent changes of protein biomarkers in the cerebrospinal fluid (CSF) can be used to identify the pathological processes in traumatic brain injury (TBI) as well as to follow the progression of the disease. We obtained CSF from a large animal model (swine) of blast-induced traumatic brain injury prior to and at 6, 24, 72 h, and 2 wk after a single exposure to blast overpressure, and determined changes in the CSF levels of neurofilament-heavy chain, neuron-specific enolase, brain-specific creatine kinase, glial fibrillary acidic protein, calcium-binding protein β (S100β), Claudin-5, vascular endothelial growth factor, and von Willebrand factor using reverse phase protein microarray. We detected biphasic temporal patterns in the CSF concentrations of all tested protein markers except S100β. The CSF levels of all markers were significantly increased 6 h after the injury compared to preinjury levels. Values were then decreased at 24 h, prior to a second increase in all markers but S100β at 72 h. At 2 wk postinjury, the CSF concentrations of all biomarkers were decreased once again; brain-specific creatine kinase, Claudin-5, von Willebrand factor, and S100β levels were no longer significantly higher than their preinjury values while neurofilament-heavy chain, neuron-specific enolase, vascular endothelial growth factor, and glial fibrillary acidic protein levels remained significantly elevated compared to baseline. Our findings implicate neuronal and glial cell damage, compromised vascular permeability, and inflammation in blast-induced traumatic brain injury, as well as demonstrate the value of determining the temporal pattern of biomarker changes that may be of diagnostic value.

Biomarkers of hypoxic-ischemic encephalopathy in newborns

As neonatal intensive care has evolved, the focus has shifted from improving mortality alone to an effort to improve both mortality and morbidity. The most frequent source of neonatal brain injury occurs as a result of hypoxic-ischemic injury. Hypoxic-ischemic injury occurs in about 2 of 1,000 full-term infants and severe injured infants will have lifetime disabilities and neurodevelopmental delays. Most recently, remarkable efforts toward neuroprotection have been started with the advent of therapeutic hypothermia and a key step in the evolution of neonatal neuroprotection is the discovery of biomarkers that enable the clinician-scientist to screen infants for brain injury, monitor progression of disease, identify injured brain regions, and assess efficacy of neuroprotective clinical trials. Lastly, biomarkers offer great hope identifying when an injury occurred shedding light on the potential pathophysiology and the most effective therapy. In this article, we will review biomarkers of HIE including S100B, neuron specific enolase, umbilical cord IL-6, CK-BB, GFAP, myelin basic protein, UCHL-1, and pNF-H. We hope to contribute to the awareness, validation, and clinical use of established as well as novel neonatal brain injury biomarkers.

Correlation of cerebral Near-infrared spectroscopy (cNIRS) and neurological markers in critically ill children

OBJECTIVE

To correlate regional brain saturations (RSO(2)) measured by cerebral Near-infrared spectroscopy (cNIRS) with serological markers indicative of neurological injury (neuron-specific enolase (NSE) and S100beta).

METHODS

Children with at least one organ failure who were undergoing cNIRS monitoring were eligible for enrollment, while children with hyperbilirubinemia and cyanotic heart disease were excluded. Children were further analyzed based on the presence of an acute neurological injury (defined as hypoxic/ischemic injury after cardiac arrest, status epilepticus, meningitis, encephalopathy) as well as survival. RSO(2) was measured continuously (every 30 s) and averages were obtained at 6 h and 24 h epochs prior to serum collection (E6 and E24, respectively). Serum was collected for NSE and S100beta, which were both determined by ELISA. Serum from children undergoing evaluation for fever in the Emergency department served as serological controls. Correlations were determined using the Pearson Product Moment Correlations.

RESULTS

A total of 26 children underwent cNIRS monitoring for a total of 47 days. Overall NSE was greater in critically ill children compared to controls, as well as in all subsets of children analyzed (acute CNS injuries, no acute CNS injuries, survivors and non-survivors). S100beta tended to be greater in critically ill children, but this did not reach statistical significance. Average RSO(2) in E6 and E24 was 68.0% +/- 1.5 and 68.6% +/- 1.6, respectively, in a total of 131,036 measurements and E6 RSO(2) was strongly, negatively correlated with S100beta in children with acute neurological injuries.

CONCLUSIONS

This is the first study to correlate averaged RSO(2) measured by cNIRS with neurological injury markers in critically ill children. We believe that this data can be used to establish thresholds for RSO(2) that can be tested in future trials to determine if this technology is predictive of long-term neurological outcome.

Reliability of S100B in predicting severity of central nervous system injury

S100B is a protein biomarker that reflects CNS injury. It can be measured in the CSF or serum with readily available immunoassay kits. The excellent sensitivity of S100B has enabled it to confirm the existence of subtle brain injury in patients with mild head trauma, strokes, and after successful resuscitation from cardiopulmonary arrest. The extent of S100B elevation has been found to be useful in predicting clinical outcome after brain injury. Elevations of S100B above certain threshold levels might be able to reliably predict brain death or mortality. A normal S100B level reliably predicts the absence of significant CNS injury. The specificity of S100B levels as a reflection of CNS injury is compromised by the findings that extra-cranial injuries can lead to elevations in the absence of brain injury. This potential problem can most likely be avoided by measuring serial S100B levels along with other biomarkers and carefully noting peripheral injuries. Serum markers GFAP and NSE are both more specific for CNS injury and have little to no extra-cranial sources. Sustained elevations of S100B over 24 h along with elevations of GFAP and NSE can more reliably predict the extent of brain injury and clinical outcomes. In the future, S100B measurements might reliably predict secondary brain injury and enable physicians to initiate therapeutic interventions in a timelier manner. S100B levels have been shown to rise hours to days before changes in ICP, neurological examinations, and neuroimaging tests. S100B levels may also be used to monitor the efficacy of treatments.

Electroencephalographic changes after pediatric cardiac surgery with cardiopulmonary bypass: is slow wave activity unfavorable?

Pediatric cardiac surgery with cardiopulmonary bypass (CPB) is frequently associated with neurologic deficits. We describe the postoperative EEG changes, assess their possible causes, and evaluate their relevance to neurologic outcome. Thirty-one children and five neonates with congenital heart disease were included. EEG recording started after intubation and continued until 22-96 h after CPB. In addition to conventional analysis, spectral analysis was performed for occipital and frontal electrodes, and differences between pre- and postoperative delta power (delta-deltaP) were calculated. Maximum values of occipital delta-deltaP that occurred within 48 h after CPB were correlated with clinical variables and with perioperative markers of oxidative stress and inflammation. Occipital delta-deltaP correlated with frontal delta-deltaP, and maximum delta-deltaP correlated with conventional rating. Distinct rise of deltaP was detected in 18 of 21 children without any acute or long-term neurologic deficits but only in five of 10 children with temporary or permanent neurologic deficits. Furthermore, maximally registered delta-deltaP was inversely associated with duration of CPB and postoperative ventilation. Maximal delta-deltaP was also inversely associated with the loss of plasma ascorbate (as an index of oxidative stress) and plasma levels of IL-6 and IL-8. Slow wave activity frequently occurs within 48 h after CPB. However, our data do not support the notion that EEG slowing is associated with adverse neurologic outcome. This is supported by the fact that EEG slowing was associated with less oxido-inflammatory stress.

Glial and neuronal proteins in serum predict outcome after severe traumatic brain injury

OBJECTIVE

To study the ability of glial (glial fibrillary acidic protein [GFAP] and S100b) and neuronal (neuron specific enolase [NSE]) protein levels in peripheral blood to predict outcome after severe traumatic brain injury.

METHODS

Eighty-five patients with severe traumatic brain injury (admission Glasgow Coma Score [GCS] < or = 8) were included. Blood samples taken at the time of hospital admission were analyzed for S100b, GFAP, and NSE. Data collected included demographic and clinical variables. Outcome was assessed using the Glasgow Outcome Scale (GOS) at 6 months post injury.

RESULTS

The median serum levels of S100b, GFAP, and NSE were raised 18.3 fold (S100b), 4.6 fold (GFAP), and twofold (NSE) compared to normal reference values. S100b, GFAP, and NSE serum levels correlated significantly with the injury severity score and CT findings but not with age, sex, or GCS. S100b, GFAP, and NSE levels were significantly higher in patients who died or had a poor outcome 6 months post injury than in those who were alive or had good outcome. S100b level >1.13 microg/L was the strongest predictor of death with 100% discrimination, but GFAP (>1.5 microg/L) and NSE (>21.7 microg/L) levels also strongly predicted death (adjusted odds ratios 5.82 [for GFAP] and 3.91 [for NSE]). S100b, GFAP, and NSE all strongly predicted poor outcome (adjusted odds ratios 5.12 [S100b], 8.82 [GFAP], and 3.95 [NSE]).

CONCLUSIONS

These results suggest that determination of serum levels of glial and neuronal proteins may add to the clinical assessment of the primary damage and prediction of outcome after severe traumatic brain injury.

Early postoperative prediction of cerebral damage after pediatric cardiac surgery

BACKGROUND

Cerebral damage is a serious complication of pediatric cardiac surgery. Early prediction of actual risk can be useful in counseling of parents, and in early diagnosis and rehabilitation therapy. Also, if all children at risk could be identified therapeutic strategies to limit perioperative cerebral damage might be developed. The aim of this study is to create a mathematical model to predict risk of neurologic sequelae within 24 hours after surgery using simple and readily available clinical measurements.

METHODS

The hospital records of 534 children after cardiac surgery were reviewed. Variables examined were age at operation, diagnosis, use of cardiopulmonary bypass, arterial and central venous oxygen saturation, serum glucose, lactate and creatine kinase, mean arterial pressure, and body temperature. The endpoint for each study patient was the occurrence or lack of occurrence of seizures, movement or developmental disorders, cerebral hemorrhage, infarction, hydrocephalus, or marked cerebral atrophy. Univariate and multivariate regression analyses were used to evaluate the predictive power of the investigated factors as well as to create a predictive model.

RESULTS

In 6.26% of children symptoms of cerebral damage were found. Significant risk factors were age at surgery, more complex malformations, metabolic acidosis, and increased lactate (odds ratio: age, 0.882/yr [0.772-1.008]; complex malformations, 10.32 [1.32-80.28]; arterial pH more than 7.35 to 0.4 [0.18-0.89]; lactate -1.018 per mg/dL [1.006-1.03]).

CONCLUSIONS

It is possible to quantify the risk of appearance of symptoms of cerebral damage after cardiac surgery within 24 hours using simple and readily available clinical measurements.

Coronary-artery bypass surgery and the brain: persisting concerns

Mortality after coronary-artery bypass surgery (CABS) has fallen steadily over recent years. Concern remains, however, about the effect of this surgery on the brain. The problem of brain damage after CABS is multifactorial, involving microembolism, disturbed perfusion, metabolic derangement, and inflammatory responses. Microemboli numbers have been linked to the likelihood of neuropsychological deterioration after surgery. Risk factors for cerebral changes after CABS include older age, gender, neurological disease, diabetes, and calcification of the aorta. These risk factors are important because, in comparison with the early 1990s, patients undergoing CABS are now older and tend to have a greater number of comorbid conditions. Changes in surgical technique, such as the introduction of arterial-line filters and membrane oxygenators, have led to a reduction of both microemboli and neuropsychological disturbance. However, the problem persists, prompting further studies on surgical technique and neuroprotective strategies.

Postoperative course of S-100B protein and neuron-specific enolase in patients after implantation of continuous and pulsatile flow LVADs

BACKGROUND

In the early post-operative period after implantation of a continuous flow left ventricular assist device (LVAD) a non-pulsatile flow occurs. We compared the post-operative time-courses of protein S-100B (S100B) and neuron-specific enolase (NSE) as biochemical markers of brain injury in patients after implantation of a continuous flow LVAD and patients receiving a pulsatile flow LVAD.

METHODS

Since 1998 the continuous flow DeBakey VAD has been implanted in 8 patients at our institution. For comparison purposes, a group of 7 consecutive patients in whom a pulsatile Novacor N100 LVAD was implanted were investigated. In both groups cardiopulmonary bypass (CPB) with cardiotomy suction was used. S100B and NSE were measured in serum pre-operatively, 4 hours after CPB, and on days 1, 3, 7, and 14 after implantation of the LVAD. A neurologic examination was performed pre-operatively and post-operatively on days 3 and 14.

RESULTS

No differences were found between groups in pre-operative characteristics. The analysis of variance with repeated measurements for S-100B and NSE showed significant time effects (p = 0.004, p = 0.009, respectively) but no group effects (p = 0.06, p = 0.26, respectively) and no interaction between groups and time (p = 0.12, p = 0.48, respectively). The pre-operative serum level of S100B was significantly higher (p = 0.03) in the DeBakey VAD group. The pre-operative serum level of NSE was similar in the 2 groups (p = 0.7). In both groups there was a significant increase of S100B and NSE immediately after surgery (S100B: p = 0.006, p = 0.019; NSE: p = 0.01, p = 0.001). The values returned to pre-operative levels in the DeBakey VAD group on day 1 after implantation and in the Novacor group for S100B on day 3 and NSE on day 1. Post-operatively the mean values of S100B and NSE in the DeBakey VAD group compared with the Novacor group were significantly elevated only on day 3 (p = 0.005, p = 0.023).No neurologic complications were noted in patients with a continuous flow LVAD, whereas in the pulsatile LVAD group 2 patients presented neurologic abnormalities during the study period.

CONCLUSIONS

The similar course of biochemical markers of brain damage in both groups may indicate that the non-pulsatile flow in the early post-operative period does not lead to increased brain injury or permeability of the brain blood barrier.Elevated levels of S100B and NSE in the post-operative period can be used as diagnostic markers of brain injury in patients after implantation of both types of LVAD.

Early detection of neurologic injury and issues of rehabilitation after pediatric cardiac extracorporeal membrane oxygenation

Neurological impairment results in a significant population of children after extracorporeal membrane oxygenation (ECMO) for treatment of otherwise intractable circulatory failure. Pre-ECMO hypoxia/ischemia, reperfusion injury, and impaired cerebral perfusion during low output situations possibly aggravated by harmful effects of a pulsatile perfusion are discussed in terms of possible etiological reasons. To develop preventive strategies or to enable curative measure, early detection of neuronal injury seems mandatory. Electroencephalographic surveillance and/or monitoring of evoked potentials and monitoring of cerebral oxygenation by means of near infrared spectroscopy or jugular venous bulb oxygen saturation, as well as measurements of serum neuron specific enolase, S-100 protein, and brain type creatine kinase can be employed clinically. To improve functional outcome following neuronal injury, early rehabilitation seems essential to minimize the resulting effects on physical, cognitive, and emotional development.