Autonomic dysfunction following traumatic brain injury: translational insights

A Systematic Review of the Relationship Between Traumatic Brain Injury and Disruptions in Heart Rate Variability

Autonomic nervous system dysfunction is increasingly recognized as a common sequela of traumatic brain injury (TBI). Heart rate variability (HRV) is a specific measure of autonomic nervous system functioning that can be used to measure beat-to-beat changes in heart rate following TBI. The objective of this systematic review was to determine the state of the literature on HRV dysfunction following TBI, assess the level of support for HRV dysfunction following TBI, and determine if HRV dysfunction predicts mortality and the severity and subsequent recovery of TBI symptoms. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Two raters coded each article and provided quality ratings with discrepancies resolved by consensus. Eighty-nine papers met the inclusion criteria. Findings indicated that TBI of any severity is associated with decreased (i.e., worse) HRV; the severity of TBI appears to moderate the relationship between HRV and recovery; decreased HRV following TBI predicts mortality beyond age; HRV disturbances may persist beyond return-to-play and symptom resolution following mild TBI. Overall, current literature suggests HRV is decreased following TBI and may be a good indicator of physiological change and predictor of important outcomes including mortality and symptom improvement following TBI.

Acute and Reversible Hypothalamic Symptoms in a Lateral Head Impact Mouse Model of Mild Traumatic Brain Injury

Central autonomic and endocrine dysfunctions following traumatic brain injury (TBI) are believed to involve the hypothalamus; however, underlying mechanisms are unknown. Although chronic deficits might be caused by irreversible tissue damage, various neuroendocrine and autonomic symptoms are only observed transiently, suggesting they might result from a temporary alteration in the activity of hypothalamic neurons. We therefore examined if a mouse model of mild TBI could induce reversible autonomic phenotypes and cause acute changes in c-Fos expression within corresponding regions of the hypothalamus. Adult C57Bl/6 male mice were lightly anesthetized with isoflurane and subjected to TBI by lateral head impact using a Gothenburg impactor. Mice treated the same way, but without the head impact served as controls (shams). We monitored body weight and core body temperature by infrared thermography and performed immunohistochemistry against c-Fos in various regions of the hypothalamus. We determined that a projectile velocity of 9 m/s significantly delayed recovery from the anesthesia without inducing skull fractures and signs of discomfort disappeared within 3 h, as assessed by grimace scale. Compared with shams, TBI mice displayed a rapid decrease in core body temperature which resolved within 48 h. Daily body weight gain was also significantly lower in TBI mice on the day following injury but recovered thereafter. c-Fos analysis revealed a significantly higher density of c-Fos-positive cells in the paraventricular nucleus and a significantly lower density in the median preoptic nucleus and medial preoptic area. We conclude that mild TBI induced by a single lateral head impact in mice at 9 m/s produces acute and reversible symptoms associated with hypothalamic dysfunction accompanied by significant changes in c-Fos expression within relevant areas of the hypothalamus. These findings support the hypothesis that a temporary alteration of neuronal activity may underlie the expression of reversible central autonomic and neuroendocrine symptoms.

Neuroinflammation Plays a Potential Role in the Medulla Oblongata After Moderate Traumatic Brain Injury in Mice as Revealed by Nontargeted Metabonomics Analysis

Moderate traumatic brain injury (mTBI) involves a series of complex pathophysiological processes in not only the area in direct contact with mechanical violence but also in other brain regions far from the injury site, which may be important factors influencing subsequent neurological dysfunction or death. The medulla oblongata (MO) is a key area for the maintenance of basic respiratory and circulatory functions, whereas the pathophysiological processes after mTBI have rarely drawn the attention of researchers. In this study, we established a closed-head cortical contusion injury model, identified 6 different time points that covered the acute, subacute, and chronic phases, and then used nontargeted metabolomics to identify and analyze the changes in differential metabolites (DMs) and metabolic pathways in the MO region. Our results showed that the metabolic profile of the MO region underwent specific changes over time: harmaline, riboflavin, and dephospho-coenzyme A were identified as the key DMs and play important roles in reducing inflammation, enhancing antioxidation, and maintaining homeostasis. Choline and glycerophospholipid metabolism was identified as the key pathway related to the changes in MO metabolism at different phases. In addition, we confirmed increases in the levels of inflammatory factors and the activation of astrocytes and microglia by Western blot and immunofluorescence staining, and these findings were consistent with the nontargeted metabolomic results. These findings suggest that neuroinflammation plays a central role in MO neuropathology after mTBI and provide new insights into the complex pathophysiologic mechanisms involved after mTBI.

Understanding antimicrobial pharmacokinetics in critically ill patients to optimize antimicrobial therapy: A narrative review

Effective treatment of sepsis not only demands prompt administration of appropriate antimicrobials but also requires precise dosing to enhance the likelihood of patient survival. Adequate dosing refers to the administration of doses that yield therapeutic drug concentrations at the infection site. This ensures a favorable clinical and microbiological response while avoiding antibiotic-related toxicity. Therapeutic drug monitoring (TDM) is the recommended approach for attaining these goals. However, TDM is not universally available in all intensive care units (ICUs) and for all antimicrobial agents. In the absence of TDM, healthcare practitioners need to rely on several factors to make informed dosing decisions. These include the patient's clinical condition, causative pathogen, impact of organ dysfunction (requiring extracorporeal therapies), and physicochemical properties of the antimicrobials. In this context, the pharmacokinetics of antimicrobials vary considerably between different critically ill patients and within the same patient over the course of ICU stay. This variability underscores the need for individualized dosing. This review aimed to describe the main pathophysiological changes observed in critically ill patients and their impact on antimicrobial drug dosing decisions. It also aimed to provide essential practical recommendations that may aid clinicians in optimizing antimicrobial therapy among critically ill patients.

Quantitative Pupillometry Predicts Return to Play and Tracks the Clinical Evolution of Mild Traumatic Brain Injury in US Military Academy Cadets: A Military Traumatic Brain Injury Initiative Study

BACKGROUND AND OBJECTIVES

The objective of this study was to determine the utility of the pupillary light reflex use as a biomarker of mild traumatic brain injury (mTBI).

METHODS

This prospective cohort study was conducted at The US Military Academy at West Point. Cadets underwent a standard battery of tests including Balance Error Scoring System, Sports Concussion Assessment Tool Fifth Edition Symptom Survey, Standard Assessment of Concussion, and measure of pupillary responses. Cadets who sustained an mTBI during training events or sports were evaluated with the same battery of tests and pupillometry within 48 hours of the injury (T1), at the initiation of a graded return to activity protocol (T2), and at unrestricted return to activity (T3).

RESULTS

Pupillary light reflex metrics were obtained in 1300 cadets at baseline. During the study period, 68 cadets sustained mTBIs. At T1 (<48 hours), cadets manifested significant postconcussion symptoms (Sports Concussion Assessment Tool Fifth Edition P < .001), and they had decreased cognitive performance (Standardized Assessment of Concussion P < .001) and higher balance error scores (Balance Error Scoring System P < .001) in comparison with their baseline assessment (T0). The clinical parameters showed normalization at time points T2 and T3. The pupillary responses demonstrated a pattern of significant change that returned to normal for several measures, including the difference between the constricted and initial pupillary diameter (T1 P < .001, T2 P < .05), dilation velocity (T1 P < .01, T2 P < .001), and percent of pupillary constriction (T1 P < .05). In addition, a combination of dilation velocity and maximum constriction velocity demonstrates moderate prediction ability regarding who can return to duty before or after 21 days (area under the curve = 0.71, 95% CI [0.56-0.86]).

CONCLUSION

This study's findings indicate that quantitative pupillometry has the potential to assist with injury identification and prediction of symptom severity and duration.

Assessing the impact of early progressive mobilization on moderate-to-severe traumatic brain injury: a randomized controlled trial

INTRODUCTION

Traumatic brain injury (TBI) is a major cause of neurodisability worldwide, with notably high disability rates among moderately severe TBI cases. Extensive previous research emphasizes the critical need for early initiation of rehabilitation interventions for these cases. However, the optimal timing and methodology of early mobilization in TBI remain to be conclusively determined. Therefore, we explored the impact of early progressive mobilization (EPM) protocols on the functional outcomes of ICU-admitted patients with moderate to severe TBI.

METHODS

This randomized controlled trial was conducted at a trauma ICU of a medical center; 65 patients were randomly assigned to either the EPM group or the early progressive upright positioning (EPUP) group. The EPM group received early out-of-bed mobilization therapy within seven days after injury, while the EPUP group underwent early in-bed upright position rehabilitation. The primary outcome was the Perme ICU Mobility Score and secondary outcomes included Functional Independence Measure motor domain (FIM-motor) score, phase angle (PhA), skeletal muscle index (SMI), the length of stay in the intensive care unit (ICU), and duration of ventilation.

RESULTS

Among 65 randomized patients, 33 were assigned to EPM and 32 to EPUP group. The EPM group significantly outperformed the EPUP group in the Perme ICU Mobility and FIM-motor scores, with a notably shorter ICU stay by 5.9 days (p < 0.001) and ventilation duration by 6.7 days (p = 0.001). However, no significant differences were observed in PhAs.

CONCLUSION

The early progressive out-of-bed mobilization protocol can enhance mobility and functional outcomes and shorten ICU stay and ventilation duration of patients with moderate-to-severe TBI. Our study's results support further investigation of EPM through larger, randomized clinical trials. Clinical trial registration ClinicalTrials.gov NCT04810273 . Registered 13 March 2021.

Decreased levels of hydrogen sulfide in the hypothalamic paraventricular nucleus contribute to sympathetic hyperactivity induced by cerebral infarction

Paroxysmal sympathetic hyperactivity (PSH) is a common clinical feature secondary to ischemic stroke (IS), but its mechanism is poorly understood. We aimed to investigate the role of H2S in the pathogenesis of PSH. IS patients were divided into malignant (MCI) and non-malignant cerebral infarction (NMCI) group. IS in rats was induced by the right middle cerebral artery occlusion (MCAO). H2S donor (NaHS) or inhibitor (aminooxy-acetic acid, AOAA) were microinjected into the hypothalamic paraventricular nucleus (PVN). Compared with the NMCI group, patients in the MCI group showed PSH, including tachycardia, hypertension, and more plasma norepinephrine (NE) that was positively correlated with levels of creatine kinase, glutamate transaminase, and creatinine respectively. The 1-year survival rate of patients with high plasma NE levels was lower. The hypothalamus of rats with MCAO showed increased activity, especially in the PVN region. The levels of H2S in PVN of the rats with MCAO were reduced, while the blood pressure and renal sympathetic discharge were increased, which could be ameliorated by NaHS and exacerbated by AOAA. NaHS completely reduced the disulfide bond of NMDAR1 in PC12 cells. The inhibition of NMDAR by MK-801 microinjected in PVN of rats with MCAO also could lower blood pressure and renal sympathetic discharge. In conclusion, PSH may be associated with disease progression and survival in patients with IS. Decreased levels of H2S in PVN were involved in regulating sympathetic efferent activity after cerebral infarction. Our results might provide a new strategy and target for the prevention and treatment of PSH.

Refractory Autonomic Instability in Mild Traumatic Brain Injury: A Case Report

Although the specific relationship between concussion and the autonomic nervous system (ANS) has not been fully elucidated, it is generally understood that the pathologic response after a traumatic brain injury (TBI) is linked with systolic cardiac dysfunction. In this case, we present a patient with multiple concussion injuries over a five-year period who exhibited severe cardiac and autonomic dysfunction, in addition to prolonged impairments in vestibular function, oculomotor function, cognitive function, and headaches. The patient is a 28-year-old male with a past medical history of multiple concussions, with the first concussion occurring due to a skiing accident in January 2015. He initially presented in October 2016 after sustaining a concussion due to a motor vehicle accident (MVA) without loss of consciousness (LOC) two weeks prior. In July 2017, the patient was involved in another MVA with a positive head strike and without LOC, causing his third concussion. After each of his first three concussions, he displayed various symptoms that eventually resolved. In October 2020, the patient suffered a syncopal ground-level fall with several minutes of LOC due to dehydration and lightheadedness, leading to his fourth concussion. His fourth concussion resulted in chronic autonomic dysfunction with resting tachycardia refractory to medical management, and he eventually underwent a cardiac ablation. Although the patient underwent a cardiac ablation, his tachycardia and dysautonomia still cause dysfunction in his daily life. With millions of people living with the sequelae of TBI, the recognition and treatment of autonomic dysfunction should be a continued focus in brain injury research.

Development of a nomogram to predict the incidence of acute kidney injury among ischemic stroke individuals during ICU hospitalization

Background

Limited clinical prediction models exist to assess the likelihood of acute kidney injury (AKI) occurrence in ischemic stroke individuals. In this retrospective study, our aim was to construct a nomogram that utilizes commonly available clinical features to predict the occurrence of AKI during intensive care unit hospitalization among this patient population.

Methods

In this study, the MIMIC-IV database was utilized to investigate potential risk factors associated with the incidence of AKI among ischemic stroke individuals. A predictive nomogram was developed based on these identified risk factors. The discriminative performance of the constructed nomogram was assessed. Calibration analysis was utilized to evaluate the calibration performance of the constructed model, assessing the agreement between predicted probabilities and actual outcomes. Furthermore, decision curve analysis (DCA) was employed to assess the clinical net benefit, taking into account the potential risks and benefits associated with different decision thresholds.

Results

A total of 2089 ischemic stroke individuals were included and randomly allocated into developing (n = 1452) and verification cohorts (n = 637). Risk factors for AKI incidence in ischemic stroke individuals, determined through LASSO and logistic regression. The constructed nomogram had good performance in predicting the occurrence of AKI among ischemic stroke patients and provided significant improvement compared to existing scoring systems. DCA demonstrated satisfactory clinical net benefit of the constructed nomogram in both the validation and development cohorts.

Conclusions

The developed nomogram exhibits robust predictive performance in forecasting AKI occurrence in ischemic stroke individuals.

Crosstalk Between the Nervous System and Systemic Organs in Acute Brain Injury

Organ crosstalk is a complex biological communication between distal organs mediated via cellular, soluble, and neurohormonal actions, based on a two-way pathway. The communication between the central nervous system and peripheral organs involves nerves, endocrine, and immunity systems as well as the emotional and cognitive centers of the brain. Particularly, acute brain injury is complicated by neuroinflammation and neurodegeneration causing multiorgan inflammation, microbial dysbiosis, gastrointestinal dysfunction and dysmotility, liver dysfunction, acute kidney injury, and cardiac dysfunction. Organ crosstalk has become increasingly popular, although the information is still limited. The present narrative review provides an update on the crosstalk between the nervous system and systemic organs after acute brain injury. Future research might help to target this pathophysiological process, preventing the progression toward multiorgan dysfunction in critically ill patients with brain injury.

Adaptive yoga versus low-impact exercise for adults with chronic acquired brain injury: a pilot randomized control trial protocol

Background

Each year, millions of Americans sustain acquired brain injuries (ABI) which result in functional impairments, such as poor balance and autonomic nervous system (ANS) dysfunction. Although significant time and energy are dedicated to reducing functional impairment in acute phase of ABI, many individuals with chronic ABI have residual impairments that increase fall risk, decrease quality of life, and increase mortality. In previous work, we have found that yoga can improve balance in adults with chronic (i.e., ≥6 months post-injury) ABI. Moreover, yoga has been shown to improve ANS and brain function in healthy adults. Thus, adults with chronic ABI may show similar outcomes. This protocol details the methods used to examine the effects of a group yoga program, as compared to a group low-impact exercise, on primary and secondary outcomes in adults with chronic ABI.

Methods

This study is a single-blind randomized controlled trial comparing group yoga to group low-impact exercise. Participants must be ≥18 years old with chronic ABI and moderate balance impairments. Group yoga and group exercise sessions occur twice a week for 1 h for 8 weeks. Sessions are led by trained adaptive exercise specialists. Primary outcomes are balance and ANS function. Secondary outcomes are brain function and structure, cognition, quality of life, and qualitative experiences. Data analysis for primary and most secondary outcomes will be completed with mixed effect statistical methods to evaluate the within-subject factor of time (i.e., pre vs. post intervention), the between-subject factor of group (yoga vs. low-impact exercise), and interaction effects. Deductive and inductive techniques will be used to analyze qualitative data.

Discussion

Due to its accessibility and holistic nature, yoga has significant potential for improving balance and ANS function, along with other capacities, in adults with chronic ABI. Because there are also known benefits of exercise and group interaction, this study compares yoga to a similar, group exercise intervention to explore if yoga has a unique benefit for adults with chronic ABI.Clinical trial registration:ClinicalTrials.gov, NCT05793827. Registered on March 31, 2023.

Long-term risk of cardiovascular disease after traumatic brain injury: screening and prevention

Traumatic brain injury (TBI) is highly prevalent among individuals participating in contact sports, military personnel, and in the general population. Although it is well known that brain injury can cause neurological and psychiatric complications, evidence from studies on individuals exposed to a single or repetitive brain injuries suggests an understudied association between TBI and the risk of developing chronic cardiovascular diseases and risk factors for cardiovascular disease. Several studies have shown that people without pre-existing comorbidities who sustain a TBI have a significantly higher risk of developing chronic cardiovascular disease, than people without TBI. Similar observations made in military and professional American-style football cohorts suggest causal pathways through which modifiable cardiovascular risk factors might mediate the relationship between brain injury and chronic neurological diseases. A better understanding of cardiovascular disease risk after TBI combined with a proactive, targeted screening programme might mitigate long-term morbidity and mortality in individuals with TBI, and improve their quality of life.

Pathophysiology, Management, and Therapeutics in Subarachnoid Hemorrhage and Delayed Cerebral Ischemia: An Overview

Subarachnoid hemorrhage (SAH) is a type of hemorrhagic stroke resulting from the rupture of an arterial vessel within the brain. Unlike other stroke types, SAH affects both young adults (mid-40s) and the geriatric population. Patients with SAH often experience significant neurological deficits, leading to a substantial societal burden in terms of lost potential years of life. This review provides a comprehensive overview of SAH, examining its development across different stages (early, intermediate, and late) and highlighting the pathophysiological and pathohistological processes specific to each phase. The clinical management of SAH is also explored, focusing on tailored treatments and interventions to address the unique pathological changes that occur during each stage. Additionally, the paper reviews current treatment modalities and pharmacological interventions based on the evolving guidelines provided by the American Heart Association (AHA). Recent advances in our understanding of SAH will facilitate clinicians' improved management of SAH to reduce the incidence of delayed cerebral ischemia in patients.

Neutrophil extracellular traps facilitate sympathetic hyperactivity by polarizing microglia toward M1 phenotype after traumatic brain injury

Traumatic brain injury (TBI), particularly diffuse axonal injury (DAI), often results in sympathetic hyperactivity, which can exacerbate the prognosis of TBI patients. A key component of this process is the role of neutrophils in causing neuroinflammation after TBI by forming neutrophil extracellular traps (NETs), but the connection between NETs and sympathetic excitation following TBI remains unclear. Utilizing a DAI rat model, the current investigation examined the role of NETs and the HMGB1/JNK/AP1 signaling pathway in this process. The findings revealed that sympathetic excitability intensifies and peaks 3 days post-injury, a pattern mirrored by the activation of microglia, and the escalated NETs and HMGB1 levels. Subsequent in vitro exploration validated that HMGB1 fosters microglial activation via the JNK/AP1 pathway. Moreover, in vivo experimentation revealed that the application of anti-HMGB1 and AP1 inhibitors can mitigate microglial M1 polarization post-DAI, effectively curtailing sympathetic hyperactivity. Therefore, this research elucidates that post-TBI, NETs within the PVN may precipitate sympathetic hyperactivity by stimulating M1 microglial polarization through the HMGB1/JNK/AP1 pathway.

Multicohort cross-sectional study of cognitive and behavioural digital biomarkers in neurodegeneration: the Living Lab Study protocol

INTRODUCTION AND AIMS

Digital biomarkers can provide a cost-effective, objective and robust measure for neurological disease progression, changes in care needs and the effect of interventions. Motor function, physiology and behaviour can provide informative measures of neurological conditions and neurodegenerative decline. New digital technologies present an opportunity to provide remote, high-frequency monitoring of patients from within their homes. The purpose of the living lab study is to develop novel digital biomarkers of functional impairment in those living with neurodegenerative disease (NDD) and neurological conditions.

METHODS AND ANALYSIS

The Living Lab study is a cross-sectional observational study of cognition and behaviour in people living with NDDs and other, non-degenerative neurological conditions. Patients (n≥25 for each patient group) with dementia, Parkinson's disease, amyotrophic lateral sclerosis, mild cognitive impairment, traumatic brain injury and stroke along with controls (n≥60) will be pragmatically recruited. Patients will carry out activities of daily living and functional assessments within the Living Lab. The Living Lab is an apartment-laboratory containing a functional kitchen, bathroom, bed and living area to provide a controlled environment to develop novel digital biomarkers. The Living Lab provides an important intermediary stage between the conventional laboratory and the home. Multiple passive environmental sensors, internet-enabled medical devices, wearables and electroencephalography (EEG) will be used to characterise functional impairments of NDDs and non-NDD conditions. We will also relate these digital technology measures to clinical and cognitive outcomes.

ETHICS AND DISSEMINATION

Ethical approvals have been granted by the Imperial College Research Ethics Committee (reference number: 21IC6992). Results from the study will be disseminated at conferences and within peer-reviewed journals.

Predictors of post-intubation hypotension in trauma patients following prehospital emergency anaesthesia: a multi-centre observational study

BACKGROUND

Post-intubation hypotension (PIH) after prehospital emergency anaesthesia (PHEA) is prevalent and associated with increased mortality in trauma patients. The objective of this study was to compare the differential determinants of PIH in adult trauma patients undergoing PHEA.

METHODS

This multi-centre retrospective observational study was performed across three Helicopter Emergency Medical Services (HEMS) in the UK. Consecutive sampling of trauma patients who underwent PHEA using a fentanyl, ketamine, rocuronium drug regime were included, 2015-2020. Hypotension was defined as a new systolic blood pressure (SBP) < 90 mmHg within 10 min of induction, or > 10% reduction if SBP was < 90 mmHg before induction. A purposeful selection logistic regression model was used to determine pre-PHEA variables associated with PIH.

RESULTS

During the study period 21,848 patients were attended, and 1,583 trauma patients underwent PHEA. The final analysis included 998 patients. 218 (21.8%) patients had one or more episode(s) of hypotension ≤ 10 min of induction. Patients > 55 years old; pre-PHEA tachycardia; multi-system injuries; and intravenous crystalloid administration before arrival of the HEMS team were the variables significantly associated with PIH. Induction drug regimes in which fentanyl was omitted (0:1:1 and 0:0:1 (rocuronium-only)) were the determinants with the largest effect sizes associated with hypotension.

CONCLUSION

The variables significantly associated with PIH only account for a small proportion of the observed outcome. Clinician gestalt and provider intuition is likely to be the strongest predictor of PIH, suggested by the choice of a reduced dose induction and/or the omission of fentanyl during the anaesthetic for patients perceived to be at highest risk.

The association between cardiac autonomic system function at the entrance to rehabilitation and walking-endurance two months later among children following-ABI

BACKGROUND

The cardiac autonomic control system function is frequently impaired after brain injury. An association exists between the cardiac autonomic control system and endurance performance.

AIM

To evaluate the association between cardiac autonomic control system indices at the beginning of the inpatient rehabilitation and walking endurance two months later among children and adolescents following acquired brain injury.

METHODS

A prospective study included 28 children and adolescents following acquired brain injury in the sub-acute phase. A Polar device (RS800CX) records heart rate as a proxy measure of autonomic function at sitting and lying supine on admission and two months later. The 6-minute walk test was assessed at the second assessment in 25 participants. Non-parametric tests were used with statistical significance defined as p < 0.05.

RESULTS

There were statistically significant differences in heart rate variability between lying and sitting positions, which were positively correlated with the 6-minutes walk test results two months later, mainly in the parasympathetic components (r_s = 0.51 p-value <0.01).

CONCLUSIONS

At the beginning of the rehabilitation of children and adolescents following acquired brain injury, a simple manipulation - position change from sitting to lying, activates cardiac autonomic control system responses. These responses are positively associated with walking endurance two months later.

High fat diet exacerbates long-term metabolic, neuropathological, and behavioral derangements in an experimental mouse model of traumatic brain injury

AIMS

Traumatic brain injury (TBI) constitutes a serious public health concern. Although TBI targets the brain, it can exert several systemic effects which can worsen the complications observed in TBI subjects. Currently, there is no FDA-approved therapy available for its treatment. Thus, there has been an increasing need to understand other factors that could modulate TBI outcomes. Among the factors involved are diet and lifestyle. High-fat diets (HFD), rich in saturated fat, have been associated with adverse effects on brain health.

MAIN METHODS

To study this phenomenon, an experimental mouse model of open head injury, induced by the controlled cortical impact was used along with high-fat feeding to evaluate the impact of HFD on brain injury outcomes. Mice were fed HFD for a period of two months where several neurological, behavioral, and molecular outcomes were assessed to investigate the impact on chronic consequences of the injury 30 days post-TBI.

KEY FINDINGS

Two months of HFD feeding, together with TBI, led to a notable metabolic, neurological, and behavioral impairment. HFD was associated with increased blood glucose and fat-to-lean ratio. Spatial learning and memory, as well as motor coordination, were all significantly impaired. Notably, HFD aggravated neuroinflammation, oxidative stress, and neurodegeneration. Also, cell proliferation post-TBI was repressed by HFD, which was accompanied by an increased lesion volume.

SIGNIFICANCE

Our research indicated that chronic HFD feeding can worsen functional outcomes, predispose to neurodegeneration, and decrease brain recovery post-TBI. This sheds light on the clinical impact of HFD on TBI pathophysiology and rehabilitation as well.

Fresh Frozen Plasma Increases Hemorrhage in Blunt Traumatic Brain Injury and Uncontrolled Hemorrhagic Shock

BACKGROUND

Blunt traumatic brain injury (bTBI) and uncontrolled hemorrhagic shock (UCHS) are common causes of mortality in polytrauma. We studied the influence of fresh frozen plasma (FFP) resuscitation in a rat model with both bTBI and UCHS before achieving hemorrhage control.

METHODS

The bTBI was induced by an external weight drop (200 g) onto the bare skull of anesthetized male Lewis (Lew/SdNHsd) rats; UCHS was induced by resection of two-thirds of the rats' tails. Fifteen minutes following trauma, bTBI+UCHS rats underwent resuscitation with FFP or lactated Ringer's solution (LR). Eight groups were evaluated: (1) Sham; (2) bTBI; (3) UCHS; (4) UCHS+FFP; (5) UCHS+LR; (6) bTBI+UCHS; (7) bTBI+UCHS+FFP; and (8) bTBI+UCHS+LR. Bleeding volume, hematocrit, lactate, mean arterial pressure (MAP), heart rate, and mortality were measured.

RESULTS

The study included 97 rats that survived the immediate trauma. Mean blood loss up to the start of resuscitation was similar among UCHS only and bTBI+UCHS rats (P=0.361). Following resuscitation, bleeding was more extensive in bTBI+UCHS+FFP rats (5.2 mL, 95% confidence interval [CI] 3.7, 6.6) than in bTBI+UCHS+LR rats (2.5 mL, 95% CI 1.2, 3.8) and bTBI+UCHS rats (1.9 mL, 95% CI 0, 3.9) (P=0.005). Overall mortality increased if bleeding was above 4.5 mL (92.3% versus 8%; P<0.001). Mortality was 83.3% (10/12) in bTBI+UCHS+FFP rats, 41.7% (5/12) in bTBI+UCHS+LR rats, and 64.3% (9/14) in bTBI+UCHS rats.

CONCLUSION

The bTBI did not exacerbate bleeding in rats undergoing UCHS. Compared to LR, FFP resuscitation was associated with a significantly increased blood loss in bTBI+UCHS rats.

The role of the microbiota-gut-brain axis in long-term neurodegenerative processes following traumatic brain injury

Traumatic brain injury (TBI) can be a devastating and debilitating disease to endure. Due to improvements in clinical practice, declining mortality rates have led to research into the long-term consequences of TBI. For example, the incidence and severity of TBI have been associated with an increased susceptibility of developing neurodegenerative disorders, such as Parkinson's or Alzheimer's disease. However, the mechanisms linking this alarming association are yet to be fully understood. Recently, there has been a groundswell of evidence implicating the microbiota-gut-brain axis in the pathogenesis of these diseases. Interestingly, survivors of TBI often report gastrointestinal complaints and animal studies have demonstrated gastrointestinal dysfunction and dysbiosis following injury. Autonomic dysregulation and chronic inflammation appear to be the main driver of these pathologies. Consequently, this review will explore the potential role of the microbiota-gut-brain axis in the development of neurodegenerative diseases following TBI.

Population pharmacokinetic model of vancomycin in postoperative neurosurgical patients

Objective: Vancomycin is commonly used in postoperative neurosurgical patients for empirical anti-infective treatment due to the low success rate of bacterial culture in cerebrospinal fluid (about 20%) and the high mortality of intracranial infection. At conventional doses, the rate of target achievement for vancomycin trough concentration is low and the pharmacokinetics of vancomycin varies greatly in these patients, which often leads to treatment failure. The objective of this study was to establish a population pharmacokinetic (PPK) model of vancomycin in postoperative neurosurgical patients for precision medicine.

Method: A total of 895 vancomycin plasma concentrations from 560 patients (497 postoperative neurosurgical patients) were retrospectively collected. The model was analyzed by nonlinear mixed effects modeling method. One-compartment model and mixed residual model was employed. The influence of covariates on model parameters was tested by forward addition and backward elimination. Goodness-of-fit, bootstrap and visual predictive check were used for model evaluation. Monte Carlo simulations were employed for dosing strategies with AUC₂₄ targets 400–600.

Result: Estimated glomerular filtration rate (eGFR), body weight (BW) and mannitol had significant influence on vancomycin clearance (CL). eGFR(mL/min)=144×(Scr/a)b×0.993age, for female, a = 0.7, Scr ≤ 0.7 mg/dl, b = −0.329, Scr > 0.7 mg/dl, b = −1.209; for male, a = 0.9, Scr ≤ 0.9 mg/dl, b = −0.411, Scr > 0.9 mg/dl, b = −1.210. Vancomycin clearance was accelerated when co-medicated with mannitol and increased with eGFR and BW. In the final model, the population typical value is 7.98 L/h for CL and 60.2 L for apparent distribution volume, CL (L/h)=7.98×(eGFR/115.2)0.8×(BW/70)0.3×eA, where A = 0.13 when co-medicated with mannitol, otherwise A = 0. The model is stable and effective, with good predictability.

Conclusion: In postoperative neurosurgical patients, a higher dose of vancomycin may be required due to the augmented renal function and the commonly used mannitol, especially in those with high body weight. Our vancomycin PPK model could be used for individualized treatment in postoperative neurosurgical patients.

Dynamic nomogram for predicting acute kidney injury in patients with acute ischemic stroke: A retrospective study

Background

This study sought to develop and validate a dynamic nomogram chart to assess the risk of acute kidney injury (AKI) in patients with acute ischemic stroke (AIS).

Methods

These data were drawn from the Medical Information Mart for Intensive Care III (MIMIC-III) database, which collects 47 clinical indicators of patients after admission to the hospital. The primary outcome indicator was the occurrence of AKI within 48 h of intensive care unit (ICU) admission. Independent risk factors for AKI were screened from the training set using univariate and multifactorial logistic regression analyses. Multiple logistic regression models were developed, and nomograms were plotted and validated in an internal validation set. Based on the receiver operating characteristic (ROC) curve, calibration curve, and decision curve analysis (DCA) to estimate the performance of this nomogram.

Results

Nomogram indicators include blood urea nitrogen (BUN), creatinine, red blood cell distribution width (RDW), heart rate (HR), Oxford Acute Severity of Illness Score (OASIS), the history of congestive heart failure (CHF), the use of vancomycin, contrast agent, and mannitol. The predictive model displayed well discrimination with the area under the ROC curve values of 0.8529 and 0.8598 for the training set and the validator, respectively. Calibration curves revealed favorable concordance between the actual and predicted incidence of AKI (p > 0.05). DCA indicates the excellent net clinical benefit of nomogram in predicting AKI.

Conclusion

In summary, we explored the incidence of AKI in patients with AIS during ICU stay and developed a predictive model to help clinical decision-making.

Photosensitivity Is Associated with Chronic Pain following Traumatic Brain Injury

Individuals with a history of traumatic brain injury (TBI) report increased rates of chronic pain. Photosensitivity is also a common chronic symptom following TBI and is prevalent among other types of chronic pain. The aim of this study was to better understand the relationship between chronic pain, pain-related disability, and photosensitivity in a TBI population. We quantified participants' visual photosensitivity thresholds (VPT) using an Ocular Photosensitivity Analyzer and measured pressure-pain sensitivity using pressure algometry. Participants also completed a battery of self-report measures related to chronic pain, TBI history, and mental health. A total of 395 participants completed testing, with 233 reporting a history of TBI. The TBI group was divided into 120 symptomatic TBI participants (s-TBI), and 113 asymptomatic TBI participants (a-TBI) based on their Neurobehavioral Symptom Inventory (NSI) scores. Participants in the s-TBI group scored significantly higher on self-reported chronic pain measures compared with a-TBI and no-TBI participants, including the Symptom Impact Questionnaire Revised (SIQR; p < 0.001) and the Michigan Body Map (MBM; p < 0.001). Despite differences in chronic pain complaints, groups displayed similar pressure-pain thresholds (p = 0.270). Additionally, s-TBI participants were more sensitive to light (lower VPT, p < 0.001), and VPT was correlated with SIQR scores across all participants (R = -0.452, p < 0.001). These data demonstrate that photosensitivity is associated with self-reported chronic pain and disability in individuals with chronic TBI symptomatology. Photosensitivity could therefore serve as a simple, more highly quantitative marker of high-impact chronic pain after TBI.

Assessing the Global Impact on the Mouse Kidney After Traumatic Brain Injury: A Transcriptomic Study

Purpose

In this study, we use animal models combined with bioinformatics strategies to investigate the potential changes in overall renal transcriptional expression after traumatic brain injury.

Methods

Microarray analysis was performed after kidney acquisition using unilateral controlled cortical impact as the primary mouse TBI model. Multi-oriented gene set enrichment analysis was performed for differentially expressed genes.

Results

The results showed that TBI affected the gene set associated with mitochondria function in kidney cells, and a negative enrichment of gene sets associated with immune cell migration and epidermal development was also observed. Analysis of the disease phenotype gene set revealed that differential expression of mitochondria-related genes was associated with lactate metabolism. Alternatively, activation and adhesion of immune cells associated with the complement system may promote autoinflammation in kidney tissue. The simulated immune cell infiltration analysis showed an increase in the proportion of activated memory CD4 T cells and a decrease in the proportion of resting memory CD4 T cells, suggesting that activated memory CD4 T cell infiltration may be involved in the inflammation of renal tissue and cause damage to renal cells, such as principal cells, mesangial cells and loops of Henle cells.

Conclusion

This study is the first to reveal the effects of brain trauma on the kidney. TBI may affect the expression of mitochondria function-related gene sets in renal cells by increasing lactate. It may also affect renal mesangial cells by inducing increased infiltration of immune cells through mechanisms related to complement system activation or autoimmune antibodies.

Plants and their Bioactive Compounds as a Possible Treatment for Traumatic Brain Injury-Induced Multi-Organ Dysfunction Syndrome

BACKGROUND & OBJECTIVE

Traumatic brain injury is an outcome of the physical or mechanical impact of external forces on the brain. Thus, the silent epidemic has complex pathophysiology affecting the brain along with extracranial or systemic complications in more than one organ system, including the heart, lungs, liver, kidney, gastrointestinal and endocrine system. which is referred to as Multi-Organ Dysfunction Syndrome. It is driven by three interconnected mechanisms such as systemic hyperinflammation, paroxysmal sympathetic hyperactivity, and immunosuppression-induced sepsis. These multifaceted pathologies accelerate the risk of mortality in clinical settings by interfering with the functions of distant organs through hypertension, cardiac arrhythmias, acute lung injury, neurogenic pulmonary edema, reduced gastrointestinal motility, Cushing ulcers, acute liver failure, acute kidney injury, coagulopathy, endocrine dysfunction, and many other impairments. The pharmaceutical treatment approach for this is highly specific in its mode of action and linked to a variety of side effects, including hallucinations, seizures, anaphylaxis, teeth, bone staining, etc. Therefore, alternative natural medicine treatments are widely accepted due to their broad complementary or synergistic effects on the physiological system with minor side effects.

CONCLUSION

This review is a compilation of the possible mechanisms behind the occurrence of multiorgan dysfunction and reported medicinal plants with organoprotective activity that have not been yet explored against traumatic brain injury and thereby, highlighting the marked possibilities of their effectiveness in the management of multiorgan dysfunction. As a result, we attempted to respond to the hypothesis against the usage of medicinal plants to treat neurodegenerative diseases.

Correlation between clinical severity and extent of autonomic cardiovascular impairment in the acute phase of subarachnoid hemorrhage

Background and aim

To assess associations between clinical severity and possible dysfunction of autonomic cardiovascular modulation within the acute phase after spontaneous subarachnoid hemorrhage (SAH).

Methods

In this prospective observational study, in 51 patients with spontaneous SAH, Hunt-and-Hess scores (H&H) were assessed and cardiovascular autonomic modulation was monitored within 24 h after SAH-onset. From 5 min time-series of R–R-intervals (RRI) and blood-pressure (BP) recordings, we calculated autonomic parameters including time-domain [RRI-coefficient-of-variation (RRI-CV) and square-root-of-the-mean-squared-differences-of-successive-RRIs (RMSSD)] and frequency-domain parameters [low- and high-frequency-powers of RRI- and BP-modulation (RRI-LF-, RRI-HF-, SBP-LF-powers) and RRI-total-powers]. Data were compared to those of 20 healthy volunteers.

Results

RRI- and BP-values did not differ between groups. Yet, parameters of sympathetic (RRI-LF-powers 141.0 (18.9–402.4) ms² vs 442.3 (246.8–921.2) ms², p = 0.001) and total autonomic modulation (RRI-CV 2.4 (1.2–3.7) ms² vs 3.7 (3.1–5.3) ms², p = 0.001) were significantly lower in patients than in controls. Subgroup analyses (patients with H&H < 3 vs H&H ≥ 3) and Spearman-rank-correlations revealed increasing loss of sympathetic (RRI-LF-powers 338.6 (179.7–710.4) ms² vs 72.1 (10.1–175.9) ms², p = 0.001, rho = − 0.524) and total autonomic modulation (RRI-CV 3.5 (2.3–5.4) ms² vs 1.6 (1.0–2.8) ms², p < 0.001, rho = − 0.519) with higher H&H-scores. Multiple-logistic-regression underlined the significant influence of H&H-scores on sympathetic (RRI-LF-powers, p = 0.033) and total autonomic modulation (RRI-CV, p = 0.040) compared to possible confounders (e.g., age, intubation).

Conclusion

Within the acute phase, spontaneous SAH induces a decrease in sympathetic and total autonomic cardiovascular modulation. Higher H&H-scores were associated with increasing autonomic dysfunction and may therefore augment the risk of cardiovascular complications and poor clinical outcome.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-022-11220-w.

Augmented Renal Clearance in Severe Infections-An Important Consideration in Vancomycin Dosing: A Narrative Review

Vancomycin is a hydrophilic antibiotic widely used in severe infections, including bacteremia and central nervous system (CNS) infections caused by Gram-positive bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), coagulase-negative staphylococci and enterococci. Appropriate antimicrobial dosage regimens can help achieve the target exposure and improve clinical outcomes. However, vancomycin exposure in serum and cerebrospinal fluid (CSF) is challenging to predict due to rapidly changing pathophysiological processes and patient-specific factors. Vancomycin concentrations may be decreased for peripheral infections due to augmented renal clearance (ARC) and increased distribution caused by systemic inflammatory response syndrome (SIRS), increased capillary permeability, and aggressive fluid resuscitation. Additionally, few studies on vancomycin’s pharmacokinetics (PK) in CSF for CNS infections. The relationship between exposure and clinical response is unclear, challenging for adequate antimicrobial therapy. Accurate prediction of vancomycin pharmacokinetics/pharmacodynamics (PK/PD) in patients with high interindividual variation is critical to increase the likelihood of achieving therapeutic targets. In this review, we describe the interaction between ARC and vancomycin PK/PD, patient-specific factors that influence the achievement of target exposure, and recent advances in optimizing vancomycin dosing schedules for severe infective patients with ARC.

Prognostic Factors for Stage 3 Acute Kidney Injury in Isolated Serious Traumatic Brain Injury

BACKGROUND

Stage 3 acute kidney injury (AKI) has been observed to develop following serious traumatic brain injury (TBI) and is associated with worse outcomes, though its incidence is not consistently established. This study aims to report the incidence of stage 3 AKI in serious isolated TBI in a large, national trauma database, and explore associated predictive factors.

METHODS

This was a retrospective cohort study using 2015-2018 data from the American College of Surgeons Trauma Quality Improvement Program (ACS-TQIP), a national database of trauma patients. Adult trauma patients admitted to the hospital with isolated serious TBI were included. Variables relating to demographics, comorbidities, vitals, hospital presentation, and course of stay were assessed. Imputed multivariable logistic regression assessed factors predictive of stage 3 AKI development.

RESULTS

A total of 342,675 patients with isolated serious TBI were included, 1,585 (0.5%) of whom developed stage 3 AKI. Variables associated with stage 3 AKI in multivariable analysis were older age, male sex, Black race, higher BMI, history of hypertension, diabetes, peripheral artery disease, chronic kidney disease, higher injury severity score, higher heart rate on arrival, lower oxygen saturation and motor Glasgow coma scale (GCS), admission to the intensive care unit (ICU) or operating room, development of catheter-associated urinary tract infections (CAUTI) or acute respiratory distress syndrome (ARDS), longer ICU stay and ventilation duration.

CONCLUSIONS

Stage 3 AKI occurred in 0.5% of serious TBI cases. Complications of ARDS and CAUTI are more likely to co-occur with stage 3 AKI in serious TBI patients.

Vestibular-autonomic interactions: beyond orthostatic dizziness

PURPOSE OF REVIEW

This review aims to summarize the current literature describing vestibular-autonomic interactions and to describe their putative role in various disorders' clinical presentations, including orthostatic dizziness and motion sensitivity.

RECENT FINDINGS

The vestibular-autonomic reflexes have long been described as they relate to cardiovascular and respiratory function. Although orthostatic dizziness may be in part related to impaired vestibulo-sympathetic reflex (orthostatic hypotension), there are various conditions that may present similarly. A recent clinical classification aims to improve identification of individuals with hemodynamic orthostatic dizziness so that appropriate recommendations and management can be efficiently addressed. Researchers continue to improve understanding of the underlying vestibular-autonomic reflexes with recent studies noting the insular cortex as a cortical site for vestibular sensation and autonomic integration and modulation. Work has further expanded our understanding of the clinical presentation of abnormal vestibular-autonomic interactions that may occur in various conditions, such as aging, peripheral vestibular hypofunction, traumatic brain injury, and motion sensitivity.

SUMMARY

The vestibular-autonomic reflexes affect various sympathetic and parasympathetic functions. Understanding these relationships will provide improved identification of underlying etiology and drive improved patient management.

The benefits of exercise for outcome improvement following traumatic brain injury: Evidence, pitfalls and future perspectives

Traumatic brain injury (TBI), also known as a silent epidemic, is currently a substantial public health problem worldwide. Given the increased energy demands following brain injury, relevant guidelines tend to recommend absolute physical and cognitive rest for patients post-TBI. Nevertheless, recent evidence suggests that strict rest does not provide additional benefits to patients' recovery. By contrast, as a cost-effective non-pharmacological therapy, exercise has shown promise for enhancing functional outcomes after injury. This article summarizes the most recent evidence supporting the beneficial effects of exercise on TBI outcomes, focusing on the efficacy of exercise for cognitive recovery after injury and its potential mechanisms. Available evidence demonstrates the potential of exercise in improving cognitive impairment, mood disorders, and post-concussion syndrome following TBI. However, the clinical application for exercise rehabilitation in TBI remains challenging, particularly due to the inadequacy of the existing clinical evaluation system. Also, a better understanding of the underlying mechanisms whereby exercise promotes its most beneficial effects post-TBI will aid in the development of new clinical strategies to best benefit of these patients.

Paroxysmal sympathetic hyperactivity during traumatic brain injury

Traumatic brain injury (TBI) is one of the leading causes of disability, morbidity, and mortality worldwide. Some of the more common etiologies of TBI include closed head injury, penetrating head injury, or an explosive blast head injury. Neuronal damage in TBI is related to both primary injury (caused by mechanical forces), and secondary injury (caused by the subsequent tissue and cellular damages). Recently, it has been well established that Paroxysmal Sympathetic Hyperactivity (PSH), also known as "Sympathetic Storm", is one of the main causes of secondary neuronal injury in TBI patients. The clinical manifestations of PSH include recurrent episodes of sympathetic hyperactivity characterized by tachycardia, systolic hypertension, hyperthermia, tachypnea with hyperpnea, and frank diaphoresis. Given the diverse manifestations of PSH and its notable impact on the outcome of TBI patients, we have comprehensively reviewed the current evidence and discussed the pathophysiology, clinical manifestations, time of onset and duration of PSH during TBI. This article reviews the different types of head injuries that most commonly lead to PSH, possible approaches to manage and minimize PSH complications in TBI and the current prognosis and outcomes of PSH in TBI patients.

Augmented Renal Clearance: What Have We Known and What Will We Do?

Augmented renal clearance (ARC) is a phenomenon of increased renal function in patients with risk factors. Sub-therapeutic drug concentrations and antibacterial exposure in ARC patients are the main reasons for clinical treatment failure. Decades of increased research have focused on these phenomena, but there are still some existing disputes and unresolved issues. This article reviews information on some important aspects of what we have known and provides suggestion on what we will do regarding ARC. In this article, we review the current research progress and its limitations, including clinical identification, special patients, risk factors, metabolism, animal models and clinical treatments, and provide some promising directions for further research in this area.

Analysis of Brain Natriuretic Peptide Levels after Traumatic Acute Subdural Hematoma and the Risk of Post-Operative Cerebral Infarction

Traumatic acute subdural hematoma (aSDH) is associated with a high mortality rate caused by post-operative cerebral infarction. Recently, brain natriuretic peptide (BNP) was considered a reliable biomarker in the acute phase of traumatic brain injuries. We therefore aimed in this study to analyze BNP levels on admission, identify the predictors of their elevation, and assess the relationship between BNP and the risk of post-operative cerebral infarction. Patients with isolated, unilateral, traumatic aSDH who were admitted to our department between July 2017 and May 2020 were enrolled in this study. On admission, cranial computer tomography (CCT) and BNP sampling were simultaneously performed. Additionally, the time between head trauma and BNP sampling (TTS) was assessed. Admission radiographic variables included hematoma volumes, midline shift, and degree of brain edema. Cerebral infarction was detected on postoperative CCT. In total, 130 patients were included in this study. Surgical treatment was performed in 82.3% (n = 107) of cases. The multiple regression analysis showed that larger hematoma volumes (p = 0.032) and advanced age (p = 0.005) were independent predictors of elevated BNP when TTS <24 h. The binomial logistical regression analysis identified BNP with a cutoff value of <29.4 pg/mL (TTS = 3-12 h, adjusted odds ratio [aOR] = 16.5, p = 0.023) as an independent predictor of post-operative cerebral infarction. Elevated BNP levels in the first 24 h post-trauma were related to larger hematoma volumes and advanced age. Further, an increased risk of post-operative cerebral infarction was identified in patients with lower BNP levels in the post-traumatic period 3-12 h.

Brain Injury and Mental Health Among the Victims of Intimate Partner Violence: A Case-Series Exploratory Study

Intimate partner violence (IPV) survivors frequently report face, head, and neck as their injury site. Many mild traumatic brain injuries (TBIs) are undiagnosed or underreported among IPV survivors while these injuries may be linked to changes in brain function or pathology. TBI sustained due to IPV often occurs over time and ranges in severity. The aim of this case-series study was to explore risk factors, symptoms, and brain changes unique to survivors of intimate partner violence with suspicion of TBI. This case-series exploratory study examines the potential relationships among IPV, mental health issues, and TBI. Participants of this study included six women: 3 women with a history of IPV without any experience of concussive blunt force to the head, and 3 women with a history of IPV with concussive head trauma. Participants completed 7T MRI of the brain, self-report psychological questionnaires regarding their mental health, relationships, and IPV, and the Structured Clinical Interview. MRI scans were analyzed for cerebral hemorrhage, white matter disturbance, and cortical thinning. Results indicated significant differences in resting-state connectivity among survivors of partner violence as well as differences in relationship dynamics and mental health symptoms. White matter hyperintensities are also observed among the survivors. Developing guidelines and recommendations for TBI-risk screening, referrals, and appropriate service provision is crucial for the effective treatment of TBI-associated IPV. Early and accurate characterization of TBI in survivors of IPV may relieve certain neuropsychological consequences.

Acute Kidney Injury at the Neurocritical Care Unit

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

Associations of initial haemodynamic profiles and neurological outcomes in children with traumatic brain injury: a secondary analysis

INTRODUCTION

Initial low systolic blood pressure (SBP) in paediatric traumatic brain injury (TBI) is associated with mortality. There is limited literature on how other haemodynamic parameters including heart rate (HR); diastolic blood pressure (DBP); mean arterial pressure (MAP); and shock index, paediatric age-adjusted (SIPA) affect not only mortality but also long-term neurological outcomes in paediatric TBI. We aimed to analyse the associations of these haemodynamic variables (HR, SBP, MAP, DBP and SIPA) with mortality and long-term neurological outcomes in isolated moderate-to-severe paediatric TBI.

METHODS

This was a secondary analysis of our primary study that analysed the association of TBI-associated coagulopathy with mortality and neurological outcome in isolated, moderate-to-severe paediatric head injury. A trauma registry-based, retrospective study of children <18 years old who presented to the emergency department with isolated, moderate-to-severe TBI from January 2010 to December 2016 was conducted. The association between initial haemodynamic variables and less favourable outcomes using Glasgow Outcome Scale-Extended Paediatric) at 6 months post injury was analysed using logistic regression.

RESULTS

Among 152 children analysed, initial systolic and diastolic hypotension (<5th percentile) (OR) for SBP 11.40, 95% CI 3.60 to 36.05, p<0.001; OR for DBP 15.75, 95% CI 3.09 to 80.21, p<0.001) and Glasgow Coma Scale scores <8 (OR 14.50, 95% CI 3.65 to 57.55, p<0.001) were associated with 'moderate-to-severe neurological disabilities', 'vegetative state' and 'death'. After adjusting for confounders, only SBP was significant (adjusted OR 5.68, 95% CI 1.40 to 23.08, p=0.015).

CONCLUSIONS

Initial systolic hypotension was independently associated with mortality and moderate-to-severe neurological deficits at 6 months post injury. Further work is required to understand if early correction of hypotension will improve long-term outcomes.

Clinical and histopathological studies on neurodegeneration and dysautonomia in buffalo calves during foot-and-mouth disease outbreaks in Egypt

Background and Aim

Signs of dysautonomia were frequently observed in calves that died during foot-and-mouth disease (FMD) virus (FMDV) outbreaks in Egypt from 2015 to 2018. This study aimed to describe the clinical and histopathological features of the central nervous system in malignant cases of FMD and excluding possible concurrent bacterial, and bovine herpes virus 4 (BHV4) infections or both.

Materials and Methods

In this study, 335 FMDV-infected buffalo calves aged 1-22 months were clinically examined and followed until recovery or death. Of the 335 calves, 134 died (malignant group) and 201 recovered after exhibiting classic symptoms of FMD (recover group). The calves were subjected to clinical examination. For the malignant group, several laboratory trials were conducted to assess the possible cause/s of dysautonomia-related viral, bacterial, or concurrent infections. Koch's postulates and polymerase chain reaction were employed. Postmortem and histopathological examinations of nervous tissue were performed.

Results

In the malignant group, signs of dysautonomia were observed before death, including partial or complete gut dysfunction, loss of anal sphincter tone, rapid breathing sounds, fluctuating body temperature, and cardiac arrhythmias. In the malignant group, histopathological examination of the spinal cord, pons, medulla oblongata, hypothalamus, cerebellum, and cerebrum revealed demyelination, neuronal degeneration, and focal areas of malacia and gliosis. The nervous tissue and heart samples from malignant cases were positive for serotype O FMDV.

Conclusion

Findings revealed in this study support the existence of neurodegeneration induced by FMDV infection in buffalo calves.

Admission Features Associated With Paroxysmal Sympathetic Hyperactivity After Traumatic Brain Injury: A Case-Control Study

OBJECTIVES

Paroxysmal sympathetic hyperactivity occurs in a subset of critically ill traumatic brain injury patients and has been associated with worse outcomes after traumatic brain injury. The goal of this study was to identify admission risk factors for the development of paroxysmal sympathetic hyperactivity in traumatic brain injury patients.

DESIGN

Retrospective case-control study of age- and Glasgow Coma Scale-matched traumatic brain injury patients.

SETTING

Neurotrauma ICU at the R. Adams Cowley Shock Trauma Center of the University of Maryland Medical System, January 2016 to July 2018.

PATIENTS

Critically ill adult traumatic brain injury patients who underwent inpatient monitoring for at least 14 days were included. Cases were identified based on treatment for paroxysmal sympathetic hyperactivity with institutional first-line therapies and were confirmed by retrospective tabulation of established paroxysmal sympathetic hyperactivity diagnostic and severity criteria. Cases were matched 1:1 by age and Glasgow Coma Scale to nonparoxysmal sympathetic hyperactivity traumatic brain injury controls, yielding 77 patients in each group.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Admission characteristics independently predictive of paroxysmal sympathetic hyperactivity included male sex, higher admission systolic blood pressure, and initial CT evidence of diffuse axonal injury, intraventricular hemorrhage/subarachnoid hemorrhage, complete cisternal effacement, and absence of contusion. Paroxysmal sympathetic hyperactivity cases demonstrated significantly worse neurologic outcomes upon hospital discharge despite being matched for injury severity at admission.

CONCLUSIONS

Several anatomical, epidemiologic, and physiologic risk factors for clinically relevant paroxysmal sympathetic hyperactivity can be identified on ICU admission. These features help characterize paroxysmal sympathetic hyperactivity as a clinical-pathophysiologic phenotype associated with worse outcomes after traumatic brain injury.

Predictors of Brain Natriuretic Peptide Serum Level Elevation in Patients with Symptomatic Chronic Subdural Hematoma: A Prospective Study

Background: Brain natriuretic peptide serum levels (BNP) on admission are frequently elevated in patients with symptomatic chronic subdural hematoma (cSDH) and predict unfavorable long-term functional outcomes. However, the reasons for these elevated levels remain unclear. Therefore, we aimed to identify the predictors of BNP elevation. Methods: Patients with unilateral symptomatic cSDH who were surgically treated in our department between November 2016 and May 2020 were enrolled. Patients’ symptoms and neurological deficits were prospectively assessed using a study questionnaire. On initial computer tomography, hematoma volumes and midline shift (MLS) values were measured to analyze the degree of brain compression. Results: In total, 100 patients were analyzed. Linear regression analysis showed that higher BNP levels were significantly associated with smaller hematoma volumes (p = 0.003) and littler MLS values (p = 0.022). Multivariate analysis revealed that presence of a neurological deficit (p = 0.041), a hematoma volume < 140 mL (p = 0.047), advanced age (p = 0.023), and head trauma within 24 h of admission (p = 0.001) were independent predictors of BNP elevation. Conclusion: In symptomatic cSDH, BNP elevation is related, among others, to the presence of neurological deficits and smaller hematoma volumes. Whether BNP elevation may coincide with the early stage of hematoma growth, i.e., immaturity of cSDH neomembrane, requires further investigations.

Fecal Microbiota Transplantation Is a Promising Method to Restore Gut Microbiota Dysbiosis and Relieve Neurological Deficits after Traumatic Brain Injury

BACKGROUND

Traumatic brain injury (TBI) can induce persistent fluctuation in the gut microbiota makeup and abundance. The present study is aimed at determining whether fecal microbiota transplantation (FMT) can rescue microbiota changes and ameliorate neurological deficits after TBI in rats.

METHODS

A controlled cortical impact (CCI) model was used to simulate TBI in male Sprague-Dawley rats, and FMT was performed for 7 consecutive days. 16S ribosomal RNA (rRNA) sequencing of fecal samples was performed to analyze the effects of FMT on gut microbiota. Modified neurological severity score and Morris water maze were used to evaluate neurobehavioral functions. Metabolomics was used to screen differential metabolites from the rat serum and ipsilateral brains. The oxidative stress indices were measured in the brain.

RESULTS

TBI induced significance changes in the gut microbiome, including the alpha- and beta-bacterial diversity, as well as the microbiome composition at 8 days after TBI. On the other hand, FMT could rescue these changes and relieve neurological deficits after TBI. Metabolomics results showed that the level of trimethylamine (TMA) in feces and the level of trimethylamine N-oxide (TMAO) in the ipsilateral brain and serum was increased after TBI, while FMT decreased TMA levels in the feces, and TMAO levels in the ipsilateral brain and serum. Antioxidant enzyme methionine sulfoxide reductase A (MsrA) in the ipsilateral hippocampus was decreased after TBI but increased after FMT. In addition, FMT elevated SOD and CAT activities and GSH/GSSG ratio and diminished ROS, GSSG, and MDA levels in the ipsilateral hippocampus after TBI.

CONCLUSIONS

FMT can restore gut microbiota dysbiosis and relieve neurological deficits possibly through the TMA-TMAO-MsrA signaling pathway after TBI.

Distant Organ Damage in Acute Brain Injury

Acute brain injuries pose a great threat to global health, having significant impact on mortality and disability. Patients with acute brain injury may develop distant organ failure, even if no systemic diseases or infection is present. The severity of non-neurologic organs' dysfunction depends on the extremity of the insult to the brain. In this comprehensive review we sought to describe the organ-related consequences of acute brain injuries. The clinician should always be aware of the interplay between central nervous system and non-neurological organs, that is constantly present. Cerebral injury is not only a brain disease, but also affects the body as whole, and thus requires holistic therapeutical approach.

Effectiveness of Pharmacological Agents and Validation of Diagnostic Scales for the Management of Paroxysmal Sympathetic Hyperactivity in Hispanics

The identification and treatment of paroxysmal sympathetic hyperactivity (PSH) still present a significant challenge. We assessed the efficacy of pharmacological agents in treating PSH symptoms and the validity of the diagnostic scales in a cohort of Hispanic patients. A retrospective chart review of cases from a single hospital was conducted in 464 records. Exclusion criteria included underlying conditions such as severe infection. Only nine patients remained in the cohort after examining their clinical records, corresponding to the following diagnoses: traumatic brain injury, subdural hemorrhage, anoxic or ischemic encephalopathy, pneumocephalus, and cerebral palsy. Using the PSH likelihood scale, six of the nine patients were identified with a score of 17 or higher, corresponding to a "probable" PSH, and three patients obtained a score between 8 and 16, corresponding to a "possible" PSH diagnosis. The top three classes of medications used were beta-blockers, antipyretics, and opioids. Benzodiazepines and neuromodulators were also frequently used in patients with trauma, but not in the ones with non-traumatic injuries. Interestingly, 75% of the patients have prescribed levothyroxine as a home medication after the PSH presentation. Medication administration did not follow a specific pattern, suggesting high variability in the management of PSH within our setting, requiring further research. Our results suggest that the pituitary axis might be involved in the progression of PSH. Establishing a specific medical code (e.g., ICD-10) describing PSH as a single entity is essential for appropriate identification and management.

Acute kidney injury after brain injury: does it exist?

Acute kidney injury (AKI) is frequent after cerebral insults, with an incidence close to 10% in both traumatic brain injury (TBI) and cerebrovascular disease. AKI in this context has substantial impact on mortality and neurological outcome. Numerous factors may play a role in the development of AKI after brain injury: intravascular volume depletion, raised-intra-abdominal pressure, rhabdomyolysis or sepsis in TBI; age, ischemic heart disease or arteriosclerotic disease in stroke. However, brain-kidney crosstalk mechanisms are complex and there remains a strong rationale for a causal relationship between brain and kidney injury. Cerebral lesions might alter renal function through a neuro-endocrine pathway combining sympathetic system, renin-angiotensin-aldosterone and glucocorticoid activation. Altogether these systems impair renal autoregulation ultimately leading to AKI. In addition, cerebral lesions might lead to a systemic inflammatory response making the kidney vulnerable for dysfunction. Indeed, inflammation and immune system activation are core mechanisms for the development of AKI. Last, direct lesions of specific area of the brain might lead to vasomotor changes and AKI. In this work, we reviewed the epidemiology of AKI after brain injury and examine potential mechanisms suggesting a causal relationship between these two entities.

Organic features of autonomic dysregulation in paediatric brain injury - Clinical and research implications for the management of patients with Rett syndrome

Rett Syndrome (RTT) is a complex neurodevelopmental disorder with autonomic nervous system dysfunction. The understanding of this autonomic dysregulation remains incomplete and treatment recommendations are lacking. By searching literature regarding childhood brain injury, we wanted to see whether understanding autonomic dysregulation following childhood brain injury as a prototype can help us better understand the autonomic dysregulation in RTT. Thirty-one (31) articles were identified and following thematic analysis the three main themes that emerged were (A) Recognition of Autonomic Dysregulation, (B) Possible Mechanisms & Assessment of Autonomic Dysregulation and (C) Treatment of Autonomic Dysregulation. We conclude that in patients with RTT (I) anatomically, thalamic and hypothalamic function should be explored, (II) sensory issues and medication induced side effects that can worsen autonomic function should be considered, and (III) diaphoresis and dystonia ought to be better managed. Our synthesis of data from autonomic dysregulation in paediatric brain injury has led to increased knowledge and a better understanding of its underpinnings, leading to the development of application protocols in children with RTT.

Placement of Surgical Feeding Tubes Among Patients With Severe Traumatic Brain Injury Requiring Exploratory Abdominal Surgery : Better Early Than Late

OBJECTIVES

The purpose of this study was to identify trauma patients who would benefit from surgical placement of an enteral feeding tube during their index abdominal trauma operation.

METHODS

We performed a retrospective analysis of all patients admitted to 2 level I trauma centers between January 2013 and February 2018 requiring urgent exploratory abdominal surgery.

RESULTS

Six-hundred and one patients required exploratory abdominal surgery within 24 hours of admission after trauma activation. Nineteen (3% of total) patients underwent placement of a feeding tube after their initial exploratory surgery. On multivariate analysis, an intracranial Abbreviated Injury Scale ≥4 (odds ratio [OR] = 9.24, 95% CI 1.09-78.26, P = .04) and a Glasgow Coma Scale ≤8 (OR = 4.39, 95% CI 1.38-13.95, P = .01) were associated with increased odds of requiring a feeding tube. All patients who required a feeding tube had an Injury Severity Score ≥15. While not statistically significant, patients with an open surgical feeding tube compared with interventional radiology/percutaneous endoscopic gastrostomy placement had lower median intensive care unit length of stay, fewer ventilator days, and shorter median total hospital length of stay.

CONCLUSIONS

Trauma patients with severe intracranial injury already requiring urgent exploratory abdominal surgery may benefit from early, concomitant placement of a feeding tube during the index abdominal operation, or at fascial closure.

Analysis of Brain Natriuretic Peptide Serum Levels in Patients with Symptomatic Chronic Subdural Hematoma: A Potential Reliable Biomarker

The purpose of this study was to analyze brain natriuretic peptide (BNP) serum levels of patients with chronic subdural hematoma (cSDH) and their clinical implication. Patients with cSDH who underwent surgery in our department between November 2016 and October 2019 were eligible for enrollment in the study. Patients with recurrent bleedings, traumatic brain injury, cSDH associated with other intracranial pathologies, and those with a history of congestive heart failure, renal or endocrine disease were excluded. We measured BNP serum levels pre- and post-operatively and at discharge. The BNP values were analyzed with respect to patient medical history and neurological condition. The Glasgow Coma Scale score and the modified Rankin Scale score classified the clinical and neurological condition at the time of admission and discharge, respectively. The data of 100 surgically treated patients with cSDH (mean age 73.2, range 42 − 94 years, male/female 3.5:1) were analyzed. Pre-operative BNP serum levels (BNP-1) were elevated in 67% of the patients (n = 67; median = 101.6 pg/mL; p < 0.001). These serum levels increased after surgery (p < 0.001) and decreased thereafter (p < 0.001), reaching a level at discharge (day 7) that was not statistically different from BNP-1 (p > 0.05). In addition, elevated BNP-1 showed a significant statistical association with the presence of atrial fibrillation (p < 0.01) and antiplatelet and/or anticoagulant therapy (p < 0.01). This study provides new evidence regarding BNP serum levels and their secretion pattern in patients with cSDH. Whether BNP-1 can predict the long-term functional outcome of patients with cSDH is being investigated in this ongoing prospective study.