Dissertations / Theses on the topic 'Mild traumatic brain injuries (mTBI)'

A quiet stance framework and a control system perspective were used to explore healthy balance and balance after mild traumatic brain injury. Linear and non-linear centre of pressure analyses were applied. The foundation was laid by reviewing literature to understand how balance is achieved, how it is represented as a control system, what factors are known to affect balance, and the cornerstone—how to choose appropriate measures to quantify balance. To understand how mild traumatic brain injury affects the brain, a scoping review of the evolution of symptoms and effects was used to form a conceptual description. Findings described phases of functional effects that resulted from neurometabolic cascade; consequently, balance and dual-task functional effects were determined to stem from widespread not focal changes in the brain. Subsequent studies were tailored to address gaps in knowledge. Linear and non-linear centre of pressure measures were first investigated in healthy young adults to determine what supplemental information could be provided by non-linear measures describing local stability and scaling. It was found that linear and non-linear measures were complementary in assessing balance system input-output, control, and integration. Furthermore, normative non-linear data were established for single leg and tandem stance. Subsequently, these measures were investigated in young adults and adolescents with recent mild traumatic brain injury based on the hypothesis that altered mechanisms affecting balance would be reflected by changes in these measures. In young adults, increased complexity of short-term scaling indicated subtle changes to balance control after injury. In adolescents, linear and non-linear measures also demonstrated changes to output, control, and temporal relations of balance. Altered balance was also demonstrated while concurrently performing a Stroop task. On the whole, changes to multiple aspects of balance supported the concept of widespread effects resulting from mild traumatic brain injury. Balance control in quiet stance was further explored using three-dimensional state space reconstruction of centre of pressure. Visual representations demonstrated that dynamic structure within centre of pressure reflected control characteristics. These control characteristics were still present after mild traumatic brain injury.

Background and aims: The provenance of post-concussion symptoms (PCS) and post-traumatic stress (PTSD) after mild traumatic brain injury (mTBI) is controversial. This thesis investigated factors influencing these two conditions separately, as well as the interplay between PCS and PTSD, in individuals with mTBI and a control sample without mTBI (orthopaedic injuries). Method: Consecutive adult attendees of an Emergency Department with mTBI or orthopaedic injury were prospectively recruited and completed the Rivermead Post-concussion Questionnaire (RPQ) and Trauma Screening Questionnaire (TSQ) for PTSD at two weeks (T1) and three months (T2) post-injury. The sample at T1 consisted of 34 with complicated mTBI, 76 with uncomplicated mTBI and 47 with orthopaedic injury, and 18 with complicated mTBI, 43 with uncomplicated mTBI and 33 orthopaedic controls at T2. Results: Although there were no differences in overall PCS symptomology between groups, a subset of PCS symptoms (headaches, dizziness and nausea) was found to be specific to mTBI at both time points. These symptoms are proposed to have a neurological basis, as opposed to a psychological basis. PTSD interacted with PCS, particularly in mTBI, such that PTSD was associated with greater “neurogenic” and “psychogenic” symptomology in this group, but only a moderate increase in psychogenic symptoms for controls. A model of the influence of PTSD on PCS is presented. PTSD was influenced by poor memory quality for the traumatic event and attribution of blame to others, but not by mTBI. Discussion and conclusions: Though mTBI may set the scene for at least neurogenic symptoms of PCS to occur, psychological mechanisms, particularly PTSD, have a significant role in the persistence of PCS. Our findings suggest the need for a clear story and sense of meaning for a traumatic event for good recovery from PTSD. Taken together, the results suggest that psychological interventions, particularly aimed at PTSD, may be most effective after mTBI.

A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine.
Sports-related mild traumatic brain injuries (mTBIs) have become an increasingly popular topic. Cognitive and physical rest are the mainstays of management, but effective evidence-based therapies do not exist. Very few studies report mean recovery times from mTBI and even less for intercollegiate athletes. The primary aim is to retrospectively compare the recovery time in athletes from a large Division I University that suffered a sports-related mTBI during 2010 - 2012 to published data for quality assessment and improvement. Since the institution's concussion management follows current guidelines, no significant difference was expected. Secondary aims included comparing recovery times between gender, sport, and league. As reported in current literature, no significant gender differences were expected. 53 athletes with sports-related mTBI (27 male and 26 female) showed a mean recovery time of 10.11 days (95 % confidence interval [CI] = 8.58 - 11.65 days), statistically different than the time reported in 1 study of 7 days, but not in another of 7 - 10 days. Mean recovery time in males and females was 9.74 days (95 % CI = 7.38 - 12.1 days) and 10.5 days (95 % CI = 8.4 - 12.6 days), respectively. Mean recovery time in National Collegiate Athletic Association (NCAA) and non-NCAA (club) athletes was 9.91 days (95 % CI = 8.27 - 11.55) and 11.25 days (95 % CI = 5.87 - 16.63), respectively. A nonparametric Wilcoxon rank-sum test showed no significant variation between genders and between NCAA and non-NCAA athletes. Subgroup statistics of 13 sports were inconclusive due to inadequate power. However, the subgroup of male football athletes showed a mean recovery time of 6.5 days (95 % CI = 4.86 - 8.14 days), which was not significantly different than published rates. Multiple confounding variables were not well controlled for including: sport, gender, concussion severity, multiple concussions, etc. However, this study did highlight areas for quality improvement in the institution's concussion management plan. Further investigation with increased power and confounding variable control is indicated for a more definitive mean time to recovery. This study is the first to detail the mean time to recovery from sports-related mTBI in an intercollegiate athletic program. Similar studies should be done at other institutions for quality assessment and improvement of 4 concussion management. Such data will be useful in establishing a baseline for measure of efficacy in future investigations of therapeutic interventions.

The purpose of this session is to examine the vestibular consequences of mild traumatic brain injury (TBI) and blast exposure. Preliminary data will be presented showing characteristics of vestibular dysfunction and postural instability related to mild TBI and blast exposure. Also reviewed will be the latest findings including recent data collected at the War Related Illness & injury Center showing vestibular impairments in those with mTBI. The target audience is audiologists, physical therapists, neurologists, otolaryngologists. This session will cover intermediate level of content.

Excerpt: With all that is currently known about symptoms that indicate mild traumatic brain injury (MTBI), it is unfortunate that many individuals go undiagnosed for long periods of time after sustaining such an injury.

Background Estimates of 1.6 million to 3.8 million concussions or mild traumatic brain injuries (mTBI) occur annually in adolescent athletes participating in contact sports (Daneshvar et al., 2011). Current clinical guidelines call for interventions to include education, assessment, screening, and long term management of injury by the adolescent's primary care provider (PCP) (Giza et al., 2013). Without proper knowledge of the injury's physiological process and progression, providers are possibly increasing the risk of continued brain injury in this population (Reddy & Collins, 2009). Purpose This doctorate of nursing practice project aimed to determine if a gap existed between provider knowledge about the current guidelines for management of mTBI in adolescent athletes of Arizona. Knowledge obtained from this survey could be further used to drive practice change. Methods A quantitative needs assessments study was conducted via data collection obtained through PCP's participation in an anonymous electronic survey using the survey software Qualtrics. Survey links were sent to potential participant's email addresses throughout Yuma County, AZ. An additional survey link was posted to the Arizona Nurses Association e-newsletter. The survey consists of 28 questions divided into three categories of demographics, knowledge, and practice questions. Outcomes Survey results were limited due to only 21 providers responding to the request for participation. From this sampling, it was determined that participant's clinical knowledge and practice related to screening, assessment, long term management, and continuity of care between the ED provider and follow up care with the primary provider were not congruent with current practice guidelines.

Introduction-Physical activity can reduce the risk of contracting many of the 'diseases of the sedentary', such as coronary heart disease and cancer (Blair et al., 1996). Recognition of this protective effect has led to the development of many programmes designed to promote the benefit of participation in sport and physical exercise (Hillary Commission, 1993; Nicholl et aI., 1995). With participation in sport, especially contact sport, the risk for injuries increases, including injuries to the head and neck (Wilberger, 1993; Wekesa et al., 1996; Pettersen, 2002). Mild traumatic brain injuries (MTBI) or concussion as used interchangeably in the literature (Maroon et al., 2000; Wills & Leathem, 2001) are an important public health concern, due to the high incidence and frequently persisting symptomatology (Evans, 1992). Mild traumatic brain injury is defined as a complex patho-physiological process affecting the brain induced by traumatic biomechanical forces (Aubry et al., 2002; McCrory et al., 2004). A sub-concussive injury or very mild traumatic brain injury (vMTBI) may be defined as an apparent brain insult with insufficient force to cause hallmark symptoms of concussion (Jordan, 2000; Webbe & Bath, 2003). The high incidence of sport related head injuries in South Africa is alarming, although the prevalence thereof is unknown and difficult to assess, as the seemingly trivial injuries frequently remain unreported (Roux et al., 1987). This is especially applicable in sport where a milder form of head injury is common. This is cause for concern as cumulative head injuries traditionally regarded as trivial or 'minor' may result in players running the risk of increasingly negative consequences following repetitive 'minor' head injuries. In contact sport such as rugby, players are at great risk of sustaining repetitive mild traumatic brain injuries. The negative outcome following these repetitive minor head injuries has been demonstrated by numerous studies on boxers and other athletes exposed to repeated MTBI and vMTBI (McLatchie et aI., 1987). The incidence of vMTBI has not yet been researched in school rugby and this study is the first to report the incidence of vMTBI in a secondary school rugby team. Obiectives - The objectives of this study were to determine the incidence, the neuropsychological consequences and the effect on the academic performance of repeated mild (MTBI) and very mild traumatic brain injuries (vMTBI) in a secondary school rugby team during one playing season. Methods - A cohort of 35 secondary school male rugby players divided into a vMTBI (group 1) (n=26) and a MTBI (group 2) (n=9) from a local secondary school's first and second team, was followed for a full competitive season by a trained Biokineticist, who was present at all the games and contact sessions played. All vMTBI and MTBI and the severity of these injuries were documented. A control (group 3) that consisted of 10 secondary school non-rugby players were compared with the vMTBI and MTBI groups. The incidence of repeated MTBI and vMTBI in a secondary school rugby team were gathered by questionnaires and observation next to the field by a trained Biokineticist. Pre-season and post-season neuropsychological tests were conducted on the research groups and the control group. The neuropsychological tests that were conducted on the three groups were the Colour Trial Test 1 and 2 (CTT 1 + 2), the Symbol Digit Modalities Test (SDMT), the Wechsler Memory Scale-Revised (WMS-R) and the Standardised Assessment of Concussion (SAC). After each match played throughout the season the research group also completed a SAC test. The academic results of the final examination (year 1) of the year of the specific rugby season were obtained, as well as the academic results of the final examination of the preceding two years (year 2 and 3). The programme STATISTICA (version 7.0, Stat soft, Tulsa, OK) was used to analyse the data. Descriptive statistics, one-way ANOVA's, two-way repeated measures ANOVA's, Post-hoc Tuckey HSD analysis and Pearson's product moment correlation were used for all the statistical analyses. Results - This study of a secondary school rugby team has shown 726 vMTBI's and 18 MTBI's throughout one rugby season. This relates to 1951 vMTBI's per 1000 player hours and 48 MTBI's per 1000 player hours. Reductions in delayed memory (p=O.O1)from preseason to post-season in a group of players with repetitive vMTBI's during a single rugby season were found. This was the first evidence of possible neurocognitive deficits towards delayed memory in very mild traumatic brain injuries at secondary school level. Statistically significant (p<=0.05)results of the SAC test totals between both the vMTBI and MTBI groups were documented in the different games throughout the rugby season and compared with the baseline test. No statistically significant differences (p<=0.05) between the pre-season and post-season's scores of the SAC test totals were documented. A decrease in academic performance in the subject Afrikaans (year 1 compared with year 2) with a p-value of p=O.O17(group 1) and p=O.O16(group 2) respectively was found. Conclusion - The findings of this study indicate a high incidence of vMTBI in a cohort of secondary school rugby players in one season, a statistically significant reduction (p=O.O1 )in delayed memory of the vMTBI rugby players and a statistically significant decrease in academic performance p=O.O17 (group 1) and p=O.O16 (group 2) in the subject Afrikaans from year 1 to year 2 final examinations.
Thesis (Ph.D. (Human Movement Science))--North-West University, Potchefstroom Campus, 2006.

Background: Case reports are presented on four Veterans, aged 29–46 years, who complained of chronic dizziness and/or postural instability following blast exposures. Two of the four individuals were diagnosed with mild traumatic brain injury and three of the four were exposed to multiple blasts. Comprehensive vestibular, balance, gait, audiometry and neuroimaging procedures were used to characterize their injuries.Case report: Vestibular assessment included videonystagmography, rotary chair and cervical and ocular vestibular evoked myogenic potentials. Balance and gait testing included the sensory organization test, preferred gait speed and the dynamic gait index. Audiometric studies included pure tone audiometry and middle-ear measurements. Neuroimaging procedures included high resolution structural magnetic resonance imaging, susceptibility-weighted imaging and diffusion-tensor imaging.Findings: Based on the neuroimaging and vestibular and balance test results, it was found that all individuals had diffuse axonal injuries and all had one or more micro-hemorrhages or vascular anomalies. Three of the four individuals had abnormal vestibular function, all had abnormally slow walking speeds and two had abnormal gait and balance dysfunction.Conclusion: The use of contemporary neuroimaging studies in conjunction with comprehensive vestibular and balance assessment provided a better understanding of the pathophysiology and pathoanatomy of dizziness following blast exposures than standard vestibular and balance testing alone.

[Truncated abstract] Controlled and automatic processing are broad categories, and how best to measure these constructs and their impact on functioning after mild traumatic brain injury (TBI) remains uncertain. The purpose of this thesis was to examine automatic and controlled processing aspects of attention after mild TBI using the Paced Auditory Serial Addition Task (PASAT) and event-related potentials (ERPs). The PASAT is one of the most frequently used tests to evaluate attentional functioning. It has been demonstrated to be a measure sensitive to both acute and longer-term effects of mild TBI, presumably due to demands for rapid processing and executive attentional control. ERPs provide a noninvasive neurophysiological index of sensory processing and cognitive functions and have demonstrated sensitivity to even minor cognitive dysfunction. The parameters provided by this functional technique may be those most likely to distinguish individuals with mild TBI from controls. Initially, it was hypothesized that successful novice PASAT performance requires the engagement of executive attention to establish novel controlled information processing strategies. Ten individuals who had suffered a mild TBI an average of 15.20 months previously were therefore expected to demonstrate processing abnormalities on the PASAT, relative to 10 healthy matched controls. Although the mild TBI group reported significant intensification of subjective symptoms since their injury, compared to controls, the mild TBI group provided a similar amount of correct PASAT responses. ... In the first experiment a visual search task consisting of an automatic detection and a controlled search condition was developed. In the second experiment the search task was performed concurrently with the PASAT task in a dual-task paradigm. In the mild TBI group, prior failure to establish more efficient forms of information processing with practice was found to significantly interfere with simultaneous performance of the PASAT task and the attention demanding condition of the search task. The pattern of impaired performance was considered to reflect a reduction in processing resources rather than a deficit in resource allocation. Dual-task performance in the control group was not associated with a large interference effect. In general, the results of this thesis suggest that individuals with mild TBI are impaired in their ability to progress from the stage of effortful controlled information processing to a stage of more efficient, automatic processing, and thus suffer a subtle attentional deficit. Following mild TBI, performance levels equivalent to controls may only be achieved with an abnormal expenditure of cognitive effort. As a result of the neuropathologic consequences of injury, individuals who have sustained a mild TBI are less able to benefit from practice, experience difficulty coping with simultaneous performance of secondary task, and are susceptible to distressing subjective symptomatology.

This study investigated, within the context of Brain Reserve Capacity (BRC) theory, whether repeated concussions resulted in residual deficits in cognitive and academic functioning of early adolescent rugby players relative to non-contact sports controls.

Objective: The long-term cognitive effects of mild traumatic brain injury (MTBI) and sport-related concussion (SRC) are not always clear. Higher-level longer-term cognitive difficulties can indicate enduring neurological damage, as part of a post-concussion syndrome (PCS). This study aimed to investigate whether cognitive performance and self-reported PCS symptoms of athletes (rugby players) relate to SRC and whether gender moderates these effects. Method: Eighty-six participants completed a questionnaire detailing SRC history (frequency and severity) and rated long-term symptoms using the Sport Concussion Assessment Tool 3 (SCAT3) symptom evaluation scales, before completing the CogState Brief Battery and STOP-IT (stop-signal response inhibition task). Results: No significant relationships between SRC dosage (frequency/severity), self-reported PCS symptoms, and cognitive test performance were identified. A greater proportion of males reported SRC compared to females, but no effect of gender was found on any of the cognitive outcome measures or self-reports of PCS symptoms. Conclusions: The results show that SRC has no observable long-term effects on cognitive test performance or PCS symptom self-reports. The analysis may have lacked power to detect effects. Analysis of individual performance over time against baseline scores may be more relevant for accurate diagnosis than relying on normative test scores. Recommendations for future research were made.

Traumatic brain injury (TBI) effects a large number of individuals, both civilians and military personnel, every year. The neuroinflammatory response mounted in the brain following a head injury continues long after the effects of initial subside. While it was initially thought to only occur in moderate or severe TBI, the deleterious effects of this cascade have recently been identified in patients with mild TBI (mTBI). Hypopituitarism is an often underreported condition and can result from TBI of all severity. The long-term sequelae of TBI can manifest in or exacerbate many other comorbidities of brain injury, such as neuroendocrine dysfunction or mental health conditions. Both TBI and hypopituitarism can present with symptoms similar to some psychiatric disorders, or exacerbation comorbid conditions. Veteran patients presenting to their primary care providers with symptoms of irritability, depression, anxiety, or cognitive and behavioral changes may meet criteria to receive diagnoses of psychiatric illnesses prevalent in the military population, while not being evaluated for pituitary dysfunction, and thus receive inadequate treatment. The proposed study aims to identify the prevalence of patients that are receiving psychiatric treatment that have both a history of mTBI and reduced levels of pituitary hormones on serum assays. By identifying a significant portion of this population, future studies can assess the impact that hormonal replacement has on success of psychotherapy, resolution of symptoms, and impact on functional status, among other factors.

Background: Mild traumatic brain injuries (mTBI) are events with potentially debilitating short- and longterm consequences and may lead to neurodegenerative diseases such as chronic traumatic encephalopathy (CTE). An incomplete understanding of the mechanisms of disease progression has led to difficulty in identifying diagnostic and prognostic markers of mTBI and CTE, while treatment therapies remain elusive. Lines of evidence suggest that the antiinflammatory and neuroprotective agents celecoxib and minocycline may mitigate the injury processes initiated by mTBI, however a thorough investigation of these compounds in this context has not been undertaken. Accordingly, the aims of this research project were to: (i) investigate the behavioural, biochemical and molecular changes that are representative of repetitive mTBI and chronic neurodegeneration; and (ii) assess the implementation of minocycline and celecoxib in the inflammatory and excitotoxic pathways that are induced following mTBI. Methods: To meet these project aims, a series of reviews were conducted to ascertain the current knowledge gaps in mTBI research. A systematic review analysed the parameters and outcomes of mTBI animal modelling. A review was also undertaken to assess the current status of blood biomarker research for mTBI and CTE, and a third review described therapeutic targets for neuroprotection following mTBI and corresponding pharmacological treatments that have been investigated. These reviews provided rationale for our series of murine studies addressing the aforementioned aims. Study 1 examined differing modelling parameters to further understand the clinical, biochemical, and gene expression response to injury. Studies 2 and 3 used the findings of Study 1 to investigate the effectiveness of minocycline and celecoxib in mitigating mTBI-induced detriment to molecular and cognitive function. Results: The systematic review identified relevant mTBI modelling platforms and reported on subsequent changes to cognitive performance, neurodegenerative proteins, and neurodestructive genes. Study 1 used cumulative impacts to replicate the mTBI pathophysiology and clinical features described in the systematic review. Our pharmacology treatment studies found molecular measures of excitotoxicity and neurodegeneration induced by repetitive mTBI showed similar patterns of neuroprotection from minocycline and celecoxib in the hippocampus and cortex. However, glial cell involvement and inflammation was normalised by celecoxib in both the acute and chronic phases of recovery, but only in the chronic phase by minocycline. Interestingly, it was observed that behavioural detriment associated with mTBI following celecoxib administration did not reflect the neuroprotective gene expression changes. Conclusion: These investigations provide novel mechanistic data regarding microglial activation, inflammation, excitotoxicity, and neurodegeneration following repetitive mTBI. This work suggests that the pathways effected by minocycline and celecoxib are of importance in the alleviation of mTBI pathophysiology at chronic recovery. In turn, these investigations may help identify reliable mTBI-related diagnostic and prognostic markers and in developing potential treatments to mitigate the harmful effects of mTBI.

Traumatic Brain Injury (TBI) is a growing global health problem. Mild forms of TBI (mTBI) such as concussions, represent the most common manifestation of this type of injury with children and youth (< 20 years old) among the most likely to sustain mTBI. There is growing evidence for the cumulative effects of repeated mTBI (rmTBI) suggesting that while a single concussion may not cause evident or long-lasting brain alterations, the summation of multiple mTBI may lead to more severe consequences. In contrast to severe TBI, lesions in mTBI patients are challenging to detect. Despite this, mTBI patients may still present with cognitive and emotional deficits. Cerebral microbleeds (CMBS), a subtle form of vascular damage, have been identified as an early hallmark in brain trauma and several neurodegenerative diseases. The cumulative effects of subtle but sustained microvascular damage could explain the persistent long-term functional deficits observed in mTBI. In this study, the awake closed-head injury (ACHI) model was used to investigate the association between rmTBI and microvascular damage in different brain regions in both male and female juvenile rats at one and seven days after the last injury. The results indicate that the injury paradigm used in this study (i.e. 8 impacts over 4 days) using the ACHI model is associated with an acute increase in sings of microvascular damage in both sexes that is no longer evident at a longer time point. These study is the first to describe the negative impact of rmTBI on CMBs in the juvenile using an awake animal model, and provides evidence for the potential involvement of this subtle form of vascular damage in the development of neurological deficits after rmTBI.
Graduate

Traumatic Brain Injury (TBI) is a global health problem and concussion, or mild TBI (mTBI), accounts for up to 75% of all brain injuries occurring annually in the US. There is also growing awareness that repeated mild traumatic brain injury (r-mTBI) can result in cumulative neuropathology and learning and memory deficits, however there is a paucity of preclinical data as to the extent these deficits manifest. R-mTBI in juvenile populations is of special interest as not only is this a high risk group, but this is also a time period when the human brain continues to mature. The hippocampus is a brain region important for learning and memory processes, and r-mTBI during the juvenile period may particularly disrupt the development of cognitive processes. To examine this issue we used a model of awake closed head injury (ACHI), and administered 8 impacts over a 4 day period to juvenile male and female rats (P25-28). At 1 or 7 days after the last injury, a cohort of rats was used for behavioural testing to study anxiety and risk-taking behaviours and cognitive abilities. From a different cohort, hippocampal slices were generated and used for in vitro electrophysiological recordings, and the capacity for long-term depression (LTD) and long-term potentiation (LTP) was examined in the medial perforant path (MPP)-dentate gyrus (DG) synapse. Our results showed that r-mTBI impaired hippocampal-dependent spatial learning and memory and that r-mTBI significantly impaired the capacity for LTD but not LTP in both sexes. These data are the first to describe the negative impact of r-mTBI on LTD in the juvenile DG in both males and females, and provide evidence for the delayed development of neurological deficits with r-mTBI.
Graduate

Previous research investigating affect and behaviour following mild Traumatic Brain Injury (mTBI) in children has produced variable results. It has been suggested that following a mTBI children may experience transitory "post-concussion" symptoms but subsequently will make a full recovery. In contrast, other studies have reported changes in children's behaviour and affect lasting even years post injury. The current study aimed to further document the impact of mTBI on behaviour and affect in children. This prospective study reports on a sample of 26 children aged between 6 and 12 years. The children were assessed at baseline, one week, three months and a subgroup at 12 months post injury. No changes were found over time on the standardised measures of behaviour and affect with the Behavioural Assessment System for Children, Second Edition (BASC2). However, on the BASC2 the children with pre-existing problems displayed higher incidence of scores in the 'At Risk' or 'Clinically Significant' range on the Externalising Problems composite scale in comparison to the children with no preexisting problems. A qualitative question was also administered to parents. Approximately half of the whole sample reported some change in their child's mood or behaviour at one week post-injury and approximately one quarter continued to report changes at three months post injury. It was also investigated whether the children who had problems or changes reported at three months post-injury differed from the other children on any pre-morbid factors, however, no significant results were found. The overall conclusions drawn from the study were that the group of children referred to the study had a higher proportion of children with pre-existing problems than that expected in the general population. Further, these children differed pre-morbidly from those without pre-existing problems on standardised behavioural measures. While no changes were found over time on standardised measures of behaviour and affect, subjective parental report suggested that in fact there may have been more subtle changes in some children's behaviour up to 3 months post-injury. These findings are worthy of further systematic investigation.

Mild Traumatic Brain Injury (mTBI), often called concussion, has become a growing public health concern, prevalent in both athletic and military settings. In response, many researchers have explored cognitive outcomes post-mTBI, with a plethora of meta-analyses summarizing these findings; however, these meta-analyses examine solely mean performances on cognitive tasks, ignoring intra-individual variability (IIV) in cognitive performance that may elucidate neuropsychological impairment following mTBI. The current thesis involved two studies, responding to both the growing meta-analytic research and limited IIV findings. Study 1: Many meta-analyses have amalgamated individual study results on post-mTBI neuropsychological outcomes. With the abundance of meta-analyses, a systematic review of meta-analyses stands as the next logical step. Method: A systematic literature search yielded 11 meta-analyses meeting inclusion criteria (i.e., English-language systematic reviews/meta-analyses covering post-mTBI observational cognitive research on late adolescents/adults), with their findings qualitatively synthesized based on moderator variables (i.e., cognitive domain, time since injury, past head injury, participant characteristics, comparison group, assessment technique, and persistent symptoms). Results: The overall effect sizes ranged for both general (range: .07-.61) and sports-related mTBI (range: .40-.81) and differed both between and within cognitive domains, with executive functions appearing most sensitive to multiple mTBI. Cognitive domains varied in recovery rates, but overall recovery occurred by 90 days post-injury for most individuals and by seven days post-injury for athletes. Greater age/education and male gender produced smaller effects sizes, while high school athletes suffered the largest deficits post-mTBI. Control-group comparisons yielded larger effects than within-person designs, while assessment techniques had limited moderating effects. Conclusions: Overall, meta-analytic review quality remained low with few studies assessing publication or study quality bias. Meta-analyses consistently identified adverse acute mTBI-related effects and fairly rapid symptom resolution. Study 2: The long-term outcomes of executive functions and IIV following mTBI are unclear due to inconsistent and limited research, respectively. Further, the relationship between physical activity (PA) and cognitive performance at young adulthood remains almost fully unexplored. In turn, the current study aimed to (a) assess the diagnostic utility of both executive functions and IIV at predicting mTBI history and (b) evaluate the interaction between PA levels and mTBI on both of these cognitive metrics. Method: Altogether 138 self-identified athletes (Mage = 19.9 ± 1.91 years, 60.8% female, 19.6% 1 mTBI, 18.1% 2+ mTBIs) completed three executive-related cognitive tasks (i.e., N-Back, Go/No-go, Local-Global). Ordinal logistic regression analyses examined the joint effect of person-mean and IIV as predictors of mTBI status. Multi-level models examined mTBI and PA levels as predictors of trial-to-trial changes in performance. Results: Only mean response time (RT) for the Local-Global task predicted mTBI status, while no IIV variables reached unique significance. PA levels predicted subtle within-task decreases in RT across Local-Global trials. Conclusions: IIV research on mTBI remains limited; however, the preliminary results do not indicate any additional predictive value of IIV indices above mean performances. For executive functions, shifting appeared most affected, with past researchers identifying post-mTBI impairment in attentional processing. Higher PA levels minutely benefited within-task shifting and mean inhibitory performance, although these finding require cautious interpretation.
Graduate
0622
jkarr@uvic.ca

Objectives: After mild traumatic brain injury (mTBI), psychological factors can contribute to persisting post-concussion symptoms (PCS). Consistent with constructive theories of memory, negative expectations for increased symptoms after mTBI may contribute to misattributing symptoms to the mTBI and underestimating pre-injury symptoms, called the “good old days’ bias” (Gunstad & Suhr, 2001). The good old days’ bias is not thought to be a general retrospective recall bias but studies to date have largely not controlled for normative memory processes including those that lead to a biased, more positive recall of the past. Therefore, the current study examines whether there is a good old days’ bias after mTBI above and beyond normal memory biases. This study also examines how soon after mTBI the good old days’ bias affects recall of pre-injury symptoms in the first month after mTBI in adolescents as well as whether the good old days’ bias causes pre-injury symptom severity to be underestimated or if symptoms are entirely forgotten. Finally, the clinical significance of symptom recall biases is investigated. Method: The sample is 42 adolescents who sustained an mTBI (ages 13-18 years; 24 males) and 42 uninjured adolescents (ages 13-18 years; 24 males, ). The mTBI group rated current and retrospective post-concussion symptom ratings within one week and again, at one month, post-injury. The control group rated current and retrospective post-concussion symptoms at baseline and one month later. Cross-sectional and longitudinal comparisons using non-parametric statistical tests were used. Results: Wilcoxon signed-rank tests showed that, by one month post-mTBI, adolescents report fewer total, physical, and emotional pre-injury symptoms than they had reported within one week of their concussion. The control group did not demonstrate this good old days’ bias. There were no between-group differences in retrospective PCS ratings at either time point. Chi-square analyses found that the mTBI group was as likely as the control group to recall “no” pre-injury/past symptoms one month post-injury after having initially reported some pre-injury symptoms. Only four more adolescents were classified as “recovered” if their one-month PCS ratings were compared with pre-injury PCS ratings made within 1-week post-concussion rather than pre-injury ratings from 1-month post-injury. Discussion: There was mixed evidence for a good old days’ bias by one month post-concussion. This bias was not demonstrated in healthy adolescents, suggesting that the good old days’ bias is found specifically after concussion. During the acute post-injury period, the good old days’ bias may only be apparent by studying changes in concussed individuals’ own PCS ratings. The good old days’ bias leads to underestimating the severity of pre-injury symptoms rather than forgetting them entirely. The good old days’ bias does not greatly affect symptom recovery tracking by one month post-concussion. Future studies should directly examine expectations about concussion and their effect on current and retrospective symptom reporting.
Graduate
2019-07-10

This thesis investigates head injuries (HIs) occurring in sports and recreation (SR) that presented to emergency departments (EDs) in Edmonton, Alberta, from April 1st, 1997 to March 31st, 2008. There were 4,950 SR HIs identified over the 11 years (5.13 HIs per 1,000 ED injury visits). Individuals less than 18 years old were 3.4 times more likely, and males were 1.25 times more likely to present with a head injury from SR (p < 0.0001). A history of one or two previous SR HIs increased the odds of subsequent HI by 2.62 and 5.94 times, respectively, while children aged 7 13 and 14 17 were more than four times more likely to sustain a HIs from SR (p < 0.001). The effects of multiple HIs occurring in children participating in SR activities needs to be addressed, due to the chronic neurobehavioral effects of HIs.
Epidemiology

Concussion affects the adolescent population in large numbers, primarily because of the popularity of team sports that are played in middle and high school. This adolescent age group is more susceptible to the adverse effects of concussion due to physiological immaturity, and recovery for this population takes longer than in adults. Speech-language pathologists, who are trained to treat cognitive-communication deficits, are present in the majority of school systems throughout the United States, and could be a useful resource to manage and treat students who incur concussion. However, speech-language pathologists historically have not treated students with concussion, and may not be receiving adequate education regarding concussion in graduate programs. This study sought to ascertain the education, training, and experience regarding concussion of speech-language pathologists in Texas secondary schools. Anonymous survey responses were collected via an Internet survey platform, yielding 49 respondents for the final data pool. The answers provided by these respondents indicate Texas speech-language pathologists are not yet receiving adequate concussion education and training. Respondents reported low confidence levels in several key areas of concussion knowledge, and doubt regarding the speech-language pathologist's role in managing concussion. Recommendations include concussion-targeted graduate school curriculum as an extension of traumatic brain injury curriculum, increased continuing education efforts by ASHA regarding concussion and the speech-language pathologist's role in treating concussion, and further advocacy by ASHA for speech-language pathologists to be part of concussion management teams based in schools.
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Indiana University-Purdue University Indianapolis (IUPUI)
Traumatic brain injury (TBI) has emerged as a major cause of morbidity among U.S. soldiers who have served in Iraq and Afghanistan. Even mild TBI (mTBI) can result in cognitive impairments that can impact how veterans experience such things as physical symptoms, emotions and behaviors, instrumental activities of daily living, interpersonal interactions, and community reintegration. The purpose of this study was to develop a comprehensive self-management intervention for veterans with mTBI to facilitate their community reintegration upon returning from deployment to combat zones. This study was conducted in two Phases. Phase I entailed collecting qualitative data regarding needs, concerns, strategies used, and advice given by eight veterans with mTBI, guided by a conceptual model derived from Ferrans’ and colleagues’ health-related quality of life model and the TBI literature. Six key categories and predominant themes emerged providing further support for the model (cognitive impairments, physical symptoms, emotions and behaviors, instrumental activities of daily living, interpersonal interactions, and community reintegration). Guided by the conceptual model, a mTBI Veteran Needs and Concerns Checklist and 14 algorithms making up the VETeranS Compensate, Adapt, REintegrate (VETSCARE) intervention were developed. Phase II entailed obtaining review of the mTBI Veteran Needs and Concerns Checklist and the 14 VETSCARE algorithms from six TBI experts. On a scale of 1 to 5, with 5 being strongly agree, expert ratings provided moderate evidence of content validity for the checklist (3.33), and for the 14 algorithms (problem relevance 3.92, accuracy 3.73, feasibility 3.80, acceptability 3.84). The average overall expert rating for the VETSCARE intervention was 3.82. The checklist and the 14 algorithms are being revised based on specific comments provided by the experts. Once revised, the mTBI Veteran Needs and Concerns Checklist and the VETSCARE intervention will be tested for feasibility in a future pilot study with veterans with mTBI who have recently returned from combat zones in Iraq and Afghanistan.

The process of controlling executive and motor behaviours is central to one’s ability to self-regulate and accomplish day-to-day goals across the lifespan. Executive and motor control share a set of underlying neural substrates that support a common set of processes, including planning, sequencing and monitoring of behaviour. They share a bidirectional relationship, such that gains or deficits in one area can have profound effects on the other. This doctoral dissertation examines the interplay between executive and motor control at three distinct stages of life and in the context of neurological conditions whose clinical manifestations shed additional light on the nature of the constructs. Central to each investigation is the methodological theme of intraindividual variability, as a means of leveraging valuable data within-persons. Chapter 2 examines executive and motor control in typically developing children and children with attention-deficit/hyperactivity disorder (ADHD). Findings suggest that dysregulation of motor processes accounts for hyperactive symptoms in ADHD and detracts from higher-order executive control. Chapter 3 examines the impact of mild traumatic brain injury (mTBI) in young adult varsity athletes, who routinely practice executive motor control by virtue of their level of play. Findings suggest that the impacts of mTBI are discernible through a dampened electrophysiological response during computerized tests of higher order executive functioning, and may not outweigh the otherwise myriad health benefits of athletic engagement. Chapter 4 examines the impact of dementia on executive motor control during gait dual-tasking in older adults. Findings suggest that the consistency of performance across multiple indicators of gait is sensitive to dementia, and that engagement in cognitive and social lifestyle behaviours is protective against likelihood of both dementia and mild cognitive impairment (MCI) classification. On mass, these findings highlight the importance of assessing executive motor control to understand the pathophysiology of neurological conditions. The potential benefits that may generalize from one area to the other offer unique opportunities for preventative and rehabilitative efforts.
Graduate

In Operations Enduring Freedom and Iraqi Freedom, explosions accounted for 81% of all injuries; this is a higher casualty percentage than in any previous wars. Blast wave overpressure has recently been associated with varying levels of traumatic brain injury in soldiers exposed to blast loading. Presently, the injury mechanism behind primary blast brain injury is not well understood due to the complex interactions between the blast wave and the human body. Despite these limitations in the understanding of head injury thresholds, head kinematics are often used to predict the overall potential for head injury. The purpose of this study was to investigate head kinematics, and predict injury from a range of simulated blast loads at varying standoff distances and differing heights of bursts. The validated Generator of body data multi-body human surrogate model allows for numerical kinematic data simulation in explicit finite element method fluid structure interaction blast modeling. Two finite element methods were investigated to simulate blast interaction with humans, an enhanced blast uncoupled method, and an Arbitrary Lagrangian Eularian fully coupled method. The enhanced blast method defines an air blast function through the application of a blast pressure wave, including ground reflections, based on the explosives relative location to a target; the pressures curves are based on the Convention Weapons databases. LBE model is efficient for parametric numerical studies of blast interaction where the target response is the only necessary result. The ALE model, unlike classical Lagrangian methods, has a fixed finite element mesh that allows material to flow through it; this enables simulation of large deformation problems such as blast in an air medium and its subsequent interaction with structures. The ALE model should be used when research into a specific blast scenario is of interest, since this method is more computationally expensive. The ALE method can evaluate a blast scenario in more detail including: explosive detonation, blast wave development and propagation, near-field fireball effects, blast wave reflection, as well as 3D blast wave interaction, reflection and refraction with a target. Both approaches were validated against experimental blast tests performed by Defense Research and Development Valcartier and ConWep databases for peak pressure, arrival time, impulse, and curve shape. The models were in good agreement with one another and follow the experimental data trend showing an exponential reduction in peak acceleration with increasing standoff distance until the Mach stem effect reached head height. The Mach stem phenomenon is a shock front formed by the merging of the incident and reflected shock waves; it increases the applied peak pressure and duration of a blast wave thus expanding the potential head injury zone surrounding a raised explosive. The enhanced blast model was in good agreement with experimental data in the near-field, and mid-field; however, overestimated the peak acceleration, and head injury criteria values in the far-field due to an over predicted pressure impulse force. The ALE model also over predicted the response based on the head injury criteria at an increased standoff distance due to smearing of the blast wave over several finite elements leading to an increased duration loading. According to the Abbreviated Injury Scale, the models predicted a maximal level 6 injury for all explosive sizes in the near-field, with a rapid acceleration of the head over approximately 1 ms. There is a drastic exponential reduction in the insult force and potential injury received with increasing standoff distance outside of the near-field region of an explosive charge.

L’objectif principal de cette thèse était d’obtenir, via l’électrophysiologie cognitive, des indices de fonctionnement post-traumatisme craniocérébral léger (TCCL) pour différents niveaux de traitement de l’information, soit l’attention sélective, les processus décisionnels visuoattentionnels et les processus associés à l’exécution d’une réponse volontaire. L’hypothèse centrale était que les mécanismes de production des lésions de même que la pathophysiologie caractérisant le TCCL engendrent des dysfonctions visuoattentionnelles, du moins pendant la période aiguë suivant le TCCL (i.e. entre 1 et 3 mois post-accident), telles que mesurées à l’aide d’un nouveau paradigme électrophysiologique conçu à cet effet. Cette thèse présente deux articles qui décrivent le travail effectué afin de rencontrer ces objectifs et ainsi vérifier les hypothèses émises. Le premier article présente la démarche réalisée afin de créer une nouvelle tâche d’attention visuospatiale permettant d’obtenir les indices électrophysiologiques (amplitude, latence) et comportementaux (temps de réaction) liés aux processus de traitement visuel et attentionnel précoce (P1, N1, N2-nogo, P2, Ptc) à l’attention visuelle sélective (N2pc, SPCN) et aux processus décisionnels (P3b, P3a) chez un groupe de participants sains (i.e. sans atteinte neurologique). Le deuxième article présente l’étude des effets persistants d’un TCCL sur les fonctions visuoattentionelles via l’obtention des indices électrophysiologiques ciblés (amplitude, latence) et de données comportementales (temps de réaction à la tâche et résultats aux tests neuropsychologiques) chez deux cohortes d’individus TCCL symptomatiques, l’une en phase subaigüe (3 premiers mois post-accident), l’autre en phase chronique (6 mois à 1 an post-accident), en comparaison à un groupe de participants témoins sains. Les résultats des articles présentés dans cette thèse montrent qu’il a été possible de créer une tâche simple qui permet d’étudier de façon rapide et peu coûteuse les différents niveaux de traitement de l’information impliqués dans le déploiement de l’attention visuospatiale. Par la suite, l’utilisation de cette tâche auprès d’individus atteints d’un TCCL testés en phase sub-aiguë ou en phase chronique a permis d’objectiver des profils d’atteintes et de récupération différentiels pour chacune des composantes étudiées. En effet, alors que les composantes associées au traitement précoce de l’information visuelle (P1, N1, N2) étaient intactes, certaines composantes attentionnelles (P2) et cognitivo-attentionnelles (P3a, P3b) étaient altérées, suggérant une dysfonction au niveau des dynamiques spatio-temporelles de l’attention, de l’orientation de l’attention et de la mémoire de travail, à court et/ou à long terme après le TCCL, ceci en présence de déficits neuropsychologiques en phase subaiguë surtout et d’une symptomatologie post-TCCL persistante. Cette thèse souligne l’importance de développer des outils diagnostics sensibles et exhaustifs permettant d’objectiver les divers processus et sous-processus cognitifs susceptible d’être atteints après un TCCL.
The main objective of this thesis was to obtain, using cognitive electrophysiology, biomarkers of mild traumatic brain injury (TBI) for different levels of information processing such as selective attention, visuo-attentional decision making and processes associated with the execution of a deliberate response. The fundamental assumption was that the lesion-producing mechanisms as well as the pathophysiology associated with mTBI leads to visuo-attentional dysfunctions, at least during the sub-acute period following the mTBI (i.e. between 1 and 3 months post-trauma), as measured by a novel electrophysiological paradigm developed for this purpose. This thesis presents two articles describing the work accomplished to meet these objectives, and verify the underlying assumptions. The first article presents the approach used to create a novel visuo-spatial attention task enabling the identification of electrophysiological (amplitude, latency) and behavioural (reaction time) indexes related to early visual and attentional processing (P1, N1, N2-nogo, P2, Ptc), selective visual attention (N2pc, SPCN) and decision-making processes (P3b, P3a) in a group of normal participants (i.e. without neurological injury). The second article presents a study of the persisting effects of a mTBI on visuo-attentional functions through the identification of targeted electrophysiological markers (amplitude, latency), and from behavioural data (task-related reaction time and neuropsychological tests results) in two cohorts of symptomatic mTBI individuals, one during the sub-acute phase (3 first months post-injury), the other during the chronic phase (6 months to 1 year post-injury), in comparison to a group of normal control participants. The results presented in this thesis indicate that it was has been possible to create a simple, rapid and low-cost task enabling the study of the various levels of information processing involved in the deployment of visuospatial attention. Subsequently, the use of this task in patients with mTBI tested during the sub-acute phase or the chronic phase allowed to identify differential impairment and recovery profiles for each of the components studied. Indeed, while the early components associated with early visual information processing (P1, N1, N2) were intact, certain attentional (P2) and cognitive-attentionnal (the P3a, P3b) components were affected, suggesting dysfunction in the spatio-temporal dynamics of attention, orientation of attention, and working memory, in the short- and/or long-term following mTBI, this is the presence of neuropsychological deficits mostly in the sub-acute phase and of persisting post-mTBI symptomatology. This thesis emphasizes the importance of developing sensitive and comprehensive diagnostic tools allowing to objectively identify the various cognitive processes and sub-processes that are likely to be affected after a mTBI.

Le traumatisme craniocérébral léger (TCCL) a des effets complexes sur plusieurs fonctions cérébrales, dont l’évaluation et le suivi peuvent être difficiles. Les problèmes visuels et les troubles de l’équilibre font partie des plaintes fréquemment rencontrées après un TCCL. En outre, ces problèmes peuvent continuer à affecter les personnes ayant eu un TCCL longtemps après la phase aiguë du traumatisme. Cependant, les évaluations cliniques conventionnelles de la vision et de l’équilibre ne permettent pas, la plupart du temps, d’objectiver ces symptômes, surtout lorsqu’ils s’installent durablement. De plus, il n’existe pas, à notre connaissance, d’étude longitudinale ayant étudié les déficits visuels perceptifs, en tant que tels, ni les troubles de l’équilibre secondaires à un TCCL, chez l’adulte. L’objectif de ce projet était donc de déterminer la nature et la durée des effets d’un tel traumatisme sur la perception visuelle et sur la stabilité posturale, en évaluant des adultes TCCL et contrôles sur une période d’un an. Les mêmes sujets, exactement, ont participé aux deux expériences, qui ont été menées les mêmes jours pour chacun des sujets. L’impact du TCCL sur la perception visuelle de réseaux sinusoïdaux définis par des attributs de premier et de second ordre a d’abord été étudié. Quinze adultes diagnostiqués TCCL ont été évalués 15 jours, 3 mois et 12 mois après leur traumatisme. Quinze adultes contrôles appariés ont été évalués à des périodes identiques. Des temps de réaction (TR) de détection de clignotement et de discrimination de direction de mouvement ont été mesurés. Les niveaux de contraste des stimuli de premier et de second ordre ont été ajustés pour qu’ils aient une visibilité comparable, et les moyennes, médianes, écarts-types (ET) et écarts interquartiles (EIQ) des TR correspondant aux bonnes réponses ont été calculés. Le niveau de symptômes a également été évalué pour le comparer aux données de TR. De façon générale, les TR des TCCL étaient plus longs et plus variables (plus grands ET et EIQ) que ceux des contrôles. De plus, les TR des TCCL étaient plus courts pour les stimuli de premier ordre que pour ceux de second ordre, et plus variables pour les stimuli de premier ordre que pour ceux de second ordre, dans la condition de discrimination de mouvement. Ces observations se sont répétées au cours des trois sessions. Le niveau de symptômes des TCCL était supérieur à celui des participants contrôles, et malgré une amélioration, cet écart est resté significatif sur la période d’un an qui a suivi le traumatisme. La seconde expérience, elle, était destinée à évaluer l’impact du TCCL sur le contrôle postural. Pour cela, nous avons mesuré l’amplitude d’oscillation posturale dans l’axe antéropostérieur et l’instabilité posturale (au moyen de la vitesse quadratique moyenne (VQM) des oscillations posturales) en position debout, les pieds joints, sur une surface ferme, dans cinq conditions différentes : les yeux fermés, et dans un tunnel virtuel tridimensionnel soit statique, soit oscillant de façon sinusoïdale dans la direction antéropostérieure à trois vitesses différentes. Des mesures d’équilibre dérivées de tests cliniques, le Bruininks-Oseretsky Test of Motor Proficiency 2nd edition (BOT-2) et le Balance Error Scoring System (BESS) ont également été utilisées. Les participants diagnostiqués TCCL présentaient une plus grande instabilité posturale (une plus grande VQM des oscillations posturales) que les participants contrôles 2 semaines et 3 mois après le traumatisme, toutes conditions confondues. Ces troubles de l’équilibre secondaires au TCCL n’étaient plus présents un an après le traumatisme. Ces résultats suggèrent également que les déficits affectant les processus d’intégration visuelle mis en évidence dans la première expérience ont pu contribuer aux troubles de l’équilibre secondaires au TCCL. L’amplitude d’oscillation posturale dans l’axe antéropostérieur de même que les mesures dérivées des tests cliniques d’évaluation de l’équilibre (BOT-2 et BESS) ne se sont pas révélées être des mesures sensibles pour quantifier le déficit postural chez les sujets TCCL. L’association des mesures de TR à la perception des propriétés spécifiques des stimuli s’est révélée être à la fois une méthode de mesure particulièrement sensible aux anomalies visuomotrices secondaires à un TCCL, et un outil précis d’investigation des mécanismes sous-jacents à ces anomalies qui surviennent lorsque le cerveau est exposé à un traumatisme léger. De la même façon, les mesures d’instabilité posturale se sont révélées suffisamment sensibles pour permettre de mesurer les troubles de l’équilibre secondaires à un TCCL. Ainsi, le développement de tests de dépistage basés sur ces résultats et destinés à l’évaluation du TCCL dès ses premières étapes apparaît particulièrement intéressant. Il semble également primordial d’examiner les relations entre de tels déficits et la réalisation d’activités de la vie quotidienne, telles que les activités scolaires, professionnelles ou sportives, pour déterminer les impacts fonctionnels que peuvent avoir ces troubles des fonctions visuomotrice et du contrôle de l’équilibre.
Mild traumatic brain injury (mTBI) has complex effects on several brain functions that can be difficult to assess and follow-up. Visual and balance problems are frequently reported after an mTBI. Furthermore, these problems can still affect mTBI individuals far beyond the acute stage of injury. However, standard clinical assessments of vision and balance most often fail to objectivize these symptoms, especially if they are lingering. Moreover, to our knowledge, no longitudinal study investigated either mTBI-related deficits of visual perception per se, or mTBI-related balance deficits in adults. The aim of this project was to determine the nature and duration of the effects of such a traumatism on visual perception as well as on postural stability, by evaluating mTBI and control adults over a one-year period. Exactly the same subjects participated in both experiments, which took place on the same days for every subject. The impact of mTBI on the visual perception of sine-wave gratings defined by first-and second-order characteristics was, first, investigated. Fifteen adults diagnosed with mTBI were assessed at 15 days, 3 months and 12 months after injury. Fifteen matched controls followed the same testing schedule. Reaction times (RTs) for flicker detection and motion direction discrimination were measured. Stimulus contrast of first- and second-order patterns was equated to control for visibility, and correct-response RT means, standard deviations (SDs), medians, and interquartile ranges (IQRs) were calculated. The level of symptoms was also evaluated to compare it to RT data. In general in mTBI, RTs were longer and more variable (ie., larger SDs and IQRs), than those of controls. In addition, mTBI participants’ RTs to first-order stimuli were shorter than those to second-order stimuli, and more irregular for first- than for second-order stimuli in the motion condition. All these observations were made over the 3 sessions. The level of symptoms observed in mTBI was higher than that of control participants and this difference did also persist up to one year after the brain injury, despite an improvement. The second experiment, then, investigated the impact of mTBI on postural control. To achieve that, antero-posterior body sway amplitude (BSA) and postural instability (given by body sway velocity root mean square, vRMS) during upright stance, feet together, on a firm surface, were measured in five different conditions: with eyes closed and in a 3D virtual reality tunnel, either static or sinusoidally moving in the antero-posterior direction at 3 different velocities. Balance measures derived from clinical tests, Bruininks-Oseretsky Test of Motor Proficiency 2nd edition (BOT-2) and Balance Error Scoring System (BESS), were also used. Participants diagnosed with mTBI exhibited more postural instability (i.e. higher body sway vRMS) than control participants at 2 weeks and at 3 months post-injury, regardless of the testing condition. These mTBI-related balance deficits were no longer present one year postinjury. These results also suggest that visual processing impairments revealed in the first experiment might have contributed to mTBI-related balance deficits. Anteroposterior BSA as well as measures derived from clinical tests for balance assessment did not appear to be sensitive enough to quantify postural deficits of mTBI participants. The combination of RT measures with particular stimulus properties appeared to be a highly sensitive method for measuring mTBI-induced visuomotor anomalies, and to provide a fine probe of the underlying mechanisms when the brain is exposed to mild trauma. Likewise, postural instability measures prove to be sensitive enough for measuring mTBI-induced balance deficits. Developing screening tests in this respect intended for early post-mTBI use would be of interest. Also, studying relationships of such deficits with performance in daily life activities, such as school, work, or sports, is crucial in order to determine the functional impacts of these alterations in visuomotor and balance functions.