Does head CT scan pathology predict outcome after mild traumatic brain injury?

Relaxed Alert Electroencephalography Screening for Mild Traumatic Brain Injury in Athletes

Due to the mildness of initial injury, many athletes with recurrent mild traumatic brain injury (mTBI) are misdiagnosed with other neuropsychiatric illnesses. This study was designed as a proof-of-principle feasibility trial for athletic trainers at a sports facility to generate electroencephalograms (EEGs) from student athletes for discriminating (mTBI) associated EEGs from uninjured ones. A total of 47 EEGs were generated, with 30 athletes recruited at baseline (BL) pre-season, after a concussive injury (IN), and post-season (PS). Outcomes included: 1) visual analyses of EEGs by a neurologist; 2) support vector machine (SVM) classification for inferences about whether particular groups belonged to the three subgroups of BL, IN, or PS; and 3) analyses of EEG synchronies including phase locking value (PLV) computed between pairs of distinct electrodes. All EEGs were visually interpreted as normal. SVM classification showed that BL and IN could be discriminated with 81% accuracy using features of EEG synchronies combined. Frontal inter-hemispheric phase synchronization measured by PLV was significantly lower in the IN group. It is feasible for athletic trainers to record high quality EEGs from student athletes. Also, spatially localized metrics of EEG synchrony can discriminate mTBI associated EEGs from control EEGs.

Serum Acylcarnitine and Long-Term Functional Prognosis after Traumatic Brain Injury with Intracranial Injury: A Multi-Center Prospective Study

Serum biomarkers have potential to help predict prognosis of traumatic brain injury (TBI). The objective of this study was to evaluate the association between serum acylcarnitine levels and functional outcomes at 1 month/6 months after injury for TBI patients with intracranial hemorrhage or diffuse axonal injury. This study is a multi-center prospective cohort study in which adult TBI patients with intracranial injury visiting the emergency departments (EDs) from December 2018 to June 2020 were enrolled. Serum acylcarnitine levels at the time of ED arrival were categorized into four groups: low (1.2-5.5 μmol/L), low-normal (5.6-10.0 μmol/L), high-normal (10.1-14.5 μmol/L), and high (1.4.6-56.6 μmol/L). The study outcome was set as poor functional recovery at 1 month/6 months after injury (Glasgow Outcome Scale score, 1-3). Multi-level logistic regression analyses were conducted to estimate association between serum acylcarnitine and functional outcomes. Among total of 549 patients, poor functional recovery at 1 month and 6 months after injury were observed in 29.1% (160/549) and 29.1% (158/543, follow-up loss n = 6). The odds for 1-month poor functional outcome increased in the high-normal and the high groups [adjusted odds ratios, AORs (95% confidence intervals, CIs): 1.56 (1.09-2.23) and 2.47 (1.63-3.75)], compared with the low-normal group) and also as a continuous variable [1.05 (1.03-1.07) for each 1 μmol/L]. Regarding 6-month mortality, the high group had significantly higher odds when compared with the low-normal group [AOR (95% CI): 2.16 (1.37-3.40)]. Higher serum acylcarnitine levels are associated with poor functional outcomes at 1 month/6 months after injury for TBI patients with intracranial injury.

Concussion and Psychological Effects: A Review of Recent Literature

ABSTRACT

The aim of this article is to provide an up-to-date review of psychological changes in association with postconcussive athletes. In particular, this article focused on the symptomatology, risk factors, and treatment of psychiatric diagnoses in patients who suffered a sports-related concussion (SRC). After an extensive review of prior and current literature, there is significant evidence that demonstrates an association of changes in mood and behavior, including new or worsening symptoms of anxiety, depression, and difficulty with attention and concentration in those who are recovering from a concussion. The goal of care in these patients is to identify and treat these psychological symptoms early to have more favorable long-term outcomes. Primary treatment should focus on psychotherapy; however, other considerations may be warranted in certain cases, such as selective serotonin reuptake inhibitors for depression and tricyclic antidepressants and gabapentin for short-term cognitive symptom improvement.

A Proof-of-Concept Electrochemical Skin Sensor for Simultaneous Measurement of Glial Fibrillary Acidic Protein (GFAP) and Interleukin-6 (IL-6) for Management of Traumatic Brain Injuries

This work demonstrates the use of a noninvasive, sweat-based dual biomarker electrochemical sensor for continuous, prognostic monitoring of a Traumatic Brain Injury (TBI) with the aim of enhancing patient outcomes and reducing the time to treatment after injury. A multiplexed SWEATSENSER was used for noninvasive continuous monitoring of glial fibrillary acidic protein (GFAP) and Interleukin-6 (IL-6) in a human sweat analog and in human sweat. Electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA) were used to measure the sensor response. The assay chemistry was characterized using Fourier Transform Infrared Spectroscopy (FTIR). The SWEATSENSER was able to detect GFAP and IL-6 in sweat over a dynamic range of 3 log orders for GFAP and 2 log orders for IL-6. The limit of detection (LOD) for GFAP detection in the sweat analog was estimated to be 14 pg/mL using EIS and the LOD for IL-6 was estimated to be 10 pg/mL using EIS. An interference study was performed where the specific signal was significantly higher than the non-specific signal. Finally, the SWEATSENSER was able to distinguish between GFAP and IL-6 in simulated conditions of a TBI in human sweat. This work demonstrates the first proof-of-feasibility of a multiplexed TBI marker combined with cytokine and inflammatory marker detection in passively expressed sweat in a wearable form-factor that can be utilized toward better management of TBIs. This is the first step toward demonstrating a noninvasive enabling technology that can enable baseline tracking of an inflammatory response.

Post-Concussion Symptoms Rule: Derivation and Validation of a Clinical Decision Rule for Early Prediction of Persistent Symptoms after a Mild Traumatic Brain Injury

Mild traumatic brain injury (mTBI) is a common problem. Depending on diagnostic criteria, 13 to 62% of those patients develop persistent post-concussion symptoms (PPCS). The main objective of this prospective multi-center study is to derive and validate a clinical decision rule (CDR) for the early prediction of PPCS. Patients aged ≥14 years were included if they presented to one of our seven participating emergency departments (EDs) within 24 h of an mTBI. Clinical data were collected in the ED, and symptom evolution was assessed at 7, 30 and 90 days post-injury using the Rivermead Post-Concussion Questionnaire (RPQ). The primary outcome was PPCS at 90 days after mTBI. A predictive model called the Post-Concussion Symptoms Rule (PoCS Rule) was developed using the methodological standards for CDR. Of the 1083 analyzed patients (471 and 612 for the derivation and validation cohorts, respectively), 15.6% had PPCS. The final model included the following factors assessed in the ED: age, sex, history of prior TBI or mental health disorder, headache in ED, cervical sprain and hemorrhage on computed tomography. The 7-day follow-up identified additional risk factors: headaches, sleep disturbance, fatigue, sensitivity to light, and RPQ ≥21. The PoCS Rule had a sensitivity of 91.4% and 89.6%, a specificity of 53.8% and 44.7% and a negative predictive value of 97.2% and 95.8% in the derivation and validation cohorts, respectively. The PoCS Rule will help emergency physicians quickly stratify the risk of PPCS in mTBI patients and better plan post-discharge resources.

Pathological Computed Tomography Features Associated With Adverse Outcomes After Mild Traumatic Brain Injury: A TRACK-TBI Study With External Validation in CENTER-TBI

Question

Are different patterns of intracranial injury on head computed tomography associated with prognosis after mild traumatic brain injury (mTBI)?

Findings

In this cohort study, subarachnoid hemorrhage, subdural hematoma, and contusion often co-occurred and were associated with both incomplete recovery and more severe impairment out to 12 months after injury, while intraventricular and/or petechial hemorrhage co-occurred and were associated with more severe impairment up to 12 months after injury; epidural hematoma was associated with incomplete recovery at some points but not with more severe impairment. Some intracranial hemorrhage patterns were more strongly associated with outcomes than previously validated demographic and clinical variables.

Meaning

In this study, different pathological features on head computed tomography carried different implications for mild traumatic brain injury prognosis to 1 year.

Importance

A head computed tomography (CT) with positive results for acute intracranial hemorrhage is the gold-standard diagnostic biomarker for acute traumatic brain injury (TBI). In moderate to severe TBI (Glasgow Coma Scale [GCS] scores 3-12), some CT features have been shown to be associated with outcomes. In mild TBI (mTBI; GCS scores 13-15), distribution and co-occurrence of pathological CT features and their prognostic importance are not well understood.

Objective

To identify pathological CT features associated with adverse outcomes after mTBI.

Design, Setting, and Participants

The longitudinal, observational Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) study enrolled patients with TBI, including those 17 years and older with GCS scores of 13 to 15 who presented to emergency departments at 18 US level 1 trauma centers between February 26, 2014, and August 8, 2018, and underwent head CT imaging within 24 hours of TBI. Evaluations of CT imaging used TBI Common Data Elements. Glasgow Outcome Scale–Extended (GOSE) scores were assessed at 2 weeks and 3, 6, and 12 months postinjury. External validation of results was performed via the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) study. Data analyses were completed from February 2020 to February 2021.

Exposures

Acute nonpenetrating head trauma.

Main Outcomes and Measures

Frequency, co-occurrence, and clustering of CT features; incomplete recovery (GOSE scores <8 vs 8); and an unfavorable outcome (GOSE scores <5 vs ≥5) at 2 weeks and 3, 6, and 12 months.

Results

In 1935 patients with mTBI (mean [SD] age, 41.5 [17.6] years; 1286 men [66.5%]) in the TRACK-TBI cohort and 2594 patients with mTBI (mean [SD] age, 51.8 [20.3] years; 1658 men [63.9%]) in an external validation cohort, hierarchical cluster analysis identified 3 major clusters of CT features: contusion, subarachnoid hemorrhage, and/or subdural hematoma; intraventricular and/or petechial hemorrhage; and epidural hematoma. Contusion, subarachnoid hemorrhage, and/or subdural hematoma features were associated with incomplete recovery (odds ratios [ORs] for GOSE scores <8 at 1 year: TRACK-TBI, 1.80 [95% CI, 1.39-2.33]; CENTER-TBI, 2.73 [95% CI, 2.18-3.41]) and greater degrees of unfavorable outcomes (ORs for GOSE scores <5 at 1 year: TRACK-TBI, 3.23 [95% CI, 1.59-6.58]; CENTER-TBI, 1.68 [95% CI, 1.13-2.49]) out to 12 months after injury, but epidural hematoma was not. Intraventricular and/or petechial hemorrhage was associated with greater degrees of unfavorable outcomes up to 12 months after injury (eg, OR for GOSE scores <5 at 1 year in TRACK-TBI: 3.47 [95% CI, 1.66-7.26]). Some CT features were more strongly associated with outcomes than previously validated variables (eg, ORs for GOSE scores <5 at 1 year in TRACK-TBI: neuropsychiatric history, 1.43 [95% CI .98-2.10] vs contusion, subarachnoid hemorrhage, and/or subdural hematoma, 3.23 [95% CI 1.59-6.58]). Findings were externally validated in 2594 patients with mTBI enrolled in the CENTER-TBI study.

Conclusions and Relevance

In this study, pathological CT features carried different prognostic implications after mTBI to 1 year postinjury. Some patterns of injury were associated with worse outcomes than others. These results support that patients with mTBI and these CT features need TBI-specific education and systematic follow-up.

Predicting outcome following mild traumatic brain injury: protocol for the longitudinal, prospective, observational Concussion Recovery (CREST) cohort study

INTRODUCTION

Mild traumatic brain injury (mTBI) is a complex injury with heterogeneous physical, cognitive, emotional and functional outcomes. Many who sustain mTBI recover within 2 weeks of injury; however, approximately 10%-20% of individuals experience mTBI symptoms beyond this 'typical' recovery timeframe, known as persistent post-concussion symptoms (PPCS). Despite increasing interest in PPCS, uncertainty remains regarding its prevalence in community-based populations and the extent to which poor recovery may be identified using early predictive markers.

OBJECTIVE

(1) Establish a research dataset of people who have experienced mTBI and document their recovery trajectories; (2) Evaluate a broad range of novel and established prognostic factors for inclusion in a predictive model for PPCS.

METHODS AND ANALYSIS

The Concussion Recovery Study (CREST) is a prospective, longitudinal observational cohort study conducted in Perth, Western Australia. CREST is recruiting adults aged 18-65 from medical and community-based settings with acute diagnosis of mTBI. CREST will create a state-wide research dataset of mTBI cases, with data being collected in two phases. Phase I collates data on demographics, medical background, lifestyle habits, nature of injury and acute mTBI symptomatology. In Phase II, participants undergo neuropsychological evaluation, exercise tolerance and vestibular/ocular motor screening, MRI, quantitative electroencephalography and blood-based biomarker assessment. Follow-up is conducted via telephone interview at 1, 3, 6 and 12 months after injury. Primary outcome measures are presence of PPCS and quality of life, as measured by the Post-Concussion Symptom Scale and the Quality of Life after Brain Injury questionnaires, respectively. Multivariate modelling will examine the prognostic value of promising factors.

ETHICS AND DISSEMINATION

Human Research Ethics Committees of Royal Perth Hospital (#RGS0000003024), Curtin University (HRE2019-0209), Ramsay Health Care (#2009) and St John of God Health Care (#1628) have approved this study protocol. Findings will be published in peer-reviewed journals and presented at scientific conferences.

TRIAL REGISTRATION NUMBER

ACTRN12619001226190.

Long-Term Presentation of Postconcussion Symptoms and Associated Factors: Analysis of Latent Class Modeling

OBJECTIVE

Postconcussion symptoms (PCS) are commonly reported by patients with mild traumatic brain injury (MTBI). Although PCS significantly recovered by 3-month postinjury, a number of patients still experienced persistent PCS for >1 year. As few researchers investigated long-term PCS endorsement, the present study thus aims to show the latent structure of long-term PCS and further uncover its associating factors.

METHODS

In total, 110 patients with MTBI and 32 healthy participants were prospectively enrolled. PCS was evaluated at 2 weeks and long-term evaluations (mean = 2.90 years) after MTBI. In addition, cognitive functions, which include memory, executive function, and information processing, and emotional disturbances, which include depression, anxiety, and irritability, were also examined at 2-week postinjury.

RESULTS

Patients reported significantly more PCS at 2-week postinjury than healthy participants did, but PCS significantly improved at long-term evaluations when comparing with PCS at acute stage after MTBI. Both of PCS at 2 weeks and long-term evaluations can be further subdivided into subgroups based on the severity of PCS, in which specific PCS (e.g., fatigue, loss of energy, insomnia, slowness of information processing, irritability, and blurred vision) can be well differentiated among subgroups at long-term evaluations.

CONCLUSIONS

This study directly showed the characteristics of long-term PCS and associating factors. It further evidenced that specific physical, cognitive, and emotional symptoms might be determinant to identify the subgroups of patients with long-term PCS endorsement.

Complicated versus uncomplicated mild traumatic brain injuries: A comparison of psychological, cognitive, and post-concussion symptom outcomes

INTRODUCTION

A complicated mild traumatic brain injury (MTBI) is defined as mild by all clinical severity indicators but is complicated due to a traumatic intracranial abnormality visible on neuroimaging. Researchers have reported mixed findings regarding whether neuropsychological and functional outcomes following complicated MTBI are worse than, or similar to, outcomes following uncomplicated MTBI. This study examined patients referred from a Taiwanese emergency department to a neurosurgical outpatient clinic. Participants with complicated MTBI, uncomplicated MTBI, and those who did not undergo head computed tomography (CT) were compared on psychological, neuropsychological, and post-concussion symptom outcomes within 21 days of injury.

METHOD

Participants with complicated MTBI (n = 42), uncomplicated MTBI (n = 77), and no head CT (n = 172) completed the Paced Auditory Serial Attention Test, Taiwanese Word Sequence Learning Test, a semantic Verbal Fluency Test, the Checklist of Post-Concussion Symptoms, and the Beck Depression and Anxiety Inventories.

RESULTS

No significant differences were observed between groups on any measure. For individual post-concussion symptoms, dizziness, anxiety, and attention difficulty were endorsed more often after uncomplicated MTBIs, but these group differences were not significant after controlling for multiple comparisons.

CONCLUSIONS

Participants with complicated MTBIs did not have worse acute or subacute outcomes than participants with uncomplicated MTBIs or no head CT. These results are consistent with many studies finding comparable outcomes between those with complicated and uncomplicated MTBIs. This study is limited by small sample size and minimal information on intracranial abnormalities, broadly categorizing groups based on positive or negative neuroimaging as opposed to specific lesion types and locations.

Personal Factors Associated With Postconcussion Symptoms 3 Months After Mild Traumatic Brain Injury

OBJECTIVE

To describe personal factors in patients with mild traumatic brain injury (MTBI) and 2 control groups and to explore how such factors were associated with postconcussion symptoms (PCSs).

DESIGN

Prospective cohort study.

SETTING

Level 1 trauma center and outpatient clinic.

PARTICIPANTS

Participants (N=541) included patients with MTBI (n=378), trauma controls (n=82), and community controls (n=81).

MAIN OUTCOME MEASURES

Data on preinjury health and work status, personality, resilience, attention deficit/hyperactivity, and substance use. Computed tomography (CT) findings and posttraumatic amnesia were recorded. Symptoms were assessed at 3 months with the British Columbia Postconcussion Symptom Inventory and labeled as PCS+ if ≥3 symptoms were reported or the total score was ≥13. Predictive models were fitted with penalized logistic regression using the least absolute shrinkage and selection operator (lasso) in the MTBI group, and model fit was assessed with optimism-corrected area under the curve (AUC) of the receiver operating characteristic curve.

RESULTS

There were few differences in personal factors between the MTBI group and the 2 control groups without MTBI. Rates of PCS+ were 20.8% for the MTBI group, 8.0% for trauma controls, and 1.3% for community controls. In the MTBI group, there were differences between the PCS+ and PCS- group on most personal factors and injury-related variables in univariable comparisons. In the lasso models, the optimism-corrected AUC for the full model was 0.79, 0.73 for the model only including personal factors, and 0.63 for the model only including injury variables. Working less than full time before injury, having preinjury pain and poor sleep quality, and being female were among the selected predictors, but also resilience and some personality traits contributed in the model. Intracranial abnormalities on CT were also a risk factor for PCS.

CONCLUSIONS

Personal factors convey important prognostic information in patients with MTBI. A vulnerable work status and preinjury health problems might indicate a need for follow-up and targeted interventions.

Persistent Postconcussion Symptoms: An Expert Consensus-Based Definition Using the Delphi Method

OBJECTIVE

To provide an expert consensus definition of persistent postconcussion symptoms following a mild traumatic brain injury (mTBI).

PARTICIPANTS

Canadian healthcare professionals caring for patients with mTBI.

DESIGN

Online Delphi process.

MAIN MEASURES

A first Delphi round documented important dimensions or criteria to consider when defining persistent symptoms. Expert opinions were then resubmitted in 4 subsequent Delphi rounds and their relevance was rated using a 9-point Likert scale. An item with a median rating of 7 or more and a sufficient level of agreement were considered consensual.

RESULTS

After 5 rounds, consensus was reached on a set of criteria that can be summarized as follows: presence of any symptom that cannot be attributed to a preexisting condition and that appeared within hours of an mTBI, that is still present every day 3 months after the trauma, and that has an impact on at least one sphere of a person's life.

CONCLUSION

This Delphi consensus proposes a set of criteria that support a more uniform definition of persistent symptoms in mild TBI among clinicians and researchers. This definition may help clinicians better identify persistent postconcussion symptoms and improve patient management.

Damage to the rat cerebrum under in vitro sinusoidal translational shear deformation

Blast waves, which induce sinusoidal shear waves within brain tissue, may cause mild traumatic brain injury (mTBI). To identify damage from a shear deformation wave, sagittal slices of rat cerebra are subjected to 50 cycles of translational shear deformation at six fixed frequencies between 25 Hz and 125 Hz and displacement amplitudes of 10% or 25% of the original length of the specimen. Each deformation frequency produces transient and apparent steady shear stress states that frequency analysis describes by their harmonic wavelet and Fourier frequency components. The dominant frequency components are integer multiples of the applied deformation frequency. The morphology of the shear stress versus time curve, and probably the type of damage, changes with deformation frequency. Damage at the lower frequencies appears to be diffuse bond breaking. Imaging and histology do not clearly detect mild damage due to bond breaking that underlies mTBI, which the analysis of the shear stress response captures. Major transitions in the morphology of the stress response in the two regions occur at about 75 Hz deformation frequency, possibly due to minor damage to cerebral substructures. An increase in deformation frequency increases the drag force between the extracellular fluid and solid matter. The deformation frequency dependence of the shear stress response makes protection against blast mTBI more difficult because the frequency content of a blast wave is not known a priori.

Towards the Development of an Integrative, Evidence-Based Suite of Indicators for the Prediction of Outcome Following Mild Traumatic Brain Injury: Results from a Pilot Study

Background: Persisting post-concussion symptoms (PPCS) is a complex, multifaceted condition in which individuals continue to experience the symptoms of mild traumatic brain injury (mTBI; concussion) beyond the timeframe that it typically takes to recover. Currently, there is no way of knowing which individuals may develop this condition. Method: Patients presenting to a hospital emergency department (ED) within 48 h of sustaining a mTBI underwent neuropsychological assessment and demographic, injury-related information and blood samples were collected. Concentrations of blood-based biomarkers neuron specific enolase, neurofilament protein-light, and glial fibrillary acidic protein were assessed, and a subset of patients also underwent diffusion tensor–magnetic resonance imaging; both relative to healthy controls. Individuals were classified as having PPCS if they reported a score of 25 or higher on the Rivermead Postconcussion Symptoms Questionnaire at ~28 days post-injury. Univariate exact logistic regression was performed to identify measures that may be predictive of PPCS. Neuroimaging data were examined for differences in fractional anisotropy (FA) and mean diffusivity in regions of interest. Results: Of n = 36 individuals, three (8.33%) were classified as having PPCS. Increased performance on the Repeatable Battery for the Assessment of Neuropsychological Status Update Total Score (OR = 0.81, 95% CI: 0.61–0.95, p = 0.004), Immediate Memory (OR = 0.79, 95% CI: 0.56–0.94, p = 0.001), and Attention (OR = 0.86, 95% CI: 0.71–0.97, p = 0.007) indices, as well as faster completion of the Trails Making Test B (OR = 1.06, 95% CI: 1.00–1.12, p = 0.032) at ED presentation were associated with a statistically significant decreased odds of an individual being classified as having PPCS. There was no significant association between blood-based biomarkers and PPCS in this small sample, although glial fibrillary acidic protein (GFAP) was significantly increased in individuals with mTBI relative to healthy controls. Furthermore, relative to healthy age and sex-matched controls (n = 8), individuals with mTBI (n = 14) had higher levels of FA within the left inferior frontal occipital fasciculus (t (18.06) = −3.01, p = 0.008). Conclusion: Performance on neuropsychological measures may be useful for predicting PPCS, but further investigation is required to elucidate the utility of this and other potential predictors.

The Rivermead Post-Concussion Questionnaire score is associated with disability and self-reported recovery six months after mild traumatic brain injury in older adults

Background/Objectives: Post-concussion syndrome refers to the adverse group of symptoms following a mild traumatic brain injury (mTBI). The Rivermead post-concussion syndrome questionnaire (RPQ) is a common clinical tool for assessing baseline post-concussion syndrome symptomology; however, it is unknown if scores on this questionnaire are associated with future disability. Therefore, the goal of this study was to determine the association between baseline RPQ scores and future disability in older adults with mTBI.Methods and Findings: This study used a prospective cohort design, using the RPQ to measure baseline post-concussion syndrome symptomatology. Disability at 6 months was measured using the Glasgow Outcome Scale-Extended (GOSE; disability), short-form 12 (SF-12; physical and mental quality of life), and self-reported recovery. Linear and logistic models adjusted for confounding factors were estimated using 200 bootstrapped samples. Individuals with higher levels of baseline symptomatology were more likely to have poor GOSE scores (RR = 2.13, 95% CI [1.51, 2.31]) and self-reported recovery (RR = 2.64, 95% CI [1.31, 8.98]) 6 months later.Conclusions: High levels of baseline symptomatology may be associated with overall disability and individual perceptions of recovery 6 months post-MTBI. While the RPQ is valid in assessing a patient's post-concussive symptoms following mTBI, it may not predict long-term physical or mental health in older adults.

Sex Differences in Traumatic Brain Injury: What We Know and What We Should Know

There is growing recognition of the problem of male bias in neuroscience research, including in the field of traumatic brain injury (TBI) where fewer women than men are recruited to clinical trials and male rodents have predominantly been used as an experimental injury model. Despite TBI being a leading cause of mortality and disability worldwide, sex differences in pathophysiology and recovery are poorly understood, limiting clinical care and successful drug development. Given growing interest in sex as a biological variable affecting injury outcomes and treatment efficacy, there is a clear need to summarize sex differences in TBI. This scoping review presents an overview of current knowledge of sex differences in TBI and a comparison of human and animal studies. We found that overall, human studies report worse outcomes in women than men, whereas animal studies report better outcomes in females than males. However, closer examination shows that multiple factors including injury severity, sample size, and experimental injury model may differentially interact with sex to affect TBI outcomes. Additionally, we explore how sex differences in mitochondrial structure and function might contribute to possible sex differences in TBI outcomes. We propose recommendations for future investigations of sex differences in TBI, which we hope will lead to improved patient management, prognosis, and translation of therapies from bench to bedside.

Postconcussion symptom reporting is not associated with diffusion tensor imaging findings in the subacute to chronic phase of recovery in military service members following mild traumatic brain injury

INTRODUCTION

The purpose of this study was to examine the relation between white matter integrity of the brain and postconcussion symptom reporting following mild traumatic brain injury (MTBI).

METHOD

Participants were 109 U.S. military service members (91.7% male) who had sustained a MTBI (n = 88) or orthopedic injury without TBI (trauma controls, TC, n = 21), enrolled from the Walter Reed National Military Medical Center, Bethesda, Maryland. Participants completed a battery of neurobehavioral symptom measures and underwent diffusion tensor imaging (DTI; General Electric 3T) of the whole brain, on average 44.9 months post injury (SD = 42.3). Measures of fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were generated for 18 regions of interest (ROIs). Participants in the MTBI group were divided into two subgroups based on International Classification of Diseases-10th Revision (ICD-10) Category C criteria for postconcussion syndrome (PCS): PCS-present (n = 41) and PCS-absent (n = 47).

RESULTS

The PCS-present group had significantly worse scores on all 13 neurobehavioral measures than the PCS-absent group (p < .001, d = 0.87-2.50) and TC group (p < .003, d = 0.84-2.06). For all ROIs, there were no significant main effects across the three groups for FA, MD, AD, and RD (all ps >.03). Pairwise comparisons revealed no significant differences for all ROIs when using FA and RD, and only two significant pairwise differences were found between PCS-present and PCS-absent groups when using MD and AD [i.e., anterior thalamic radiation and cingulate gyrus (supracallosal) bundle].

CONCLUSIONS

Consistent with past research, but not all studies, postconcussion symptom reporting was not associated with white matter integrity in the subacute to chronic phase of recovery following MTBI.

Emotional reserve and prolonged post-concussive symptoms and disability: a Swedish prospective 1-year mild traumatic brain injury cohort study

OBJECTIVE

Prolonged post-concussive symptoms (PCS) affect a significant minority of patients withmild traumatic brain injury (mTBI). The aetiology is multifactorial depending on preinjury as well as peri-injury and postinjury factors. In this study, we examine outcome from an emotional reserve perspective.

DESIGN

Prospective cohort study.

SETTING

Patients were recruited from three emergency departments in major university hospitals in Stockholm, Sweden. Follow-up data were collected in an outpatient setting at one of the recruiting hospitals.

PARTICIPANTS

122 patients with a history of blunt head trauma (aged 15-65 years; admitted for mTBI within 24 hours after trauma (Glasgow Coma Scale score of 14-15, loss of consciousness <30 min and/or post-traumatic amnesia <24 hours). Exclusion criteria were other significant physical injury and other major neurological disorder, including previous significant head injury.

PROCEDURE

Recruitment in three emergency departments. Initial assessments were made within 1 week after the injury. Patients were mailed the follow-up questionnaires 1 year postinjury.

OUTCOME MEASURES

A psychiatric assessment was performed at 1 week post injury. The participants also completed a personality inventory, measures of psychological resilience, depression, anxiety and post-traumatic symptoms. One-year outcome was measured by the Rivermead Post Concussion Symptoms and the Rivermead Head Injury Follow-Up questionnaires.

RESULTS

The psychiatric assessment revealed more symptoms of anxiety, depression and post-traumatic symptoms in the acute stage for patients who later developed PCS.After 1 year, 94 participants were still in the programme (male/female 57/37) and 12% matched the extended criteria for PCS (≥3 symptoms and ≥2 disabilities). PCS patients reported more preinjury and concurrent psychiatric problems, lower level of functioning before the injury and experienced more stress. They showed higher somatic trait anxiety, embitterment, mistrust and lower level of psychological resilience than recovered participants.

CONCLUSION

Intrapersonal emotional reserve shape the emergence and persistence of PCS after mTBI.

Reduced Functional Connectivity in Adults with Persistent Post-Concussion Symptoms: A Functional Near-Infrared Spectroscopy Study

Concussion, or mild traumatic brain injury (mTBI), accounts for ∼80% of all TBIs across North America. The majority of mTBI patients recover within days to weeks; however, 14-36% of the time, acute mTBI symptoms persist for months or even years and develop into persistent post-concussion symptoms (PPCS). There is a need to find biomarkers in patients with PPCS, to improve prognostic ability and to provide insight into the pathophysiology underlying chronic symptoms. Recent research has pointed toward impaired network integrity and cortical communication as a biomarker. In this study we investigated functional near-infrared spectroscopy (fNIRS) as a technique to assess cortical communication deficits in adults with PPCS. Specifically, we aimed to identify cortical communication patterns in prefrontal and motor areas during rest and task, in adult patients with persistent symptoms. We found that (1) the PPCS group showed reduced connectivity compared with healthy controls, (2) increased symptom severity correlated with reduced coherence, and (3) connectivity differences were best distinguishable during task and in particular during the working memory task (n-back task) in the right and left dorsolateral prefrontal cortex (DLPFC). These data show that reduced brain communication may be associated with the pathophysiology of mTBI and that fNIRS, with a relatively simple acquisition paradigm, may provide a useful biomarker of this injury.

Acute Clinical Predictors of Symptom Recovery in Emergency Department Patients with Uncomplicated Mild Traumatic Brain Injury or Non-Traumatic Brain Injuries

There is a subset of patients with mild traumatic brain injury (mTBI) who report persistent symptoms that impair their functioning and quality of life. Being able to predict which patients will experience prolonged symptom recovery would help clinicians target resources for clinical follow-up to those most in need, and would facilitate research to develop precision medicine treatments for mTBI. The purpose of this study was to investigate the predictors of symptom recovery in a prospective sample of emergency department trauma patients with either mTBI or non-mTBI injuries. Subjects were examined at several time points from within 72 h to 45 days post-injury. We quantified and compared the value of a variety of demographic, injury, and clinical assessment (symptom, neurocognitive) variables for predicting self-reported symptom duration in both mTBI (n = 89) and trauma control (n = 73) patients. Several injury-related and neuropsychological variables assessed acutely (< 72 h) post-injury predicted symptom duration, particularly loss of consciousness (mTBI group), acute somatic symptom burden (both groups), and acute reaction time (both groups), with reasonably good model fit when including all of these variables (area under the receiver operating characteristic curve [AUC] = 0.76). Incorporating self-reported litigation involvement modestly increased prediction further (AUC = 0.80). The results highlight the multifactorial nature of mTBI recovery, and injury recovery more generally, and the need to incorporate a variety of variables to achieve adequate prediction. Further research to improve this model and validate it in new and more diverse trauma samples will be useful to build a neurobiopsychosocial model of recovery that informs treatment development.

Predicting Outcome 12 Months after Mild Traumatic Brain Injury in Patients Admitted to a Neurosurgery Service

Objective

Accurate outcome prediction models for patients with mild traumatic brain injury (MTBI) are key for prognostic assessment and clinical decision-making. Using multivariate machine learning, we tested the unique and added predictive value of (1) magnetic resonance imaging (MRI)-based brain morphometric and volumetric characterization at 4-week postinjury and (2) demographic, preinjury, injury-related, and postinjury variables on 12-month outcomes, including global functioning level, postconcussion symptoms, and mental health in patients with MTBI.

Methods

A prospective, cohort study of patients (n = 147) aged 16–65 years with a 12-month follow-up. T1-weighted 3 T MRI data were processed in FreeSurfer, yielding accurate cortical reconstructions for surface-based analyses of cortical thickness, area, and volume, and brain segmentation for subcortical and global brain volumes. The 12-month outcome was defined as a composite score using a principal component analysis including the Glasgow Outcome Scale Extended, Rivermead Postconcussion Questionnaire, and Patient Health Questionnaire-9. Using leave-one-out cross-validation and permutation testing, we tested and compared three prediction models: (1) MRI model, (2) clinical model, and (3) MRI and clinical combined.

Results

We found a strong correlation between observed and predicted outcomes for the clinical model (r = 0.55, p < 0.001). The MRI model performed at the chance level (r = 0.03, p = 0.80) and the combined model (r = 0.45, p < 0.002) were slightly weaker than the clinical model. Univariate correlation analyses revealed the strongest association with outcome for postinjury factors of posttraumatic stress (Posttraumatic Symptom Scale-10, r = 0.61), psychological distress (Hospital Anxiety and Depression Scale, r = 0.52), and widespread pain (r = 0.43) assessed at 8 weeks.

Conclusion

We found no added predictive value of MRI-based measures of brain cortical morphometry and subcortical volumes over and above demographic and clinical features.

Neuropsychological Outcomes in Patients with Complicated Versus Uncomplicated Mild Traumatic Brain Injury: 6-Month Follow-Up

OBJECTIVE

To compare the extent of persistent neuropsychological impairment in patients with complicated mild traumatic brain injury (mTBI) and those with uncomplicated mTBI.

METHODS

Sixty-one patients with mTBI (Glasgow Coma Scale score 13-15) were recruited prospectively, categorized according to baseline computed tomography findings, and subjected to neuropsychological assessment at initial admission (n = 61) as well as at a 6-month follow-up (n = 30). The paired t test, Cohen's d effect size calculation, and repeated-measures analysis of variance were used to establish the differences between the 2 groups in terms of neuropsychological performance.

RESULTS

A trend toward poorer neuropsychological performance among the patients with complicated mTBI was observed during admission; however, performance in this group improved over time. In contrast, the uncomplicated mTBI group showed slower recovery, especially in tasks of memory, visuospatial processing, and executive functions, at follow-up.

CONCLUSIONS

Our findings suggest that despite the broad umbrella designation of mTBI, the current classification schemes of injury severity for mild neurotrauma should be revisited. They also raise questions about the clinical relevance of both traumatic focal lesions and the absence of visible traumatic lesions on brain imaging studies in patients with milder forms of head trauma.

A Novel Tool for Evaluation of Mild Traumatic Brain Injury Patients in the Emergency Department: Does Robotic Assessment of Neuromotor Performance Following Injury Predict the Presence of Postconcussion Symptoms at Follow-up?

OBJECTIVES

Postconcussion symptoms (PCS) are a common complication of mild traumatic brain injury (TBI). Currently, there is no validated clinically available method to reliably predict at the time of injury who will subsequently develop PCS. The purpose of this study was to determine if PCS following mild TBI can be predicted during the initial presentation to an emergency department (ED) using a novel robotic-assisted assessment of neurologic function.

METHODS

All patients presenting to an urban ED with a chief complaint of head injury within the preceding 24 hours were screened for inclusion from March 2013 to April 2014. The enrollment criteria were as follows: 1) age of 18 years or greater, 2) ability and willingness to provide written informed consent, 3) blunt head trauma and clinical diagnosis of isolated mild TBI by the treating physician, and 4) blood alcohol level of <100 mg/dL. Eligible mild TBI patients were enrolled and their neuromotor function was assessed in the ED using a battery of five tests that cover a range of proprioceptive, visuomotor, visuospatial, and executive function performance metrics. At 3 weeks postinjury, participants were contacted via telephone to complete the Rivermead Post-Concussion Symptoms Questionnaire to assess the presence of significant PCS.

RESULTS

A total of 66 mild TBI patients were enrolled in the study with 42 of them completing both the ED assessment and the follow-up; 40 patients were included in the analyses. The area under the receiver operating characteristic curve (AUC) for the entire test battery was 0.72 (95% confidence interval [CI] = 0.54 to 0.90). The AUC for tests that primarily measure visuomotor and proprioceptive performance were 0.80 (95% CI = 0.65 to 0.95) and 0.71 (95% CI = 0.53 to 0.89), respectively.

CONCLUSIONS

The robotic-assisted test battery has the ability to discriminate between subjects who developed PCS and those who did not. Additionally, poor visuomotor and proprioceptive performance were most strongly associated with subsequent PCS.

Three Month Follow-Up of Rat Mild Traumatic Brain Injury: A Combined [18F]FDG and [11C]PK11195 Positron Emission Study

Mild traumatic brain injury (mTBI) is the most common cause of head trauma. The time course of functional pathology is not well defined, however. The purpose of this study was to evaluate the consequences of mTBI in rats over a period of 3 months by determining the presence of neuroinflammation ([¹¹C]PK11195) and changes in brain metabolism ([¹⁸F]FDG) with positron emission tomography (PET) imaging. Male Sprague-Dawley rats were divided in mTBI (n = 8) and sham (n = 8) groups. In vivo PET imaging and behavioral tests (open field, object recognition, and Y-maze) were performed at different time points after induction of the trauma. Differences between groups in PET images were explored using volume-of-interest and voxel-based analysis. mTBI did not result in death, skull fracture, or suppression of reflexes. Weight gain was reduced (p = 0.003) in the mTBI group compared with the sham-treated group. No statistical differences were found in the behavioral tests at any time point. Volume-of-interest analysis showed neuroinflammation limited to the subacute phase (day 12) involving amygdala, globus pallidus, hypothalamus, pons, septum, striatum, and thalamus (p < 0.03, d > 1.2). Alterations in glucose metabolism were detected over the 3 month period, with increased uptake in the medulla (p < 0.04, d ≥ 1.2), and decreased uptake in the globus pallidus, striatum, and thalamus (p < 0.04, d ≤ 1.2). Similar findings were observed in the voxel-based analysis (p < 0.05 at corrected cluster level). As a consequence of the mTBI, and in the absence of apparent behavioral alterations, relative brain glucose metabolism was found altered in several brain regions, which mostly correspond with those presenting neuroinflammation in the subacute stage.

Concussion is confusing us all

It is time to stop using the term concussion as it has no clear definition and no pathological meaning. This confusion is increasingly problematic as the management of ‘concussed’ individuals is a pressing concern. Historically, it has been used to describe patients briefly disabled following a head injury, with the assumption that this was due to a transient disorder of brain function without long-term sequelae. However, the symptoms of concussion are highly variable in duration, and can persist for many years with no reliable early predictors of outcome. Using vague terminology for post-traumatic problems leads to misconceptions and biases in the diagnostic process, producing uninterpretable science, poor clinical guidelines and confused policy. We propose that the term concussion should be avoided. Instead neurologists and other healthcare professionals should classify the severity of traumatic brain injury and then attempt to precisely diagnose the underlying cause of post-traumatic symptoms.

Neuropsychological outcome and diffusion tensor imaging in complicated versus uncomplicated mild traumatic brain injury

This study examined whether intracranial neuroimaging abnormalities in those with mild traumatic brain injury (MTBI) (i.e., “complicated” MTBIs) are associated with worse subacute outcomes as measured by cognitive testing, symptom ratings, and/or diffusion tensor imaging (DTI). We hypothesized that (i) as a group, participants with complicated MTBIs would report greater symptoms and have worse neurocognitive outcomes than those with uncomplicated MTBI, and (ii) as a group, participants with complicated MTBIs would show more Diffusion Tensor Imaging (DTI) abnormalities. Participants were 62 adults with MTBIs (31 complicated and 31 uncomplicated) who completed neurocognitive testing, symptom ratings, and DTI on a 3T MRI scanner approximately 6-8 weeks post injury. There were no statistically significant differences between groups on symptom ratings or on a broad range of neuropsychological tests. When comparing the groups using tract-based spatial statistics for DTI, no significant difference was found for axial diffusivity or mean diffusivity. However, several brain regions demonstrated increased radial diffusivity (purported to measure myelin integrity), and decreased fractional anisotropy in the complicated group compared with the uncomplicated group. Finally, when we extended the DTI analysis, using a multivariate atlas based approach, to 32 orthopedic trauma controls (TC), the findings did not reveal significantly more areas of abnormal DTI signal in the complicated vs. uncomplicated groups, although both MTBI groups had a greater number of areas with increased radial diffusivity compared with the trauma controls. This study illustrates that macrostructural neuroimaging changes following MTBI are associated with measurable changes in DTI signal. Of note, however, the division of MTBI into complicated and uncomplicated subtypes did not predict worse clinical outcome at 6-8 weeks post injury.

Integration of New Technology for Research in the Emergency Department: Feasibility of Deploying a Robotic Assessment Tool for Mild Traumatic Brain Injury Evaluation

The objective of this paper is to demonstrate the effective deployment of a robotic assessment tool for the evaluation of mild traumatic brain injury (mTBI) patients in a busy, resource-constrained, urban emergency department (ED). Methods: Functional integration of new robotic technology for research in the ED presented several obstacles that required a multidisciplinary approach, including participation from electrical and computer engineers, emergency medicine clinicians, and clinical operations staff of the hospital. Our team addressed many challenges in deployment of this advanced technology including: 1) adapting the investigational device for the unique clinical environment; 2) acquisition and maintenance of appropriate testing space for point-of-care assessment; and 3) dedicated technical support and upkeep of the device. Upon successful placement of the robotic device in the ED, the clinical study required screening of all patients presenting to the ED with complaints of head injury. Eligible patients were enrolled and tested using a robot-assisted test battery. Three weeks after the injury, patients were contacted to complete follow-up assessments. Results: Adapting the existing technology to meet anticipated physical constraints of the ED was performed by engineering a mobile platform. Due to the large footprint of the device, it was frequently moved before ultimately being fully integrated into the ED. Over 14 months, 1423 patients were screened. Twenty-eight patients could not be enrolled because the device was unavailable due to operations limitations. Technical problems with the device resulted in failure to include 20 patients. A total of 66 mTBI patients were enrolled and 42 of them completed both robot-assisted testing and follow-up assessment. Successful completion of screening and enrollment demonstrated that the challenges associated with integration of investigational devices into the ED can be effectively addressed through a collaborative patient-oriented research model. Conclusion: Effective deployment and use of new robotic technology for research in an urban academic ED required significant planning, coordination, and collaboration with key personnel from multiple disciplines. Clinical Impact: A pilot clinical study on mTBI patients using the robotic device provided useful data without disrupting the ED workflow. Integration of this technology into the ED serves as an important step toward pursing active clinical research in an acute care setting.

Minor and repetitive head injury

Traumatic brain injury (TBI) is the leading cause of death and disability in the young, active population and expected to be the third leading cause of death in the whole world until 2020. The disease is frequently referred to as the silent epidemic, and many authors highlight the "unmet medical need" associated with TBI.The term traumatically evoked brain injury covers a heterogeneous group ranging from mild/minor/minimal to severe/non-salvageable damages. Severe TBI has long been recognized to be a major socioeconomical health-care issue as saving young lives and sometimes entirely restituting health with a timely intervention can indeed be extremely cost efficient.Recently it has been recognized that mild or minor TBI should be considered similarly important because of the magnitude of the patient population affected. Other reasons behind this recognition are the association of mild head injury with transient cognitive disturbances as well as long-term sequelae primarily linked to repeat (sport-related) injuries.The incidence of TBI in developed countries can be as high as 2-300/100,000 inhabitants; however, if we consider the injury pyramid, it turns out that severe and moderate TBI represents only 25-30 % of all cases, while the overwhelming majority of TBI cases consists of mild head injury. On top of that, or at the base of the pyramid, are the cases that never show up at the ER - the unreported injuries.Special attention is turned to mild TBI as in recent military conflicts it is recognized as "signature injury."This chapter aims to summarize the most important features of mild and repetitive traumatic brain injury providing definitions, stratifications, and triage options while also focusing on contemporary knowledge gathered by imaging and biomarker research.Mild traumatic brain injury is an enigmatic lesion; the classification, significance, and its consequences are all far less defined and explored than in more severe forms of brain injury.Understanding the pathobiology and pathomechanisms may aid a more targeted approach in triage as well as selection of cases with possible late complications while also identifying the target patient population where preventive measures and therapeutic tools should be applied in an attempt to avoid secondary brain injury and late complications.

Gender differences in neurological emergencies part II: a consensus summary and research agenda on traumatic brain injury

Traumatic brain injury (TBI) is a major cause of death and disability worldwide. There is strong evidence that gender and sex play an important role across the spectrum of TBI, from pathophysiology to clinical care. In May 2014, Academic Emergency Medicine held a consensus conference "Gender-Specific Research in Emergency Care: Investigate, Understand, and Translate How Gender Affects Patient Outcomes." A TBI working group was formed to explore what was known about the influence of sex and gender on TBI and to identify gaps for future research. The findings resulted in four major recommendations to guide the TBI research agenda.

Diffusion tensor imaging findings and postconcussion symptom reporting six weeks following mild traumatic brain injury

The purpose of this study is to examine the relation between the microstructural architecture of white matter, as measured by diffusion tensor imaging (DTI), and postconcussion symptom reporting 6-8 weeks following mild traumatic brain injury (MTBI). Participants were 108 patients prospectively recruited from a Level 1 Trauma Center (Vancouver, BC, Canada) following an orthopedic injury [i.e., 36 trauma controls (TCs)] or MTBI (n = 72). DTI of the whole brain was undertaken using a Phillips 3T scanner at 6-8 weeks postinjury. Participants also completed a 5 h neurocognitive test battery and a brief battery of self-report measures (e.g., depression, anxiety, and postconcussion symptoms). The MTBI sample was divided into two groups based on ICD-10 criteria for postconcussional syndrome (PCS): first, PCS-present (n = 20) and second, PCS-absent (n = 52). There were no significant differences across the three groups (i.e., TC, PCS-present, and PCS-absent) for any of the neurocognitive measures (p = .138-.810). For the self-report measures, the PCS-present group reported significantly more anxiety and depression symptoms compared with the PCS-absent and TC groups (p < .001, d = 1.63-1.89, very large effect sizes). For the DTI measures, there were no significant differences in fractional anisotropy, axial diffusivity, radial diffusivity, or mean diffusivity when comparing the PCS-present and PCS-absent groups. However, there were significant differences (p < .05) in MD and RD when comparing the PCS-present and TC groups. There were significant differences in white matter between TC subjects and the PCS-present MTBI group, but not the PCS-absent MTBI group. Within the MTBI group, white-matter changes were not a significant predictor of ICD-10 PCS.

Missing a follow-up after mild traumatic brain injury--does it matter?

OBJECTIVE

This study sought to identify potential differing clinical characteristics between patients with a mild traumatic brain injury (MTBI) who attended a planned follow-up session and not. This study investigated whether clinical characteristics and attendance for a planned follow-up service 2-months after injury could be related to return-to-work (RTW) 1-year later.

METHOD

Prospective cohort study of 343 patients with MTBI admitted consecutively to the Department of Neurosurgery in 2009-2011. Demographic and clinical data were obtained from the hospital files and data about sick leave from The Norwegian Labour and Welfare Service. Patients were categorized into two groups according to their attendance.

RESULTS

One hundred and sixty-one (67%) patients attended (AG) and 80 (33%) did not (NAG) attend their follow-up appointments. The AG had significantly more frequently intracranial pathology on CT scan, had consumed less alcohol and were older. Logistic regression showed that follow-up attendance (OR = 16.89) and sick leave before injury (OR = 9.70) are unfavourably related to RTW at 12-months. Skull fracture and cause of injury had no influence of the outcome.

CONCLUSION

Not attending the follow-up has a favourable outcome after MBTI, indicating that these patients have a reduced need for medical and rehabilitation support for their brain injury.