Causes of Death Following 1 Year Postinjury Among Individuals With Traumatic Brain Injury

Cardiorespiratory fitness assessment and training in the early sub-acute phase of recovery following traumatic brain injury: a systematic review

OBJECTIVES

To examine the safety of cardiorespiratory fitness (CRF) assessment and training in the early sub-acute phase of recovery (≤3 months) following moderate-to-extremely severe traumatic brain injury (TBI).

METHODS

A systematic review was completed in accordance with the PRISMA guidelines. Studies investigating adults and adolescents ≥15 years with moderate-to-extremely severe TBI were considered for inclusion. The methodological quality of the included studies was evaluated according to the McMaster Guidelines for Critical Review Form - Quantitative Studies.

RESULTS

Eleven studies with a total of 380 participants were included in the review. Adverse events (AEs) and symptom monitoring were poorly reported. Only four studies reported on the occurrence of AEs, with a total of eight AEs reported. Three of the reported AEs were concussion-like symptoms with no further exercise-induced symptom exacerbation reported. No serious AEs were reported.

CONCLUSION

There is no evidence to suggest that CRF assessment and training is unsafe in the early sub-acute phase of recovery following moderate-to-extremely severe TBI. However, despite the low AE and symptom exacerbation rates identified, a timeframe for safe commencement was unable to be established due to poor reporting and/or monitoring of exercise-induced symptoms and AEs in the current literature.

Dysregulated brain-gut axis in the setting of traumatic brain injury: review of mechanisms and anti-inflammatory pharmacotherapies

Traumatic brain injury (TBI) is a chronic and debilitating disease, associated with a high risk of psychiatric and neurodegenerative diseases. Despite significant advancements in improving outcomes, the lack of effective treatments underscore the urgent need for innovative therapeutic strategies. The brain-gut axis has emerged as a crucial bidirectional pathway connecting the brain and the gastrointestinal (GI) system through an intricate network of neuronal, hormonal, and immunological pathways. Four main pathways are primarily implicated in this crosstalk, including the systemic immune system, autonomic and enteric nervous systems, neuroendocrine system, and microbiome. TBI induces profound changes in the gut, initiating an unrestrained vicious cycle that exacerbates brain injury through the brain-gut axis. Alterations in the gut include mucosal damage associated with the malabsorption of nutrients/electrolytes, disintegration of the intestinal barrier, increased infiltration of systemic immune cells, dysmotility, dysbiosis, enteroendocrine cell (EEC) dysfunction and disruption in the enteric nervous system (ENS) and autonomic nervous system (ANS). Collectively, these changes further contribute to brain neuroinflammation and neurodegeneration via the gut-brain axis. In this review article, we elucidate the roles of various anti-inflammatory pharmacotherapies capable of attenuating the dysregulated inflammatory response along the brain-gut axis in TBI. These agents include hormones such as serotonin, ghrelin, and progesterone, ANS regulators such as beta-blockers, lipid-lowering drugs like statins, and intestinal flora modulators such as probiotics and antibiotics. They attenuate neuroinflammation by targeting distinct inflammatory pathways in both the brain and the gut post-TBI. These therapeutic agents exhibit promising potential in mitigating inflammation along the brain-gut axis and enhancing neurocognitive outcomes for TBI patients.

Prevalence of Cardiovascular Conditions After Traumatic Brain Injury: A Comparison Between the Traumatic Brain Injury Model Systems and the National Health and Nutrition Examination Survey

BACKGROUND

The purpose of this study is to compare the prevalence of self-reported cardiovascular conditions among individuals with moderate to severe traumatic brain injury (TBI) to a propensity-matched control cohort.

METHODS AND RESULTS

A cross-sectional study described self-reported cardiovascular conditions (hypertension, congestive heart failure [CHF], myocardial infarction [MI], and stroke) from participants who completed interviews between January 2015 and March 2020 in 2 harmonized large cohort studies, the TBI Model Systems and the National Health and Nutrition Examination Survey. Mixed-effect logistic regression models were used to compare the prevalence of cardiovascular conditions after 1:1 propensity-score matching based on age, sex, race, ethnicity, body mass index, education level, and smoking status. The final sample was 4690 matched pairs. Individuals with TBI were more likely to report hypertension (odds ratio [OR], 1.18 [95% CI, 1.08-1.28]) and stroke (OR, 1.70 [95% CI, 1.56-1.98]) but less likely to report CHF (OR, 0.81 [95% CI, 0.67-0.99]) or MI (OR, 0.66 [95% CI, 0.55-0.79]). There was no difference in rate of CHF or MI for those ≤50 years old; however, rates of CHF and MI were lower in the TBI group for individuals >50 years old. Over 65% of individuals who died before the first follow-up interview at 1 year post-TBI were >50 years old, and those >50 years old were more likely to die of heart disease than those ≤50 years old (17.6% versus 8.6%).

CONCLUSIONS

Individuals with moderate to severe TBI had an increased rate of self-reported hypertension and stroke but lower rate of MI and CHF than uninjured adults, which may be due to survival bias.

Experimental Models of Hospital-Acquired Infections After Traumatic Brain Injury: Challenges and Opportunities

Patients hospitalized after a moderate or severe traumatic brain injury (TBI) are at increased risk of nosocomial infections, including bacterial pneumonia and other upper respiratory tract infections. Infections represent a secondary immune challenge for vulnerable TBI patients that can lead to increased morbidity and poorer long-term prognosis. This review first describes the clinical significance of infections after TBI, delving into the known mechanisms by which a TBI can alter systemic immunological responses towards an immunosuppressive state, leading to promotion of increased vulnerability to infections. Pulmonary dysfunction resulting from respiratory tract infections is considered in the context of neurotrauma, including the bidirectional relationship between the brain and lungs. Turning to pre-clinical modeling, current laboratory approaches to study experimental TBI and lung infections are reviewed, to highlight findings from the limited key studies to date that have incorporated both insults. Then, practical decisions for the experimental design of animal studies of post-injury infections are discussed. Variables associated with the host animal, the infectious agent (e.g., species, strain, dose, and administration route), as well as the timing of the infection relative to the injury model are important considerations for model development. Together, the purpose of this review is to highlight the significant clinical need for increased pre-clinical research into the two-hit insult of a hospital-acquired infection after TBI to encourage further scientific enquiry in the field.

Acute gastrointestinal permeability after traumatic brain injury in mice precedes a bloom in Akkermansia muciniphila supported by intestinal hypoxia

Traumatic brain injury (TBI) increases gastrointestinal morbidity and associated mortality. Clinical and preclinical studies implicate gut dysbiosis as a consequence of TBI and an amplifier of brain damage. However, little is known about the association of gut dysbiosis with structural and functional changes of the gastrointestinal tract after an isolated TBI. To assess gastrointestinal dysfunction, mice received a controlled cortical impact or sham brain injury and intestinal permeability was assessed at 4 h, 8 h, 1 d, and 3 d after injury by oral administration of 4 kDa FITC Dextran prior to euthanasia. Quantification of serum fluorescence revealed an acute, short-lived increase in permeability 4 h after TBI. Despite transient intestinal dysfunction, no overt morphological changes were evident in the ileum or colon across timepoints from 4 h to 4 wks post-injury. To elucidate the timeline of microbiome changes after TBI, 16 s gene sequencing was performed on DNA extracted from fecal samples collected prior to and over the first month after TBI. Differential abundance analysis revealed that the phylum Verrucomicrobiota was increased at 1, 2, and 3 d after TBI. The Verrucomicrobiota species was identified by qPCR as Akkermansia muciniphila, an obligate anaerobe that resides in the intestinal mucus bilayer and produces short chain fatty acids (e.g. butyrate) utilized by intestinal epithelial cells. We postulated that TBI promotes intestinal changes favorable for the bloom of A. muciniphila. Consistent with this premise, the relative area of mucus-producing goblet cells in the medial colon was significantly increased at 1 d after injury, while colon hypoxia was significantly increased at 3 d. Our findings reveal acute gastrointestinal functional changes coupled with an increase of beneficial bacteria suggesting a potential compensatory response to systemic stress after TBI.

NCOA4-mediated ferritinophagy aggravate intestinal oxidative stress and ferroptosis after traumatic brain injury

Intestinal injury caused by traumatic brain injury (TBI) seriously affects patient prognosis; however, the underlying mechanisms are unknown. Recent studies have demonstrated that ferritinophagy-mediated ferroptosis is involved in several intestinal disorders. However, uncertainty persists regarding the role of ferritinophagy-mediated ferroptosis in the intestinal damage caused by TBI. High-throughput transcriptional sequencing was used to identify the genes that were differentially expressed in the intestine after TBI. The intestinal tissues were harvested for hematoxylin and eosin staining (HE), immunofluorescence, and western blot (WB). Lipid peroxide markers and iron content in the intestines were determined using the corresponding kits. High throughput sequencing revealed that the ferroptosis signaling pathway was enriched, demonstrating that intestinal damage caused by TBI may include ferroptosis. Chiu's score, tight junction proteins, and lipid peroxide indicators demonstrated that TBI caused an intestinal mucosal injury that persisted for several days. The ferroptosis pathway-related proteins, ferritin heavy polypeptide 1 (Fth1) and glutathione peroxidase 4 (GPX4), exhibited dynamic changes. The results indicated that lipid peroxide products were markedly increased, whereas antioxidant enzymes were markedly decreased. WB analysis demonstrated that the expression levels of nuclear receptor coactivator 4 (NCOA4), LC3II/LC3I, and p62 were markedly upregulated, whereas those of GPX4 and Fth1 were markedly downregulated. In addition, ferrostatin-1 attenuates intestinal ferroptosis and injury post-TBI in vivo. Intriguingly, 3-methyladenine (3-MA) reduces intestinal ferritin decomposition, iron accumulation, and ferroptosis after TBI. Moreover, 3-MA markedly reduced intestinal apoptosis. In conclusion, NCOA4 mediated ferritinophagy and ferroptosis play roles in intestinal oxidative stress injury post-TBI. This study provides a deeper understanding of the mechanisms underlying intestinal damage following TBI.

Host-Microbiome Interactions: Tryptophan Metabolism and Aromatic Hydrocarbon Receptors after Traumatic Brain Injury

Traumatic brain injury refers to the damage caused to intracranial tissues by an external force acting on the head, leading to both immediate and prolonged harmful effects. Neuroinflammatory responses play a critical role in exacerbating the primary injury during the acute and chronic phases of TBI. Research has demonstrated that numerous neuroinflammatory responses are mediated through the "microbiota-gut-brain axis," which signifies the functional connection between the gut microbiota and the brain. The aryl hydrocarbon receptor (AhR) plays a vital role in facilitating communication between the host and microbiota through recognizing specific ligands produced directly or indirectly by the microbiota. Tryptophan (trp), an indispensable amino acid in animals and humans, represents one of the key endogenous ligands for AhR. The metabolites of trp have significant effects on the functioning of the central nervous system (CNS) through activating AHR signalling, thereby establishing bidirectional communication between the gut microbiota and the brain. These interactions are mediated through immune, metabolic, and neural signalling mechanisms. In this review, we emphasize the co-metabolism of tryptophan in the gut microbiota and the signalling pathway mediated by AHR following TBI. Furthermore, we discuss the impact of these mechanisms on the underlying processes involved in traumatic brain injury, while also addressing potential future targets for intervention.

Traumatic brain injury as a chronic disease: insights from the United States Traumatic Brain Injury Model Systems Research Program

Traumatic brain injury (TBI) is a global health priority, associated with substantial burden. Historically conceptualised as an injury event with finite recovery, TBI is now recognised as a chronic condition that can affect multiple domains of health and function, some of which might deteriorate over time. Many people who have had a TBI remain moderately to severely disabled at 5 years, are rehospitalised up to 10 years post-injury, and have a reduced lifespan relative to the general population. Understanding TBI as a chronic disease process can be highly informative for optimising care, which has traditionally focused on acute care. Chronic brain injury care models must be informed by a holistic understanding of long-term outcomes and the factors that can affect how care needs evolve over time. The United States Traumatic Brain Injury Model Systems of Care follows up individuals with moderate-to-severe TBI for over 30 years, allowing characterisation of the chronic (2-30 years or more post injury) functional, cognitive, behavioural, and social sequelae experienced by individuals who have had a moderate-to-severe TBI and the implications for their health and quality of life. Older age, social determinants of health, and lower acute functional status are associated with post-recovery deterioration, while younger age and greater functional independence are associated with risky health behaviours, including substance misuse and re-injury. Systematically collected data on long-term outcomes across multiple domains of health and function are needed worldwide to inform the development of models for chronic disease management, including the proactive surveillance of commonly experienced health and functional challenges.

Risk factors and outcomes of lower respiratory tract infections after traumatic brain injury: a retrospective observational study

Background

Traumatic brain injury (TBI) is a public health problem with a high burden in terms of disability and death. Infections are a common complication, with respiratory infections being the most frequent. Most available studies have addressed the impact of ventilator-associated pneumonia (VAP) after TBI; therefore, we aim to characterize the hospital impact of a broader entity, lower respiratory tract infections (LRTIs).

Methods

This observational, retrospective, single-center cohort study describes the clinical features and risk factors associated with LRTIs in patients with TBI admitted to an intensive care unit (ICU). We used bivariate and multivariate logistic regressions to identify the risk factors associated with developing LRTI and determine its impact on hospital mortality.

Results

We included 291 patients, of whom 77% (225/291) were men. The median (IQR) age was 38 years (28-52 years). The most common cause of injury was road traffic accidents 72% (210/291), followed by falls 18% (52/291) and assault at 3% (9/291). The median (IQR) Glasgow Coma Scale (GCS) score on admission was 9 (6-14), and 47% (136/291) were classified as severe TBI, 13% (37/291) as moderate TBI, and 40% (114/291) as mild TBI. The median (IQR) injury severity score (ISS) was 24 (16-30). Nearly 48% (141/291) of patients presented at least one infection during hospitalization, and from those, 77% (109/141) were classified as LRTIs, which included tracheitis 55% (61/109), ventilator-associated pneumonia (VAP) 34% (37/109), and hospital-acquired pneumoniae (HAP) 19% (21/109). After multivariable analysis, the following variables were significantly associated with LRTIs: age (OR 1.1, 95% CI 1.01-1.2), severe TBI (OR 2.7, 95% CI 1.1-6.9), AIS thorax (OR 1.4, 95 CI 1.1-1.8), and mechanical ventilation on admission (OR 3.7, 95% CI 1.1-13.5). At the same time, hospital mortality did not differ between groups (LRTI 18.6% vs. No LRTI 20.1%, p = 0.7), and ICU and hospital length of stay (LOS) were longer in the LRTI group (median [IQR] 12 [9-17] vs. 5 [3-9], p < 0.01) and (median [IQR] 21 [13-33] vs. 10 [5-18], p = 0.01), respectively. Time on the ventilator was longer for those with LRTIs.

Conclusion

The most common site/location of infection in patients with TBI admitted to ICU is respiratory. Age, severe TBI, thoracic trauma, and mechanical ventilation were identified as potential risk factors. LRTI was associated with prolonged ICU, hospital stay, and more days on a ventilator, but not with mortality.

Dynamic predictors of in-hospital and 3-year mortality after traumatic brain injury: A retrospective cohort study

BACKGROUND

Mortality risks after Traumatic Brain Injury (TBI) are understudied in critical illness. We sought to identify risks of mortality in critically ill patients with TBI using time-varying covariates.

METHODS

This single-center, six-year (2006-2012), retrospective cohort study measured demographics, injury characteristics, and daily data of acute TBI patients in the Intensive Care Unit (ICU). Time-varying Cox proportional hazards models assessed in-hospital and 3-year mortality.

RESULTS

Post-TBI ICU patients (n = 2664) experienced 20% in-hospital mortality (n = 529) and 27% (n = 706) 3-year mortality. Glasgow Coma Scale motor subscore (hazard ratio (HR) 0.58, p < 0.001), pupil reactivity (HR 3.17, p < 0.001), minimum glucose (HR 1.44, p < 0.001), mSOFA score (HR 1.81, p < 0.001), coma (HR 2.26, p < 0.001), and benzodiazepines (HR 1.38, p < 0.001) were associated with in-hospital mortality. At three years, public insurance (HR 1.78, p = 0.011) and discharge disposition (HR 4.48, p < 0.001) were associated with death.

CONCLUSIONS

Time-varying characteristics influenced in-hospital mortality post-TBI. Socioeconomic factors primarily affect three-year mortality.

Microbiological Profile and the Resistance Pattern of Pathogens in Neurosurgical Patients from a New Delhi Trauma Center

BACKGROUND

Neurosurgical patients are considered to be at higher risk for infections including nosocomial infections compared with other critically ill individuals. Empirical antimicrobial therapy is of utmost importance for the survival of infected neurosurgical patients.

METHODS

The microbial distribution and antimicrobial resistance patients from January 2012 to December 2021 (10 years) were analyzed retrospectively. Identification was done using VITEK-2 and MALDI-TOF systems. Antimicrobial susceptibility testing was determined by the Kirby Bauer Disk Diffusion Agar method (Clinical and Laboratory Standards Institute) and VITEK-2.

RESULTS

A total of 48,474 samples were received, out of which 10,134 (21%) had growth. Respiratory specimens showed the maximum isolation of pathogens (42% n = 4292). The predominant bacterial pathogens were gram negative (n = 8972; 88.5%), whereas gram positives were only 11.5% (n = 1162) of the total organisms. Among the gram positives, the most common was Staphylococcus aureus (64.6%), and among gram negatives, the most common pathogen was Acinetobacter baumanni (38.6%). The weighted average of the drug-resistance profile across all gram positives was >50% for fluoroquinolones (levofloxacin, ciprofloxacin), gentamicin, erythromycin, and ampicillin, and in the case of gram negatives it was >90% for ampicillin-sulbactam, ticarcillin, cefazolin, cefotaxime, and ceftriaxone. Thirty-two patients were found to have candidemia, out of which 6 were C. albicans and the rest were nonalbican. Six neurosurgery patients had infection with C. auris, 4 from blood samples and 2 from urine.

CONCLUSIONS

This study will add to the current knowledge and provide a better understanding of pathogen profile and resistance patterns in traumatic brain injury patients.

Use of Anti-epileptic Drugs for Post Traumatic Seizure: A Global Survey

BACKGROUND

Post traumatic seizures (PTS) and post traumatic epilepsy (PTE) are potential consequences of traumatic brain injury (TBI). There is no consensus regarding its management among treating doctors.

PURPOSE

We have undertaken a global survey to assess the variability of management practices of PTS and PTE and highlight the pressing need to formulate uniform practice guidelines.

METHODS

A questionnaire consisting of sixteen questions were developed with the help of Google survey and sent through e-mail, or social media platforms like WhatsApp, Facebook messenger or Telegram, to practicing Neurologists and Neurosurgeons round the world.

RESULTS

There were a total of 220 responses. Majority of our responders (n = 202; 91.8%) would start an anti-epileptic (AED) prophylaxis to prevent PTS; 18 people (8.18%) told that they would not start AED prophylaxis for TBI. Phenytoin (n = 98; 48.5%) followed by Levetiracetam (n = 78; 38.6%) was the preferred drug, although the latter was significantly preferred by high and upper middle-income countries (p<.001). Majority (n = 99; 49%) would not use it beyond two weeks. Most clinicians would manage PTE with a single drug (n = 160; 72.7%) either Phenytoin (n = 69; 31.3%) or levetiracetam (n = 67; 30.4%). Most of them (n = 174; 86%) would treat for less than one year.

CONCLUSIONS

Practices in the management of PTS and PTE vary widely among clinicians. Our study point towards the need for the development of a more robust and comprehensive practice guidelines for the management of the same.

Patient age affects sex-based differences in post-traumatic mortality: a national trauma registry study in Japan

PURPOSE

Sex-based differences in post-traumatic mortality have been widely discussed for quite some time. We hypothesized that age-related pathophysiologic changes would affect sex-based differences in post-traumatic mortality and aimed to verify the hypothesis using a nationwide trauma registry in Japan.

METHODS

This was a retrospective analysis of trauma patients registered in The Japanese Trauma Data Bank. We stratified the study population into the following three subsets based on age: (1) pediatric subset (age ≤ 14), (2) adult subset (age 15-50) and (3) senior adult subset (age ≥ 51). We evaluated both sex-based differences in mortality in each subset separately using multivariate logistic regression analysis and the two-way interaction effect for predicted survival between the continuous increase of age and the sexes using a nonlinear multivariate regression model.

RESULTS

We included 122,819 trauma patients who fulfilled the inclusion criteria and classified them into the 3 subsets according to age. Male patients were more likely to die compared to female patients only in the senior adult subset (adjusted odds ratio: 1.26; 95% confidence interval: 1.18-1.36), whereas there were no statistically significant differences in the other two subsets. Furthermore, non-linear logistic regression analysis revealed that predicted survival probability in male patients decreased more sharply in accordance with the increase of age compared to that in female patients (p for interaction: 0.051).

CONCLUSION

Age-related change in post-traumatic mortality was significantly different between males and females, and male patients had a relatively higher risk of death in the older population.

Machine Learning for Predicting In-Hospital Mortality After Traumatic Brain Injury in Both High-Income and Low- and Middle-Income Countries

BACKGROUND

Machine learning (ML) holds promise as a tool to guide clinical decision making by predicting in-hospital mortality for patients with traumatic brain injury (TBI). Previous models such as the international mission for prognosis and clinical trials in TBI (IMPACT) and the corticosteroid randomization after significant head injury (CRASH) prognosis calculators can potentially be improved with expanded clinical features and newer ML approaches.

OBJECTIVE

To develop ML models to predict in-hospital mortality for both the high-income country (HIC) and the low- and middle-income country (LMIC) settings.

METHODS

We used the Duke University Medical Center National Trauma Data Bank and Mulago National Referral Hospital (MNRH) registry to predict in-hospital mortality for the HIC and LMIC settings, respectively. Six ML models were built on each data set, and the best model was chosen through nested cross-validation. The CRASH and IMPACT models were externally validated on the MNRH database.

RESULTS

ML models built on National Trauma Data Bank (n = 5393, 84 predictors) demonstrated an area under the receiver operating curve (AUROC) of 0.91 (95% CI: 0.85-0.97) while models constructed on MNRH (n = 877, 31 predictors) demonstrated an AUROC of 0.89 (95% CI: 0.81-0.97). Direct comparison with CRASH and IMPACT models showed significant improvement of the proposed LMIC models regarding AUROC (P = .038).

CONCLUSION

We developed high-performing well-calibrated ML models for predicting in-hospital mortality for both the HIC and LMIC settings that have the potential to influence clinical management and traumatic brain injury patient trajectories.

Organizational characteristics of Brain Injury Clubhouse Model programs

OBJECTIVE

We provide an overview of the Clubhouse Model and the history and development of Brain Injury Clubhouses. We describe organizational-level characteristics associated with eight Brain Injury Clubhouses to address gaps in the literature and inform future studies or program development.

METHODS

A electronic survey, the Clubhouse Profile Questionnaire (CPQ) was tailored for Brain Injury Clubhouses. The CPQ gathers program-level data that can be used to identify active ingredients of Clubhouses, understand best practices, examine, and evaluate program characteristics. The brain injury version of the CPQ was administered to a sample of eight Clubhouses affiliated with the International Brain Injury Clubhouse Association as part of a project designed to gather data on Clubhouse program characteristics and describe sociodemographic characteristics of people served by Brain Injury Clubhouses.

RESULTS

CPQ data from eight Brain Injury Clubhouses was analyzed. Brain Injury Clubhouse programs in this sample served approximately 17 members per day. There was wide variability in the size, funding and funding mechanisms, and length of operation of Brain Injury Clubhouses in this study.

CONCLUSIONS

Findings suggest that Brain Injury Clubhouses offer a wide range of services and supports. Additional research on the impact of Brain Injury Clubhouses is needed.

Peripheral Infection after Traumatic Brain Injury Augments Excitability in the Perilesional Cortex and Dentate Gyrus

Peripheral infections occur in up to 28% of patients with traumatic brain injury (TBI), which is a major etiology for structural epilepsies. We hypothesized that infection occurring after TBI acts as a “second hit” and facilitates post-traumatic epileptogenesis. Adult male Sprague–Dawley rats were subjected to lateral fluid-percussion injury or sham-operation. At 8 weeks post-injury, rats were treated with lipopolysaccharide (LPS, 5 mg/kg) to mimic Gram-negative peripheral infection. T2-weighted magnetic resonance imaging was used to detect the cortical lesion type (small focal inflammatory [TBI_FI] vs. large cavity-forming [TBI_CF]). Spontaneous seizures were detected with video-electroencephalography, and seizure susceptibility was determined by the pentylenetetrazole (PTZ) test. Post-PTZ neuronal activation was assessed using c-Fos immunohistochemistry. LPS treatment increased the percentage of rats with PTZ-induced seizures among animals with TBI_FI lesions (p < 0.05). It also increased the cumulative duration of PTZ-induced seizures (p < 0.01), particularly in the TBI_FI group (p < 0.05). The number of c-Fos immunopositive cells was higher in the perilesional cortex of injured animals compared with sham-operated animals (p < 0.05), particularly in the TBI-LPS group (p < 0.05). LPS treatment increased the percentage of injured rats with bilateral c-Fos staining in the dentate gyrus (p < 0.05), particularly in the TBI_FI group (p < 0.05). Our findings demonstrate that peripheral infection after TBI increases PTZ-induced seizure susceptibility and neuronal activation in the perilesional cortex and bilaterally in the dentate gyrus, particularly in animals with prolonged perilesional T2 enhancement. Our data suggest that treatment of infections and reduction of post-injury neuro-inflammation are important components of the treatment regimen aiming at preventing epileptogenesis after TBI.

Antimicrobial immunity impedes CNS vascular repair following brain injury

Traumatic brain injury (TBI) and cerebrovascular injury are leading causes of disability and mortality worldwide. Systemic infections often accompany these disorders and can worsen outcomes. Recovery after brain injury depends on innate immunity, but the effect of infections on this process is not well understood. Here, we demonstrate that systemically introduced microorganisms and microbial products interfered with meningeal vascular repair after TBI in a type I interferon (IFN-I)-dependent manner, with sequential infections promoting chronic disrepair. Mechanistically, we discovered that MDA5-dependent detection of an arenavirus encountered after TBI disrupted pro-angiogenic myeloid cell programming via induction of IFN-I signaling. Systemic viral infection similarly blocked restorative angiogenesis in the brain parenchyma after intracranial hemorrhage, leading to chronic IFN-I signaling, blood-brain barrier leakage and a failure to restore cognitive-motor function. Our findings reveal a common immunological mechanism by which systemic infections deviate reparative programming after central nervous system injury and offer a new therapeutic target to improve recovery.

Neutrophil-to-Lymphocyte Ratios and Infections after Traumatic Brain Injury: Associations with Hospital Resource Utilization and Long-Term Outcome

Traumatic brain injury (TBI) induces immune dysfunction that can be captured clinically by an increase in the neutrophil-to-lymphocyte ratio (NLR). However, few studies have characterized the temporal dynamics of NLR post-TBI and its relationship with hospital-acquired infections (HAI), resource utilization, or outcome. We assessed NLR and HAI over the first 21 days post-injury in adults with moderate-to-severe TBI (n = 196) using group-based trajectory (TRAJ), changepoint, and mixed-effects multivariable regression analysis to characterize temporal dynamics. We identified two groups with unique NLR profiles: a high (n = 67) versus a low (n = 129) TRAJ group. High NLR TRAJ had higher rates (76.12% vs. 55.04%, p = 0.004) and earlier time to infection (p = 0.003). In changepoint-derived day 0–5 and 6–20 epochs, low lymphocyte TRAJ, early in recovery, resulted in more frequent HAIs (p = 0.042), subsequently increasing later NLR levels (p ≤ 0.0001). Both high NLR TRAJ and HAIs increased hospital length of stay (LOS) and days on ventilation (p ≤ 0.05 all), while only high NLR TRAJ significantly increased odds of unfavorable six-month outcome as measured by the Glasgow Outcome Scale (GOS) (p = 0.046) in multivariable regression. These findings provide insight into the temporal dynamics and interrelatedness of immune factors which collectively impact susceptibility to infection and greater hospital resource utilization, as well as influence recovery.

The timeframe for safe resumption of high-level mobility following traumatic brain injury is currently unknown: a systematic review

PURPOSE

To examine the safety of high-level mobility (HLM) prescription in the early sub-acute phase of recovery following moderate-to-extremely severe traumatic brain injury (TBI) with specific focus on provocation of concussion-like symptoms.

DESIGN

Systematic review. PROSPERO ID: CRD42017069369.

MAIN MEASURES

Extracted data included study design, brain injury severity, time to commence HLM, type of HLM, physiological and symptom monitoring, and rate of adverse events.

RESULTS

Nineteen studies were included in the review. Fifteen studies included participants who commenced HLM within 6 weeks of injury, with the earliest time to commencement being 3 days. Overall, adverse events and symptom monitoring were poorly reported. A total of six adverse events were reported across three studies. One of the six adverse events was a concussion-like symptom. No falls were reported. No studies monitored concussion-like symptom provocation in direct relation to HLM.

CONCLUSION

A safe timeframe for return to HLM after moderate-to-extremely severe TBI could not be determined due to insufficient reporting of symptom monitoring and adverse events. Further research into the safety of HLM in the early sub-acute rehabilitative stage after moderate-to-extremely severe TBI is required in order to better understand potential sequelae in this population.IMPLICATIONS FOR REHABILITATIONHigh-level mobility assessment and training is commonly reported in the early sub-acute phase of recovery following moderate-to-extremely severe traumatic brain injury.There is no consensus on a safe timeframe to commence high-level mobility assessment or training after moderate-to-extremely severe traumatic brain injury.High-level mobility assessment and training appears to be safe in the early sub-acute phase following moderate-to-extremely severe traumatic brain injury, however, adverse events and symptoms are poorly reported.Clinicians should continue to proceed with caution when assessing and prescribing high-level mobility for patients with moderate-to-extremely severe traumatic brain injury in the early sub-acute phase of recovery and monitor for risks such as falls and exacerbation of concussion-like symptoms.

Brain-gut axis dysfunction in the pathogenesis of traumatic brain injury

Traumatic brain injury (TBI) is a chronic and progressive disease, and management requires an understanding of both the primary neurological injury and the secondary sequelae that affect peripheral organs, including the gastrointestinal (GI) tract. The brain-gut axis is composed of bidirectional pathways through which TBI-induced neuroinflammation and neurodegeneration impact gut function. The resulting TBI-induced dysautonomia and systemic inflammation contribute to the secondary GI events, including dysmotility and increased mucosal permeability. These effects shape, and are shaped by, changes in microbiota composition and activation of resident and recruited immune cells. Microbial products and immune cell mediators in turn modulate brain-gut activity. Importantly, secondary enteric inflammatory challenges prolong systemic inflammation and worsen TBI-induced neuropathology and neurobehavioral deficits. The importance of brain-gut communication in maintaining GI homeostasis highlights it as a viable therapeutic target for TBI. Currently, treatments directed toward dysautonomia, dysbiosis, and/or systemic inflammation offer the most promise.

Cause of Death after Traumatic Brain Injury: A Population-Based Health Record Review Analysis Referenced for Nonhead Trauma

INTRODUCTION

Traumatic brain injury (TBI) is a leading cause of disability and is associated with decreased survival. Although it is generally accepted that TBI increases risk of death in acute and postacute periods after injury, causes of premature death after TBI in the long term are less clear.

METHODS

A cohort sample of Olmsted County, Minnesota, residents with confirmed TBI from January 1987 through December 1999 was identified. Each case was assigned an age- and sex-matched non-TBI referent case, called regular referent. Confirmed TBI cases with simultaneous nonhead injuries were identified, labeled special cases. These were assigned 2 age- and sex-matched special referents with nonhead injuries of similar severity. Underlying causes of death in each case were categorized using death certificates, International Classification of Diseases, Ninth Revision, International Statistical Classification of Diseases, Tenth Revision, and manual health record review. Comparisons were made over the study period and among 6-month survivors.

RESULTS

Case-regular referent pairs (n = 1,257) were identified over the study period, and 221 were special cases. In total, 237 deaths occurred among these pairs. A statistically significant difference was observed between total number of deaths among all cases (n = 139, 11%) and regular referents (n = 98, 8%) (p = 0.006) over the entire period. This outcome was not true for special cases (32/221, 14%) and special referents (61/441, 14%) (p = 0.81). A greater proportion of deaths by external cause than all other causes was observed in all cases (52/139, 37%) versus regular referents (3/98, 3%) and in special cases (13/32, 41%) versus special referents (5/61, 8%) (p < 0.001 for both). Among all case-referent pairs surviving 6 months, no difference was found between total number of deaths (p = 0.82). The underlying cause of death between these 2 groups was significantly different for external causes only (p < 0.01). For special cases surviving 6 months versus special referents, no difference was observed in total number of deaths (p = 0.24) or underlying causes of death (p = 1.00) between groups.

DISCUSSION/CONCLUSION

This population-based case-matched referent study showed that increased risk of death after TBI existed only during the first 6 months after injury, and the difference was due to external causes.

Acute colitis during chronic experimental traumatic brain injury in mice induces dysautonomia and persistent extraintestinal, systemic, and CNS inflammation with exacerbated neurological deficits

BACKGROUND

Disruptions of brain-gut axis have been implicated in the progression of a variety of gastrointestinal (GI) disorders and central nervous system (CNS) diseases and injuries, including traumatic brain injury (TBI). TBI is a chronic disease process characterized by persistent secondary injury processes which can be exacerbated by subsequent challenges. Enteric pathogen infection during chronic TBI worsened cortical lesion volume; however, the pathophysiological mechanisms underlying the damaging effects of enteric challenge during chronic TBI remain unknown. This preclinical study examined the effect of intestinal inflammation during chronic TBI on associated neurobehavioral and neuropathological outcomes, systemic inflammation, and dysautonomia.

METHODS

Dextran sodium sulfate (DSS) was administered to adult male C57BL/6NCrl mice 28 days following craniotomy (Sham) or TBI for 7 days to induce intestinal inflammation, followed by a return to normal drinking water for an additional 7 to 28 days for recovery; uninjured animals (Naïve) served as an additional control group. Behavioral testing was carried out prior to, during, and following DSS administration to assess changes in motor and cognitive function, social behavior, and mood. Electrocardiography was performed to examine autonomic balance. Brains were collected for histological and molecular analyses of injury lesion, neurodegeneration, and neuroinflammation. Blood, colons, spleens, mesenteric lymph nodes (mLNs), and thymus were collected for morphometric analyses and/or immune characterization by flow cytometry.

RESULTS

Intestinal inflammation 28 days after craniotomy or TBI persistently induced, or exacerbated, respectively, deficits in fine motor coordination, cognition, social behavior, and anxiety-like behavior. Behavioral changes were associated with an induction, or exacerbation, of hippocampal neuronal cell loss and microglial activation in Sham and TBI mice administered DSS, respectively. Acute DSS administration resulted in a sustained systemic immune response with increases in myeloid cells in blood and spleen, as well as myeloid cells and lymphocytes in mesenteric lymph nodes. Dysautonomia was also induced in Sham and TBI mice administered DSS, with increased sympathetic tone beginning during DSS administration and persisting through the first recovery week.

CONCLUSION

Intestinal inflammation during chronic experimental TBI causes a sustained systemic immune response and altered autonomic balance that are associated with microglial activation, increased neurodegeneration, and persistent neurological deficits.

Respiratory-Swallow Coordination Training Improves Swallowing Safety and Efficiency in a Person With Anoxic Brain Injury

Purpose The aim of this study was to assess the effects of respiratory-swallow coordination training (RSCT) on respiratory-swallow coordination (RSC), swallowing safety (penetration/aspiration), and swallowing efficiency (pharyngeal residue) in a person with anoxic brain injury. Method A 68-year-old man with anoxic brain injury, tachypnea, and severe dysphagia was recruited to participate in a prospective AABAA single-subject experimental design. RSC, swallowing safety, and swallowing efficiency were measured at each assessment using respiratory inductive plethysmography and flexible endoscopic evaluations of swallowing. Data were analyzed descriptively using Cohen's d effect size. Outcome measures were compared pre-RSCT to post-RSCT, and pre-RSCT to a 1-month retention assessment. Results Improvements in RSC were observed immediately post-RSCT (d = 0.60). These improvements were maintained upon retention assessment 1 month later (d = 0.60). Additionally, improvements in swallowing safety (d = 1.73), efficiency (d = 1.73), and overall dysphagia severity (d = 1.73) were observed immediately post-RSCT and were maintained upon retention assessment 1 month later (d = 1.73). Conclusions Clinically meaningful improvements in RSC were observed following four sessions of RSCT, which were subsequently associated with large improvements in swallowing safety and efficiency. RSCT may be an efficacious, clinically feasible skill-based exercise for people with anoxic brain injury, suboptimal RSC, and dysphagia. Future work is needed to expand these findings in a larger cohort of people with dysphagia.

Concordance between current American Academy of Sleep Medicine and Centers for Medicare and Medicare scoring criteria for obstructive sleep apnea in hospitalized persons with traumatic brain injury: a VA TBI Model System study

STUDY OBJECTIVES

The objective of this study was to compare obstructive sleep apnea (OSA), demographic, and traumatic brain injury (TBI) characteristics across the American Academy of Sleep Medicine (AASM) and Centers for Medicare and Medicare (CMS) scoring rules in moderate to severe TBI undergoing inpatient neurorehabilitation.

METHODS

This is a secondary analysis from a prospective clinical trial of sleep apnea at 6 TBI Model System study sites (n = 248). Scoring was completed by a centralized center using both the AASM and CMS criteria for OSA. Hospitalization and injury characteristics were abstracted from the medical record, and demographics were obtained by interview by trained research assistants using TBI Model System standard procedures.

RESULTS

OSA was prevalent using the AASM (66%) and CMS (41.5%) criteria with moderate to strong agreement (weighted κ = 0.64; 95% confidence interval = 0.58-0.70). Significant differences were observed for participants meeting AASM and CMS criteria (concordant group) compared with those meeting criteria for AASM but not CMS (discordant group). At an apnea-hypopnea index ≥ 5 events/h, the discordant group (n = 61) had lower Emergency Department Glasgow Coma Scale Scores consistent with greater injury severity (median, 5 vs 13; P = .0050), younger age (median, 38 vs 58; P < .0001), and lower body mass index (median, 22.1 vs 24.8; P = .0007) compared with the concordant group (n = 103). At an apnea-hypopnea index ≥ 15 events/h, female sex but no other differences were noted, possibly because of the smaller sample size.

CONCLUSIONS

The underestimation of sleep apnea using CMS criteria is consistent with prior literature; however, this is the first study to report the impact of the criteria in persons with moderate to severe TBI during a critical stage of neural recovery. Management of comorbidities in TBI has become an increasing focus for optimizing TBI outcomes. Given the chronic morbidity after moderate to severe TBI, the impact of CMS policy for OSA diagnosis for persons with chronic disability and young age are considerable.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Comparison of Sleep Apnea Assessment Strategies to Maximize TBI Rehabilitation Participation and Outcome; Identifier: NCT03033901.

Physical Activity Intolerance and Cardiorespiratory Dysfunction in Patients with Moderate-to-Severe Traumatic Brain Injury

Moderate-to-severe traumatic brain injury (TBI) is a chronic health condition with multi-systemic effects. Survivors face significant long-term functional limitations, including physical activity intolerance and disordered sleep. Persistent cardiorespiratory dysfunction is a potentially modifiable yet often overlooked major contributor to the alarmingly high long-term morbidity and mortality rates in these patients. This narrative review was developed through systematic and non-systematic searches for research relating cardiorespiratory function to moderate-to-severe TBI. The literature reveals patients who have survived moderate-to-severe TBI have ~ 25-35% reduction in maximal aerobic capacity 6-18 months post-injury, resting pulmonary capacity parameters that are reduced 25-40% for weeks to years post-injury, increased sedentary behavior, and elevated risk of cardiorespiratory-related morbidity and mortality. Synthesis of data from other patient populations reveals that cardiorespiratory dysfunction is likely a consequence of ventilator-induced diaphragmatic dysfunction (VIDD), which is not currently addressed in TBI management. Thus, cardiopulmonary exercise testing should be routinely performed in this patient population and those with cardiorespiratory deficits should be further evaluated for diaphragmatic dysfunction. Lack of targeted treatment for underlying cardiorespiratory dysfunction, including VIDD, likely contributes to physical activity intolerance and poor functional outcomes in these patients. Interventional studies have demonstrated that short-term exercise training programs are effective in patients with moderate-to-severe TBI, though improvement is variable. Inspiratory muscle training is beneficial in other patient populations with diaphragmatic dysfunction, and may be valuable for patients with TBI who have been mechanically ventilated. Thus, clinicians with expertise in cardiorespiratory fitness assessment and exercise training interventions should be included in patient management for individuals with moderate-to-severe TBI.

Lifelong consequences of brain injuries during development: From risk to resilience

Traumatic brain injuries in children represent a major public health issue and even relatively mild injuries can have lifelong consequences. However, the outcomes from these injuries are highly heterogeneous, with most individuals recovering fully, but a substantial subset experiencing prolonged or permanent disabilities across a number of domains. Moreover, brain injuries predispose individuals to other kinds of neuropsychiatric and somatic illnesses. Critically, the severity of the injury only partially predicts subsequent outcomes, thus other factors must be involved. In this review, we discuss the psychological, social, neuroendocrine, and autonomic processes that are disrupted following traumatic brain injury during development, and consider the mechanisms the mediate risk or resilience after traumatic brain injury in this vulnerable population.

Readmissions After Acute Hospitalization for Traumatic Brain Injury

BACKGROUND

Traumatic brain injury (TBI) is associated with functional deficits, impaired cognition, and medical complications that continue well after the initial injury. Many patients seek medical care at other health care facilities after discharge, rather than returning to the admitting trauma center, making assessment of readmission rates and readmission diagnoses difficult to determine. The objective of this study was to determine the incidence and factors associated with readmission to any acute care hospital after an index admission for TBI.

MATERIALS AND METHODS

The Nationwide Readmission Database was queried for all patients admitted with a TBI during the first 3 mo of 2015. Nonelective readmissions for this population were then collected for the remainder of 2015. Patients who died during the index admission were excluded. Demographic data, injury mechanism, type of TBI, the number of readmissions, days from discharge to readmission, readmission diagnosis, and mortality were studied.

RESULTS

Of the 15,277 patients with an index admission for TBI, 5296 patients (35%) required at least 1 readmission. Forty percent of readmissions occurred within the first 30 d after discharge from the index trauma admission. The most common primary diagnosis on readmission was SDH, followed by septicemia, urinary tract infection, and aspiration. Readmission rates increased with age, with 75% of readmissions occurring in patients aged >65 y. Initial discharge to a skilled nursing facility (Relative Risk [RR], 1.60) or leaving the hospital against medical advice (RR, 1.59) increased the risk of readmission. Patients with fall as their mechanism of injury and a subdural hematoma were more likely to require readmission compared with other types of mechanisms with TBI (RR, 1.59 and RR, 1.21, respectively; P < 0.001). Notably, the first readmission was to a different hospital for 39.5% of patients and 46.9% of patients had admissions to at least one facility outside that of their original presentation.

CONCLUSIONS

Hospital readmission is common for patients discharged after TBI. Elderly patients who fall with resultant subdural hematoma are at especially high risk for complications and readmission. Understanding potentially preventable causes for readmission can be used to guide discharge planning pathways to decrease morbidity in this patient population.

Infections after a traumatic brain injury: The complex interplay between the immune and neurological systems

Traumatic brain injury (TBI) is a serious global health issue, being the leading cause of death and disability for individuals under the age of 45, and one of the largest causes of global neurological disability. In addition to the brain injury itself, it is increasingly appreciated that a TBI may also alter the systemic immune response in a way that renders TBI patients more vulnerable to infections in the acute post-injury period. Such infections pose an additional challenge to the patient, increasing rates of mortality and morbidity, and worsening neurological outcomes. Hospitalization, surgical interventions, and a state of immunosuppression induced by injury to the central nervous system (CNS), may all contribute to the high rate of infections seen in the population with TBI. Ongoing research to better understand the immunomodulators that underlie TBI-induced immunosuppression may aid in the development of effective therapeutic strategies to improve the recovery trajectory for patients. This review first describes the clinical scenario, posing the question of whether TBI patients are more susceptible to infections such as pneumonia, and if so, why? We then consider how cross-talk between the injured brain and the systemic immune system occurs, and further, how the additional immune challenge of an acquired infection can contribute to ongoing neuroinflammation and neurodegeneration after a TBI. Experimental models combining TBI with infection are discussed, as well as current treatment options available for this double-barreled insult. The aims of this review are to summarize current understanding of the bidirectional relationship between the CNS and the immune system when faced with a mechanical trauma combined with a concomitant infection, and to highlight key outstanding questions that remain in the field.

External causes of death after severe traumatic brain injury in a multicentre inception cohort: clinical description and risk factors

Objective: To characterize the clinical profile of patients dying from external causes (EC) following severe traumatic brain injury (TBI). Design and Methods: Data from 2545 patients forming the NSW-BIRP inception cohort discharged from post-acute inpatient rehabilitation between 1 July 1990 and 1 October 2007 were retrospectively reviewed. Standardized mortality ratios (SMRs) were calculated for EC sub-categories. Demographic, clinical and rehabilitation service factors were compared between deaths from EC, deaths from other causes (OC), and non-deceased. Clinical profiles of EC sub-categories were analysed descriptively. Results: Overall, patients with TBI were 5.2x more likely to die from EC relative to the general population. Risk of death was elevated in all EC sub-categories examined, with the largest risks relating to other accidental threats to breathing (SMR = 33.0; 95%CI = 13.79-60.45) and falls (SMR = 14.3; 95%CI = 5.01-28.39). The EC group were younger, more likely to have pre-injury psychiatric histories, less severe injuries, greater functional independence, and die earlier than the OC group. There was considerable heterogeneity in the clinical profiles of patients dying from different EC sub-categories. Conclusions: EC constitutes one of the largest causes of mortality following TBI in patients surviving beyond the post-acute phase. Potential implications for risk modification and prevention of premature and avoidable deaths are discussed.

Association Between Traumatic Brain Injury and Risk of Suicide

IMPORTANCE

Traumatic brain injuries (TBIs) can have serious long-term consequences, including psychiatric disorders. However, few studies have assessed the association between TBI and risk of suicide.

OBJECTIVE

To examine the association between TBI and subsequent suicide.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cohort study using nationwide registers covering 7 418 391 individuals (≥10 years) living in Denmark (1980-2014) with 164 265 624 person-years' follow-up; 567 823 (7.6%) had a medical contact for TBI. Data were analyzed using Poisson regression adjusted for relevant covariates, including fractures not involving the skull, psychiatric diagnoses, and deliberate self-harm.

EXPOSURE

Medical contacts for TBI recorded in the National Patient Register (1977-2014) as mild TBI (concussion), skull fracture without documented TBI, and severe TBI (head injuries with evidence of structural brain injury).

MAIN OUTCOMES AND MEASURES

Suicide recorded in the Danish Cause of Death register until December 31, 2014.

RESULTS

Of 34 529 individuals who died by suicide (mean age, 52 years [SD, 18 years]; 32.7% women; absolute rate 21 per 100 000 person-years [95% CI, 20.8-21.2]), 3536 (10.2%) had medical contact: 2701 with mild TBI, 174 with skull fracture without documented TBI, and 661 with severe TBI. The absolute suicide rate was 41 per 100 000 person-years (95% CI, 39.2-41.9) among those with TBI vs 20 per 100 000 person-years (95% CI, 19.7-20.1) among those with no diagnosis of TBI. The adjusted incidence rate ratio (IRR) was 1.90 (95% CI, 1.83-1.97). Compared with those without TBI, severe TBI (absolute rate, 50.8 per 100 000 person-years; 95% CI, 46.9-54.6) was associated with an IRR of 2.38 (95% CI, 2.20-2.58), whereas mild TBI (absolute rate, 38.6 per 100 000 person-years; 95% CI, 37.1-40.0), and skull fracture without documented TBI (absolute rate, 42.4 per 100 000 person-years; 95% CI, 36.1-48.7) had an IRR of 1.81 (95% CI, 1.74-1.88) and an IRR of 2.01 (95% CI, 1.73-2.34), respectively. Suicide risk was associated with number of medical contacts for TBI compared with those with no TBI contacts: 1 TBI contact, absolute rate, 34.3 per 100 000 person-years (95% CI, 33.0-35.7; IRR, 1.75; 95% CI, 1.68-1.83); 2 TBI contacts, absolute rate, 59.8 per 100 000 person-years (95% CI, 55.1-64.6; IRR, 2.31; 95% CI, 2.13-2.51); and 3 or more TBI contacts, absolute rate, 90.6 per 100 000 person-years (95% CI, 82.3-98.9; IRR, 2.59; 95% CI, 2.35-2.85; all P < .001 for the IRR's). Compared with the general population, temporal proximity since the last medical contact for TBI was associated with risk of suicide (P<.001), with an IRR of 3.67 (95% CI, 3.33-4.04) within the first 6 months and an incidence IRR of 1.76 (95% CI, 1.67-1.86) after 7 years.

CONCLUSIONS AND RELEVANCE

In this nationwide registry-based retrospective cohort study individuals with medical contact for TBI, compared with the general population without TBI, had increased suicide risk.

Risk of Infection and Sepsis in Pediatric Patients with Traumatic Brain Injury Admitted to Hospital Following Major Trauma

Head injury accounts for 29% of all traumatic deaths in children. Sepsis is significantly associated with an increased risk of mortality in adult traumatic brain injury patients. In the pediatric population, this relationship is not well understood. The objective of this study was to compare the proportion of pediatric traumatic brain injury (TBI) patients and trauma patients without brain injury (NTBI) who developed sepsis or any infection during their index hospital admission. We performed a retrospective study of all trauma patients <18 years of age, admitted to trauma centres in Alberta, Canada from January 1, 2003 to December 31, 2012. Patients who died within 24 hrs of trauma (n = 147) and those with burns as the primary mechanism of injury (n = 53) were excluded. Hospital admission data for the remaining 2556 patients was analyzed. 1727 TBI patients and 829 NTBI patients were included. TBI was associated with lower odds of developing sepsis (OR 0.32 95% CI 0.14–0.77 p = 0.011). TBI was not found to be independently associated with developing any infectious complication after adjusting for confounding by Injury Severity Score (OR 1.25 95% CI 0.90–1.74 p = 0.180). These relationships warrant further study.

NADPH oxidases in traumatic brain injury - Promising therapeutic targets?

Traumatic brain injury (TBI) is a major cause of death and disability worldwide. Despite intense investigation, no neuroprotective agents for TBI have yet translated to the clinic. Recent efforts have focused on identifying potential therapeutic targets that underlie the secondary TBI pathology that evolves minutes to years following the initial injury. Oxidative stress is a key player in this complex cascade of secondary injury mechanisms and prominently contributes to neurodegeneration and neuroinflammation. NADPH oxidase (NOX) is a family of enzymes whose unique function is to produce reactive oxygen species (ROS). Human post-mortem and animal studies have identified elevated NOX2 and NOX4 levels in the injured brain, suggesting that these two NOXs are involved in the pathogenesis of TBI. In support of this, NOX2 and NOX4 deletion studies have collectively revealed that targeting NOX enzymes can reduce oxidative stress, attenuate neuroinflammation, promote neuronal survival, and improve functional outcomes following TBI. In addition, NOX inhibitor studies have confirmed these findings and demonstrated an extended critical window of efficacious TBI treatment. Finally, the translational potential, caveats, and future directions of the field are highlighted and discussed throughout the review.

Six-year review of traumatic brain injury in a regional trauma unit: demographics, contributing factors and service provision in Ireland

BACKGROUND

Traumatic brain injury (TBI) represents a significant burden of care for acute surgical services, particularly in the absence of on-site neurosurgical cover or sufficient post-acute rehabilitation facilities. We examine factors contributing to TBI, prolonged lengths of stay (LoS) and implications for hospital resources. Long-term outcomes are assessed.

METHODS

This is a retrospective cohort study of patients admitted to a regional trauma unit with TBI from 2008 to 2013. Patients with LoS > 48 h were assessed. Demographic, clinical and longitudinal mortality data were collected using electronic clinical and radiological systems and chart review.

RESULTS

A total of 690 patients presented with TBI from 2008 to 2013; 213 patients with LoS > 48 h were assessed. One hundred and thirty (61%) were male. Mean age was 56 years (±SD 24). Mechanical fall was the most frequent injury mechanism (n = 120/213, 56%). Twenty-five per cent were associated with alcohol consumption; these were more likely to be male, involved in an Road Traffic Accident (RTA) or assault and necessitate transfer to a neurosurgical unit (p < 0.001, p = 0.029, p < 0.001, p = 0.05). A total of 112 patients(53%) had a prolonged LoS (>2 weeks). Mean LoS was 20 days (±SD 35), increasing to 39 days for patients requiring neurosurgical intervention. The 12-month all-cause mortality rate was 12%.

CONCLUSIONS

TBIs result in significant utilisation of acute inpatient bed days. Improved rehabilitation services and strategies to reduce acute hospital LoS are warranted.

Rehospitalization Over 10 Years Among Survivors of TBI: A National Institute on Disability, Independent Living, and Rehabilitation Research Traumatic Brain Injury Model Systems Study

OBJECTIVE

To describe the rates and causes for rehospitalization over 10 years after moderate-severe traumatic brain injury (TBI), and to characterize longitudinal trajectories of the probability of rehospitalization using generalized linear mixed models and individual growth curve models conditioned on factors that help explain individual variability in rehospitalization risk over time.

DESIGN

Secondary analysis of data from a multicenter longitudinal cohort study.

SETTING

Acute inpatient rehabilitation facilities and community follow-up.

PARTICIPANTS

Individuals 16 years and older with a primary diagnosis of TBI.

MAIN OUTCOME MEASURES

Rehospitalization (and reason for rehospitalization) as reported by participants or proxy during follow-up telephone interviews at 1, 2, 5, and 10 years postinjury.

RESULTS

The greatest number of rehospitalizations occurred in the first year postinjury (27.8% of the sample), and the rates of rehospitalization remained largely stable (22.1%-23.4%) at 2, 5, and 10 years. Reasons for rehospitalization varied over time: Orthopedic and reconstructive surgery rehospitalizations were most common in year 1, whereas general health maintenance was most common by year 2 with rates increasing at each follow-up. Longitudinal models indicate that multiple demographic and injury-related factors are associated with the probability of rehospitalization over time.

CONCLUSIONS

These findings can inform the content and timing of interventions to improve health and longevity after TBI.

Deletion of NADPH oxidase 4 reduces severity of traumatic brain injury

Traumatic brain injury (TBI) contributes to over 30% of injury-related deaths and is a major cause of disability without effective clinical therapies. Oxidative stress contributes to neurodegeneration, neuroinflammation, and neuronal death to amplify the primary injury after TBI. NADPH oxidase (NOX) is a major source of reactive oxygen species following brain injury. Our current study addresses the functional role of the NOX4 isoform in the damaged cortex following TBI. Adult male C57BL/6 J and NOX4^-/- mice received a controlled cortical impact and lesion size, NOX4 expression, oxidative stress, neurodegeneration, and cell death were assessed in the injured cerebral cortex. The results revealed that NOX4 mRNA and protein expression were significantly upregulated at 1-7 days post-TBI in the injured cerebral cortex. Expression of the oxidative stress markers, 8-OHdG, 4-HNE, and nitrotyrosine was upregulated at 2 and 4 days post-TBI in the WT injured cerebral cortex, and nitrotyrosine primarily colocalized with neurons. In the NOX4^-/- mice, expression of these oxidative stress markers, 8-OHdG, 4-HNE, and nitrotyrosine were significantly attenuated at both timepoints. In addition, examination of NOX4^-/- mice revealed a reduced number of apoptotic (TUNEL⁺) and degenerating (FJB⁺) cells in the perilesional cortex after TBI, as well as a smaller lesion size compared with the WT group. The results of this study implicate a functional role for NOX4 in TBI induced oxidative damage and neurodegeneration and raise the possibility that targeting NOX4 may have therapeutic efficacy in TBI.

Survival and mortality following TBI

OBJECTIVES

Evaluation of life expectancy (LE) post traumatic brain injury (TBI) is important for planning services for patients and for dealing with medico-legal aspects. We hypothesized that LE for patients who survived 2 years post injury is equal to that of the general population (GP).

METHODS

A cohort of 279 patients was assembled during a 5-year period and was followed for 22-27 years. During follow-up, 32 patients (11.5%) died, creating a huge censored data (88.5%). Analyses included standard mortality ratio (SMR), Kaplan-Meier method (KM), Cox proportional hazards regression analysis (PH) and calculations of life expectancy.

RESULTS

About 77% of the patients were under 35 years of age at injury. This age cut-off point yielded differences for survival longevity by χ² tests (p < 0.0001), by KM analysis (p < 0.0001) and by Cox PH regression analysis (p < 0.0001, HR = 13.95). SMR for the entire cohort was 1.86. Shortening of LE in comparison with the GP is 3.58 years. Estimated shortening of LE by severity for mild, moderate and severe injury were -0.51, 4.11 and 13.77 years, respectively.

CONCLUSIONS

Patients with mild TBI have a LE similar to the GP, and a reduction in LE was closely related to moderate and severe brain injury.

Knockdown of miR-155 protects microglia against LPS-induced inflammatory injury via targeting RACK1: a novel research for intracranial infection

Background

Intracranial infection, one of the complications of traumatic brain injury, is usually associated with inflammation. Several microRNAs (miRNAs), including miR-155, have been reported to be critical modulators in peripheral and central nervous system inflammation. In this study, we investigated the role of miR-155 in lipopolysaccharide (LPS)-induced inflammatory injury in mouse microglia BV2 cells.

Results

The expression level of miR-155 was significantly up-regulated after LPS stimulation in BV2 cells. LPS administration decreased BV2 cell viability, promoted apoptosis and increased the release of pro-inflammatory cytokines; while miR-155 knockdown rescued BV2 cell from LPS-induced injury. RACK1 was a directly target of miR-155. Interestingly, miR-155 knockdown did not attenuate LPS-induced inflammatory injury when RACK1 was knocked down. The mechanistic study indicated that miR-155 knockdown deactivated MAPK/NF-κB and mTOR signaling pathways under LPS-treated conditions.

Conclusions

Knockdown of miR-155 protected mouse microglia BV2 cells from LPS-induced inflammatory injury via targeting RACK1 and deactivating MAPK/NF-κB and mTOR signaling pathways.

The Role of the Oligodendrocyte Lineage in Acute Brain Trauma

An acute brain injury is commonly characterized by an extended cellular damage. The post-injury process of scar formation is largely determined by responses of various local glial cells and blood-derived immune cells. The role of astrocytes and microglia have been frequently reviewed in the traumatic sequelae. Here, we summarize the diverse contributions of oligodendrocytes (OLs) and their precursor cells (OPCs) in acute injuries. OLs at the lesion site are highly sensitive to a damaging insult, provoked by Ca²⁺ overload after hyperexcitation originating from increased levels of transmitters. At the lesion site, differentiating OPCs can replace injured oligodendrocytes to guarantee proper myelination that is instrumental for healthy brain function. In contrast to finally differentiated and non-dividing OLs, OPCs are the most proliferative cells of the brain and their proliferation rate even increases after injury. There exist even evidence that OPCs might also generate some type of astrocyte beside OLs. Thereby, OPCs can contribute to the generation and maintenance of the glial scar. In the future, detailed knowledge of the molecular cues that help to prevent injury-evoked glial cell death and that control differentiation and myelination of the oligodendroglial lineage will be pivotal in developing novel therapeutic approaches.

The Safety Assessment Measure for persons with traumatic brain injury: Item pool development and content validity

BACKGROUND

Persons with moderate to severe TBI are at increased risk for unintentional injury or harm in the home and community; however, there is currently no standard measure of safety risk they face now and in the future.

OBJECTIVE

To develop comprehensive and content valid scales and item pools for assessing safety and risk for persons with moderate to severe traumatic brain injuries.

METHOD

Qualitative psychometric methods for developing scales and items were used including literature review, item development and revision, focus groups with interdisciplinary rehabilitation staff (n = 26) for rating content validity, and cognitive interviewing of TBI family members (n = 9) for assuring item clarity.

RESULTS

The Safety Assessment Measure is comprised of 6 primary scales - Cognitive Capacity, Visuomotor Capacity, Wheelchair Use, Risk Perception, Self-Regulation, and Compliance Failures with Safety Recommendations - in which family caregivers or clinicians rate the risk for unintentional injury or harm in adults who have sustained moderate or severe TBI. The scale item pools encompass a broad spectrum of everyday activities that pose risk in the home and community and were rated as having excellent levels of content validity.

CONCLUSIONS

The Safety Assessment Measure scales and items cover a broad range of instrumental activities of daily living that can increase the risk of unintentional injuries or harm. Empirical evidence suggests that the Safety Assessment Measure items have excellent content validity. Future research should use modern psychometric methods to examine each scale unidimensionality, model fit, and precision.

Traumatic Brain Injury Incidence, Clinical Overview, and Policies in the US Military Health System Since 2000

Exposure to explosive armaments during Operation Iraqi Freedom and Operation Enduring Freedom contributed to approximately 14% of the 352 612 traumatic brain injury (TBI) diagnoses in the US military between 2000 and 2016. The US Department of Defense issued guidelines in 2009 to (1) standardize TBI diagnostic criteria; (2) classify TBI according to mechanism and severity; (3) categorize TBI symptoms as somatic, psychological, or cognitive; and (4) systematize types of care given during the acute and rehabilitation stages of TBI treatment. Polytrauma and associated psychological and neurologic conditions may create barriers to optimal rehabilitation from TBI. Given the completion of recent combat operations and the transition of TBI patients into long-term care within the US Department of Veterans Affairs system, a review of the literature concerning TBI is timely. Long-term follow-up care for patients who have sustained TBI will remain a critical issue for the US military.

Analysis on the risk factors of intracranial infection secondary to traumatic brain injury

OBJECTIVE

To discuss the characteristics and risk factors for intracranial infection post traumatic brain injury to prevent and better the clinical care.

METHODS

Retrospective study of 520 patients with traumatic brain injury were included, 308 male and 212 female. The risky factors of intracranial infection were identified.

RESULTS

Thirty two cases (6.54%, 32/520) of intracranial infection were diagnosed. Intracranial infection most likely happened 4-10 days after injury. Cerebrospinal fluid leakage, drainage, multiple craniotomies were significant related to intracranial infection. Logistic regression predicted cerebrospinal fluid leakage and drainage as independent factors.

CONCLUSION

Intracranial infection is a serious complication after traumatic brain injury. Patients with drainage or cerebrospinal fluid leakage are more risky for intracranial infection. Aggressive precaution should be taken to better outcome.

Pathologic electrographic changes after experimental traumatic brain injury

OBJECTIVE

To investigate possible electroencephalography (EEG) correlates of epileptogenesis after traumatic brain injury (TBI) using the fluid percussion model.

METHODS

Experiments were conducted on adult 2- to 4-month-old male Sprague-Dawley rats. Two groups of animals were studied: (1) the TBI group with depth and screw electrodes implanted immediately after the fluid percussion injury (FPI) procedure, and (2) a naive age-matched control group with the same electrode implantation montage. Pairs of tungsten microelectrodes (50 μm outer diameter) and screw electrodes were implanted in neocortex inside the TBI core, areas adjacent to TBI, and remote areas. EEG activity, recorded on the day of FPI, and continuously for 2 weeks, was analyzed for possible electrographic biomarkers of epileptogenesis. Video-EEG monitoring was also performed continuously in the TBI group to capture electrographic and behavioral seizures until the caps came off (28-189 days), and for 1 week, at 2, 3, and 6 months of age, in the control group.

RESULTS

Pathologic high-frequency oscillations (pHFOs) with a central frequency between 100 and 600 Hz, were recorded from microelectrodes, beginning during the first two post-FPI weeks, in 7 of 12 animals in the TBI group (58%) and never in the controls. pHFOs only occurred in cortical areas within or adjacent to the TBI core. These were associated with synchronous multiunit discharges and popSpikes, duration 15-40 msec. Repetitive pHFOs and EEG spikes (rHFOSs) formed paroxysmal activity, with a unique arcuate pattern, in the frequency band 10-16 Hz in the same areas as isolated pHFOs, and these events were also recorded by screw electrodes. Although loss of caps prevented long-term recordings from all rats, pHFOs and rHFOSs occurred during the first 2 weeks in all four animals that later developed seizures, and none of the rats without these events developed late seizures.

SIGNIFICANCE

pHFOs, similar to those associated with epileptogenesis in the status rat model of epilepsy, may also reflect epileptogenesis after FPI. rHFOSs could be noninvasive biomarkers of epileptogenesis.

Glutamine Synthetase: Role in Neurological Disorders

Glutamine synthetase (GS) is an ATP-dependent enzyme found in most species that synthesizes glutamine from glutamate and ammonia. In brain, GS is exclusively located in astrocytes where it serves to maintain the glutamate-glutamine cycle, as well as nitrogen metabolism. Changes in the activity of GS, as well as its gene expression, along with excitotoxicity, have been identified in a number of neurological conditions. The literature describing alterations in the activation and gene expression of GS, as well as its involvement in different neurological disorders, however, is incomplete. This review summarizes changes in GS gene expression/activity and its potential contribution to the pathogenesis of several neurological disorders, including hepatic encephalopathy, ischemia, epilepsy, Alzheimer's disease, amyotrophic lateral sclerosis, traumatic brain injury, Parkinson's disease, and astroglial neoplasms. This review also explores the possibility of targeting GS in the therapy of these conditions.

The protective effect of different airway humidification liquids to lung after tracheotomy in traumatic brain injury: The role of pulmonary surfactant protein-A (SP-A)

The purpose of this study was to establish a rat model of a brain injury with tracheotomy and compared the wetting effects of different airway humidification liquids, afterward, the best airway humidification liquid was selected for the clinical trial, thus providing a theoretical basis for selecting a proper airway humidification liquid in a clinical setting. Rats were divided into a sham group, group A (0.9% NaCl), group B (0.45% NaCl), group C (0.9% NaCl+ambroxol) and group D (0.9% NaCl+Pulmicort). An established rat model of traumatic brain injury with tracheotomy was used. Brain tissue samples were taken to determine water content, while lung tissue samples were taken to determine wet/dry weight ratio (W/D), histological changes and expression levels of SP-A mRNA and SP-A protein. 30 patients with brain injury and tracheotomy were selected and divided into two groups based on the airway humidification liquid instilled in the trachea tube, 0.45% NaCl and 0.9% NaCl+ambroxol. Blood was then extracted from the patients to measure the levels of SP-A, interleukin-6 (IL-6), interleukin-8 (IL-8) and tumour necrosis factor-α (TNF-α). The difference between group C and other groups in lung W/D and expression levels of SP-A mRNA and SP-A protein was significant (P<0.05). In comparison, the histological changes showed that the lung tissue damage was smallest in group C compared to the three other groups. Aspect of patients, 0.45% NaCl group and 0.9% NaCl+ambroxol group were significantly different in the levels of SP-A, IL-6, IL-8 and TNF-α (P<0.01). In the present study, 0.9% NaCl+ambroxol promote the synthesis and secretion of pulmonary surfactant, and has anti-inflammatory and antioxidant effects, which inhibit the release of inflammatory factors and cytokines, making it an ideal airway humidification liquid.