Population-Based Study of the Risk of In-Hospital Death After Traumatic Brain Injury: The Role of Sepsis

Immunonutrition with Omega-3 Fatty Acid Supplementation in Severe TBI: Retrospective Analysis of Patient Characteristics and Outcomes

Early evidence-based medical interventions to improve patient outcomes after traumatic brain injury (TBI) are lacking. In patients admitted to the ICU after TBI, optimization of nutrition is an emerging field of interest. Specialized enteral nutrition (EN) formulas that include immunonutrition containing omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been developed and are used for their proposed anti-inflammatory and proimmune properties; however, their use has not been rigorously studied in human TBI populations. A single-center, retrospective, descriptive observational study was conducted at the LAC + USC Medical Center. Patients with severe TBI (sTBI, Glasgow Coma Scale score ≤ 8) who remained in the ICU for ≥2 weeks and received EN were identified between 2017 and 2022 using the institutional trauma registry. Those who received immunonutrition formulas containing n-3 PUFAs were compared with those who received standard, polymeric EN with regard to baseline characteristics, clinical markers of inflammation and immune function, and short-term clinical outcomes. A total of 151 patients with sTBI were analyzed. Those who received immunonutrition with n-3 PUFA supplementation were more likely to be male, younger, Hispanic/Latinx, and have polytrauma needing non-central nervous system surgery. No differences in clinical markers of inflammation or infection rate were found. In multivariate regression analysis, immunonutrition was associated with reduced hospital length of stay (LOS). ICU LOS was also reduced in the subgroup of patients with polytrauma and TBI. This study identifies important differences in patient characteristics and outcomes associated with the EN formula prescribed. Study results can directly inform a prospective pragmatic study of immunonutrition with n-3 PUFA supplementation aimed to confirm the biomechanistic and clinical benefits of the intervention.

Characteristics, Outcomes, and Its Associated Factors Among Patients Hospitalized With Mild Traumatic Brain Injuries

OBJECTIVE

The aim of the study is to investigate the characteristics and hospital outcomes of patients with mild traumatic brain injuries.

DESIGN

A total of 1940 patients with mild traumatic brain injuries from seven community hospitals between 2017 and 2019 were identified using International Classification of Disease codes and an documented initial Glasgow Coma Scale score of 13-15. A stepwise logistic regression was used to identify demographics and clinical characteristics associated with in-hospital mortality and home discharge.

RESULTS

The median age was 69 yrs old with 66.6% associated with falls at admission. Subdural hemorrhage was the most common brain lesion and more common in the group with falls. Increased age, male sex, epidural hemorrhage, presence of hemiplegia, paraplegia, renal disease, cancer, hospital-acquired sepsis, anemia, and use of direct vasodilator were associated with increased odds of in-hospital mortality. Increased age, medical coverage by Medicare, cerebral edema, lower initial Glasgow Coma Scale, length of stay, comorbidity of acute myocardiac infarction, and use of thiamine and opioids were associated with decreased likelihood of discharge to home.

CONCLUSIONS

Recognizing characteristics of hospitalized patients with mild traumatic brain injuries and their association with increased in-hospital mortality and nonhome discharge can be useful for improving care of this vulnerable population.

Immunonutrition with Omega-3 Fatty Acid Supplementation in Severe TBI: Retrospective Analysis of Patient Characteristics and Outcomes

Background

Early evidence-based medical interventions to improve patient outcomes after traumatic brain injury (TBI) are lacking. In patients admitted to the ICU after TBI, optimization of nutrition is an emerging field of interest. Specialized enteral nutrition (EN) formulas that include immunonutrition containing omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been developed and are used for their proposed anti-inflammatory and pro-immune properties; however, their use has not been rigorously studied in human TBI populations.

Methods

A single-center, retrospective, descriptive observational study was conducted at LAC + USC Medical Center. Patients with severe TBI (sTBI, Glasgow Coma Scale score ≤ 8) who remained in the ICU for ≥ 2 weeks and received EN were identified between 2017 and 2022 using the institutional trauma registry. Those who received immunonutrition formulas containing n-3 PUFAs were compared to those who received standard, polymeric EN in regard to baseline characteristics, clinical markers of inflammation and immune function, and short-term clinical outcomes.

Results

A total of 151 patients with sTBI were analyzed. Those who received immunonutrition with n-3 PUFA supplementation were more likely to be male, younger, Hispanic/Latinx, and have polytrauma needing non-central nervous system surgery. No differences in clinical markers of inflammation or infection rate were found. In multivariate regression analysis, immunonutrition was associated with reduced hospital length of stay (LOS). ICU LOS was also reduced in the subgroup of patients with polytrauma and TBI.

Conclusion

This study identifies important differences in patient characteristics and outcomes associated with the EN formula prescribed. Study results can directly inform a prospective pragmatic study of immunonutrition with n-3 PUFA supplementation aimed to confirm the biomechanistic and clinical benefits of the intervention.

Pneumonia in Nervous System Injuries: An Analytic Review of Literature and Recommendations

Pneumonia is one of the most common complications in intensive care units and is the most common nosocomial infection in this setting. Patients with neurocritical conditions who are admitted to ICUs are no exception, and in fact, are more prone to infections such as pneumonia because of factors such as swallow dysfunction, need for mechanical ventilation, longer length of stay in hospitals, etc. Common central nervous system pathologies such as ischemic stroke, traumatic brain injury, subarachnoid hemorrhage, intracerebral hemorrhage, neuromuscular disorders, status epilepticus, and demyelinating diseases can cause long in-hospital admissions and increase the risk of pneumonia each with a mechanism of its own. Brain injury-induced immunosuppression syndrome is usually considered the common mechanism through which patients with critical central nervous system conditions become susceptible to different kinds of infection including pneumonia. Evaluating the patients and assessment of the risk factors can lead our attention toward better infection control in this population and therefore decrease the risk of infections in central nervous system injuries.

Beyond the Brain: Peripheral Interactions after Traumatic Brain Injury

Traumatic brain injury (TBI) is a leading cause of death and disability, and there are currently no pharmacological treatments known to improve patient outcomes. Unquestionably, contributing toward a lack of effective treatments is the highly complex and heterogenous nature of TBI. In this review, we highlight the recent surge of research that has demonstrated various central interactions with the periphery as a potential major contributor toward this heterogeneity and, in particular, the breadth of research from Australia. We describe the growing evidence of how extracranial factors, such as polytrauma and infection, can significantly alter TBI neuropathology. In addition, we highlight how dysregulation of the autonomic nervous system and the systemic inflammatory response induced by TBI can have profound pathophysiological effects on peripheral organs, such as the heart, lung, gastrointestinal tract, liver, kidney, spleen, and bone. Collectively, this review firmly establishes TBI as a systemic condition. Further, the central and peripheral interactions that can occur after TBI must be further explored and accounted for in the ongoing search for effective treatments.

Sepsis in Traumatic Brain Injury: Epidemiology and Outcomes

BACKGROUND

Traumatic brain injury (TBI) is a leading cause of death and disability. Risk factors for in-hospital mortality include older age, co-morbidity, and TBI severity. Few studies have investigated the role of sepsis in individuals with TBI.

METHODS

We studied adult patients with TBI admitted to intensive care over a 5-year period. Patient characteristics were identified by linking clinical and administrative databases. Charts of individuals with TBI and sepsis were manually reviewed. Predictors of ICU and hospital mortality were identified using logistic regression modeling.

RESULTS

Four hundred eighty-six individuals with TBI were admitted to intensive care. Sixteen (3.3%) developed sepsis. Pneumonia was the most common source (94%). Staphylococcus aureus was the most common pathogen (75%). ICU lengths of stay (LOS) (12.2 days [interquartile range (IQR) 4.4-23.5] versus 3.7 days [IQR 1.7-8.2]; p < 0.001) and hospital LOS (28.0 days [IQR 11.8-41.4] versus 15.3 days [IQR 5.0-30.9]; p = 0.017) were longer in patients with TBI and sepsis. Sepsis was not associated with ICU (adjusted odds ratio [aOR] 0.51; 95%CI 0.12-2.27; p = 0.38) or hospital (aOR 0.78; 95% CI 0.21-2.96; p = 0.78) mortality, though age (aOR 1.02; 95% CI 1.00-1.04; p = 0.014 for hospital mortality), severe TBI (aOR 3.71; 95% CI 1.52-9.08; p = 0.004 for ICU mortality and 4.10; 95% CI 1.95-8.65; p < 0.001 for hospital mortality), and APACHE II score (aOR 1.19; 95% CI 1.11-1.28; p < 0.001 for ICU mortality and 1.22; 95% CI 1.14-1.31; p < 0.001 for hospital mortality) were.

CONCLUSION

Sepsis in patients with TBI was not associated with mortality; however, sepsis was associated with increased health care utilization (ICU and hospital LOS).

Inflammation in Traumatic Brain Injury

There is an increasing evidence that inflammation contributes to clinical and functional outcomes in traumatic brain injury (TBI). Many successful target-engaging, lesion-reducing, symptom-alleviating, and function-improving interventions in animal models of TBI have failed to show efficacy in clinical trials. Timing and immunological context are paramount for the direction, quality, and intensity of immune responses to TBI and the resulting neuroanatomical, clinical, and functional course. We present components of the immune system implicated in TBI, potential immune targets, and target-engaging interventions. The main objective of our article is to point toward modifiable molecular and cellular mechanisms that may modify the outcomes in TBI, and contribute to increasing the translational value of interventions that have been identified in animal models of TBI.

A cross-sectional analysis of variables associated with morbidity and mortality in postoperative neurosurgical patients diagnosed with sepsis

BACKGROUND

Sepsis is a systemic, inflammatory response to infection associated with significant morbidity and mortality. There is a considerable lack of literature exploring sepsis in neurosurgery. We aimed to identify variables that were correlated with mortality and increased morbidity as defined by readmission and increased length of stay in postoperative neurosurgical patients that met a sepsis diagnosis.

METHODS

A retrospective chart review was conducted of 105 patients who underwent a neurosurgical operation at our institution from 2012 to 2017 who were discharged with at least one sepsis diagnosis code and who did not have a preoperative infection. We identified variables that were correlated with mortality, readmission, and increased length of stay.

RESULTS

Patients who survived were preferentially distributed towards lower ASA Physical Status Classification scores. A larger percentage of patients who did not survive had cranial surgery, whereas patients who survived were more likely to have undergone spinal surgery. Higher respiratory rates, higher maximum lactic acid levels, positive sputum cultures, and lower incoming Glasgow Coma Scores (GCS) were significantly correlated with mortality. A larger fraction of readmitted patients had positive surgical site cultures but had negative sputum cultures. Length of hospitalization was correlated with incoming GCS, non-elective operations, and Foley catheter, arterial line, central line, and endotracheal tube duration.

CONCLUSIONS

Neurosurgical postoperative patients diagnosed with sepsis may be risk stratified for mortality, readmission, and increased length of stay based on certain variables that may help direct their care. Further prospective studies are needed to explore causal relationships.

Clinical Predictors of 3- and 6-Month Outcome for Mild Traumatic Brain Injury Patients with a Negative Head CT Scan in the Emergency Department: A TRACK-TBI Pilot Study

A considerable subset of mild traumatic brain injury (mTBI) patients fail to return to baseline functional status at or beyond 3 months postinjury. Identifying at-risk patients for poor outcome in the emergency department (ED) may improve surveillance strategies and referral to care. Subjects with mTBI (Glasgow Coma Scale 13–15) and negative ED initial head CT < 24 h of injury, completing 3- or 6-month functional outcome (Glasgow Outcome Scale-Extended; GOSE), were extracted from the prospective, multicenter Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) Pilot study. Outcomes were dichotomized to full recovery (GOSE = 8) vs. functional deficits (GOSE < 8). Univariate predictors with p < 0.10 were considered for multivariable regression. Adjusted odds ratios (AOR) were reported for outcome predictors. Significance was assessed at p < 0.05. Subjects who completed GOSE at 3- and 6-month were 211 (GOSE < 8: 60%) and 185 (GOSE < 8: 65%). Risk factors for 6-month GOSE < 8 included less education (AOR = 0.85 per-year increase, 95% CI: (0.74–0.98)), prior psychiatric history (AOR = 3.75 (1.73–8.12)), Asian/minority race (American Indian/Alaskan/Hawaiian/Pacific Islander) (AOR = 23.99 (2.93–196.84)), and Hispanic ethnicity (AOR = 3.48 (1.29–9.37)). Risk factors for 3-month GOSE < 8 were similar with the addition of injury by assault predicting poorer outcome (AOR = 3.53 (1.17–10.63)). In mTBI patients seen in urban trauma center EDs with negative CT, education, injury by assault, Asian/minority race, and prior psychiatric history emerged as risk factors for prolonged disability.

Comorbidity in adults with traumatic brain injury and all-cause mortality: a systematic review

OBJECTIVES

Comorbidity in traumatic brain injury (TBI) has been recognised to alter the clinical course of patients and influence short-term and long-term outcomes. We synthesised the evidence on the effects of different comorbid conditions on early and late mortality post-TBI in order to (1) examine the relationship between comorbid condition(s) and all-cause mortality in TBI and (2) determine the influence of sociodemographic and clinical characteristics of patients with a TBI at baseline on all-cause mortality.

DESIGN

Systematic review.

DATA SOURCES

Medline, Central, Embase, PsycINFO and bibliographies of identified articles were searched from May 1997 to January 2019.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Included studies met the following criteria: (1) focused on comorbidity as it related to our outcome of interest in adults (ie, ≥18 years of age) diagnosed with a TBI; (2) comorbidity was detected by any means excluding self-report; (3) reported the proportion of participants without comorbidity and (4) followed participants for any period of time.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers extracted the data and assessed risk of bias using the Quality in Prognosis Studies tool. Data were synthesised through tabulation and qualitative description.

RESULTS

A total of 27 cohort studies were included. Among the wide range of individual comorbid conditions studied, only low blood pressure was a consistent predictors of post-TBI mortality. Other consistent predictors were traditional sociodemographic risk factors. Higher comorbidity scale, scores and the number of comorbid conditions were not consistently associated with post-TBI mortality.

CONCLUSIONS

Given the high number of comorbid conditions that were examined by the single studies, research is required to further substantiate the evidence and address conflicting findings. Finally, an enhanced set of comorbidity measures that are suited for the TBI population will allow for better risk stratification to guide TBI management and treatment.

PROSPERO REGISTRATION NUMBER

CRD42017070033.

Healthcare-Associated Infections in the Neurocritical Care Unit

PURPOSE OF REVIEW

This article summarizes updated data and knowledge on healthcare-associated infections in the neurocritical care unit, with a focus on central nervous system infections and systemic infectious complications in patients with acute brain disease. It also reviews the concept of brain injury-induced immune modulation, an underlying mechanism to explain why the neuro-ICU population is particularly susceptible to infections.

RECENT FINDINGS

Healthcare-associated infections in the neuro-ICU are common: up to 40 % of meningitides in the developed world are now healthcare-associated. The number of gram-negative infections is rising. New diagnostic approaches attempt to aid in the diagnosis of healthcare-associated meningitis and ventriculitis. Healthcare-associated infections in the neurocritical care unit remain a challenge for diagnosis, treatment, and prevention. Gaining a better understanding of at-risk patients and development of preventative strategies will be the goal for future investigation.

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.

Labour market attachment after mild traumatic brain injury: nationwide cohort study with 5-year register follow-up in Denmark

OBJECTIVES

Sickness absence after mild traumatic brain injury (mTBI) is frequent due to postconcussive symptoms. We examined labour market attachment following mTBI up to 5 years postinjury.

DESIGN AND SETTING

Nationwide cohort study with register follow-up.

PARTICIPANTS

Patients between 18 and 60 years with mTBI (International Classification of Diseases, version 10 diagnosis S06.0) were extracted from the Danish National Patient Register (n=19 732). Controls were matched on sex, age and municipality (n=18 640). Patients with spinal cord and column injuries, traumatic brain injury and concussions 5 years preinjury or as secondary diagnosis to the concussion in the inclusion period were excluded.

PRIMARY AND SECONDARY OUTCOME MEASURES

Data were extracted from the Danish Register for Evaluation of Marginalization. Primary outcome was 'not attending ordinary work' defined as receiving any social transfer payment. Secondary outcomes were health-related benefits, limited attachment to the labour market, permanent lack of attachment to the labour market and death.

RESULTS

5 years after diagnosis, 43% of patients were not attending ordinary work. The odds increased from 6 months (OR 1.30, 95% CI 1.24 to 1.36) to 5 years (OR 1.54, 95% CI 1.45 to 1.63). The odds of health-related benefits were 32% (OR 1.32, 95% CI 1.22 to 1.42) at 6 months and 22% (OR 1.22, 95% CI 1.12 to 1.33) at 5 years. Limited attachment to the labour market showed increased odds at 5 years (OR 1.38, 95% CI 1.27 to 1.51) and the odds of permanent lack of attachment to the labour market were higher for patients compared with controls (OR 2.59, 95% CI 2.30 to 2.92). Death was more than two times higher at 5 years postinjury (OR 2.62, 95% CI 2.10 to 3.26).

CONCLUSIONS

43% of concussed patients were not attending ordinary work 5 years postinjury and received health and social transfer benefits. We conclude that mTBI has a long-term impact on labour market attachment. Prevention and treatment of persisting postconcussive symptoms should be considered.

TRIAL REGISTRATION NUMBER

NCT03214432; Results.

Temporal Delays Along the Neurosurgical Care Continuum for Traumatic Brain Injury Patients at a Tertiary Care Hospital in Kampala, Uganda

BACKGROUND

Significant care continuum delays between acute traumatic brain injury (TBI) and definitive surgery are associated with poor outcomes. Use of the "3 delays" model to evaluate TBI outcomes in low- and middle-income countries has not been performed.

OBJECTIVE

To describe the care continuum, using the 3 delays framework, and its association with TBI patient outcomes in Kampala, Uganda.

METHODS

Prospective data were collected for 563 TBI patients presenting to a tertiary hospital in Kampala from 1 June to 30 November 2016. Four time intervals were constructed along 5 time points: injury, hospital arrival, neurosurgical evaluation, computed tomography (CT) results, and definitive surgery. Time interval differences among mild, moderate, and severe TBI and their association with mortality were analyzed.

RESULTS

Significant care continuum differences were observed for interval 3 (neurosurgical evaluation to CT result) and 4 (CT result to surgery) between severe TBI patients (7 h for interval 3 and 24 h for interval 4) and mild TBI patients (19 h for interval 3 and 96 h for interval 4). These postarrival delays were associated with mortality for mild (P = .05) and moderate TBI (P = .03) patients. Significant hospital arrival delays for moderate TBI patients were associated with mortality (P = .04).

CONCLUSION

Delays for mild and moderate TBI patients were associated with mortality, suggesting that quality improvement interventions could target current triage practices. Future research should aim to understand the contributors to delays along the care continuum, opportunities for more effective resource allocation, and the need to improve prehospital logistical referral systems.

Systemic Estrone Production and Injury-Induced Sex Hormone Steroidogenesis after Severe Traumatic Brain Injury: A Prognostic Indicator of Traumatic Brain Injury-Related Mortality

Extensive pre-clinical studies suggest that sex steroids are neuroprotective in experimental traumatic brain injury (TBI). However, clinical trials involving sex hormone administration have not shown beneficial results, and our observational cohort studies show systemic estradiol (E2) production to be associated with adverse outcomes. Systemic E2 is produced via aromatization of testosterone (T) or reduction of estrone (E1). E1, also produced via aromatization of androstenedione (Andro) and is a marker of T-independent E2 production. We hypothesized that E1 would be (1) associated with TBI-related mortality, (2) the primary intermediate for E2 production, and (3) associated with adipose tissue-specific aromatase transcription. We assessed 100 subjects with severe TBI and 8 healthy controls. Serum levels were measured on days 0-3 post-TBI for key steroidogenic precursors (progesterone), aromatase pathway intermediates (E1, E2, T, Andro), and the adipose tissue-specific aromatase transcription factors cortisol, tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6). E1 was elevated after TBI versus controls. High E1 was associated with higher progesterone, cortisol, and IL-6 (p < 0.05). Multivariable logistic regression demonstrated that those in the highest E1 tertile had increased odds for mortality (adjusted OR = 5.656, 95% CI = 1.102-29.045, p = 0.038). Structural equation models show that early serum E2 production is largely T independent, occurring predominantly through E1 metabolism. Acute serum E1 functions as a mortality marker for TBI through aromatase-dependent E1 production and T-independent E2 production. Further work should evaluate risk factors for high E2 production and how systemic E2 and its key intermediate E1 contribute to the extracerebral consequences of severe TBI.

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.

Chronic Alterations in Systemic Immune Function after Traumatic Brain Injury

There is a compelling link between severe brain trauma and immunosuppression in patients with traumatic brain injury (TBI). Although acute changes in the systemic immune compartment have been linked to outcome severity, the long-term consequences of TBI on systemic immune function are unknown. Here, adult male C57Bl/6 mice underwent moderate-level controlled cortical impact (CCI) or sham surgery, and systemic immune function was evaluated at 1, 3, 7, 14, and 60 days post-injury. Bone marrow, blood, thymus, and spleen were examined by flow cytometry to assess changes in immune composition, reactive oxygen species (ROS) production, phagocytic activity, and cytokine production. Bone marrow derived macrophages (BMDMs) from sham and 60-day CCI mice were cultured for immune challenge studies using lipopolysaccharide (LPS) and interleukin-4 (IL-4) models. Acutely, TBI caused robust bone marrow activation and neutrophilia. Neutrophils and monocytes exhibited impairments in respiratory burst, cytokine production, and phagocytosis; in contrast, ROS levels and pro-inflammatory cytokine production were chronically elevated at 60 days post-injury. Cultures of BMDMs from chronic CCI mice demonstrated defects in LPS- and IL-4-induced polarization when compared with stimulated BMDMs from sham mice. TBI also caused thymic involution, inverted CD4:CD8 ratios, chronic T lymphopenia, greater memory conversion, increased T cell activation, impaired interferon γ induction, and chronically elevated Th1 cytokine and ROS production. Collectively, our in-depth phenotypic and functional analyses demonstrate that TBI induces widespread suppression of innate and adaptive immune responses after TBI. Moreover, at chronic time points, TBI mice exhibit hallmarks of accelerated immune aging, displaying chronic deficits in systemic immune function.

The influence of immunological stressors on traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide, and typically involves a robust immune response. Although a great deal of preclinical research has been conducted to identify an effective treatment, all phase III clinical trials have been unsuccessful to date. These translational shortcomings are in part due to a failure to recognize and account for the heterogeneity of TBI, including how extracranial factors can influence the aftermath of TBI. For example, most preclinical studies have utilized isolated TBI models in young adult males, while clinical trials typically involve highly heterogeneous patient populations (e.g., different mechanisms of injury, a range of ages, presence of polytrauma or infection). This paper will review the current, albeit limited literature related to how TBI is affected by common concomitant immunological stressors. In particular, discussion will focus on whether extracranial trauma (i.e., polytrauma), infection, and age/immunosenescence can influence TBI pathophysiology, and thereby may result in a different brain injury than what would have occurred in an isolated TBI. It is concluded that these immunological stressors are all likely to be TBI modifiers that should be further studied and could impact translational treatment strategies.

Investigating the Variability in Mild Traumatic Brain Injury Definitions: A Prospective Cohort Study

OBJECTIVE

To prospectively compare the proportion of traumatic brain injuries (TBIs) that would be classified as mild by applying different published definitions of mild TBI to a large prospectively collected dataset, and to examine the variability in the proportions included by various definitions.

DESIGN

Prospective observational study.

SETTING

Hospital emergency departments.

PARTICIPANTS

Children (N=11,907) aged 3 to 16 years (mean age, 8.2±3.9y). Of the participants, 3868 (32.5%) were girls, and 7374 (61.9%) of the TBIs were the result of a fall. Median Glasgow Coma Scale score was 15.

MAIN OUTCOME MEASURES

We applied 17 different definitions of mild TBI, identified through a published systematic review, to children aged 3 to 16 years. Adjustments and clarifications were made to some definitions. The number and percentage identified for each definition is presented.

RESULTS

Adjustments had to be made to the 17 definitions to apply to the dataset: none in 7, minor to substantial in 10. The percentage classified as mild TBI across definitions varied from 7.1% (n=841) to 98.7% (n=11,756) and varied by age group.

CONCLUSIONS

When applying the 17 definitions of mild TBI to a large prospective multicenter dataset of TBI, there was wide variability in the number of cases classified. Clinicians and researchers need to be aware of this variability when examining literature concerning children with mild TBI.

Impact of early positive cultures in the elderly with traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality in the United States, especially in the elderly, who have the highest rates of TBI-related hospitalizations and deaths among all age groups. Sepsis is one of many risk factors that is associated with higher mortality and longer length of hospital stay in this population partially due to the immunosuppressive effects of TBI. The significance of early indicators of infection, such as a positive blood, sputum, or urine culture, is not well described. The purpose of this study was to determine if early positive cultures predict higher mortality in elderly patients with TBI.

METHODS

All trauma patients aged ≥65 years with TBI, admitted between January 1, 2009 and December 31, 2013 to the surgical intensive care unit, were retrospectively reviewed. Clinical data including results from sputum, blood, and urine cultures were reviewed.

RESULTS

Overall, 288 elderly patients with TBI were identified, and 92 (32%) had a positive culture. Patients with positive cultures had longer intensive care unit (median 6.0 versus 2.0 days, P < 0.001) and ventilation days (median 7.0 versus 2.0 days, P < 0.001). Patients who had positive cultures within 2-3 days of admission had a higher adjusted hazard ratio for mortality than those patients who had positive cultures after 6 or more days.

CONCLUSIONS

In elderly patients with TBI, early positive cultures are associated with a higher risk of mortality. Further research is required to determine the role of obtaining cultures on admission in this subpopulation of trauma patients.

A prospective neurosurgical registry evaluating the clinical care of traumatic brain injury patients presenting to Mulago National Referral Hospital in Uganda

Background

Traumatic Brain Injury (TBI) is disproportionally concentrated in low- and middle-income countries (LMICs), with the odds of dying from TBI in Uganda more than 4 times higher than in high income countries (HICs). The objectives of this study are to describe the processes of care and determine risk factors predictive of poor outcomes for TBI patients presenting to Mulago National Referral Hospital (MNRH), Kampala, Uganda.

Methods

We used a prospective neurosurgical registry based on Research Electronic Data Capture (REDCap) to systematically collect variables spanning 8 categories. Univariate and multivariate analysis were conducted to determine significant predictors of mortality.

Results

563 TBI patients were enrolled from 1 June– 30 November 2016. 102 patients (18%) received surgery, 29 patients (5.1%) intended for surgery failed to receive it, and 251 patients (45%) received non-operative management. Overall mortality was 9.6%, which ranged from 4.7% for mild and moderate TBI to 55% for severe TBI patients with GCS 3–5. Within each TBI severity category, mortality differed by management pathway. Variables predictive of mortality were TBI severity, more than one intracranial bleed, failure to receive surgery, high dependency unit admission, ventilator support outside of surgery, and hospital arrival delayed by more than 4 hours.

Conclusions

The overall mortality rate of 9.6% in Uganda for TBI is high, and likely underestimates the true TBI mortality. Furthermore, the wide-ranging mortality (3–82%), high ICU fatality, and negative impact of care delays suggest shortcomings with the current triaging practices. Lack of surgical intervention when needed was highly predictive of mortality in TBI patients. Further research into the determinants of surgical interventions, quality of step-up care, and prolonged care delays are needed to better understand the complex interplay of variables that affect patient outcome. These insights guide the development of future interventions and resource allocation to improve patient outcomes.

Complications following hospital admission for traumatic brain injury: A multicenter cohort study

PURPOSE

To evaluate the incidence, determinants and impact on outcome of in-hospital complications in adults with traumatic brain injury (TBI).

MATERIALS AND METHODS

We conducted a multicenter cohort study of TBI patients admitted between 2007 and 2012 in an inclusive Canadian trauma system. Risk ratios of complications, odds ratios of mortality and geometric mean ratios of length of stay (LOS) were calculated using generalized linear models with adjustment for prognostic indicators and hospital cluster effects.

RESULTS

Of 12,887 patients, 3.2% had at least one neurological complication and 22.6% a non-neurological complication. Mechanical ventilation, head injury severity, blood transfusion and neurosurgical intervention had the strongest correlation with neurological complications. Mechanical ventilation, the Glasgow Coma Scale, blood transfusion and concomitant injuries had the strongest correlation with non-neurological complications. Neurological and non-neurological complications were associated with a 85% and 53% increase in the odds of mortality, and a 60% and two-fold increases in LOS, respectively.

CONCLUSIONS

More than 20% of patients with TBI developed a complication. Many of these complications were associated with increased mortality and LOS. Results highlight the importance of prevention strategies adapted to treatment decisions and underline the need to improve knowledge on the underuse and overuse of clinical interventions.

The effect of concomitant peripheral injury on traumatic brain injury pathobiology and outcome

Background

Traumatic injuries are physical insults to the body that are prevalent worldwide. Many individuals involved in accidents suffer injuries affecting a number of extremities and organs, otherwise known as multitrauma or polytrauma. Traumatic brain injury is one of the most serious forms of the trauma-induced injuries and is a leading cause of death and long-term disability. Despite over dozens of phase III clinical trials, there are currently no specific treatments known to improve traumatic brain injury outcomes. These failures are in part due to our still poor understanding of the heterogeneous and evolving pathophysiology of traumatic brain injury and how factors such as concomitant extracranial injuries can impact these processes.

Main body

Here, we review the available clinical and pre-clinical studies that have investigated the possible impact of concomitant injuries on traumatic brain injury pathobiology and outcomes. We then list the pathophysiological processes that may interact and affect outcomes and discuss promising areas for future research. Taken together, many of the clinical multitrauma/polytrauma studies discussed in this review suggest that concomitant peripheral injuries may increase the risk of mortality and functional deficits following traumatic brain injury, particularly when severe extracranial injuries are combined with mild to moderate brain injury. In addition, recent animal studies have provided strong evidence that concomitant injuries may increase both peripheral and central inflammatory responses and that structural and functional deficits associated with traumatic brain injury may be exacerbated in multiply injured animals.

Conclusions

The findings of this review suggest that concomitant extracranial injuries are capable of modifying the outcomes and pathobiology of traumatic brain injury, in particular neuroinflammation. Though additional studies are needed to further identify the factors and mechanisms involved in central and peripheral injury interactions following multitrauma and polytrauma, concomitant injuries should be recognized and accounted for in future pre-clinical and clinical traumatic brain injury studies.

Traumatic Brain Injury and Peripheral Immune Suppression: Primer and Prospectus

Nosocomial infections are a common occurrence in patients following traumatic brain injury (TBI) and are associated with an increased risk of mortality, longer length of hospital stay, and poor neurological outcome. Systemic immune suppression arising as a direct result of injury to the central nervous system (CNS) is considered to be primarily responsible for this increased incidence of infection, a view strengthened by recent studies that have reported novel changes in the composition and function of the innate and adaptive arms of the immune system post-TBI. However, our knowledge of the mechanisms that underlie TBI-induced immune suppression is equivocal at best. Here, after summarizing our current understanding of the impact of TBI on peripheral immunity and discussing CNS-mediated regulation of immune function, we propose roles for a series of novel mechanisms in driving the immune suppression that is observed post-TBI. These mechanisms, which have never been considered before in the context of TBI-induced immune paresis, include the CNS-driven emergence into the circulation of myeloid-derived suppressor cells and suppressive neutrophil subsets, and the release from injured tissue of nuclear and mitochondria-derived damage associated molecular patterns. Moreover, in an effort to further our understanding of the mechanisms that underlie TBI-induced changes in immunity, we pose throughout the review a series of questions, which if answered would address a number of key issues, such as establishing whether manipulating peripheral immune function has potential as a future therapeutic strategy by which to treat and/or prevent infections in the hospitalized TBI patient.

Sepsis in intensive care unit patients with traumatic brain injury: factors associated with higher mortality

Objective

Patients with traumatic brain injury are particularly susceptible to sepsis, which may exacerbate the systemic inflammatory response and lead to organ dysfunction. The influence of clinical variables on the mortality of intensive care unit patients with traumatic brain injury and sepsis was investigated.

Methods

The present investigation was a retrospective study involving 175 patients with traumatic brain injury who were treated in a period of 1 year at a reference hospital for trauma and who had sepsis, severe sepsis, or septic shock. Demographic and clinical data were obtained, and the SOFA score was calculated at the time sepsis was found and after 72 hours.

Results

There was a predominance of young men with severe traumatic brain injury, multiple head injuries, sepsis with a pulmonary focus, prolonged hospital stay, and high mortality (37.7%). Circulatory and respiratory failure had a high incidence, but renal and coagulation failure were less frequent, and liver failure was not observed. After logistic regression, the presence of septic shock and respiratory failure 72 hours after the sepsis diagnosis was associated with higher mortality, with an odds ratio of 7.56 (95%CI=2.04-27.31, p=0.0024) and 6.62 (95%CI=1.93-22.78, p=0.0027), respectively. In addition, there was a higher mortality among patients who had no organ failure on D1 but who developed the condition after 72 hours of sepsis and in those patients who already had organ failure at the time sepsis was diagnosed and remained in this condition after 72 hours.

Conclusion

Septic shock and progressive organ (particularly respiratory) dysfunction increases the mortality of patients with traumatic brain injury and sepsis.

Substance P mediates reduced pneumonia rates after traumatic brain injury

OBJECTIVES

Traumatic brain injury results in significant morbidity and mortality and is associated with infectious complications, particularly pneumonia. However, whether traumatic brain injury directly impacts the host response to pneumonia is unknown. The objective of this study was to determine the nature of the relationship between traumatic brain injury and the prevalence of pneumonia in trauma patients and investigate the mechanism of this relationship using a murine model of traumatic brain injury with pneumonia.

DESIGN

Data from the National Trauma Data Bank and a murine model of traumatic brain injury with postinjury pneumonia.

SETTING

Academic medical centers in Cincinnati, OH, and Boston, MA.

PATIENTS/SUBJECTS

Trauma patients in the National Trauma Data Bank with a hospital length of stay greater than 2 days, age of at least 18 years at admission, and a blunt mechanism of injury. Subjects were female ICR mice 8-10 weeks old.

INTERVENTIONS

Administration of a substance P receptor antagonist in mice.

MEASUREMENTS AND MAIN RESULTS

Pneumonia rates were measured in trauma patients before and after risk adjustment using propensity scoring. In addition, survival and pulmonary inflammation were measured in mice undergoing traumatic brain injury with or without pneumonia. After risk adjustment, we found that traumatic brain injury patients had significantly lower rates of pneumonia compared to blunt trauma patients without traumatic brain injury. A murine model of traumatic brain injury reproduced these clinical findings with mice subjected to traumatic brain injury demonstrating increased bacterial clearance and survival after induction of pneumonia. To determine the mechanisms responsible for this improvement, the substance P receptor was blocked in mice after traumatic brain injury. This treatment abrogated the traumatic brain injury-associated increases in bacterial clearance and survival.

CONCLUSIONS

The data demonstrate that patients with traumatic brain injury have lower rates of pneumonia compared to non-head-injured trauma patients and suggest that the mechanism of this effect occurs through traumatic brain injury-induced release of substance P, which improves innate immunity to decrease pneumonia.

Inhibition of the membrane attack complex of the complement system reduces secondary neuroaxonal loss and promotes neurologic recovery after traumatic brain injury in mice

Traumatic brain injury (TBI) is the leading cause of disability and death in young adults. The secondary neuroinflammation and neuronal damage that follows the primary mechanical injury is an important cause of disability in affected people. The membrane attack complex (MAC) of the complement system is detected in the traumatized brain early after TBI; however, its role in the pathology and neurologic outcome of TBI has not yet been investigated. We generated a C6 antisense oligonucleotide that blocks MAC formation by inhibiting C6, and we compared its therapeutic effect to that of Ornithodoros moubata complement inhibitor (OmCI), a known inhibitor of C5 activation that blocks generation of the anaphylatoxin C5a and C5b, an essential component of MAC. Severe closed head injury in mice induced abundant MAC deposition in the brain. Treatment with C6 antisense reduced C6 synthesis (85%) and serum levels (90%), and inhibited MAC deposition in the injured brain (91-96%). Treatment also reduced accumulation of microglia/macrophages (50-88%), neuronal apoptosis, axonal loss and weight loss (54-93%), and enhanced neurologic performance (84-92%) compared with placebo-treated controls after injury. These data provide the first evidence, to our knowledge, that inhibition of MAC formation in otherwise complement-sufficient animals reduces neuropathology and promotes neurologic recovery after TBI. Given the importance of maintaining a functional complement opsonization system to fight infections, a critical complication in TBI patients, inhibition of the MAC should be considered to reduce posttraumatic neurologic damage. This work identifies a novel therapeutic target for TBI and will guide the development of new therapy for patients.

Procalcitonin as a marker of sepsis and outcome in patients with neurotrauma: an observation study

BACKGROUND

Procalcitonin (PCT) is a reliable biomarker of sepsis and infection. The level of PCT associated with sepsis and infection in patients with traumatic brain injury is currently unknown. The purpose of this study was to investigate the value of PCT and C-reactive protein (CRP) as diagnostic markers of sepsis and to evaluate the prognostic value of these markers related to the severity of injury, sepsis and mortality.

METHODS

105 adult patients with neurotrauma were enrolled in this study from June 2011 to February 2013. PCT and CRP were measured at admission and 2, 3, 5 and 7 days after admission. The sepsis criteria established by American College of Chest Physicians /Society of Critical Care Medicine Consensus Conference were used to identify patients. Injury Severity Score (ISS) and Glasgow Coma Score (GCS) were used to assess the severity of the injury. All these patients were monitored for 28 days.

RESULTS

At admission, the median level of PCT was consistent with the severity of brain injury as follows: mild 0.08 ng/ml (0.05 - 0.13), moderate 0.25 ng/ml (0.11 - 0.55) and severe 0.31 ng/ml (0.17 - 0.79), but the range of CRP levels varied greatly within the given severity of brain injury. Seventy-one (67.6%) patients developed sepsis. The initial levels of PCT at admission were statistically higher in patients with sepsis, compared with patients with systemic inflammatory response syndrome (SIRS), but there were no differences in the initial concentration of CRP between sepsis and SIRS. After adjusting for these parameters, multivariate logistic regression analysis revealed that PCT was an independent risk factor for septic complications (p < 0.05). The areas under the ROCs at admission for the prediction of mortality were 0.76 (p < 0.05) and 0.733 for PCT and CRP, respectively.

CONCLUSIONS

Increased levels of PCT during the course of the ICU stay could be an important indicator for the early diagnosis of sepsis after neurotrauma. In addition, high serum levels of PCT in patients with neurotrauma at admission indicate an increased risk of septic complications, and the daily measurement of PCT assists in guiding antibiotic therapy in neurotrauma patients.

Incidence of sport-related traumatic brain injury and risk factors of severity: a population-based epidemiologic study

PURPOSE

Few studies of sport-related traumatic brain injury (TBI) are population-based or rely on directly observed data on cause, demographic characteristics, and severity. This study addresses the epidemiology of sport-related TBI in a large population.

METHODS

Data on all South Carolina hospital and emergency department encounters for TBI, 1998-2011, were analyzed. Annual incidence rate of sport-related TBI was calculated, and rates were compared across demographic groups. Sport-related TBI severity was modeled as a function of demographic and TBI characteristics using logistic regression.

RESULTS

A total of 16,642 individuals with sport-related TBI yielded an average annual incidence rate of 31.5/100,000 population with a steady increase from 19.7 in 1998 to 45.6 in 2011. The most common mechanisms of sport-related TBI were kicked in football (38.1%), followed by fall injuries in sports (20.3%). Incidence rate was greatest in adolescents ages 12-18 (120.6/100,000/persons). Severe sport-related TBI was strongly associated with off-road vehicular sport (odds ratio [OR], 4.73; 95% confidence interval [95% CI], 2.92-7.67); repeated head trauma (OR, 4.36; 95% CI, 3.69-5.15); equestrian sport (OR, 2.73; 95% CI, 1.64-4.51); and falls during sport activities (OR, 2.72; 95% CI, 1.67-4.46).

CONCLUSIONS

The high incidence of sport-related TBI in youth, potential for repetitive mild TBI, and its long-term consequences on learning warrants coordinated surveillance activities and population-based outcome studies.

Sepsis: a review for the neurohospitalist

Sepsis represents a major challenge in medicine. It begins as a systemic response to infection that can affect virtually any organ system, including the central and peripheral nervous systems. Akin to management of stroke, early recognition and treatment of sepsis are just as crucial to a successful outcome. Sepsis can precipitate myasthenic crisis and lead to encephalopathy and critical illness neuropathy. Stroke and traumatic brain injury can predispose a patient to develop sepsis, whereas Guillain-Barré syndrome is similarly not uncommon following infection. This review article will first describe the essential principles of sepsis recognition, pathophysiology, and management and will then briefly cover the neurologic aspects associated with sepsis. Vigilant awareness of the clinical features of sepsis and timeliness of intervention can help clinicians prevent progression of this disease to a multisystem organ failure, which can be difficult to reverse even after the original source of infection is under control.

The utility of procalcitonin in critically ill trauma patients

BACKGROUND

Procalcitonin (PCT), the prohormone of calcitonin, has an early and highly specific increase in response to systemic bacterial infection. The objectives of this study were to determine the natural history of PCT for patients with critical illness and trauma, the utility of PCT as a marker of sepsis versus systemic inflammatory response syndrome (SIRS), and the association of PCT level with mortality.

METHODS

PCT assays were done on eligible patients with trauma admitted to the trauma intensive care unit (ICU) of a Level I trauma center from June 2009 to June 2010, at hours 0, 6, 12, 24, and daily until discharge from ICU or death. Patients were retrospectively diagnosed with SIRS or sepsis by researchers blinded to PCT results.

RESULTS

A total of 856 PCT levels from 102 patients were analyzed, with mean age of 49 years, 63% male, 89% blunt trauma, mean Injury Severity Score of 21, and hospital mortality of 13%. PCT concentration for patients with sepsis, SIRS, and neither were evaluated. Mean PCT levels were higher for patients with sepsis versus SIRS (p < 0.0001). Patients with a PCT concentration of 5 ng/mL or higher had an increased mortality when compared with those with a PCT of less than 5 ng/mL in a univariate analysis (odds ratio, 3.65; 95% confidence interval, 1.03-12.9; p = 0.04). In a multivariate logistic analysis, PCT was found to be the only significant predictor for sepsis (odds ratio, 2.37; 95% confidence interval,1.23-4.61, p = 0.01).

CONCLUSION

PCT levels are significantly higher in ICU patients with trauma and sepsis and may help differentiate sepsis from SIRS in critical illness. An elevated PCT level was associated with increased mortality.

Effects of non-neurological complications on traumatic brain injury outcome

Traumatic brain injury (TBI) affects over 1.5 million Americans annually and consumes a significant amount of healthcare dollars. Identification of complications and factors that impact recovery from TBI is important in improving outcome and allocating appropriate resources. Understanding the role of non-neurologic complications such as sepsis, acute kidney injury, and respiratory problems on TBI outcome and mortality is critical.