Subjective and Performance-Based Cognition and Their Associations with Head Injury History in Older Former National Football League Players

PURPOSE

Investigate the association between self-reported subjective and performance-based cognition among older (50-70 years) former professional American football players, as well as the relationship of cognitive measures with concussion history and years of football participation, as a proxy for repetitive head impact exposure.

METHODS

Among older former National Football League (NFL) players ( N = 172; mean age = 60.69 ± 5.64), associations of subjective (Patient Reported Outcome Measurement Information System Cognitive Function-Short Form) and performance-based cognitive measures (Brief Test of Adult Cognition by Telephone [BTACT] Executive Function and Episodic Memory indices) were assessed via univariable and multivariable regression models, with a priori covariates of depression and race. A similar univariate and multivariable regression approach assessed associations between concussion history and years of football participation with subjective and performance-based cognitive measures. In a sample subset ( n = 114), stability of subjective cognitive rating was assessed via partial correlation.

RESULTS

Subjective ratings of cognition were significantly associated with performance-based assessment, with moderate effect sizes (episodic memory ηp2 = 0.12; executive function ηp2 = 0.178). These associations were weakened, but remained significant ( P s < 0.05), with the inclusion of covariates. Greater concussion history was associated with lower subjective cognitive function ( ηp2 = 0.114, P < 0.001), but not performance-based cognition. The strength of association between concussion history and subjective cognition was substantially weakened with inclusion of covariates ( ηp2 = 0.057). Years of participation were not associated with measures of subjective or objective cognition ( P s > 0.05).

CONCLUSIONS

These findings reinforce the importance of comprehensive evaluation reflecting both subjective and objective measures of cognition, as well as the consideration of patient-specific factors, as part of a comprehensive neurobehavioral and health assessment of older former contact sport athletes.

Long-term effects of mTBIs includes a higher dependency on visual inputs to control vertical posture

This study investigated the hypothesis that individuals living with long-term effects of mild traumatic brain injury (mTBI) develop an increased dependency on visual inputs to control upright posture. To test this hypothesis, we quantified visuo-postural dependency indices (VPDIs) calculated for multiple postural behavioral markers extracted from the body's center of pressure coordinates signals. These signals were recorded during the execution of a quiet bipedal stance under Vision and No-Vision experimental conditions. VPDIs were calculated as the normalized pair-wise subtraction of recordings obtained under Vision and No-Vision. A total of one hundred and twenty-nine volunteers were organized into two groups: mTBI group (n = 50) and neurotypical control group (n = 79). Consistent with our hypothesis, the results reveal that balance behavior of participants with mTBI deteriorate more abruptly in the absence of visual inputs when compared to neurotypical controls. These impairments might increase the likelihood of recurrent injuries and falls when time-constrained reactions are needed in daily activities, sports practice, or military operations. Additionally, the methodology used in this study shows to be potentially useful to aid future investigations of neural circuitry impaired by mTBI. It also provides indices of recovery for future clinical trials testing mTBI-related clinical interventions.

Healthcare Providers' Self-Reported Pediatric Mild Traumatic Brain Injury Diagnosis, Prognosis, and Management Practices: Findings From the 2019 DocStyles Survey

OBJECTIVE

To assess adherence to 5 key recommendations in the Centers for Disease Control and Prevention evidence-based guideline on pediatric mild traumatic brain injury, this article presents results from the 2019 DocStyles survey.

STUDY DESIGN

Cross-sectional, web-based survey of 653 healthcare providers.

RESULTS

Most healthcare providers reported adhering to the recommendations regarding the use of computed tomography and providing education and reassurance to patients and their families. However, less than half reported routinely examining their patients with mild traumatic brain injury (mTBI) using age-appropriate, validated symptom scales, assessing for risk factors for prolonged recovery, and advising patients to return to noncontact, light aerobic activities within 2 to 3 days. Self-reported mTBI diagnosis, prognosis, and management practices varied by specialty. Only 3.8% of healthcare providers answered all 7 questions in a way that is most consistent with the 5 recommendations examined from the Centers for Disease Control and Prevention Pediatric mTBI Guideline.

CONCLUSION

This study highlights several important information gaps regarding pediatric mTBI diagnosis and management. Further efforts to improve adoption of guideline recommendations may be beneficial to ensure optimal outcomes for children following an mTBI.

Developing a Mobile App for Concussion to aid Patient Empowerment and Symptom Management

Despite the high prevalence of concussions each year in Canada, access to consistent and science-based information on how to self-manage these injuries remains a significant hurdle for many patients. Currently, available mobile applications (apps) focus mainly on supporting patients with sports-related concussions, although falls account for more traumatic brain injuries (TBI) than sports-related TBI's in Alberta. Patients from a broader demographic may be limited from accessing information on how to correctly manage and track their symptoms as they feel that currently available resources are not applicable to them. Through collaboration between health system leaders, expert consultations, patients, and university students, a mobile app was designed as a platform to help patients manage and track symptoms at home, as well as to clarify misleading information and misconceptions surrounding injury. The team engaged numerous physicians, patient advisors, and health system leaders to improve upon the features of currently-existing concussion apps such as symptom tracking, insight into concussion, and strategies for returning to work/school that are more inclusive to adult, non-sports related injuries. We believe that these features will advance recovery by alleviating the burden of uncertainty and confusion for patients and their family members.

Improved Mild Closed Head Traumatic Brain Injury Outcomes With a Brain-Computer Interface Amplified Cognitive Remediation Training

This study is a retrospective chart review of 200 clients who participated in a non-verbal restorative cognitive remediation training (rCRT) program between 2012 and 2020. Each client participated in the program for about 16 weeks, and the study as a whole occurred over a five-year period. The program was applied to effect proper neural functional remodeling needed to support resilient, flexible, and adaptable behaviors after encountering a mild closed head traumatic brain injury (mTBI). The rCRT program focused on improving functional performance in executive cognitive control networks as defined by fMRI studies. All rCRT activities were delivered in a semi-game-like manner, incorporating a brain-computer interface (BCI) that provided in-the-moment neural network performance integrity metrics (nPIMs) used to adjust the level of play required to properly engage long-term potentiation (LTP) and long-term depression (LTD) network learning rules.

This study reports on t-test and Reliable Change Index (RCI) changes found within individual cognitive abilities’ performance metrics derived from the Woodcock-Johnson Cognitive Abilities III Test. We compared pre- and post-scores from seven cognitive abilities considered dependent on executive cognitive control networks against seven non-executive control abilities. We observed significant improvements (p < 10^-4) with large Cohen’s deffect sizes (0.78-1.20) across 13 of 14 cognitive ability domains with a medium effect size (0.49) on the remaining one. The mean percent change for the pooled trained domain was double that observed for the pooled untrained domain, at 17.2% versus 8.3%, respectively. To further adjust for practice effects, practice effect RCI values were computed and further supported the effectiveness of the rCRT (trained RCI 1.4-4.8; untrained RCI 0.­08-0.75).

Multimodal Assessment of Sport-Related Concussion

OBJECTIVE

The purpose of this study was to determine which assessments best identify athletes with sport-related concussion (SRC) from healthy controls in the acute/early subacute phase (within 10 days of SRC) of injury.

DESIGN

Prospective, cohort study.

SETTING

Specialty concussion clinic.

PARTICIPANTS

Sixty-four athletes with SRC (52% male) and 59 matched (age and sex), healthy controls (56% male) aged 12 to 20 years (Mean [M] = 15.07, Standard Deviation [SD] = 2.23).

ASSESSMENT

Participants completed symptom, cognitive, vestibular/oculomotor, near point of convergence (NPC), and balance assessments.

MAIN OUTCOME MEASURES

Univariate analyses were conducted to compare athletes with SRC to healthy controls across all assessments. Assessments that significantly differed between the SRC group and healthy controls were used as predictors in an enter method logistic regression (LR) model and subsequent forward stepwise LR.

RESULTS

Results of LR analyses indicated that symptom inventory and symptom provocation on vestibular/oculomotor assessments significantly predicted athletes with SRC versus controls. The forward stepwise LR accurately classified 84.6% of the overall sample (78.3% of athletes with SRC and 91.2% of controls were accurately predicted) and accounted for 60.5% of the variance in predicting athletes with SRC versus controls. Total symptom inventory score (P = 0.003) and vestibular/oculomotor symptom provocation (P < 0.01) were the most sensitive and specific measures in a comprehensive, multimodal assessment for distinguishing athletes with SRC from healthy controls within 10 days of injury.

CONCLUSIONS

Elements within a multimodal evaluation that are the most robust at discriminating athletes with SRC from healthy controls in the acute/early subacute phase of injury include symptom report and provocation of symptoms on vestibular/oculomotor assessment. These assessments should be considered in conjunction with other objective assessments (ie, NPC measurement and cognitive testing) as part of a comprehensive evaluation of SRC.

Cognition and Other Predictors of Functional Disability Among Veterans With Mild Traumatic Brain Injury and Posttraumatic Stress Disorder

BACKGROUND

Limitations in everyday functioning are frequently reported by veterans with a history of mild traumatic brain injury (mTBI) and/or posttraumatic stress disorder (PTSD). Multiple factors are associated with functional disability among veterans, including depression, poor social support, cognition, and substance use. However, the degree to which these factors, particularly cognitive capacities, contribute to functional limitations remains unclear.

METHODS

We evaluated performance on tests of processing speed, executive functioning, attention, and memory as predictors of functioning on the World Health Organization Disability Assessment Scale (WHODAS) 2.0 in 288 veterans. Participants were placed in one of the following groups: PTSD-only, mTBI-only, mTBI + PTSD, and neither PTSD nor mTBI (deployed control group). Cognitive test performances were evaluated as predictors of WHODAS 2.0 functional ratings in regression models that included demographic variables and a range of mood, behavioral health, and postconcussive symptom ratings.

RESULTS

Multiple cognitive test performances predicted WHODAS 2.0 scores in the deployed control group, but they generally did not predict functioning in the clinical groups when accounting for demographics, mood, behavioral health, and postconcussive symptoms.

CONCLUSIONS

In veterans with mTBI and/or PTSD, cognitive test performances are less associated with everyday functioning than mood and postconcussive symptoms.

Fatigue Is Associated With Global and Regional Thalamic Morphometry in Veterans With a History of Mild Traumatic Brain Injury

OBJECTIVE

Fatigue is a complex, multidimensional phenomenon that commonly occurs following traumatic brain injury (TBI). The thalamus-a structure vulnerable to both primary and secondary injuries in TBI-is thought to play a pivotal role in the manifestation of fatigue. We explored how neuroimaging markers of local and global thalamic morphometry relate to the subjective experience of fatigue post-TBI.

METHODS

Sixty-three Veterans with a history of mild TBI underwent structural magnetic resonance imaging and completed questionnaires related to fatigue and psychiatric symptoms. FMRIB's Software (FSL) was utilized to obtain whole brain and thalamic volume estimates, as well as to perform regional thalamic morphometry analyses.

RESULTS

Independent of age, sex, intracranial volume, posttraumatic stress disorder, and depressive symptoms, greater levels of self-reported fatigue were significantly associated with decreased right (P = .026) and left (P = .046) thalamic volumes. Regional morphometry analyses revealed that fatigue was significantly associated with reductions in the anterior and dorsomedial aspects of the right thalamic body (P < .05). Similar trends were observed for the left thalamic body (P < .10).

CONCLUSIONS

Both global and regional thalamic morphometric changes are associated with the subjective experience of fatigue in Veterans with a history of mild TBI. These findings support a theory in which disruption of thalamocorticostriatal circuitry may result in the manifestation of fatigue in individuals with a history of neurotrauma.

Characteristics and outcomes of physical activity interventions for individuals with mild traumatic brain injury: a scoping review protocol

INTRODUCTION

Traumatic brain injury (TBI) is a major public health problem, and it is estimated that 85% of TBIs are diagnosed as mild and are commonly referred to as a concussion. In adults, symptoms are expected to resolve within 10-14 days after the injury, but up to 15% of individuals continue to have symptoms beyond this period. Recent clinical recommendations suggest the use of physical activity (PA) as a therapy to manage persisting symptoms. However, the recommendations regarding PA lack clarity about important intervention parameters to help clinicians deliver the intervention. The objectives of this scoping review are thus to identify the characteristics, the measurement tools, the health-related outcomes and the reported effectiveness of PA-based interventions for adults with persisting symptoms of a mild TBI (mTBI).

METHODS AND ANALYSIS

This scoping review protocol will follow Arksey and O'Malley's six-step iterative process enhanced by another study and will be conducted by a team of researchers and clinical experts. Five databases (MEDLINE, CINAHL, PsycINFO, SPORTDiscuss and Embase), as well as Google, will be searched using an extensive search strategy to capture relevant scientific and grey literature. Articles will be selected if they report on an intervention designed to have an impact on health-related outcomes or participation among individuals having sustained an mTBI. A data extraction form based on the Consensus on Exercise Reporting Template and the Template for Intervention Description and Replication checklists will be created. Quantitative and qualitative data will be analysed accordingly, synthesised and collated in tables.

ETHICS AND DISSEMINATION

This scoping review generates new knowledge from published and publicly available literature; thus, an ethical approval is unnecessary to conduct this research. Dissemination of the results will involve all team members in activities aimed to facilitate knowledge uptake among TBI rehabilitation clinical experts locally, nationally and internationally.

The Gaze Stabilization Test Following Concussion

BACKGROUND

Concussion can cause vestibular dysfunction and oculomotor abnormalities which can lead to dizziness and protracted recovery time. There are few clinically useful, functional measures of the vestibulo-ocular reflex (VOR) post-concussion.

PURPOSE

The purpose of this study was to examine the gaze stabilization test (GST) in those referred for vestibular physical therapy following concussion, to determine the association between GST and other measures of recovery following concussion, and to examine the effect of demographic variables on GST performance.

RESEARCH DESIGN

Retrospective chart review.

STUDY SAMPLE

One hundred fifty-eight individuals who sustained a concussion and were referred to vestibular physical therapy.

DATA COLLECTION AND ANALYSIS

Horizontal and vertical GST scores (HGST and VGST), neurocognitive testing results, and demographic data were extracted retrospectively from the patient health record. Correlations between GST velocity and neurocognitive test results and between GST and patient-reported outcomes were examined. Differences in GST performance among patient subgroups were examined using one-way analysis of variance.

RESULTS

Subjects included individuals aged 12 to 43 years (mean = 20, standard deviation [SD] = 7), with most having sport-related concussion (67%). The mean time from injury to GST was 215 days (SD = 241) and the mean time from physical therapy evaluation to GST was 48 days (SD = 54). HGST and VGST had a weak positive correlation to the Activities-Specific Balance Confidence Scale (r = 0.20, r = 0.21) and weak negative correlation to the Dizziness Handicap Inventory (r = -0.18, r = -0.22). HGST had a weak positive correlation to the visual motor processing speed domain of the immediate post-concussion assessment and cognitive test (r = 0.20). Male patients achieved significantly higher velocities than female patients on HGST and VGST (p = 0.02, p = 0.01).

CONCLUSIONS

The present study details the use of GST in patients with concussion and demonstrates an association with common outcome measures in vestibular rehabilitation. Results indicate that patients who achieved higher velocities on GST perceived lower handicap due to dizziness and had higher confidence in their balance. GST may be a relevant test of VOR in this population, as it is a more functional test of the VOR required for sports. Future work is needed to further evaluate the role of GST in concussion management.

Use of general practice before and after mild traumatic brain injury: a nationwide population-based cohort study in Denmark

OBJECTIVES

Traumatic brain injury (TBI) is commonly seen in the emergency department (ED). Approximately 85%-90% of TBIs are mild (mTBI). Some cause symptoms such as headache, dizziness, anxiety, blurred vision, insomnia and concentration difficulties, collectively known as postconcussion syndrome (PCS). Some studies suggest that recovery from mTBI is complete. Others find that symptoms persist for months, even years. The aim of this study was to describe the use of general practice, before and after mTBI, as a proxy for symptoms in a large cohort.

DESIGN

Nationwide population-based matched cohort study.

SETTING

Danish EDs and general practice.

PARTICIPANTS

All patients (aged ≥18 years), first-time diagnosed with mTBI in a Danish ED between 1 January 1998 and 31 December 2010 (n=93 517). Ten reference persons per patient with mTBI were randomly matched on gender, age and general practice (n=935 170).

PRIMARY OUTCOME

Overall use of general practice; consultations relating to mental and physical health.

RESULTS

We found higher use of general practice during the first year after mTBI for all ages, both genders and all types of contacts. Age 18-40 years: women, incidence rate ratio (IRR) 1.59 (95% CI 1.57 to 1.61); men, IRR 1.82 (95% CI 1.80 to 1.85). Age 41-65 years: women, IRR 1.75 (95% CI 1.72 to 1.78); men, IRR 1.85(95% CI 1.82 to 1.89). Age 66+ years: women, IRR 1.55 (95% CI 1.52 to 1.58); men, IRR 1.55 (95% CI 1.51 to 1.59). After the first year, the use decreased to the level before mTBI. Individuals with mTBI and higher use of general practice before mTBI had lower socioeconomic status and more comorbidities (P<0.001).

CONCLUSIONS

The use of general practice was higher in the first year after mTBI, specifically in the first 3 months. Patients with mTBI had different healthcare-seeking behaviour several years before diagnosis than their matched reference persons. Pretraumatic morbidity should be considered in the evaluation of PCS.

Technical Report of the Use of a Novel Eye Tracking System to Measure Impairment Associated with Mild Traumatic Brain Injury

This technical report details the results of an uncontrolled study of EyeGuide Focus, a 10-second concussion management tool which relies on eye tracking to determine the potential impairment of visual attention, an indicator often of mild traumatic brain injury (mTBI). Essentially, people who can visually keep steady and accurate attention on a moving object in their environment likely suffer from no impairment. However, if after a potential mTBI event, subjects cannot keep attention on a moving object in a normal way as demonstrated on their previous healthy baseline tests. This may indicate possible neurological impairment. Now deployed at multiple locations across the United States, Focus (EyeGuide, Lubbock, Texas, United States) to date, has recorded more than 4,000 test scores. Our data analysis of these results shows the promise of Focus as a low-cost, ocular-based impairment test for assessing potential neurological impairment caused by mTBI in subjects ages eight and older. 

Epidemiology and clinical characteristics of traumatic brain injury in Lebanon: A systematic review

BACKGROUND

Traumatic brain injury (TBI) is a debilitating medical and emerging public health problem that is affecting people worldwide due to a multitude of factors including both domestic and war-related acts. The objective of this paper is to systematically review the status of TBI in Lebanon - a Middle Eastern country with a weak health system that was chartered by several wars and intermittent outbursts of violence - in order to identify the present gaps in knowledge, direct future research initiatives and to assist policy makers in planning progressive and rehabilitative policies.

METHODS

OVID/Medline, PubMed, Scopus databases and Google Scholar were lastly searched on April 15, 2016 to identify all published research studies on TBI in Lebanon. Studies published in English, Arabic or French that assessed Lebanese patients afflicted by TBI in Lebanon were warranting inclusion in this review. Case reports, reviews, biographies and abstracts were excluded. Throughout the whole review process, reviewers worked independently and in duplicate during study selection, data abstraction and methodological assessment using the Downs and Black Checklist.

RESULTS

In total, 11 studies were recognized eligible as they assessed Lebanese patients afflicted by TBI on Lebanese soils. Considerable methodological variation was found among the identified studies. All studies, except for two that evaluated domestic causes such as falls, reported TBI due to war-related injuries. Age distribution of TBI victims revealed two peaks, young adults between 18 and 40 years, and older adults aged 60 years and above, where males constituted the majority. Only three studies reported rates of mild TBI. Mortality, rehabilitation and systemic injury rates were rarely reported and so were the complications involved; infections were an exception.

CONCLUSION

Apparently, status of TBI in Lebanon suffers from several gaps which need to be bridged through implementing more basic, epidemiological, clinical and translational research in this field in the future.

Six Degree-of-Freedom Measurements of Human Mild Traumatic Brain Injury

This preliminary study investigated whether direct measurement of head rotation improves prediction of mild traumatic brain injury (mTBI). Although many studies have implicated rotation as a primary cause of mTBI, regulatory safety standards use 3 degree-of-freedom (3DOF) translation-only kinematic criteria to predict injury. Direct 6DOF measurements of human head rotation (3DOF) and translation (3DOF) have not been previously available to examine whether additional DOFs improve injury prediction. We measured head impacts in American football, boxing, and mixed martial arts using 6DOF instrumented mouthguards, and predicted clinician-diagnosed injury using 12 existing kinematic criteria and 6 existing brain finite element (FE) criteria. Among 513 measured impacts were the first two 6DOF measurements of clinically diagnosed mTBI. For this dataset, 6DOF criteria were the most predictive of injury, more than 3DOF translation-only and 3DOF rotation-only criteria. Peak principal strain in the corpus callosum, a 6DOF FE criteria, was the strongest predictor, followed by two criteria that included rotation measurements, peak rotational acceleration magnitude and Head Impact Power (HIP). These results suggest head rotation measurements may improve injury prediction. However, more 6DOF data is needed to confirm this evaluation of existing injury criteria, and to develop new criteria that considers directional sensitivity to injury.

Low-level laser therapy effectively prevents secondary brain injury induced by immediate early responsive gene X-1 deficiency

A mild insult to the brain can sometimes trigger secondary brain injury, causing severe postconcussion syndrome, but the underlying mechanism is ill understood. We show here that secondary brain injury occurs consistently in mice lacking immediate early responsive gene X-1 (IEX-1), after a gentle impact to the head, which closely simulates mild traumatic brain injury in humans. The pathologic lesion was characterized by extensive cell death, widespread leukocyte infiltrates, and severe tissue loss. On the contrary, a similar insult did not induce any secondary injury in wild-type mice. Strikingly, noninvasive exposure of the injured head to a low-level laser at 4 hours after injury almost completely prevented the secondary brain injury in IEX-1 knockout mice. The low-level laser therapy (LLLT) suppressed proinflammatory cytokine expression like interleukin (IL)-1β and IL-6 but upregulated TNF-α. Moreover, although lack of IEX-1 compromised ATP synthesis, LLLT elevated its production in injured brain. The protective effect of LLLT may be ascribed to enhanced ATP production and selective modulation of proinflammatory mediators. This new closed head injury model provides an excellent tool to investigate the pathogenesis of secondary brain injury as well as the mechanism underlying the beneficial effect of LLLT.

Hypertonic saline as a therapy for pediatric concussive pain: a randomized controlled trial of symptom treatment in the emergency department

OBJECTIVE

Three-percent hypertonic saline (HTS) is a hyperosmotic therapy used in pediatric traumatic brain injury to treat increased intracranial pressure and cerebral edema. It also promotes plasma volume expansion and cerebral perfusion pressure, immunomodulation, and anti-inflammatory response. We hypothesized that HTS will improve concussive symptoms of mild traumatic brain injury.

METHODS

The study was a prospective, double-blind, randomized controlled trial. Children, 4 to 7 years of age with a Glasgow Coma Scale score greater than 13, were enrolled from a pediatric emergency department following closed-head injury upon meeting Acute Concussion Evaluation criteria with head pain. Patients were randomized to receive 10 mL/kg of HTS or normal saline (NS) over 1 hour. Self-reported pain values were obtained using the Wong-Baker FACES Pain Rating Scale initially, immediately following fluids, and at 2 to 3 days of discharge. The primary outcome measure was change in self-reported pain following fluid administration. Secondary outcome measures were a change in pain and postconcussive symptoms within 2 to 3 days of fluid administration. We used an intention-to-treat analysis.

RESULTS

Forty-four patients, ranging from 7 to 16 years of age with comparable characteristics, were enrolled in the study; 23 patients (52%) received HTS, and 21 (48%) received NS. There was a significant difference (P < 0.001) identified in the self-reported improvement of pain following fluid administration between the HTS group (mean improvement = 3.5) and the NS group (mean improvement = 1.1). There was a significant difference (P = 0.01) identified in the self-reported improvement of pain at 2 to 3 days after treatment between the HTS group (mean improvement = 4.6) and the NS group (mean improvement = 3.0). We were unable to determine a difference in other postconcussive symptoms following discharge.

CONCLUSIONS

Three-percent HTS is more effective than NS in acutely reducing concussion pain in children.

Interventions provided in the acute phase for mild traumatic brain injury: a systematic review

BACKGROUND

Most patients who sustain mild traumatic brain injury (mTBI) have persistent symptoms at 1 week and 1 month after injury. This systematic review investigated the effectiveness of interventions initiated in acute settings for patients who experience mTBI.

METHODS

We performed a systematic review of all randomized clinical trials evaluating any intervention initiated in an acute setting for patients experiencing acute mTBI. All possible outcomes were included. The primary sources of identification were MEDLINE, Embase, PsycINFO, CINAHL, and the Cochrane Central register of Controlled Trials, from 1980 to August 2012. Hand searching of proceedings from five meetings related to mTBI was also performed. Study selection was conducted by two co-authors, and data abstraction was completed by a research assistant specialized in conducting systematic reviews. Study quality was evaluated using Cochrane's Risk of Bias assessment tool.

RESULTS

From a potential 15,156 studies, 1,268 abstracts were evaluated and 120 articles were read completely. Of these, 15 studies fulfilled the inclusion/exclusion criteria. One study evaluated a pharmacological intervention, two evaluated activity restriction, one evaluated head computed tomography scan versus admission, four evaluated information interventions, and seven evaluated different follow-up interventions. Use of different outcome measures limited the possibilities for analysis. However, a meta-analysis of three studies evaluating various follow-up strategies versus routine follow-up or no follow-up failed to show any effect on three outcomes at 6 to 12 months post-trauma. In addition, a meta-analysis of two studies found no effect of an information intervention on headache at 3 months post-injury.

CONCLUSIONS

There is a paucity of well-designed clinical studies for patients who sustain mTBI. The large variability in outcomes measured in studies limits comparison between them.

A review of magnetic resonance imaging and diffusion tensor imaging findings in mild traumatic brain injury

Mild traumatic brain injury (mTBI), also referred to as concussion, remains a controversial diagnosis because the brain often appears quite normal on conventional computed tomography (CT) and magnetic resonance imaging (MRI) scans. Such conventional tools, however, do not adequately depict brain injury in mTBI because they are not sensitive to detecting diffuse axonal injuries (DAI), also described as traumatic axonal injuries (TAI), the major brain injuries in mTBI. Furthermore, for the 15 to 30 % of those diagnosed with mTBI on the basis of cognitive and clinical symptoms, i.e., the "miserable minority," the cognitive and physical symptoms do not resolve following the first 3 months post-injury. Instead, they persist, and in some cases lead to long-term disability. The explanation given for these chronic symptoms, i.e., postconcussive syndrome, particularly in cases where there is no discernible radiological evidence for brain injury, has led some to posit a psychogenic origin. Such attributions are made all the easier since both posttraumatic stress disorder (PTSD) and depression are frequently co-morbid with mTBI. The challenge is thus to use neuroimaging tools that are sensitive to DAI/TAI, such as diffusion tensor imaging (DTI), in order to detect brain injuries in mTBI. Of note here, recent advances in neuroimaging techniques, such as DTI, make it possible to characterize better extant brain abnormalities in mTBI. These advances may lead to the development of biomarkers of injury, as well as to staging of reorganization and reversal of white matter changes following injury, and to the ability to track and to characterize changes in brain injury over time. Such tools will likely be used in future research to evaluate treatment efficacy, given their enhanced sensitivity to alterations in the brain. In this article we review the incidence of mTBI and the importance of characterizing this patient population using objective radiological measures. Evidence is presented for detecting brain abnormalities in mTBI based on studies that use advanced neuroimaging techniques. Taken together, these findings suggest that more sensitive neuroimaging tools improve the detection of brain abnormalities (i.e., diagnosis) in mTBI. These tools will likely also provide important information relevant to outcome (prognosis), as well as play an important role in longitudinal studies that are needed to understand the dynamic nature of brain injury in mTBI. Additionally, summary tables of MRI and DTI findings are included. We believe that the enhanced sensitivity of newer and more advanced neuroimaging techniques for identifying areas of brain damage in mTBI will be important for documenting the biological basis of postconcussive symptoms, which are likely associated with subtle brain alterations, alterations that have heretofore gone undetected due to the lack of sensitivity of earlier neuroimaging techniques. Nonetheless, it is noteworthy to point out that detecting brain abnormalities in mTBI does not mean that other disorders of a more psychogenic origin are not co-morbid with mTBI and equally important to treat. They arguably are. The controversy of psychogenic versus physiogenic, however, is not productive because the psychogenic view does not carefully consider the limitations of conventional neuroimaging techniques in detecting subtle brain injuries in mTBI, and the physiogenic view does not carefully consider the fact that PTSD and depression, and other co-morbid conditions, may be present in those suffering from mTBI. Finally, we end with a discussion of future directions in research that will lead to the improved care of patients diagnosed with mTBI.

Differential effect of first versus second concussive episodes on wavelet information quality of EEG

OBJECTIVE

Recent reports have suggested that long-term residual brain dysfunctions from mild traumatic brain injury (MTBI) that are often overlooked by clinical criteria may be detected using advanced research methods. The aim of the present study was to examine the feasibility of EEG wavelet information quality measures (EEG-IQ) in monitoring alterations of brain functions as well as to determine the differential rate of recovery between the first and second concussive episodes.

METHODS

Student-athletes at high risk for MTBI (n=265) were tested prior to concussive episodes as a baseline. From this subject pool, twenty one athletes who suffered from two concussive episodes within one athletic season and were tested on days 7, 14 and 21 post-first and second injuries using a within-subjects design. Specifically, EEG was recorded and processed using wavelet entropy (EEG-IQ) algorithm along with a battery of neuropsychological (NS) tests. Spatial distribution of EEG-IQ and its dynamics in conjunction with NS data were analyzed prior to and after MTBI.

RESULTS

No neuropsychological deficits were present in concussed subjects beyond 7 days post-injury after first and second concussions. However, EEG-IQ measures were significantly reduced primarily at temporal, parietal and the occipital regions (ROIs) after first and especially after second MTBI (p<0.01) beyond 7 days post-injury. Rate of recovery of EEG-IQ measures was significantly slower after second MTBI compared to those after the first concussion (p<0.01).

CONCLUSIONS

EEG-IQ measures may reveal alterations in the brain of concussed individuals that are most often overlooked by current assessment tools. In this regard, EEG-IQ may potentially be a valuable tool for assessing and monitoring residual brain dysfunction in "asymptomatic" MTBI subjects.

SIGNIFICANCE

The results demonstrate the potential utility of EEG-IQ measures to classify concussed individuals at various stages of recovery.