Long-term structural changes after mTBI and their relation to post-concussion symptoms

Concussion incidence and mechanisms differ between elite females and males in Australian Football

OBJECTIVES

To investigate the incidence and the game circumstances of concussion in the professional female (AFLW) and male (AFL) competitions of Australian Football, to identify potential targets for risk reduction.

DESIGN

Retrospective cohort.

METHODS

Concussion data were obtained from the AFL injury database, which included all concussions sustained by AFL (Male) players from 2015 to 18 and AFLW (Female) players from 2017 to 19. Concussions were diagnosed by experienced clinicians utilising standardised concussion assessment tools and injury definitions, as well as video review. Video footage was analysed to determine the circumstances each concussion occurred, which included the action and the contact-point of impact.

RESULTS

The incidence of concussion was higher in the AFLW (Female) compared to the AFL (Male) (IRR = 2.12, 95 %CI 1.54 to 2.92). Video footage was available for 194/252 (77 %) concussions in the AFL and 35/44 (80 %) concussions in the AFLW. Male players were most frequently concussed during marking contests (28 %) with primary impact from the upper limb (22 %) or the shoulder (19 %). Conversely, being bumped (23 %) or tackled (20 %) were the main actions associated with concussion in female players, with the head (29 %) or the ground (23 %) the most common contact-points of impact.

CONCLUSIONS

In elite Australian Football a higher incidence of concussion was demonstrated in female compared to male players. The mechanisms associated with concussion were also found to differ between male and female competitions, suggesting that different injury prevention interventions may be beneficial. In particular, a review of tackling and bumping skills training and education in the AFLW may reduce the risk of concussion.

Non-Invasive Vagus Nerve Stimulation Improves Brain Lesion Volume and Neurobehavioral Outcomes in a Rat Model of Traumatic Brain Injury

Abstract Traumatic brain injury (TBI) continues to be a major cause of death and disability worldwide. This study assessed the effectiveness of non-invasive vagus nerve stimulation (nVNS) in reducing brain lesion volume and improving neurobehavioral performance in a rat model of TBI. Animals were randomized into three experimental groups: (1) TBI with sham stimulation treatment (Control), (2) TBI treated with five lower doses (2-min) nVNS, and (3) TBI treated with five higher doses (2 × 2-min) nVNS. We used the gammaCore nVNS device to deliver stimulations. Magnetic resonance imaging studies were performed 1 and 7 days post-injury to confirm lesion volume. We observed smaller brain lesion volume in the lower dose nVNS group compared with the control group on days 1 and 7. The lesion volume for the higher dose nVNS group was significantly smaller than either the lower dose nVNS or the control groups on days 1 and 7 post-injury. The apparent diffusion coefficient differences between the ipsilateral and contralateral hemispheres on day 1 were significantly smaller for the higher dose (2 × 2 min) nVNS group than for the control group. Voxel-based morphometry analysis revealed an increase in the ipsilateral cortical volume in the control group caused by tissue deformation and swelling. On day 1, these abnormal volume changes were 13% and 55% smaller in the lower dose and higher dose nVNS groups, respectively, compared with the control group. By day 7, nVNS dampened cortical volume loss by 35% and 89% in the lower dose and higher dose nVNS groups, respectively, compared with the control group. Rotarod, beam walking, and anxiety performances were significantly improved in the higher-dose nVNS group on day 1 compared with the control group. The anxiety indices were also improved on day 7 post-injury compared with the control and the lower-dose nVNS groups. In conclusion, the higher dose nVNS (five 2 × 2-min stimulations) reduced brain lesion volume to a level that further refined the role of nVNS therapy for the acute treatment of TBI. Should nVNS prove effective in additional pre-clinical TBI models and later in clinical settings, it would have an enormous impact on the clinical practice of TBI in both civilian and military settings, as it can easily be adopted into routine clinical practice.

Neuroanatomical restoration of salience network links reduced headache impact to cognitive function improvement in mild traumatic brain injury with posttraumatic headache

BACKGROUND

Neuroanatomical alterations have been associated with cognitive deficits in mild traumatic brain injury (MTBI). However, most studies have focused on the abnormal gray matter volume in widespread brain regions using a cross-sectional design in MTBI. This study investigated the neuroanatomical restoration of key regions in salience network and the outcomes in MTBI.

METHODS

Thirty-six MTBI patients with posttraumatic headache (PTH) and 34 matched healthy controls were enrolled in this study. All participants underwent magnetic resonance imaging scans and were assessed with clinical measures during the acute and subacute phases. Surface-based morphometry was conducted to get cortical thickness (CT) and cortical surface area (CSA) of neuroanatomical regions which were defined by the Desikan atlas. Then mixed analysis of variance models were performed to examine CT and CSA restoration in patients from acute to subacute phase related to controls. Finally, mediation effects models were built to explore the relationships between neuroanatomical restoration and symptomatic improvement in patients.

RESULTS

MTBI patients with PTH showed reduced headache impact and improved cognitive function from the acute to subacute phase. Moreover, patients experienced restoration of CT of the left caudal anterior cingulate cortex (ACC) and left insula and cortical surface area of the right superior frontal gyrus from acute to subacute phase. Further mediation analysis found that CT restoration of the ACC and insula mediated the relationship between reduced headache impact and improved cognitive function in patients.

CONCLUSIONS

These results showed that neuroanatomical restoration of key regions in salience network correlated reduced headache impact with cognitive function improvement in MTBI with PTH, which further substantiated the vital role of salience network and provided an alternative clinical target for cognitive improvement in MTBI patients with PTH.

The Impact of a Recent Concussion on College-Aged Individuals with Co-Occurring Anxiety: A Qualitative Investigation

College-aged individuals with anxiety are vulnerable to developing persistent concussion symptoms, yet evidence-based treatments for this population are limited. Understanding these individuals' perspectives is critical for developing effective interventions. We conducted qualitative interviews with 17 college-aged individuals (18-24 years old) with a recent (≤10 weeks) concussion and at least mild anxiety (≥5 on the GAD-7 questionnaire) to understand the life impact of their concussion. We identified 5 themes: (1) disruption to daily activities (e.g., reduced participation in hobbies and physical activity); (2) disruption to relationships (e.g., reduced social engagement, feeling dismissed by others, stigma, and interpersonal friction); (3) disruptions in school/work (e.g., challenges participating due to light sensitivity, cognitive or sleep disturbance, and related emotional distress); (4) changes in view of the self (e.g., feeling "unlike oneself", duller, or more irritable), and (5) finding "silver linings" after the injury (e.g., increased motivation). Concussions impact the lives of college-aged individuals with co-occurring anxiety in a broad range of domains, many of which remain largely neglected in standard concussion clinical assessment and treatment. Assessing and addressing these issues has the potential to limit the negative impact of concussion, promote recovery, and potentially help prevent persistent concussion symptoms in this at-risk population.

Imaging of White Matter Injury Correlates with Plasma and Tissue Biomarkers in Pediatric Porcine Model of Traumatic Brain Injury

Traumatic brain injury (TBI) causes significant white matter injury, which has been characterized by various rodent and human clinical studies. The exact time course of imaging changes in a pediatric brain after TBI and its relation to biomarkers of injury and cellular function, however, is unknown. To study the changes in major white matter structures using a valid model of TBI that is comparable to a human pediatric brain in terms of size and anatomical features, we utilized a four-week-old pediatric porcine model of injury with controlled cortical impact (CCI). Using diffusion tensor imaging differential tractography, we show progressive anisotropy changes at major white matter tracts such as the corona radiata and inferior fronto-occipital fasciculus between day 1 and day 30 after injury. Moreover, correlational tractography shows a large part of bilateral corona radiata having positive correlation with the markers of cellular respiration. In contrast, bilateral corona radiata has a negative correlation with the plasma biomarkers of injury such as neurofilament light or glial fibrillary acidic protein. These are expected correlational findings given that higher integrity of white matter would be expected to correlate with lower injury biomarkers. We then studied the magnetic resonance spectroscopy findings and report decrease in a N-acetylaspartate/creatinine (NAA/Cr) ratio at the pericontusional cortex, subcortical white matter, corona radiata, thalamus, genu, and splenium of corpus callosum at 30 days indicating injury. There was also an increase in choline/creatinine ratio in these regions indicating rapid membrane turnover. Given the need for a pediatric TBI model that is comparable to human pediatric TBI, these data support the use of a pediatric pig model with CCI in future investigations of therapeutic agents. This model will allow future TBI researchers to rapidly translate our pre-clinical study findings into clinical trials for pediatric TBI.

[Formula: see text]Persistent post-concussion symptoms in children: pre-injury social difficulties and acute stress reaction as risk factors

Following mild traumatic brain injury (mTBI) children usually experience one or more somatic, cognitive, and/or emotional-behavioral post-concussion symptoms (PCS). PCS may be transient, however for some children, persistent post-concussion symptoms (PPCS) might linger for months or years. Identifying risk factors for PPCS may allow earlier interventions for patients at greater risk. We examined pre-injury social difficulties and acute stress reaction as risk factors to PPCS in children. Participants were 83 children (aged 8-16) with mTBI. In a prospective follow-up, pre-injury social difficulties, 24-hours post-concussion symptoms, and acute stress reactions were tested as predictors of one-week and four-months PCS reports. Parents' reports, self-reports, and neurocognitive tests were employed. One-week PCS level was associated with acute stress, and not with 24-hours post-concussion symptoms or pre-injury social difficulties. Four-months PCS level was predicted by pre-injury social difficulties and 24-hours post-concussion symptoms, with no contribution of acute stress. Interestingly, less symptoms at 24-hour from injury were associated with a higher level of PCS at four months. Cognitive functioning at four months was predicted by acute stress, with no contribution of 24-hours post-concussion symptoms or pre-injury social difficulties. Cognitive functioning did not differ between children with and without PPCS. In conclusion, non-injury, socio-emotional factors (pre-injury social difficulties, acute stress) should be considered, alongside injury-related factors, in predicting recovery from mTBI. Pre-injury social difficulties and stress reaction to the traumatic event might pose an emotional burden and limit one's social support during recovery, thus require clinical attention in children following mTBI.

Investigating the use of plasma pTau181 in retired contact sports athletes

BACKGROUND

Considering the wide range of outcomes following sport-related concussions, biomarkers are needed to detect underlying pathological changes. The objective was to analyze the use of plasma phosphorylated tau 181 (pTau181) as a non-invasive measure of underlying brain changes in a cohort of retired contact sports athletes at risk of neurodegeneration.

METHODS

Fifty-four retired contact sport athletes and 27 healthy controls whose blood plasma was analyzed for pTau181 were included. A portion (N = 21) of retired athletes had a 2-years follow-up visit. All participants had completed a neuropsychological battery and MRI imaging.

RESULTS

Plasma pTau181 was significantly higher in retired athletes compared to healthy controls (8.94 ± 5.08 pg/mL vs. 6.00 ± 2.53 pg/mL, respectively; 95% BCa CI 1.38-4.62; p = 0.02); and was significantly associated with fornix fractional anisotropy values only in the athletes group (β = - 0.002; 95% BCa CI - 0.003 to - 0.001; p = 0.002). When the retired athletes cohort was divided into high vs. normal pTau181 groups, the corpus callosum (CC) volume and white-matter integrity was significantly lower in high pTau181 compared to older healthy controls (CC volume: 1.57 ± 0.19 vs. 2.02 ± 0.32, p = 0.002; CC medial diffusivity: 0.96 ± 0.04 × 10^-3 mm²/s vs. 0.90 ± 0.03 × 10^-3 mm²/s, p = 0.003; CC axial diffusivity: 1.49 ± 0.04 × 10^-3 mm²/s vs. 1.41 ± 0.02 × 10^-3 mm²/s, p < 0.001, respectively).

CONCLUSIONS

Although high plasma pTau181 levels were associated with abnormalities in CC and fornix, baseline pTau181 did not predict longitudinal changes in regional brain volumes or white-matter integrity in the athletes. pTau181 may be useful for identifying those with brain abnormalities related to repeated concussion but not for predicting progression.

The effect of transcranial direct current stimulation on cognitive performance in youth with persistent cognitive symptoms following concussion: a controlled pilot study

OBJECTIVE

Explore the feasibility, tolerability, and early efficacy of transcranial direct current stimulation (tDCS) as a therapeutic intervention for youth with cognitive persistent post-concussion symptoms (PPCS).

HYPOTHESIS

tDCS improves performance on a dual task working memory (WM) paradigm in youth with cognitive PPCS.

PARTICIPANTS

Twelve youth experiencing cognitive PPCS.

DESIGN

A quasi-randomized pilot trial was used to explore the tolerability of, and performance differences on, a dual N-Back WM task paired with active or sham tDCS over 3 sessions.

MEASURES

Accuracy and reaction time on WM task and self-report of tDCS tolerability.

RESULTS

Trends toward increases in accuracy from Day 1 to 3 seen in both groups. Active tDCS group performed better than sham on Day 2 in N-Back level N2 (p = .019), and marginally better than the sham group on Day 3 in level N3 (p = .26). Participants reported tDCS as tolerable; compared to the active tDCS group, the sham group reported more "considerable" (p = .078) and "strong" symptoms (p = .097).

CONCLUSION

tDCS is a promising tool for enhancing WM performance and is a feasible and tolerable adjunct to behavioral interventions in youth with cognitive PPCS. A clinical trial to demonstrate efficacy is warranted.

Prognosis and Diagnostic Biomarkers of Mild Traumatic Brain Injury: Current Status and Future Prospects

Mild traumatic brain injury (mTBI) is the most prevalent type of TBI (80-90%). It is characterized by a loss consciousness for less than 30 minutes, post-traumatic amnesia for less than 24 hours, and Glasgow Coma Score of 13-15. Accurately diagnosing mTBIs can be a challenge because the majority of these injuries do not show noticeable or visible changes on neuroimaging studies. Appropriate determination of mTBI is tremendously important because it might lead in some cases to post-concussion syndrome, cognitive impairments including attention, memory, and speed of information processing problems. The scientists have studied different methods to improve mTBI diagnosis and enhanced approaches that would accurately determine the severity of the trauma. The present review focuses on discussing the role of biomarkers as potential key factors in diagnosing mTBI. The present review focuses on 1) protein based peripheral and CNS markers, 2) genetic biomarkers, 3) imaging biomarkers, 4) neurophysiological biomarkers, and 5) the studies and clinical trials in mTBI. Each section provides information and characteristics on different biomarkers for mTBI.

Longitudinal Analysis of Persistent Postconcussion Symptoms, Probable TBI, and Intimate Partner Violence Perpetration Among Veterans

OBJECTIVE

To determine veterans' intimate partner violence (IPV) perpetration following report of traumatic brain injury (TBI) and persistent postconcussion symptoms (PPCSs).

SETTING

Five Department of Veterans Affairs (VA) medical centers.

PARTICIPANTS

Veterans with nonmissing data on main measures, resulting in N = 1150 at baseline and N = 827 at follow-up.

DESIGN

Prospective cohort study with secondary data analysis of self-reported TBI, PPCSs, and IPV perpetration, controlling for common predictors of IPV, including binge drinking, marijuana use, pain intensity, and probable posttraumatic stress disorder.

MAIN MEASURES

VA TBI Screening Tool to assess for probable TBI and PPCSs; Conflict Tactics Scale-Revised (CTS-2S) to assess for IPV perpetration.

RESULTS

Almost half (48%) of participants reported IPV perpetration at follow-up. Both probable TBI and higher PPCSs at baseline were associated with overall IPV perpetration and more frequent IPV perpetration at follow-up. Only PPCSs significantly predicted IPV perpetration after controlling for common predictors of IPV perpetration. Neither probably TBI nor PPCSs predicted frequency of IPV perpetration.

CONCLUSION

When considered alongside common risk factors for IPV perpetration, PPCS was uniquely associated with the likelihood of IPV perpetration in this veteran sample. Given post-9/11 veterans' elevated risk for head injury, findings emphasize the distinctive value of PPCSs in understanding risk for IPV perpetration. We recommend increased assessment for PPCSs in clinical practice among veterans enrolled in VA care and highlight several important areas for future research and intervention development.

Longitudinal changes in brain parenchyma due to mild traumatic brain injury during the first year after injury

Chronic gray matter (GM) atrophy is a known consequence of moderate and severe traumatic brain injuries but has not been consistently shown in mild traumatic brain injury (mTBI). The aim of this study was to investigate the longitudinal effect of uncomplicated mTBI on the brain's GM and white matter (WM) from 6 weeks to 12 months after injury. Voxel-based-morphometry (VBM) was computed with the T1-weighted images of 48 uncomplicated mTBI patients and 37 orthopedic controls. Over the period from 6 weeks to 12 months, only patients who experienced uncomplicated mTBI, but not control participants, showed significant GM decrease predominantly in the right hemisphere along the GM-CSF border in lateral and medial portions of the sensorimotor cortex extending into the rolandic operculum, middle frontal gyrus, insula, and temporal pole. Additionally, only mTBI patients, but not controls, experienced significant WM decrease predominantly in the right hemisphere in the superior fasciculus longitudinalis, arcuate fasciculus, and cortical-pontine tracts as well as a significant WM increase in left arcuate fasciculus and left capsula extrema. We did not observe any significant change in the controls for the same time interval or any significant group differences in GM and WM probability at each of the two timepoints. This suggests that the changes along the brain tissue borders observed in the mTBI group represent a reorganization associated with subtle microscopical changes in intracortical myelin and not a direct degenerative process as a result of mTBI.

Acute and Chronic Effects of Multiple Concussions on Midline Brain Structures

BACKGROUND AND OBJECTIVES

To test the hypothesis that a history of concussion (HOC) causes greater disturbances in cerebral blood flow (CBF) and white matter microstructure of midline brain structures after subsequent concussions, during the acute and chronic phases of recovery.

METHODS

In this longitudinal MRI study, 61 athletes with uncomplicated concussion (36 with HOC) were imaged at the acute phase of injury (1-7 days after injury), the subacute phase (8-14 days), medical clearance to return to play (RTP), 1 month after RTP, and 1 year after RTP. A normative group of 167 controls (73 with HOC) were also imaged. Each session assessed CBF of the cingulate cortex, along with fractional anisotropy (FA) and mean diffusivity (MD) of the corpus callosum. Linear mixed models tested for interactions of HOC with time since injury. The Sport Concussion Assessment Tool (SCAT) was also used to evaluate effects of HOC on symptoms, cognition, and balance.

RESULTS

Athletes with HOC had significantly greater declines in midcingulate CBF subacutely (z = -3.29, p = 0.002) and greater declines in posterior cingulate CBF at 1 year after RTP (z = -2.42, p = 0.007). No significant effects of HOC were seen for FA, whereas athletes with HOC had higher MD of the splenium at RTP (z = 2.54, p = 0.008). These effects were seen in the absence of significant differences in SCAT domains (|z| ≤ 1.14, p ≥ 0.256) or time to RTP (z = 0.23, p = 0.818).

DISCUSSION

Results indicate subacute and chronic effects of HOC on cingulate CBF and callosal microstructure in the absence of differences in clinical indices. These findings provide new insights into physiologic brain recovery after concussion, with cumulative effects of repeated injury detected among young, healthy athletes.

Acute Diffusion Tensor and Kurtosis Imaging and Outcome following Mild Traumatic Brain Injury

In this prospective cohort study, we investigated associations between acute diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) metrics and persistent post-concussion symptoms (PPCS) 3 months after mild traumatic brain injury (mTBI). Adult patients with mTBI (n = 176) and community controls (n = 78) underwent 3 Tesla magnetic resonance imaging (MRI) within 72 h post-injury, estimation of cognitive reserve at 2 weeks, and PPCS assessment at 3 months. Eight DTI and DKI metrics were examined with Tract-Based Spatial Statistics. Analyses were performed in the total sample in uncomplicated mTBI only (i.e., without lesions on clinical MRI), and with cognitive reserve both controlled for and not. Patients with PPCS (n = 35) had lower fractional anisotropy (in 2.7% of all voxels) and kurtosis fractional anisotropy (in 6.9% of all voxels), and higher radial diffusivity (in 0.3% of all voxels), than patients without PPCS (n = 141). In uncomplicated mTBI, only fractional anisotropy was significantly lower in patients with PPCS. Compared with controls, patients with PPCS had widespread deviations in all diffusion metrics. When including cognitive reserve as a covariate, no significant differences in diffusion metrics between patients with and without PPCS were present, but patients with PPCS still had significantly higher mean, radial, and axial diffusivity than controls. In conclusion, patients who developed PPCS had poorer white matter microstructural integrity acutely after the injury, compared with patients who recovered and healthy controls. Differences became less pronounced when cognitive reserve was controlled for, suggesting that pre-existing individual differences in axonal integrity accounted for some of the observed differences.

Cannabis and Athletic Performance

Cannabis is widely used for both recreational and medicinal purposes on a global scale. There is accumulating interest in the use of cannabis and its constituents for athletic recovery, and in some instances, performance. Amidst speculation of potential beneficial applications, the effects of cannabis and its two most abundant constituents, delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), remain largely un-investigated. The purpose of this review is to critically evaluate the literature describing the effects of whole cannabis, THC, and CBD, on athletic performance and recovery. While investigations of whole cannabis and THC have generally shown either null or detrimental effects on exercise performance in strength and aerobic-type activities, studies of sufficient rigor and validity to conclusively declare ergogenic or ergolytic potential in athletes are lacking. The ability of cannabis and THC to perturb cardiovascular homeostasis warrants further investigation regarding mechanisms by which performance may be affected across different exercise modalities and energetic demands. In contrast to cannabis and THC, CBD has largely been scrutinized for its potential to aid in recovery. The beneficial effects of CBD on sleep quality, pain, and mild traumatic brain injury may be of particular interest to certain athletes. However, research in each of these respective areas has yet to be thoroughly investigated in athletic populations. Elucidating the effects of whole cannabis, THC, and CBD is pertinent for both researchers and practitioners given the widespread use of these products, and their potential to interact with athletes' performance and recovery.

Diffusion Tensor Imaging Correlates of Concussion Related Cognitive Impairment

Introduction: Cognitive impairment after concussion has been widely reported, but there is no reliable imaging biomarker that predicts the severity of cognitive decline post-concussion. This study tests the hypothesis that patients with a history of concussion and persistent cognitive impairment have fractional anisotropy (FA) and mean diffusivity (MD) values from diffusion tensor imaging (DTI) that are specifically associated with poor performance on the Montreal Cognitive Assessment (MoCA). Methods: Fifty-three subjects (19 females) with concussions and persistent cognitive symptoms had MR imaging and the MoCA. Imaging was analyzed by atlas-based, whole-brain DTI segmentation and FLAIR lesion segmentation. Then, we conducted a random forest-based recursive feature elimination (RFE) with 10-fold cross-validation on the entire dataset, and with partial correlation adjustment for age and lesion load. Results: RFE showed that 11 DTI variables were found to be important predictors of MoCA scores. Partial correlation analyses, corrected for age and lesion load, showed significant correlations between MoCA scores and right fronto-temporal regions: inferior temporal gyrus MD (r = -0.62, p = 0.00001), middle temporal gyrus MD (r = -0.54, p = 0.0001), angular gyrus MD (r = -0.48, p = 0.0008), and inferior frontal gyrus FA (r = 0.44, p = 0.002). Discussion: This is the first study to demonstrate a correlation between MoCA scores and DTI variables in patients with a history of concussion and persistent cognitive impairment. This kind of research will significantly increase our understanding of why certain persons have persistent cognitive changes after concussion which, in turn, may allow us to predict persistent impairment after concussion and suggest new interventions.

Reduced Brainstem Volume After Mild Traumatic Brain Injury

Supplemental digital content is available in the text.

Objective

The aims of this study were to investigate changes in regional brain volume after concussion (mild traumatic brain injury) and to examine the relationship between change in brain volume and cognitive deficits.

Design

Twenty-eight patients with mild traumatic brain injury and 27 age-matched controls were included in this study. Magnetic resonance imaging (3 T) data were obtained from the participants. Structural brain volume changes were examined using tensor-based morphometry, which identifies regional structural differences in the whole brain, including cerebrospinal fluid, gray matter, and white matter. Volume contraction and expansion were compared between groups using a two-sample t test. The association between time post-injury or neurocognitive function and volumetric changes was examined using regression analysis.

Results

Individuals with mild traumatic brain injury exhibited volume reduction in the brainstem, including the pontine reticular formation. Regional cerebral volume changes were not associated with time post-injury but were significantly associated with neurocognitive function, especially with executive card sorting test, forward digit span test, and performance on verbal learning test. The greater regional cerebral volume was associated with better cognitive performance after mild traumatic brain injury.

Conclusion

Decreased brainstem volume may indicate its vulnerability to traumatic injury, and cerebral volume in specific regions was positively associated with patients’ cognitive function after injury.

Effectiveness of PitchSafe on Knowledge and Attitude of Baseball-Related Concussion

Background

Traumatic brain injuries (TBIs), specifically concussions, affect many athletes and have dangerous immediate and long-term sequelae. Lack of awareness surrounding concussion impedes prevention, identification, and treatment. This study aims to assess parental knowledge and attitudes regarding concussions in youth baseball before and after administering an educational intervention called PitchSafe. PitchSafe is a short video that contains examples of baseball-related head injuries such as collisions, falls, and direct hits by baseballs; the signs and symptoms of a concussion; testimony from a former baseball player who sustained a TBI playing baseball; and a brochure detailing the potential signs, symptoms, and treatment plans associated with concussions.

Methodology

The Rosenbaum Concussion Knowledge and Attitudes Survey (RoCKAS) was used to assess three indices of parental understanding of concussion: Concussion Knowledge Index (CKI), Concussion Attitudes Index (CAI), and signs and symptoms of concussions (SS). The RoCKAS was administered at baseline and after the PitchSafe tool was administered. Parents were re-assessed one year following the initial distribution of survey materials utilizing the long-term follow-up (LTFU) RoCKAS. A paired sample t-test was conducted to compare the baseline, post-intervention (PI), and LTFU CKI, CAI, and SS among participants.

Results

The mean scores for CKI were 68% ± 12%, 76% ± 4%, and 76% ± 5% for baseline, PI, and LTFU, respectively. The mean scores for SS were 46% ± 20%, 62% ± 14%, and 64% ± 16% for baseline, PI, and LTFU, respectively. The mean scores for CAI were 87% ± 6%, 91% ± 5%, and 92% ± 4% for baseline, PI, and LTFU, respectively.

Conclusions

PitchSafe increased youth baseball parents’ long-term knowledge of concussions, ability to identify signs and symptoms of concussions, and may promote safer attitudes toward concussions. These findings support more widespread use of educational tools through social media and in clinical settings.

Post-traumatic Headache and Mild Traumatic Brain Injury: Brain Networks and Connectivity

PURPOSE OF REVIEW

Post-traumatic headache (PTH) consequent to mild traumatic brain injury (mTBI) is a complex, multidimensional, chronic neurological disorder. The purpose of this review is to evaluate the current neuroimaging studies on mTBI and PTH with a specific focus on brain networks and connectivity patterns.

RECENT FINDINGS

We present findings on PTH incidence and prevalence, as well as the latest neuroimaging research findings on mTBI and PTH. Additionally, we propose a new strategy in studying PTH following mTBI. The diversity and heterogeneity of pathophysiological mechanisms underlying mild traumatic brain injury pose unique challenges on how we interpret neuroimaging findings in PTH. Evaluating alterations in the intrinsic brain network connectivity patterns using novel imaging and analytical techniques may provide additional insights into PTH disease state and therefore inform effective treatment strategies.

Cortical Volume and Thickness in Youth Several Years After Concussion

OBJECTIVE

The long-term effects of pediatric concussion on brain morphometry remain poorly delineated. This study used magnetic resonance imaging (MRI) to investigate cortical volume and thickness in youth several years after concussion.

METHODS

Participants aged 8-19 years old with a history of concussion (n = 37) or orthopedic injury (n = 20) underwent MRI, rated their postconcussion symptoms, and completed cognitive testing on average 2.6 years (SD = 1.6) after injury. FreeSurfer was used to obtain cortical volume and thickness measurements as well as determine any significant correlations between brain morphometry, postconcussion symptoms (parent and self-report), and cognitive functioning.

RESULTS

No significant group differences were found for either cortical volume or thickness. Youth with a history of concussion had higher postconcussion symptom scores (both parent and self-report Postconcussion Symptom Inventory) than the orthopedic injury group, but symptom ratings did not significantly correlate with cortical volume or thickness. Across both groups, faster reaction time on a computerized neurocognitive test battery (CNS Vital Signs) was associated with a thinner cortex in the left pars triangularis of the inferior frontal gyrus and the left caudal anterior cingulate. Better verbal memory was associated with a thinner cortex in the left rostral middle frontal gyrus.

CONCLUSION

Findings do not support differences in cortical volume or thickness approximately 2.5 years postconcussion in youth, suggesting either long-term cortical recovery or no cortical differences as a result of injury. Further research using a longitudinal study design and larger samples is needed.

Behavioral, axonal, and proteomic alterations following repeated mild traumatic brain injury: Novel insights using a clinically relevant rat model

A history of mild traumatic brain injury (mTBI) is linked to a number of chronic neurological conditions, however there is still much unknown about the underlying mechanisms. To provide new insights, this study used a clinically relevant model of repeated mTBI in rats to characterize the acute and chronic neuropathological and neurobehavioral consequences of these injuries. Rats were given four sham-injuries or four mTBIs and allocated to 7-day or 3.5-months post-injury recovery groups. Behavioral analysis assessed sensorimotor function, locomotion, anxiety, and spatial memory. Neuropathological analysis included serum quantification of neurofilament light (NfL), mass spectrometry of the hippocampal proteome, and ex vivo magnetic resonance imaging (MRI). Repeated mTBI rats had evidence of acute cognitive deficits and prolonged sensorimotor impairments. Serum NfL was elevated at 7 days post injury, with levels correlating with sensorimotor deficits; however, no NfL differences were observed at 3.5 months. Several hippocampal proteins were altered by repeated mTBI, including those associated with energy metabolism, neuroinflammation, and impaired neurogenic capacity. Diffusion MRI analysis at 3.5 months found widespread reductions in white matter integrity. Taken together, these findings provide novel insights into the nature and progression of repeated mTBI neuropathology that may underlie lingering or chronic neurobehavioral deficits.

Altered motor system function in post-concussion syndrome as assessed via transcranial magnetic stimulation

•

Study examining corticospinal and cortical activity in post-concussion.

•

Reduction in GABAB-mediated inhibition observed.

•

These changes were associated with depression-related symptoms.

Objective

It is unclear why specific individuals incur chronic symptoms following a concussion. This exploratory research aims to identify and characterize any neurophysiological differences that may exist in motor cortex function in post-concussion syndrome (PCS).

Methods

Fifteen adults with PCS and 13 healthy, non-injured adults were tested. All participants completed symptom questionnaires, and transcranial magnetic stimulation (TMS) was used to measure intracortical and transcallosal excitability and inhibition in the dominant motor cortex.

Results

Cortical silent period (p = 0.02, g = 0.96) and ipsilateral silent period (p = 0.04, g = 0.78) were shorter in the PCS group compared to the control group which may reflect reduced GABA-mediated inhibition in PCS. Furthermore, increased corticomotor excitability was observed in the left hemisphere but not the right hemisphere.

Conclusions

These data suggest that persistent neurophysiological differences are present in those with PCS. The exact contributing factors to such changes remain to be investigated by future studies.

Significance

This study provides novel evidence of lasting neurophysiological changes in PCS.

Prospective study of the association between sport-related concussion and brain morphometry (3T-MRI) in collegiate athletes: study from the NCAA-DoD CARE Consortium

OBJECTIVES

To determine the acute and early long-term associations of sport-related concussion (SRC) and subcortical and cortical structures in collegiate contact sport athletes.

METHODS

Athletes with a recent SRC (n=99) and matched contact (n=91) and non-contact sport controls (n=95) completed up to four neuroimaging sessions from 24 to 48 hours to 6 months postinjury. Subcortical volumes (amygdala, hippocampus, thalamus and dorsal striatum) and vertex-wise measurements of cortical thickness/volume were computed using FreeSurfer. Linear mixed-effects models examined the acute and longitudinal associations between concussion and structural metrics, controlling for intracranial volume (or mean thickness) and demographic variables (including prior concussions and sport exposure).

RESULTS

There were significant group-dependent changes in amygdala volumes across visits (p=0.041); this effect was driven by a trend for increased amygdala volume at 6 months relative to subacute visits in contact controls, with no differences in athletes with SRC. No differences were observed in any cortical metric (ie, thickness or volume) for primary or secondary analyses.

CONCLUSION

A single SRC had minimal associations with grey matter structure across a 6-month time frame.

Microstructure of the Corpus Callosum Long after Pediatric Concussion

OBJECTIVE

The long-term effects of pediatric concussion on white matter microstructure are poorly understood. This study investigated long-term changes in white matter diffusion properties of the corpus callosum in youth several years after concussion.

METHODS

Participants were 8-19 years old with a history of concussion (n = 36) or orthopedic injury (OI) (n = 21). Mean time since injury for the sample was 2.6 years (SD = 1.6). Participants underwent diffusion magnetic resonance imaging, completed cognitive testing, and rated their post-concussion symptoms. Measures of diffusivity (fractional anisotropy, mean, axial, and radial diffusivity) were extracted from white matter tracts in the genu, body, and splenium regions of the corpus callosum. The genu and splenium tracts were further subdivided into 21 equally spaced regions along the tract and diffusion values were extracted from each of these smaller regions.

RESULTS

White matter tracts in the genu, body, and splenium did not differ in diffusivity properties between youth with a history of concussion and those with a history of OI. No significant group differences were found in subdivisions of the genu and splenium after correcting for multiple comparisons. Diffusion metrics did not significantly correlate with symptom reports or cognitive performance.

CONCLUSIONS

These findings suggest that at approximately 2.5 years post-injury, youth with prior concussion do not have differences in their corpus callosum microstructure compared to youth with OI. Although these results are promising from the perspective of long-term recovery, further research utilizing longitudinal study designs is needed to confirm the long-term effects of pediatric concussion on white matter microstructure.

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.

Structural and Volumetric Brain MRI Findings in Mild Traumatic Brain Injury

BACKGROUND AND PURPOSE

Routine MR imaging findings are frequently normal following mild traumatic brain injury and have a limited role in diagnosis and management. Advanced MR imaging can assist in detecting pathology and prognostication but is not readily available outside research settings. However, 3D isotropic sequences with ∼1-mm³ voxel size are available on community MR imaging scanners. Using such sequences, we compared radiologists' findings and quantified regional brain volumes between a mild traumatic brain injury cohort and non-brain-injured controls to describe structural imaging findings associated with mild traumatic brain injury.

MATERIALS AND METHODS

Seventy-one military personnel with persistent symptoms and 75 controls underwent 3T MR imaging. Three neuroradiologists interpreted the scans using common data elements. FreeSurfer was used to quantify regional gray and white matter volumes.

RESULTS

WM hyperintensities were seen in 81% of the brain-injured group versus 60% of healthy controls. The odds of ≥1 WM hyperintensity in the brain-injured group was about 3.5 times the odds for healthy controls (95% CI, 1.58-7.72; P = .002) after adjustment for age. A frontal lobe-only distribution of WM hyperintensities was more commonly seen in the mild traumatic brain injury cohort. Furthermore, 7 gray matter, 1 white matter, and 2 subcortical gray matter regions demonstrated decreased volumes in the brain-injured group after multiple-comparison correction. The mild traumatic brain injury cohort showed regional parenchymal volume loss.

CONCLUSIONS

White matter findings are nonspecific and therefore a clinical challenge. Our results suggest that prior trauma should be considered in the differential diagnosis of multifocal white matter abnormalities with a clinical history of mild traumatic brain injury, particularly when a frontal predilection is observed.

Mapping brain recovery after concussion: From acute injury to 1 year after medical clearance

OBJECTIVE

To test the hypothesis that concussion-related brain alterations seen at symptomatic injury and medical clearance to return to play (RTP) will have dissipated by 1 year after RTP.

METHODS

For this observational study, 24 athletes with concussion were scanned longitudinally within 1 week after injury, at RTP, and 1 year after RTP. A large control cohort of 122 athletes were also scanned before the season. Each imaging session assessed global functional connectivity (Gconn) and cerebral blood flow (CBF), along with white matter fractional anisotropy (FA) and mean diffusivity (MD). The main effects of concussion on MRI parameters were evaluated at each postinjury time point. In addition, covariation was assessed between MRI parameters and clinical measures of acute symptom severity and time to RTP.

RESULTS

Different aspects of brain physiology showed different patterns of recovery over time. Both Gconn and FA displayed no significant effects at 1 year after RTP, whereas CBF and MD exhibited persistent long-term effects. The effects of concussion on MRI parameters were also dependent on acute symptom severity and time to RTP for all postinjury time points.

CONCLUSION

This study provides the first longitudinal evaluation of concussion focused on time of RTP and 1 year after medical clearance, using multiple different MRI measures to assess brain structure and function. These findings significantly enhance our understanding of the natural course of brain recovery after a concussion.

Differences in corpus callosum injury between cerebral concussion and diffuse axonal injury

BACKGROUND

We investigated differences in corpus callosum (CC) injuries between patients with concussion and those with diffuse axonal injury (DAI) by using diffusion tensor tractography (DTT).

METHODS

Twenty-nine patients with concussion, 21 patients with DAI, and 25 control subjects were recruited. We reconstructed the whole CC and 5 regions of the CC after applying Hofer classification (I, II, III, IV, and V). The whole CC and each region of the CC were analyzed to measure DTT parameters (fractional anisotropy [FA], apparent diffusion coefficient [ADC], and fiber number [FN]).

RESULTS

In the whole CC, significant differences were observed in all DTT parameters between the concussion and control groups and the DAI and control groups (P < .05). Among the 5 regions of the CC, significant differences were observed in FA and ADC between the concussion and control groups and the DAI and control groups (P < .05). Significant differences in FN were observed in CC regions I and II (connected with the prefrontal lobe and secondary motor area) between the concussion and control groups, in CC regions I, II, III, and IV (connected with the frontoparietal lobes) between the DAI and control groups, and in CC regions III, IV (connected with the motor-sensory cortex) between the concussion and DAI groups (P < .05).

CONCLUSION

It was observed that both concussion and DAI patients showed diffuse neural injuries in the whole CC and all 5 regions of the CC. Neural FN results revealed that concussion patients appeared to be specifically injured in the anterior part of the CC connected with the frontal lobe, whereas DAI patients were injured in more diffuse regions connected with whole frontoparietal lobes.

Cortical thinning in military blast compared to non-blast persistent mild traumatic brain injuries

In the military, explosive blasts are a significant cause of mild traumatic brain injuries (mTBIs). The symptoms associated with blast mTBIs causes significant economic burdens and a diminished quality of life for many service members. At present, the distinction of the injury mechanism (blast versus non-blast) may not influence TBI diagnosis. However, using noninvasive imaging, this study reveals significant distinctions between the blast and non-blast TBI mechanisms. A cortical whole-brain thickness analysis was performed using structural high-resolution T1-weighted MRI to identify the effects of blasts in persistent mTBI (pmTBI) subjects. A total of 41 blast pmTBI subjects were individually age- and gender-matched to 41 non-blast pmTBI subjects. Using FreeSurfer, cortical thickness was quantified for the blast group, relative to the non-blast group. Cortical thinning was identified within the blast mTBI group, in two clusters bilaterally. In the left hemisphere, the cluster overlapped with the lateral orbitofrontal, rostral middle frontal, medial orbitofrontal, superior frontal, rostral anterior cingulate and frontal pole cortices (p < 0.02, two-tailed, size = 1680 mm²). In the right hemisphere, the cluster overlapped with the lateral orbitofrontal, rostral middle frontal, medial orbitofrontal, pars orbitalis, pars triangularis and insula cortices (p < 0.002, two-tailed, cluster size = 2453 mm²). Self-report assessments suggest significant differences in the Post-Traumatic Stress Disorder Checklist-Civilian Version (p < 0.05, Bonferroni-corrected) and the Neurobehavioral Symptom Inventory (p < 0.01, uncorrected) between the blast and non-blast mTBI groups. These results suggest that blast may cause a unique injury pattern related to a reduction in cortical thickness within specific brain regions which could affect symptoms. No other study has found cortical thickness difference between blast and non-blast mTBI groups and further replication is needed to confirm these initial observations.

White matter during concussion recovery: Comparing diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI)

Concussion pathophysiology in humans remains incompletely understood. Diffusion tensor imaging (DTI) has identified microstructural abnormalities in otherwise normal appearing brain tissue, using measures of fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD). The results of prior DTI studies suggest that acute alterations in microstructure persist beyond medical clearance to return to play (RTP), but these measures lack specificity. To better understand the observed effects, this study combined DTI with neurite orientation dispersion and density imaging (NODDI), which employs a more sophisticated description of water diffusion in the brain. A total of 66 athletes were recruited, including 33 concussed athletes, scanned within 7 days after concussion and at RTP, along with 33 matched controls. Both univariate and multivariate methods identified DTI and NODDI parameters showing effects of concussion on white matter. Spatially extensive decreases in FA and increases in AD and RD were associated with reduced intra-neurite water volume, at both the symptomatic phase of injury and RTP, indicating that effects persist beyond medical clearance. Subsequent analyses also demonstrated that concussed athletes with higher symptom burden and a longer recovery time had greater reductions in FA and increased AD, RD, along with increased neurite dispersion. This study provides the first longitudinal evaluation of concussion from acute injury to RTP using combined DTI and NODDI, significantly enhancing our understanding of the effects of concussion on white matter microstructure.

Imaging Post-Traumatic Headache

PURPOSE OF REVIEW

Headache is a frequent and debilitating symptom after mild traumatic brain injury, yet little is known about its pathophysiology and most effective treatments. The goal of this review is to summarize findings from imaging studies used during the clinical evaluation and research investigation of post-traumatic headache (PTH).

RECENT FINDINGS

There are no published recommendations or guidelines for when to acquire imaging studies of the head or neck in patients with PTH. Clinical acumen is required to determine if imaging is needed to assess for a secondary cause of headache which may have been precipitated or unmasked by the trauma. Several guidelines for when to image the patient with mild traumatic brain injury (mTBI) in the emergency setting consider headache among the deciding factors. In the research arena, imaging techniques including proton spectroscopy magnetic resonance imaging, diffusion tensor imaging, magnetic resonance morphometry, and functional neck x-rays have been employed with the goal of identifying diagnostic and prognostic factors for PTH and to help understand its underlying pathophysiologic mechanisms. Results indicate that changes in regional cortical thickness and damage to specific white matter tracts warrant further research. Future research should interrogate whether these imaging findings contribute to the classification and prognosis of PTH. Current research provides evidence that imaging findings associated with PTH may be distinct from those attributable to mTBI. A variety of imaging techniques have potential to further our understanding of the pathophysiologic processes underlying PTH as well as to provide diagnostic and prognostic indicators. However, considerable work must be undertaken for this to be realized.

Altered cortical activation and connectivity patterns for visual attention processing in young adults post-traumatic brain injury: A functional near infrared spectroscopy study

AIMS

This study aimed at understanding the neurobiological mechanisms associated with inattention induced by traumatic brain injury (TBI). To eliminate the potential confounding caused by the heterogeneity of TBI, we focused on young adults postsports-related concussion (SRC).

METHODS

Functional near-infrared spectroscopy (fNIRS) data were collected from 27 young adults post-SRC and 27 group-matched normal controls (NCs), while performing a visual sustained attention task. Task responsive cortical activation maps and pairwise functional connectivity among six regions of interest were constructed for each subject. Correlations among the brain imaging measures and clinical measures of attention were calculated in each group.

RESULTS

Compared to the NCs, the SRC group showed significantly increased brain activation in left middle frontal gyrus (MFG) and increased functional connectivity between right inferior occipital cortex (IOC) bilateral calcarine gyri (CG). The left MFG activation magnitude was significantly negatively correlated with the hyperactive/impulsive symptom severity measure in the NCs, but not in the patients. The right hemisphere CG-IOC functional connectivity showed a significant positive correlation with the hyperactive/impulsive symptom severity measure in patients, but not in NCs.

CONCLUSION

The current data suggest that abnormal left MFG activation and hyper-communications between right IOC and bilateral CG during visual attention processing may significantly contribute to behavioral manifestations of attention deficits in patients with TBI.

Concussion and the autonomic nervous system: An introduction to the field and the results of a systematic review

BACKGROUND

Recent evidence suggests that autonomic nervous dysfunction may be one of many potential factors contributing to persisting post-concussion symptoms.

OBJECTIVE

This is the first systematic review to explore the impact of concussion on multiple aspects of autonomic nervous system functioning.

METHODS

The methods employed are in compliance with the American Academy of Neurology (AAN) and PRISMA standards. Embase, MEDLINE, PsychINFO, and Science Citation Index literature searches were performed using relevant indexing terms for articles published prior to the end of December 2016. Data extraction was performed by two independent groups, including study quality indicators to determine potential risk for bias according to the 4-tiered classification scheme of the AAN.

RESULTS

Thirty-six articles qualified for inclusion in the analysis. Only three studies (one Class II and two Class IV) did not identify anomalies in measures of ANS functioning in concussed populations.

CONCLUSIONS

The evidence supports the conclusion that it is likely that concussion causes autonomic nervous system anomalies. An awareness of this relationship increases our understanding of the physical impact of concussion, partially explains the overlap of concussion symptoms with other medical conditions, presents opportunities for further research, and has the potential to powerfully inform treatment decisions.

Less Cortical Thickness in Patients With Persistent Post-Traumatic Headache Compared With Healthy Controls: An MRI Study

OBJECTIVE

To investigate differences in cortical thickness in patients with persistent post-traumatic headache (PPTH) relative to healthy controls and to interrogate whether cortical morphology relates to headache burden (headache frequency, years with post-traumatic headache, PTH) in patients with PPTH.

BACKGROUND

PTHs are one of the most common symptoms following concussion. In some patients, PTHs continue for longer than three months and are classified as PPTH. This study has two main goals: (1) To delineate the neuropathology of PPTH, by interrogating differences in cortical thickness in patients with PPTH relative to healthy controls. (2) To interrogate potential associations between brain morphology and headache burden in patients with PPTH by examining whether cortical thickness relates to frequency of headaches or years lived with PTH.

METHODS

Adults with PPTH diagnosed according to ICHD 3 beta diagnostic criteria and healthy controls underwent brain MRI on a 3 Tesla scanner. Vertex-by-vertex whole brain estimates of cortical thickness were automatically calculated using FreeSurfer v5.3. Differences in cortical thickness in patients with PPTH relative to healthy controls were determined using a general linear model design. Associations were explored between regional clusters where patients with PPTH showed cortical thickness differences compared with healthy controls with headache frequency and years lived with PPTH.

RESULTS

This study included 33 patients with PPTH and 33 healthy control subjects (healthy controls: median age = 33.0, IQR = 15.5; patients with PPTH: median age = 36.0, IQR = 20.5; P = .56). Patients with PPTH had less cortical thickness relative to healthy controls in the left and right superior frontal, caudal middle frontal, and precentral cortex as well as less cortical thickness in the right supramarginal, right superior and inferior parietal, and right precuneus region (P < .05, Monte Carlo corrected for multiple comparisons). There were no regions where patients with PPTH had more cortical thickness relative to healthy controls. A correlation analysis of regions that showed less cortical thickness in patients with PPTH demonstrated a negative correlation between left and right superior frontal thickness with headache frequency (P < .05). There was no association between regional cortical thickness and years lived with PPTH.

CONCLUSION

Compared with healthy controls, patients with PPTH had less cortical thickness in bilateral frontal regions and right hemisphere parietal regions. For patients with PPTH, more frequent headaches were related to less thickness in the left and right superior frontal regions, potentially indicating that brain morphology changes in the superior frontal regions in patients with PPTH are modified by headache frequency.

Functional and Structural Network Recovery after Mild Traumatic Brain Injury: A 1-Year Longitudinal Study

Brain connectivity after mild traumatic brain injury (mTBI) has not been investigated longitudinally with respect to both functional and structural networks together within the same patients, crucial to capture the multifaceted neuropathology of the injury and to comprehensively monitor the course of recovery and compensatory reorganizations at macro-level. We performed a prospective study with 49 mTBI patients at an average of 5 days and 1 year post-injury and 49 healthy controls. Neuropsychological assessments as well as resting-state functional and diffusion-weighted magnetic resonance imaging were obtained. Functional and structural connectome analyses were performed using network-based statistics. They included a cross-sectional group comparison and a longitudinal analysis with the factors group and time. The latter tracked the subnetworks altered at the early phase and, in addition, included a whole-brain group × time interaction analysis. Finally, we explored associations between the evolution of connectivity and changes in cognitive performance. The early phase of mTBI was characterized by a functional hypoconnectivity in a subnetwork with a large overlap of regions involved within the classical default mode network. In addition, structural hyperconnectivity in a subnetwork including central hub areas such as the cingulate cortex was found. The impaired functional and structural subnetworks were strongly correlated and revealed a large anatomical overlap. One year after trauma and compared to healthy controls we observed a partial normalization of both subnetworks along with a considerable compensation of functional and structural connectivity subsequent to the acute phase. Connectivity changes over time were correlated with improvements in working memory, divided attention, and verbal recall. Neuroplasticity-induced recovery or compensatory processes following mTBI differ between brain regions with respect to their time course and are not fully completed 1 year after trauma.

Sleep Quantity and Quality during Acute Concussion: A Pilot Study

STUDY OBJECTIVES

A number of subjective and objective studies provide compelling evidence of chronic post-concussion changes in sleep, yet very little is known about the acute effects of concussion on sleep quality and quantity. Therefore, the purpose of this prospective pilot study was to use actigraphy to examine the changes in sleep quality and quantity acutely following concussion at home rather than in a hospital or sleep laboratory.

METHODS

Seventeen young adults (7 with acute concussion, 10 controls) were recruited for this study. All participants completed two 5-day testing sessions separated by 30 days from intake (controls) or day of injury (concussion). Participants wore actigraphs and kept a sleep journal. Sleep parameter outcomes included nighttime total sleep time (nTST), 24-h total sleep time (TST), wake after sleep onset (WASO), and sleep efficiency (SE). The coefficient of variation (CV) for each sleep parameter was computed for each session.

RESULTS

nTST and TST CV was significantly greater in the concussion group. There is the additional indication that individuals with a concussion may require and obtain more sleep shortly after injury and subsequently have a shorter duration of sleep at 1 mo post-injury. This pattern was not seen in the measures of sleep quality (WASO, SE).

CONCLUSIONS

Individuals with a concussion demonstrated increased nighttime sleep duration variability. This increase persisted at 1 mo post-injury and may be associated with previously documented self-reports of poor sleep quality lasting months and years after a concussion. Additionally, this increase may predispose individuals to numerous negative health outcomes if left untreated.

Statements of Agreement From the Targeted Evaluation and Active Management (TEAM) Approaches to Treating Concussion Meeting Held in Pittsburgh, October 15-16, 2015

BACKGROUND

Conventional management for concussion involves prescribed rest and progressive return to activity. Recent evidence challenges this notion and suggests that active approaches may be effective for some patients. Previous concussion consensus statements provide limited guidance regarding active treatment.

OBJECTIVE

To describe the current landscape of treatment for concussion and to provide summary agreements related to treatment to assist clinicians in the treatment of concussion.

METHODS

On October 14 to 16, 2015, the Targeted Evaluation and Active Management (TEAM) Approaches to Treating Concussion meeting was convened in Pittsburgh, Pennsylvania. Thirty-seven concussion experts from neuropsychology, neurology, neurosurgery, sports medicine, physical medicine and rehabilitation, physical therapy, athletic training, and research and 12 individuals representing sport, military, and public health organizations attended the meeting. The 37 experts indicated their agreement on a series of statements using an audience response system clicker device.

RESULTS

A total of 16 statements of agreement were supported covering (1) Summary of the Current Approach to Treating Concussion, (2) Heterogeneity and Evolving Clinical Profiles of Concussion, (3) TEAM Approach to Concussion Treatment: Specific Strategies, and (4) Future Directions: A Call to Research. Support (ie, response of agree or somewhat agree) for the statements ranged from to 97% to 100%.

CONCLUSION

Concussions are characterized by diverse symptoms and impairments and evolving clinical profiles; recovery varies on the basis of modifying factors, injury severity, and treatments. Active and targeted treatments may enhance recovery after concussion. Research is needed on concussion clinical profiles, biomarkers, and the effectiveness and timing of treatments.

ABBREVIATIONS

ARS, audience response systemCDC, Centers for Disease Control and PreventionDoD, Department of DefensemTBI, mild traumatic brain injuryNCAA, National Collegiate Athletic AssociationNFL, National Football LeagueNIH, National Institutes of HealthRCT, randomized controlled trialRTP, return to playSRC, sport- and recreation-related concussionTBI, traumatic brain injuryTEAM, Targeted Evaluation and Active Management.

Lifetime Multiple Mild Traumatic Brain Injuries Are Associated with Cognitive and Mood Symptoms in Young Healthy College Students

Background/objectives

Repetitive mild traumatic brain injury (mTBI, also known as concussion) has been associated with a range of long-term mood and cognitive deficits, including executive dysfunction. Previous research in athletes suggests that cognitive and mood problems are associated with a history of repetitive mTBI. However, to date, no studies have examined the impact of a lifetime accumulation of repetitive mTBIs on cognition, particularly executive functioning, and mood in a sample of young adults who were not athletes. Therefore, the present study looked at potential effects of repetitive mTBIs on self-reported cognitive complaints, executive functioning, and mood in young adults.

Methods

Eighty-four total students responded, and 26 of those were excluded from analyses due to reporting only 1 mTBI. The final sample consisted of 58 healthy young adults (mean age = 22.84, STD = 4.88) who completed the Cognitive Complaint Index (CCI), the Behavior Rating Inventory of Executive Function, adult version (BRIEF-A), and the Beck Depression Inventory, second edition (BDI-II). Twenty-nine participants denied having an mTBI history, and 29 reported 2 or more lifetime mTBIs (range 2–7).

Results

Young otherwise healthy adults with a lifetime history of repetitive mTBI compared to those that reported no history of mTBI reported more change in cognitive functioning over the past 5 years, worse executive functioning, and more symptoms of depression. As the number of lifetime mTBIs increased, scores on the CCI, BRIEF-A, and BDI-II also increased, indicating worse functioning.

Conclusion

These findings suggest that a lifetime accumulation of two or more mTBIs as compared to a history of no reported mTBIs may result in worse cognitive functioning and symptoms of depression in young adults.

Diffusion Tensor Imaging Findings in Post-Concussion Syndrome Patients after Mild Traumatic Brain Injury: A Systematic Review

Objectives

To review the evidence for the use of diffusion tensor imaging (DTI) parameters in the human brain as a diagnostic tool for and predictor of post-concussion syndrome (PCS) after a mild traumatic brain injury (mTBI).

Design

Systematic review.

Data sources

All relevant studies in AMED, Embase, MEDLINE, Ovid, PubMed, Scopus, and Web of Science through 20 May, 2016.

Study selection

Studies that analyze traditional DTI measures [fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD)] and the severity of PCS symptoms or the development of PCS in humans after an mTBI.

Data extraction

Population studied, patient source, mTBI diagnosis method, PCS diagnosis method, DTI values measured, significant findings, and correlation between DTI findings and PCS.

Data synthesis

Ten studies investigated correlations between DTI values and PCS symptom severity or between DTI values and the development of PCS in mTBI patients. Decreased FA and increased MD and RD were associated with the development and severity of PCS. AD was not found to change significantly. Brain regions found to have significant changes in DTI parameters varied from study to study, although the corpus callosum was most frequently cited as having abnormal DTI parameters in PCS patients.

Conclusion

DTI abnormalities correlate with PCS incidence and symptom severity, as well as indicate an increased risk of developing PCS after mTBI. Abnormal DTI findings should prompt investigation of the syndrome to ensure optimal symptom management at the earliest stages. Currently, there is no consensus in the literature about the use of one DTI parameter in a specific region of the brain as a biomarker for PCS because no definite trends for DTI parameters in PCS subjects have been identified. Further research is required to establish a standard biomarker for PCS.

Long-Term Anesthetic-Dependent Hypoactivity after Repetitive Mild Traumatic Brain Injuries in Adolescent Mice

Recent evidence supports the hypothesis that repetitive mild traumatic brain injuries (rmTBIs) culminate in neurological impairments and chronic neurodegeneration, which have wide-ranging implications for patient management and return-to-play decisions for athletes. Adolescents show a high prevalence of sports-related head injuries and may be particularly vulnerable to rmTBIs due to ongoing brain maturation. However, it remains unclear whether rmTBIs, below the threshold for acute neuronal injury or symptomology, influence long-term outcomes. To address this issue, we first defined a very mild injury in adolescent mice (postnatal day 35) as evidenced by an increase in Iba-1- labeled microglia in white matter in the acutely injured brain, in the absence of indices of cell death, axonal injury, and vasogenic edema. Using this level of injury severity and Avertin (2,2,2-tribromoethanol) as the anesthetic, we compared mice subjected to either a single mTBI or 2 rmTBIs, each separated by 48 h. Neurobehavioral assessments were conducted at 1 week and at 1 and 3 months postimpact. Mice subjected to rmTBIs showed transient anxiety and persistent and pronounced hypoactivity compared to sham control mice, alongside normal sensorimotor, cognitive, social, and emotional function. As isoflurane is more commonly used than Avertin in animal models of TBI, we next examined long-term outcomes after rmTBIs in mice that were anesthetized with this agent. However, there was no evidence of abnormal behaviors even with the addition of a third rmTBI. To determine whether isoflurane may be neuroprotective, we compared the acute pathology after a single mTBI in mice anesthetized with either Avertin or isoflurane. Pathological findings were more pronounced in the group exposed to Avertin compared to the isoflurane group. These collective findings reveal distinct behavioral phenotypes (transient anxiety and prolonged hypoactivity) that emerge in response to rmTBIs. Our findings further suggest that selected anesthetics may confer early neuroprotection after rmTBIs, and as such mask long-term abnormal phenotypes that may otherwise emerge as a consequence of acute pathogenesis.

The Rise of Concussions in the Adolescent Population

Background:

Concussion injuries have been highlighted to the American public through media and research. While recent studies have shown increased traumatic brain injuries (TBIs) diagnosed in emergency departments across the United States, no studies have evaluated trends in concussion diagnoses across the general US population in various age groups.

Purpose:

To evaluate the current incidence and trends in concussions diagnosed across varying age groups and health care settings in a large cross-sectional population.

Study Design:

Descriptive epidemiological study.

Methods:

Administrative health records of 8,828,248 members of a large private-payer insurance group in the United States were queried. Patients diagnosed with concussion from years 2007 through 2014 were stratified by year of diagnosis, age group, sex, classification of concussion, and health care setting of diagnosis (eg, emergency department vs physician’s office). Chi-square testing was used for statistical analysis.

Results:

From a cohort of 8,828,248 patients, 43,884 patients were diagnosed with a concussion. Of these patients, 55% were male and over 32% were in the adolescent age group (10-19 years old). The highest incidence of concussion was seen in patients aged 15 to 19 years (16.5/1000 patients), followed by those aged 10 to 14 years (10.5/1000 patients), 20 to 24 years (5.2/1000 patients), and 5 to 9 years (3.5/1000 patients). Overall, there was a 60% increase in concussion incidence from 2007 to 2014. The largest increases were in the 10- to 14-year (143%) and 15- to 19-year (87%) age groups. Based on International Classification of Disease–9th Revision classification, 29% of concussions were associated with some form of loss of consciousness. Finally, 56% of concussions were diagnosed in the emergency department and 29% in a physician’s office, with the remainder in urgent care clinics or inpatient settings.

Conclusion:

The incidence of concussion diagnosed in the general US population is increasing, driven largely by a substantial rise in the adolescent age group. The youth population should be prioritized for ongoing work in concussion education, diagnosis, treatment, and prevention.

Clinical Relevance:

The rise of concussions in the adolescent age group across the general population is concerning, and clinical efforts to prevent these injuries are needed.

A voxel-based meta-analysis of diffusion tensor imaging in mild traumatic brain injury

Microstructural damage to white matter and resultant abnormal structural connectivity are a potential underlying pathophysiological mechanism of mild traumatic brain injury (mTBI). Many Tract-Based Spatial Statics studies have investigated the pathophysiology of mTBI, but they yielded inconsistent results potentially due to insufficient statistical power in spite of methodological homogeneity. We used anisotropic effect size signed differential mapping (AES-SDM) to integrate previous studies that recruited patients without a psychiatric history. AES-SDM revealed that fractional anisotropy values were significantly lower in mTBI patients than in control in three clusters. The peak of the largest cluster was in the left thalamus and the cluster extended to the splenium of the corpus callosum and to the anterior thalamic radiation. The second largest cluster was situated in the left forceps minor, and the third largest cluster was in the right superior longitudinal fasciculus III. These results suggest that the pathophysiology of mTBI includes abnormal structural connectivity between the thalamus and the prefrontal cortex, and abnormal intra- and inter-hemispheric structural connectivity involving the prefrontal cortex.

Sleep, Sleep Disorders, and Mild Traumatic Brain Injury. What We Know and What We Need to Know: Findings from a National Working Group

Disturbed sleep is one of the most common complaints following traumatic brain injury (TBI) and worsens morbidity and long-term sequelae. Further, sleep and TBI share neurophysiologic underpinnings with direct relevance to recovery from TBI. As such, disturbed sleep and clinical sleep disorders represent modifiable treatment targets to improve outcomes in TBI. This paper presents key findings from a national working group on sleep and TBI, with a specific focus on the testing and development of sleep-related therapeutic interventions for mild TBI (mTBI). First, mTBI and sleep physiology are briefly reviewed. Next, essential empirical and clinical questions and knowledge gaps are addressed. Finally, actionable recommendations are offered to guide active and efficient collaboration between academic, industry, and governmental stakeholders.