Neuroimaging and Neuropsychological Studies in Sports-Related Concussions in Adolescents: Current State and Future Directions

Cumulative effects of subsequent concussions on the neural patterns of young rugby athletes: data from event-related potentials

Our study aimed at detecting a potential cumulative effect of subsequent concussions on the neural activation patterns of young rugby athletes with or without concussion history. Event-related brain potential (ERP) data from 24 rugby players, 22-year-old on average, were retrospectively examined. All underwent a Sport Concussion Assessment Tool (SCAT2) during preseason and an on-site ERP task (P300) following a recent concussion event (<48 hours). Sixteen players suffered at least one concussion in the previous 3 years and eight were without self-reported past concussion. While no differences were reported between groups regarding symptom appraisal on the SCAT2 assessment, ERP revealed significantly decreased P3b amplitude and a trend for increased P3b latency in players who experienced prior concussions. Our data thus support the cumulative effect of concussions on neuroelectric events in young rugby players, highlighting the importance of managing player's concussion load to reduce the risk of long-term injuries.

The effects of sports-related concussion history on female adolescent brain activity and connectivity for bilateral lower extremity knee motor control

Sports-related concussions (SRCs) are associated with neuromuscular control deficits in athletes following return to play. However, the connection between SRC and potentially disrupted neural regulation of lower extremity motor control has not been investigated. The purpose of this study was to investigate brain activity and connectivity during a functional magnetic resonance imaging (fMRI) lower extremity motor control task (bilateral leg press) in female adolescent athletes with a history of SRC. Nineteen female adolescent athletes with a history of SRC and nineteen uninjured (without a history of SRC) age- and sport-matched control athletes participated in this study. Athletes with a history of SRC exhibited less neural activity in the left inferior parietal lobule/supramarginal gyrus (IPL) during the bilateral leg press compared to matched controls. Based upon signal change detected in the brain activity analysis, a 6 mm region of interest (seed) was defined to perform secondary connectivity analyses using psychophysiological interaction (PPI) analyses. During the motor control task, the left IPL (seed) was significantly connected to the right posterior cingulate gyrus/precuneus cortex and right IPL for athletes with a history of SRC. The left IPL was significantly connected to the left primary motor cortex (M1) and primary somatosensory cortex (S1), right inferior temporal gyrus, and right S1 for matched controls. Altered neural activity in brain regions important for sensorimotor integration and motor attention, combined with unique connectivity to regions responsible for attentional, cognitive, and proprioceptive processing, indicate compensatory neural mechanisms may underlie the lingering neuromuscular control deficits associated with SRC.

Neurophysiological Markers to Guide Return to Sport After Sport-Related Concussion

SUMMARY

Sport-related concussion (SRC) has been defined as a subset of mild traumatic brain injury (mTBI), without structural abnormalities, reflecting a functional disturbance. Over the past decade, SRC has gained increasing awareness and attention, which coincides with an increase in incidence rates. Because this injury has been considered one of the most challenging encounters for clinicians, there is a need for objective biomarkers to aid in diagnosis (i.e., presence/severity) and management (i.e., return to sport) of SRC/mTBI.The primary aim of this article was to present state-of-the-art neurophysiologic methods (e.g., electroencephalography, magnetoencephalography, transcranial magnetic stimulation, and autonomic nervous system) that are appropriate to investigate the complex pathophysiological process of a concussion. A secondary aim was to explore the potential for evidence-based markers to be used in clinical practice for SRC management. The article concludes with a discussion of future directions for SRC research with specific focus on clinical neurophysiology.

Public Awareness of the Fencing Response as an Indicator of Traumatic Brain Injury: Quantitative Study of Twitter and Wikipedia Data

BACKGROUND

Traumatic brain injury (TBI) is a disruption in normal brain function caused by an impact of external forces on the head. TBI affects millions of individuals per year, many potentially experiencing chronic symptoms and long-term disability, creating a public health crisis and an economic burden on society. The public discourse around sport-related TBIs has increased in recent decades; however, recognition of a possible TBI remains a challenge. The fencing response is an immediate posturing of the limbs, which can occur in individuals who sustain a TBI and can be used as an overt indicator of TBI. Typically, an individual demonstrating the fencing response exhibits extension in 1 arm and flexion in the contralateral arm immediately upon impact to the head; variations of forearm posturing among each limb have been observed. The tonic posturing is retained for several seconds, sufficient for observation and recognition of a TBI. Since the publication of the original peer-reviewed article on the fencing response, there have been efforts to raise awareness of the fencing response as a visible sign of TBI through publicly available web-based platforms, such as Twitter and Wikipedia.

OBJECTIVE

We aimed to quantify trends that demonstrate levels of public discussion and awareness of the fencing response over time using data from Twitter and Wikipedia.

METHODS

Raw Twitter data from January 1, 2010, to December 31, 2019, were accessed using the RStudio package academictwitteR and queried for the text "fencing response." Data for page views of the Fencing Response Wikipedia article from January 1, 2010, to December 31, 2019, were accessed using the RStudio packages wikipediatrend and pageviews. Data were clustered by weekday, month, half-year (to represent the American football season vs off-season), and year to identify trends over time. Seasonal regression analysis was used to analyze the relationship between the number of fencing response tweets and page views and month of the year.

RESULTS

Twitter mentions of the fencing response and Wikipedia page views increased overall from 2010 to 2019, with hundreds of tweets and hundreds of thousands of Wikipedia page views per year. Twitter mentions peaked during the American football season, especially on and following game days. Wikipedia page views did not demonstrate a clear weekday or seasonal pattern, but instead had multiple peaks across various months and years, with January having more page views than May.

CONCLUSIONS

Here, we demonstrated increased awareness of the fencing response over time using public data from Twitter and Wikipedia. Effective scientific communication through free public platforms can help spread awareness of clinical indicators of TBI, such as the fencing response. Greater awareness of the fencing response as a "red-flag" sign of TBI among coaches, athletic trainers, and sports organizations can help with medical care and return-to-play decisions.

Neuroimaging Markers for Determining Former American Football Players at Risk for Alzheimer's Disease

NFL players, by virtue of their exposure to traumatic brain injury (TBI), are at higher risk of developing dementia and Alzheimer's disease (AD) than the general population. Early recognition and intervention before the onset of clinical symptoms could potentially avert/delay the long-term consequences of these diseases. Given that AD is thought to have a long pre-clinical incubation period, the aim of the current research was to determine whether former NFL players show evidence of incipient dementia in their structural imaging before diagnosis of AD. To identify neuroimaging markers of AD, against which former NFL players would be compared, we conducted a whole-brain volumetric analysis using a cohort of AD patients (ADNI clinical database) to produce a set of brain regions demonstrating sensitivity to early AD pathology (i.e., the “AD fingerprint”). A group of 46 former NFL players' brain magnetic resonance images were then interrogated using the AD fingerprint, that is, the former NFL subjects were compared volumetrically to AD patients using a T1-weighted magnetization-prepared rapid gradient echo sequence. The FreeSurfer image analysis suite (version 6.0) was used to obtain volumetric and cortical thickness data. The Automated Neuropsychological Assessment Metric-Version 4 was used to assess current cognitive functioning. A total of 55 brain regions demonstrated significant atrophy or ex vacuo dilatation bilaterally in AD patients versus controls. Of the 46 former NFL players, 41% demonstrated a greater than expected number of atrophied/dilated AD regions compared with age-matched controls, presumably reflecting AD pathology.

Greater symptom burden results in reduced exercise tolerance in adolescents following concussion

OBJECTIVES

To explore the relationship between symptoms and exercise tolerance in adolescents following concussion.

METHODS

A retrospective analysis of 417 adolescents who attended a concussion service between January 2015 and April 2021 was performed, with 149 meeting eligibility criteria for inclusion. Post-Concussion Symptom Scale (PCSS) and graded exercise tolerance time (min) were assessed at initial and follow-up visits. Spearman's correlation was used to examine the relationship between PCSS scores and exercise time.

RESULTS

Adolescents (n = 149, 13.9 ± 1.7 years, 66.4% male) presented at 28.6 ± 19.7 days post-injury. Statistically significant correlations were identified between initial (r = -0.36, p < .001) and follow-up (r = -0.41, p < .001) PCSS scores and exercise time among all participants. Initial PCSS and initial exercise time were inversely correlated for males (r = -0.24, p = .018) and females (r = -0.22, p = .127). Follow-up PCSS and follow-up exercise time were inversely correlated for males (r = -0.30, p = .003) and females (r = -0.35, p = .014).

CONCLUSION

There is a statistically significant relationship between higher PCSS and poorer exercise time and both factors should be considered together to provide the most accurate assessment, particularly in females.

Altered white matter diffusivity and subtle motor function in a pilot cohort of adolescents with sports-related concussion

Background and objective:

Adolescents with sports-related concussion (SRC) demonstrate acute and persistent deficits in subtle motor function. However, there is limited research examining related neurological underpinnings. This pilot study examined changes in motor-associated white matter pathways using diffusion tensor imaging (DTI) and their relationship with subtle motor function.

Methods:

Twelve adolescents with SRC (12–17 years) within two-weeks post-injury and 13 never-injured neurotypical peers completed DTI scanning. A subset of 6 adolescents with SRC returned for a follow-up visit post-medical clearance from concussion. Subtle motor function was evaluated using the Physical and Neurological Examination of Subtle Signs (PANESS).

Results:

Adolescents with SRC showed higher mean diffusivity (MD) of the superior corona radiata and greater subtle motor deficits compared to controls. Across all participants, greater subtle motor deficits were associated with higher (more atypical) MD of the superior corona radiata. Preliminary longitudinal analysis indicated reduction in fractional anisotropy of the corpus callosum but no change in the MD of the superior corona radiata from the initial visit to the follow-up visit post-medical clearance.

Conclusions:

These findings support preliminary evidence for a brain–behavior relationship between superior corona radiata microstructure and subtle motor deficits in adolescents with SRC that merits further investigation.

Perceptual-Motor Efficiency and Concussion History Are Prospectively Associated With Injury Occurrences Among High School and Collegiate American Football Players

Background:

After a sport-related concussion (SRC), the risk for lower extremity injury is approximately 2 times greater, and the risk for another SRC may be as much as 3 to 5 times greater.

Purpose:

To assess the predictive validity of screening methods for identification of individual athletes who possess an elevated risk of SRC.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

Metrics derived from a smartphone flanker test software application and self-ratings of both musculoskeletal function and overall wellness were acquired from American high school and college football players before study participation. Occurrences of core or lower extremity injury (CLEI) and SRC were documented for all practice sessions and games for 1 season. Receiver operating characteristic and logistic regression analyses were used to identify variables that provided the greatest predictive accuracy for CLEI or SRC occurrence.

Results:

Overall, there were 87 high school and 74 American college football players included in this study. At least 1 CLEI was sustained by 45% (39/87) of high school players and 55% (41/74) of college players. Predictors of CLEI included the flanker test conflict effect ≥69 milliseconds (odds ratio [OR], 2.12; 90% CI, 1.24-3.62) and a self-reported lifetime history of SRC (OR, 1.70; 90% CI, 0.90-3.23). Of players with neither risk factor, only 38% (29/77) sustained CLEI compared with 61% (51/84) of players with 1 or both of the risk factors (OR, 2.56; 90% CI, 1.50-4.36). SRC was sustained by 7 high school players and 3 college players. Predictors of SRC included the Overall Wellness Index score ≤78 (OR, 9.83; 90% CI, 3.17-30.50), number of postconcussion symptoms ≥4 (OR, 8.35; 90% CI, 2.71-25.72), the Sport Fitness Index score ≤78 (OR, 5.16; 90% CI, 1.70-15.65), history of SRC (OR, 4.03; 90% CI, 1.35-12.03), and the flanker test inverse efficiency ratio ≥1.7 (OR, 3.19; 90% CI, 1.08-9.47).

Conclusion:

Survey responses and smartphone flanker test metrics predicted greater injury incidence among individual football players classified as high-risk compared with that for players with a low-risk profile.

Diffusion Tensor Imaging in Sport-Related Concussion: A Systematic Review Using an a priori Quality Rating System

Diffusion tensor imaging (DTI) of brain white matter (WM) may be useful for characterizing the nature and degree of brain injury after sport-related concussion (SRC) and assist in establishing objective diagnostic and prognostic biomarkers. This study aimed to conduct a systematic review using an a priori quality rating strategy to determine the most consistent DTI-WM changes post-SRC. Articles published in English (until June 2020) were retrieved by standard research engine and gray literature searches (N = 4932), using PRISMA guidelines. Eligible studies were non-interventional naturalistic original studies that conducted DTI within 6 months of SRC in current athletes from all levels of play, types of sports, and sex. A total of 29 articles were included in the review, and after quality appraisal by two raters, data from 10 studies were extracted after being identified as high quality. High-quality studies showed widespread moderate-to-large WM differences when SRC samples were compared to controls during the acute to early chronic stage (days to weeks) post-SRC, including both increased and decreased fractional anisotropy and axial diffusivity and decreased mean diffusivity and radial diffusivity. WM differences remained stable in the chronic stage (2-6 months post-SRC). DTI metrics were commonly associated with SRC symptom severity, although standardized SRC diagnostics would improve future research. This indicates that microstructural recovery is often incomplete at return to play and may lag behind clinically assessed recovery measures. Future work should explore interindividual trajectories to improve understanding of the heterogeneous and dynamic WM patterns post-SRC.

Second Impact Syndrome. Myth or reality?

INTRODUCTION

Second impact syndrome (SIS) is a devastating condition occurring in sport-induced mild brain injury. SIS is drastically defined by anamnestic, clinical and radiological criteria, which is unusual in the field of cranial traumatology. The purpose of this study was to provide a literature review of this syndrome.

MATERIAL AND METHODS

We conducted a literature review of all published studies on PubMed. The keywords were "second impact syndrome and catastrophic head injury", "second impact syndrome and sport", "repeat concussion and catastrophic brain injury", "catastrophic head injury and concussion", "catastrophic head injury", "concussion and second impact syndrome", "concussion and repetitive head injury".

RESULTS

Eighty-two full-text articles were assessed for eligibility. Finally, 41 studies were included in qualitative synthesis and 21 were included in quantitative synthesis.

DISCUSSION

The number of cases reported in the literature was extremely small compared to the population at risk, i.e., the number of athletes exposed to repeated concussions. SIS was similar to talk and die syndrome, with which it shares certain characteristics. If we consider SIS according to "talk and deteriorate tables", it opens up interesting perspectives because they are specific in children and adolescents. Taking into account the scarcity of this syndrome, one may question whether athlete-intrinsic features may be involved in at least some cases of SIS. On a pathophysiological level, many explanations remained unsatisfactory because they were unable to explain all the clinical phenomena and observed lesions. Triggering the trigeminocardiac reflex is a crucial element in explaining the sequence of clinical events. Its association with a state of neurogenic inflammation provides an almost complete explanation for this particular condition. Finally, on a practical level, a concussion occurring during the playing of a sport must be considered as any other injury before allowing a return to play.