Concussions are injuries that can result in debilitating symptoms, suffered by people of all ages, with children being at elevated risk for injury. Falls account for over 20% of head injuries worldwide, and up to 50% of concussive injuries in children. Following a concussion, children typically take longer for symptoms to resolve compared to adults. It is unknown whether or not children are more, less, or equally susceptible to concussive injury based on the mechanical response, with researchers divided on the subject. There is currently a paucity of published data for concussive injuries in children, with few studies investigating impact biomechanics and strain response in the brain using FE models. Those that exist typically rely on scaled adult models that do not capture age-dependent geometric properties, material properties of tissues, and the developmental stage of the brain reflected by the patterns of grey and white matter within the brain. Newer child models are being developed, however at present they are focused on car crash investigations that do not offer an accurate reflection of sports-related impacts, and those that could be experienced from day-to-day activities since impact characteristics (e.g. magnitude, duration, surface compliance) differ largely between these types of events. Strain magnitudes differ between events causing concussion in adults (falls, collisions, punches, and projectiles), so it follows that the unique impact characteristics of car crash events do not typically coincide with those associated with sports impacts. Car crash events can result in much longer impact durations compared to sporting impacts (100 ms duration in car crashes vs. 5-30 ms in sports impacts). The purpose of this thesis was to assess how the mechanical response of the brain in young children near 6 years old differs from an adult brain in cases resulting in concussive injury for sports impacts. Study one created a novel FE model of a 6-year-old brain, using medical images to extract an accurate representation of the geometry and tissues inside the head of a 6-year-old child. The developmental stage of the younger brain was captured using a highly-refined mesh to accurately represent the folds of white matter within the cerebrum. With no intracranial data for child cadavers available, published data of adult cadavers was used to validate the brain motion from impacts. Comparisons were made to a scaled adult model to highlight how the different model constructions influence brain motion and resulting strains. The new model showed higher correlation to the cadaver data compared to the scaled model, and yielded “good biofidelity” measures when assessed using a modified version of the normalized integral square error method. For young children, the new model was proposed to be more appropriate for concussion investigations as it captures age-appropriate geometry, material properties, and developmental stage of the brain, reflected in the patterns and volumes of grey and white matter within the brain. Study two tested the model for sensitivity across three levels of surface compliance and impact velocity consistent with sport impact events, and compared strain responses to a scaled adult model. The 6-year-old model showed unique strain responses compared to the scaled adult model with peak strains being lower across most impact events. Strain patterns also differed between models, with less strain being transmitted into the white matter in the 6-year-old model. Low compliance impacts yielded highest differences in strains (~30%), moderate compliance impacts yielded more similar strains (~9% lower), with high compliance impacts showing a location dependent response with frontal impacts being 14% lower, and side impacts being 9% higher than the scaled model. The sensitivity study characterized the model responses, allowing for better comparisons between the two different model constructions. Study three then compared the strain responses of reconstructed real-world concussive events for both children and adults. Forty cases of concussion from falls in children and adults (20 children aged 5-7, 20 adults) were reconstructed using physical models, with the measured impact kinematics used to load the FE models. Concussive cases of children showed lower strains than adults, finding a velocity driven relationship since the child concussions occurred at lower impact velocities compared to the adults. Lower peak strains, as well as cumulative strains in the child cases suggest that children are vulnerable to concussion at lower strain compared to adults. Protective strategies for children should address this vulnerability, no longer relying on product scaling to create head protection for youth.

Thesis (M.A.)--Boston University / Sports-related concussions are a very large public health concern and have only recently been brought into the national spotlight, thanks largely to the increased media coverage following the deaths of several current and former players of the National Football League (NFL). This problem extends not only to professional athletes, but reaches down through college, high school and to our youth athletes as well. The symptoms resulting from concussion are diverse and include both acute and long-term effects, and could have particularly debilitating effects on the developing brains of young athletes. Various neurocognitive deficits, as well as neurodegenerative diseases such as chronic traumatic encephalopathy (CTE) have been associated with concussions. Research about both the short and long-term effects of concussions has been growing in recent years, and will continue to grow as advanced neuroimaging tools and biomarkers become better developed. This will improve diagnostic capabilities, result in better prognoses, as well as treatments and prevention. This review analyzes current literature in order to evaluate the lasting impacts of sports-related concussions. By showing the effects of sports-related concussions, especially on the developing brain, policy changes aimed at the prevention of concussion in sports will be suggested, specifically in terms of mitigating the adverse effects of concussions on brain development.

Masters of Science - Msc (Physiotherapy) / Concussion is one of the most common injuries in contact sports such as rugby and hockey. Concussion awareness has dramatically increased over the last 20 years. Concussion is a mild traumatic brain injury that often gets overlooked but can be fatal if not taken seriously. Early diagnosis and appropriate management of concussion is vital for safely integrating a player back into sport. Return to play guidelines serves to ensure the safety of the players. Even though a few studies have investigated the knowledge of concussion and the return to play guidelines amongst therapists, there are no South African studies focusing on high school rugby and hockey players.

xiii, 122 p. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / Currently the information on attention-balance control interactions following concussion is incomplete and not given particular consideration during clinical examinations of concussion. The purposes of this dissertation were to (1) test different gait paradigms for their sensitivity of identifying concussion symptoms and to (2) test how individual components of attention interact with gait performance. The long-term goal of this study is to establish more functional and succinct protocols for return-to-play decisions. Grade II (AAN guidelines) concussed individuals were recruited to participate in testing at 2, 6, 14, and 28 days post-injury. Gait and components of attention were analyzed during each session through a number of different paradigms. Control subjects were matched by stature, age, and athletic participation. The results indicate that the dynamic balance deficits following a concussion are immediately identified with an attention dividing gait task. Obstacle crossing identified more conservative adaptations 2 weeks after injury. A task combining the two did not clearly identify concussion deficits. Two components of attention showed promise as interacting with gait to cause balance deficits. The spatial orientation component showed an interaction with obstacle avoidance indicating that the same concussed individuals that had poor spatial orientation of attention also came closer to hitting the obstacle during crossings. An analysis of divided attention showed that concussed individuals performing poorly in one task also performed poorly in the other during a dual-task paradigm, but during any one particular trial there was a trade-off between task performances, which was not present in control individuals. The findings of this dissertation point to the use of a divided attention task to distinguish concussed individuals from healthy individuals immediately after a possible injurious event. How several different components of attention interact with gait performance is identified. Finally, if a concussion has occurred, an obstacle crossing task might be suitable for a long-term analysis of full recovery of balance control. Ultimately, it is my hope that the information provided here will lead to functionally relevant and clinically executable tests of concussed individuals before they are placed in harm's way due purely to an incomplete diagnosis of their injuries. / Adviser: Li-Shan Chou

Cognitive and motor impairments have been identified as signs following a concussion which may compromise the performance of everyday tasks or physical activities. However, little work has been done in the adolescent population using laboratory based measurements of attention or balance control to identify recovery from concussion. Therefore, the purpose of this dissertation was to prospectively and longitudinally observe how individuals who have sustained a concussion recover on measures of attention and gait balance control in comparison to individually matched, healthy control subjects from within 72 hours of injury up to two months following injury. Individuals were identified as sustaining a concussion by healthcare professionals and began participation in the study within 72 hours of injury. They then returned to the laboratory at approximately 1 week, 2 weeks, 1 month, and 2 months post-injury. Control subjects were individually matched by sex, age, height, and weight and tested in similar time increments. Attentional abilities were measured via multiple computerized testing assessments, and gait balance control was measured with whole-body motion analysis. The results indicated that following concussion, adolescents display deficits in conflict resolution ability, task switching ability, and gait balance control during dual-task walking for a time period of up to two months following injury in comparison to a matched control group. During dual-task walking, the complexity of the cognitive task performed may affect adolescents with concussion to a greater degree than matched control subjects. Adolescents also displayed regressions to gait stability recovery following their return to physical activities. Finally, adolescents with concussion displayed greater gait balance control deficits than young adults with concussion throughout the two months of testing when each group was compared to a respective healthy control group. Results from this dissertation indicate that concussion affects cognitive and motor functions in adolescents, who display deficits throughout two months post-injury. Computerized attentional tests and dual-task dynamic balance control assessments represent a multifaceted approach to concussion management and may provide another assessment battery for healthcare professionals to utilize in order to identify recovery following concussion. This dissertation includes previously published/unpublished co-authored material.

Primary objective. The goals of this project were to review the current literature regarding the role of the speech-language pathologist (SLP) in concussion management and to conduct a survey of SLPs with experience in concussion care to determine their current practices and perspectives. Design and methods. An online survey consisting of 41 questions was emailed to SLPs throughout the U.S. and Canada. Responses were anonymously collected from 60 SLPs, and the responses were analyzed. Results and conclusions. Results showed that SLPs who work in concussion care are generally knowledgeable and confident despite how recently concussion has become part of SLP practice. There has been improvement in the types of assessment tools used in concussion cases, but there is a need for more sensitive instruments. Findings point to the need for increased availability of concussion training for SLPs and the need for continued research into current clinical practices.

abstract: The recent spotlight on concussion has illuminated deficits in the current standard of care with regard to addressing acute and persistent cognitive signs and symptoms of mild brain injury. This stems, in part, from the diffuse nature of the injury, which tends not to produce focal cognitive or behavioral deficits that are easily identified or tracked. Indeed it has been shown that patients with enduring symptoms have difficulty describing their problems; therefore, there is an urgent need for a sensitive measure of brain activity that corresponds with higher order cognitive processing. The development of a neurophysiological metric that maps to clinical resolution would inform decisions about diagnosis and prognosis, including the need for clinical intervention to address cognitive deficits. The literature suggests the need for assessment of concussion under cognitively demanding tasks. Here, a joint behavioral- high-density electroencephalography (EEG) paradigm was employed. This allows for the examination of cortical activity patterns during speech comprehension at various levels of degradation in a sentence verification task, imposing the need for higher-order cognitive processes. Eight participants with concussion listened to true-false sentences produced with either moderately to highly intelligible noise-vocoders. Behavioral data were simultaneously collected. The analysis of cortical activation patterns included 1) the examination of event-related potentials, including latency and source localization, and 2) measures of frequency spectra and associated power. Individual performance patterns were assessed during acute injury and a return visit several months following injury. Results demonstrate a combination of task-related electrophysiology measures correspond to changes in task performance during the course of recovery. Further, a discriminant function analysis suggests EEG measures are more sensitive than behavioral measures in distinguishing between individuals with concussion and healthy controls at both injury and recovery, suggesting the robustness of neurophysiological measures during a cognitively demanding task to both injury and persisting pathophysiology. / Dissertation/Thesis / Ph.D. Speech and Hearing Science 2014

The effects of repeated mild concussive head injury on professional rugby players were examined. Data were collected for rugby players (n=26) and cricket player controls (n=21) using a comprehensive neuropsychological test battery comprising five modalities (Verbal Memory, Visual Memory, Verbal Fluency, Visuoperceptual Tracking and Hand Motor Dexterity) and a self-report Postconcussive Symptomology Questionnaire. Group statistical comparisons of the percentage of individuals with deficit were carried out for (i) rugby versus cricket; (ii) rugby forwards versus rugby backs; and (iii) rugby forwards versus cricket. Rugby players performed significantly poorer than controls on SA W AIS Digit Symbol Substitution subtest and on the Trail Making Test. On Digits Forward and Digit Symbol Incidental Recall, the results approached significance with the rugby players showing a tendency toward impairment on these tests. Rugby players exhibited impairment in areas of visuoperceptual tracking, speed of information processing and attention, and there are tendencies of impairment in verbal and/or visual memory. Results obtained on the self-report questionnaire strongly reinforced cognitive test results and a significant proportion of rugby players reported difficulties with sustained attention, memory and lowered frustration tolerance as well as symptoms of anxiety and depression. It was consistently noted that players in the more full contact positions (rugby forwards) were most susceptible to impairment, confirming that these players, who are exposed to repeated mild head injuries, are at greater risk of exhibiting postconcussive sequelae.

The effects of repeated mild concussive head injury on professional rugby players were examined. Data were collected for rugby players (n=26) and cricket player controls (n=21) using a comprehensive neuropsychological test battery comprising five modalities (Verbal Memory, Visual Memory, Verbal Fluency, Visuoperccptual Tracking and Hand Motor Dexterity) and a self-report Postconcussive Symptomology Questionnaire. Group statistical comparisons of the percentage of individuals with deficit were carried out for (i) rugby versus cricket; (ii) rugby forwards versus rugby backs; and (iii) rugby forwards versus cricket. Rugby players performed significantly poorer than controls on SA W AIS Digit Symbol Substitution subtest and on the Trail Making Test. On Digits Forward and Digit Symbol Incidental Recall, the results approached significance with the rugby players showing a tendency toward impairment on these tests. Rugby players exhibited impairment in areas of visuoperceptual tracking, speed of information processing and attention, and there are tendencies of impairment in verbal and/or visual memory. Results obtained on the self-report questionnaire strongly reinforced cognitive test results and a significant proportion of rugby players reported difficulties with sustained attention, memory and lowered frustration tolerance as well as symptoms of anxiety and depression. It was consistently noted that players in the more full contact positions (rugby forwards) were most susceptible to impairment, confirming that these players, who are exposed to repeated mild head injuries, are at greater risk of exhibiting postconcussive sequelae / KMBT_363 / Adobe Acrobat 9.54 Paper Capture Plug-in

Traumatic brain injuries (TBI) are one of the leading causes of disability worldwide (Zitnay, 2008), yet one of the least understood neurological conditions (Duncan, 2005). Research has examined short-term deficits; however, less focus has been on the consequences of multiple concussions. Previous electroencephalography (EEG) concussion research has examined the N200 and P300 human event-related potential (ERP) components, yielding inconclusive results (Duncan, Kosmidis & Mirsky, 2005). An ERP component not as frequently examined is the reward positivity, generated by the anterior cingulate cortex (ACC), a region which experiences increased anatomical stress following injury. In this study, 51 students from the University of Victoria took a ‘Concussion Survey’ to determine participant history and groups; no history of concussion, a single injury or multiple injuries (2+). Participants performed an oddball and decision-making task while EEG data was collected. No significant differences were found between groups for the N200, P300 or reward positivity peak latencies or amplitudes. Both concussion groups yielded attenuated peak amplitudes, but no differences existed between the group with a single concussion versus multiple. Unexpectedly, N200 and reward positivity peak latencies were greater in the group with single injuries, compared to those with a history of multiple concussions. This study adds to a continuous line of inconclusive research on the N200 and P300, suggesting minimal cognitive deficits result from concussive injuries. Furthermore, no noticeable differences were observed between groups with a single versus multiple injuries. While the ACC is located in a region of increased stress following TBI, functional deficits impacting the reward positivity may not be as significant as previously hypothesized. Results may be impacted by confounding variables, including not reliably being able to account for time since injury, injury severity and differences in gender dispersion of participants. With concussions on the rise, continued research, particularly longitudinally and within-subjects is critical for the advancement of both TBI prevention and management. / Graduate