Lifetime Traumatic Brain Injury and Risk of Post-Concussive Symptoms in the Millennium Cohort Study

Traumatic brain injury (TBI) is prevalent among active duty military service members, with studies reporting up to 23% experiencing at least one TBI, with 10-60% of service members reporting at least one subsequent repeat TBI. A TBI has been associated with an increased risk of cumulative effects and long-term neurobehavioral symptoms, impacting operational readiness in the short-term and overall health in the long term. The association between multiple TBI and post-concussive symptoms (PCS), however, defined as symptoms that follow a concussion or TBI, in the military has not been adequately examined. Previous studies in military populations are limited by methodological issues including small sample sizes, the use of non-probability sampling, or failure to include the total number of TBI. To overcome these limitations, we examined the association between the total lifetime number of TBI and total number of PCS among U.S. active duty military service members who participated in the Millennium Cohort Study. A secondary data analysis was conducted using the Millennium Cohort Study's 2014 survey (n = 28,263) responses on self-reported TBI and PCS (e.g., fatigue, restlessness, sleep disturbances, poor concentration, or memory loss). Zero-inflated negative binomial models calculated prevalence ratios (PRs) and 95% confidence intervals (CIs) for the unadjusted and adjusted associations between lifetime TBIs and PCS. A third of military participants reported experiencing one or more TBIs during their lifetime with 72% reporting at least one PCS. As the mean number of PCS increased, mean lifetime TBIs increased. The mean number of PCS by those with four or more TBI (4.63) was more than twice that of those with no lifetime TBI (2.28). One, two, three, and four or more TBI had 1.10 (95% CI: 1.06-1.15), 1.19 (95% CI: 1.14-1.25), 1.23 (95% CI: 1.17-1.30), and 1.30 times (95% CI: 1.24-1.37) higher prevalence of PCS, respectively. The prevalence of PCS was 2.4 (95% CI: 2.32-2.48) times higher in those with post-traumatic stress disorder than their counterparts. Active duty military service members with a history of TBI are more likely to have PCS than those with no history of TBI. These results suggest an elevated prevalence of PCS as the number of TBI increased. This highlights the need for robust, longitudinal studies that can establish a temporal relationship between repetitive TBI and incidence of PCS. These findings have practical relevance for designing both workplace safety prevention measures and treatment options regarding the effect on and from TBI among military personnel.

The multifaceted roles of activating transcription factor 3 (ATF3) in inflammatory responses - Potential target to regulate neuroinflammation in acute brain injury

Activating transcription factor 3 (ATF3) is one of the most important transcription factors that respond to and exert dual effects on inflammatory responses. Recently, the involvement of ATF3 in the neuroinflammatory response to acute brain injury (ABI) has been highlighted. It functions by regulating neuroimmune activation and the production of neuroinflammatory mediators. Notably, recent clinical evidence suggests that ATF3 may serve as a potential ideal biomarker of the long-term prognosis of ABI patients. This mini-review describes the essential inflammation modulatory roles of ATF3 in different disease contexts and summarizes the regulatory mechanisms of ATF3 in the ABI-induced neuroinflammation.

Transcranial Color-Coded Sonography With Angle Correction As a Screening Tool for Raised Intracranial Pressure

OBJECTIVES

Transcranial Doppler (TCD) has been evaluated as a noninvasive intracranial pressure (ICP) assessment tool. Correction for insonation angle, a potential source of error, with transcranial color-coded sonography (TCCS) has not previously been reported while evaluating ICP with TCD. Our objective was to study the accuracy of TCCS for detection of ICP elevation, with and without the use of angle correction.

DESIGN

Prospective study of diagnostic accuracy.

SETTING

Academic neurocritical care unit.

PATIENTS

Consecutive adults with invasive ICP monitors.

INTERVENTIONS

Ultrasound assessment with TCCS.

MEASUREMENTS AND MAIN RESULTS

End-diastolic velocity (EDV), time-averaged peak velocity (TAPV), and pulsatility index (PI) were measured in the bilateral middle cerebral arteries with and without angle correction. Concomitant mean arterial pressure (MAP) and ICP were recorded. Estimated cerebral perfusion pressure (CPP) was calculated as estimated CPP (CPPe) = MAP × (EDV/TAPV) + 14, and estimated ICP (ICPe) = MAP-CPPe. Sixty patients were enrolled and 55 underwent TCCS. Receiver operating characteristic curve analysis of ICPe for detection of invasive ICP greater than 22 mm Hg revealed area under the curve (AUC) 0.51 (0.37-0.64) without angle correction and 0.73 (0.58-0.84) with angle correction. The optimal threshold without angle correction was ICPe greater than 18 mm Hg with sensitivity 71% (29-96%) and specificity 28% (16-43%). With angle correction, the optimal threshold was ICPe greater than 21 mm Hg with sensitivity 100% (54-100%) and specificity 30% (17-46%). The AUC for PI was 0.61 (0.47-0.74) without angle correction and 0.70 (0.55-0.92) with angle correction.

CONCLUSIONS

Angle correction improved the accuracy of TCCS for detection of elevated ICP. Sensitivity was high, as appropriate for a screening tool, but specificity remained low.

Do They Have a Choice? Surrogate Decision-Making After Severe Acute Brain Injury

OBJECTIVES

In the early phase of severe acute brain injury (SABI), surrogate decision-makers must make treatment decisions in the face of prognostic uncertainty. Evidence-based strategies to communicate uncertainty and support decision-making are lacking. Our objective was to better understand surrogate experiences and needs during the period of active decision-making in SABI, to inform interventions to support SABI patients and families and improve clinician-surrogate communication.

DESIGN

We interviewed surrogate decision-makers during patients' acute hospitalization for SABI, as part of a larger ( n = 222) prospective longitudinal cohort study of patients with SABI and their family members. Constructivist grounded theory informed data collection and analysis.

SETTING

One U.S. academic medical center.

PATIENTS

We iteratively collected and analyzed semistructured interviews with 22 surrogates for 19 patients.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Through several rounds of coding, interview notes, reflexive memos, and group discussion, we developed a thematic model describing the relationship between surrogate perspectives on decision-making and surrogate experiences of prognostic uncertainty. Patients ranged from 20 to 79 years of age (mean = 55 years) and had primary diagnoses of stroke ( n = 13; 68%), traumatic brain injury ( n = 5; 26%), and anoxic brain injury after cardiac arrest ( n = 1; 5%). Patients were predominantly male ( n = 12; 63%), whereas surrogates were predominantly female ( n = 13; 68%). Two distinct perspectives on decision-making emerged: one group of surrogates felt a clear sense of agency around decision-making, whereas the other group reported a more passive role in decision-making, such that they did not even perceive there being a decision to make. Surrogates in both groups identified prognostic uncertainty as the central challenge in SABI, but they managed it differently. Only surrogates who felt they were actively deciding described time-limited trials as helpful.

CONCLUSIONS

In this qualitative study, not all surrogate "decision-makers" viewed themselves as making decisions. Nearly all struggled with prognostic uncertainty. Our findings underline the need for longitudinal prognostic communication strategies in SABI targeted at surrogates' current perspectives on decision-making.

Autophagy and Apoptosis in Acute Brain Injuries: From Mechanism to Treatment

Significance: Autophagy and apoptosis are two important cellular mechanisms behind brain injuries, which are severe clinical situations with increasing incidences worldwide. To search for more and better treatments for brain injuries, it is essential to deepen the understanding of autophagy, apoptosis, and their interactions in brain injuries. This article first analyzes how autophagy and apoptosis participate in the pathogenetic processes of brain injuries respectively and mutually, then summarizes some promising treatments targeting autophagy and apoptosis to show the potential clinical applications in personalized medicine and precision medicine in the future. Recent Advances: Most current studies suggest that apoptosis is detrimental to brain recovery. Several studies indicate that autophagy can cause unnecessary death of neurons after brain injuries, while others show that autophagy is beneficial for acute brain injuries (ABIs) by facilitating the removal of damaged proteins and organelles. Whether autophagy is beneficial or detrimental in ABIs depends on many factors, and the results from different research groups are diverse or even controversial, making this topic more appealing to be explored further. Critical Issues: Neuronal autophagy and apoptosis are two primary pathological processes in ABIs. How they interact with each other and how their regulations affect the outcome and prognosis of brain injuries remain uncertain, making these answers more critical. Future Directions: Insights into the interplay between autophagy and apoptosis and the accurate regulations of their balance in ABIs may promote personalized and precise treatments in the field of brain injuries. Antioxid. Redox Signal. 38, 234-257.

Association between Serum Neurofilament Light and Glial Fibrillary Acidic Protein Levels and Head Impact Burden in Women's Collegiate Water Polo

Recent investigations have identified water polo athletes as at risk for concussions and repetitive subconcussive head impacts. Head impact exposure in collegiate varsity women's water polo, however, has not yet been longitudinally quantified. We aimed to determine the relationship between cumulative and acute head impact exposure across pre-season training and changes in serum biomarkers of brain injury. Twenty-two Division I collegiate women's water polo players were included in this prospective observational study. They wore sensor-installed mouthguards during all practices and scrimmages during eight weeks of pre-season training. Serum samples were collected at six time points (at baseline, before and after scrimmages during weeks 4 and 7, and after the eight-week pre-season training period) and assayed for neurofilament light (NfL) and glial fibrillary acidic protein (GFAP) using Simoa^® Human Neurology 2-Plex B assay kits. Serum GFAP increased over time (e.g., an increase of 0.6559 pg/mL per week; p = 0.0087). Neither longitudinal nor acute pre-post scrimmage changes in GFAP, however, were associated with head impact exposure. Contrarily, an increase in serum NfL across the study period was associated with cumulative head impact magnitude (sum of peak linear acceleration: B = 0.015, SE = 0.006, p = 0.016; sum of peak rotational acceleration: B = 0.148, SE = 0.048, p = 0.006). Acute changes in serum NfL were not associated with head impacts recorded during the two selected scrimmages. Hormonal contraceptive use was associated with lower serum NfL and GFAP levels over time, and elevated salivary levels of progesterone were also associated with lower serum NfL levels. These results suggest that detecting increases in serum NfL may be a useful way to monitor cumulative head impact burden in women's contact sports and that female-specific factors, such as hormonal contraceptive use and circulating progesterone levels, may be neuroprotective, warranting further investigations.

DAMPs and RAGE Pathophysiology at the Acute Phase of Brain Injury: An Overview

Early or primary injury due to brain aggression, such as mechanical trauma, hemorrhage or is-chemia, triggers the release of damage-associated molecular patterns (DAMPs) in the extracellular space. Some DAMPs, such as S100B, participate in the regulation of cell growth and survival but may also trigger cellular damage as their concentration increases in the extracellular space. When DAMPs bind to pattern-recognition receptors, such as the receptor of advanced glycation end-products (RAGE), they lead to non-infectious inflammation that will contribute to necrotic cell clearance but may also worsen brain injury. In this narrative review, we describe the role and ki-netics of DAMPs and RAGE at the acute phase of brain injury. We searched the MEDLINE database for “DAMPs” or “RAGE” or “S100B” and “traumatic brain injury” or “subarachnoid hemorrhage” or “stroke”. We selected original articles reporting data on acute brain injury pathophysiology, from which we describe DAMPs release and clearance upon acute brain injury, and the implication of RAGE in the development of brain injury. We will also discuss the clinical strategies that emerge from this overview in terms of biomarkers and therapeutic perspectives

Computed tomography vs magnetic resonance imaging for identifying acute lesions in pediatric traumatic brain injury

BACKGROUND AND OBJECTIVE

Pediatric traumatic brain injury (TBI) is a leading cause of morbidity and mortality in children. Computed tomography (CT) is the modality of choice to screen for brain injuries. MRI may provide more clinically relevant information. The purpose of this study was to compare lesion detection between CT and MRI after TBI.

METHODS

Retrospective cohort of children (0-21 years) with TBI between 2008 and 2010 at a Level 1 pediatric trauma center with a head CT scan on day of injury and a brain MRI scan within 2 weeks of injury. Agreement between CT and MRI was determined by κ statistic and stratified by injury mechanism.

RESULTS

One hundred five children were studied. Of these, 78% had mild TBI. The MRI scan was obtained a median of 1 day (interquartile range, 1-2) after CT. Overall, CT and MRI demonstrated poor agreement (κ=-0.083; P=.18). MRI detected a greater number of intraparenchymal lesions (n=36; 34%) compared with CT (n=16; 15%) (P<.001). Among patients with abusive head trauma, MRI detected intraparenchymal lesions in 16 (43%), compared with only 4 (11%) lesions with CT (P=.03). Of 8 subjects with a normal CT scan, 6 out of 8 had abnormal lesions on MRI.

CONCLUSIONS

Compared with CT, MRI identified significantly more intraparenchymal lesions in pediatric TBI, particularly in children with abusive head trauma. The prognostic value of identification of intraparenchymal lesions by MRI is unknown but warrants additional inquiry. Risks and benefits from early MRI (including sedation, time, and lack of radiation exposure) compared with CT should be weighed by clinicians.