The varied impact parameters that characterize an impact to the head have shown to influence the resulting type and severity of outcome injury, both in terms of the dynamic response, and the corresponding deformation of neural tissue. Therefore, when determining head injury risks through event reconstruction, it is important to understand how individual impact characteristics influence these responses. The effect of inbound mass had not yet been documented in the literature. The purpose of this study was to determine the effects of inbound mass on the dynamic impact response and brain tissue deformation. A 50th percentile Hybrid III adult male head form was impacted using a simple pendulum system. Impacts to a centric and a non-centric impact location were performed with six varied inbound masses at a velocity of 4.0 m/s. The peak linear and peak angular accelerations were measured. A finite element model, (UCDBTM) was used to determine brain deformation, namely peak maximum principal strain and peak von Mises stress. Inbound mass produced significant differences for peak linear acceleration for centric (F(5, 24) = 217.55, p=.0005) and non-centric (F(5, 24) = 161.98, p=.0005), and for peak angular acceleration for centric (F(5, 24) = 52.51, p=.0005) and non-centric (F(5, 24) = 4.18, p=.007) impact locations. A change in inbound mass also had a significant effect on peak maximum principal strain for centric (F(5, 24) = 11.04, p=.0005) and non-centric (F(5, 24) = 5.87, p =.001), and for peak von Mises stress for centric (F(5, 24) = 24.01, p=.0005) and non-centric (F(5, 24) = 4.62, p=.004) impact locations. These results indicate the inbound mass of an impact should be of consideration when determining risks and prevention to head and brain injury.

Diss. (sammanfattning) Umeå : Umeå universitet, 2006. / Härtill 3 uppsatser.

In the past decade, numerous studies have examined the correlation between repetitive head trauma in athletes who participated in contact sports and the development of various personality, behavioral, and cognitive changes. Autopsy data from these athletes have uncovered unique patterns of neuropathology that are believed to be associated with the observed clinical symptoms, and together characterize a condition known as chronic traumatic encephalopathy (CTE). Historically, the condition was known as “dementia pugilistica” commonly found in boxers; however, recent studies have identified cases of CTE in retired football players, hockey players, soccer players, war veterans, and other non-athletes. CTE is a progressive disease and clinical signs often appear many years after the trauma. These symptoms frequently include depression, aggression, suicidality, short-term memory loss, and executive functioning impairments. Postmortem examinations of individuals with CTE reveal distinct gross and microscopic pathology, including atrophy of the frontal and temporal cortices, sulcal accumulation of hyperphosphorylated tau, -amyloid deposition, and TAR DNA-binding protein 43 abnormalities. Although current hypotheses suggest that repetitive head trauma causes the development of CTE, the lack of prospective studies hinders our ability to definitively determine its etiology. Likewise, the inability to diagnose CTE in vivo has constrained our attempts to systematically examine the disease’s progressive nature. The goal of this paper is to review the past and current literature on CTE in boxers and football players. We also discuss current hypotheses concerning CTE’s clinical presentation and neuropathology, and situate CTE within the context of other neurodegenerative diseases. Finally, we address the current limitations of CTE research and propose key objectives for future studies.

abstract: Concussion, a subset of mild traumatic brain injury (mTBI), has recently been brought to the forefront of the media due to a large lawsuit filed against the National Football League. Concussion resulting from injury varies in severity, duration, and type, based on many characteristics about the individual that research does not presently understand. Chronic fatigue, poor working memory, impaired self-awareness, and lack of attention to task are symptoms commonly present post-concussion. Currently, there is not a standard method of assessing concussion, nor is there a way to track an individual's recovery, resulting in misguided treatment for better prognosis. The aim of the following study was to determine patient specific higher-order cognitive processing deficits for clinical diagnosis and prognosis of concussion. Six individuals (N=6) were seen during the acute phase of concussion, two of whom were seen subsequently when their symptoms were deemed clinically resolved. Subjective information was collected from both the patient and from neurology testing. Each individual completed a task, in which they were presented with degraded speech, taxing their higher-order cognitive processing. Patient specific behavioral patterns are noted, creating a unique paradigm for mapping subjective and objective data for each patient's strategy to compensate for deficits and understand speech in a difficult listening situation. Keywords: concussion, cognitive processing / Dissertation/Thesis / M.S. Speech and Hearing Science 2013

There is increasing evidence that repeat mild traumatic brain injury (rmTBI) may result in cumulative and long-term symptoms, more pronounced behavioural deficits, and neurodegeneration. Children have a greater susceptibility to head injury and represent a significant at risk population for rmTBI, especially those that participate in contact sports. Despite this, there is a paucity of data on rmTBI pathophysiology in the juvenile brain. The current study utilizes a novel awake closed head injury (ACHI) model to deliver repeat injuries to fully conscious juvenile rats. The ACHI model avoids the potential confounds of anaesthesia, and facilitates the assessment of neurological function immediately after each impact. Results indicate that the ACHI model produces acute neurological deficits after each impact, and that repeat injury worsens outcomes. Behavioural testing identified transient anxiety-like behaviour and motor impairment in response to rmTBI. The functional impairments and affective behaviour were in the absence of tau protein pathology. This study represents the first investigation of the consequences of rmTBI on the juvenile brain using an awake model of brain injury. / Graduate

Falls and collisions are the most common types of events leading to sports-related concussions where impacts to the head play an important role on the onset of traumatic brain injury. Each event can be described by impact parameters that define the loading conditions on the head and brain and are necessary for accurate accident reconstruction employing physical impact tests, anthropometric headforms, and finite element (FE) modelling. It was the purpose of this research to describe the effects and interactions of impact velocity, compliance, mass and impact location on head acceleration and brain tissue strain measures associated with risk of concussions in sports. Impact parameters were varied to capture responses from no-injury up to concussive levels. Study one examined the effect of impact parameters on fall events simulated using a monorail drop tower. Impact mass was varied using three different headforms representing child, adolescent, and adult sizes measuring peak linear and angular acceleration and maximum principal strain. Regression analysis revealed that impact compliance was the most influential on peak linear and angular acceleration measures, meanwhile FE strain was most affected by changes in impact velocity. Smaller headforms tend to produce higher acceleration and strain values, supporting the need for age and size related mechanical definitions of risk. Study two examined the effect of impact parameters for collision events simulated using a multi-mass pendulum to represent common striking masses in sport measuring peak linear and angular acceleration and strain. Study three provided further insight into collision impacts by evaluating the distribution of peak strains in different brain lobes and the volume of the brain experiencing strains passed a critical level. Results show that compliance was similarly the most influential on peak head acceleration whereas peak strain and volume were most affected by impact velocity. Mass-velocity interactions had effects where a 9 kg mass had greater response than 15 kg, but similar to 21 kg. The temporal lobe consistently contained the highest strains with the rear boss non-centric impact location producing the largest values. Interacting impact parameters illustrate the challenges with predicting associated risk of concussion from head collisions in sport and supports the need to identify effective performance ranges of protective materials.

The identification of sport-related concussion (mild traumatic brain injury [mTBI]), its neurocognitive sequelae, and subsequent management have become a top priority within a spectrum of research disciplines at the intersection of psychology and sports medicine. To properly understand the complex neurocognitive changes associated with sport-related concussion in high school age individuals, multiple aspects of the injury were explored including the psychobiological nature of the injury, diagnostic concerns, normative adolescent neurocognitive development and abnormal changes as a result of the injury, and risk for further injury. While a wealth of literature exists in these areas, one aspect in particular, neurocognitive changes associated with sport-related mTBI in adolescents, is the focus of this research study. A review of the current research reveals a lack of exploration into neurocognitive deficits over-time as early as adolescence. To advance the understanding of how sport-related concussions may influence neurocognitive performance during this vulnerable age for brain development, multiple group comparisons were conducted to determine differences based upon reported concussion history. Results suggest that adolescents who experience sport-related concussion demonstrate significantly reduced levels of neurocognitive performance in several domains on initial baseline testing. Furthermore, these findings generally persist upon follow-up neurocognitive testing during adolescence. Thus, persistent neurocognitive deficits found during adolescence may have profound implications for brain development and concussion management.

The varied impact parameters that characterize an impact to the head have shown to influence the resulting type and severity of outcome injury, both in terms of the dynamic response, and the corresponding deformation of neural tissue. Therefore, when determining head injury risks through event reconstruction, it is important to understand how individual impact characteristics influence these responses. The effect of inbound mass had not yet been documented in the literature. The purpose of this study was to determine the effects of inbound mass on the dynamic impact response and brain tissue deformation. A 50th percentile Hybrid III adult male head form was impacted using a simple pendulum system. Impacts to a centric and a non-centric impact location were performed with six varied inbound masses at a velocity of 4.0 m/s. The peak linear and peak angular accelerations were measured. A finite element model, (UCDBTM) was used to determine brain deformation, namely peak maximum principal strain and peak von Mises stress. Inbound mass produced significant differences for peak linear acceleration for centric (F(5, 24) = 217.55, p=.0005) and non-centric (F(5, 24) = 161.98, p=.0005), and for peak angular acceleration for centric (F(5, 24) = 52.51, p=.0005) and non-centric (F(5, 24) = 4.18, p=.007) impact locations. A change in inbound mass also had a significant effect on peak maximum principal strain for centric (F(5, 24) = 11.04, p=.0005) and non-centric (F(5, 24) = 5.87, p =.001), and for peak von Mises stress for centric (F(5, 24) = 24.01, p=.0005) and non-centric (F(5, 24) = 4.62, p=.004) impact locations. These results indicate the inbound mass of an impact should be of consideration when determining risks and prevention to head and brain injury.

Since the introduction of helmets the incidence of traumatic brain injuries (TBI) in ice hockey has greatly decreased, but the incidence of concussions has essentially remained unchanged. Despite goaltenders in ice hockey being the only players on the ice for the entire game, few have assessed the performance of ice hockey goaltender masks. In ice hockey, goaltenders are exposed to impacts from collisions, falls and projectiles. The objective of this study was to assess the protective capacity of ice hockey goaltender masks for three accident events associated with concussion. A helmeted and unhelmeted medium NOCSAE headform were tested under conditions representing three common accident events in ice hockey. Falls were reconstructed using a monorail drop. A pneumatic linear impactor was used to reconstruct collisions and projectile impacts were reconstructed using a pneumatic puck launcher. Three impact locations and three velocities were selected for each accident event based on video analysis of real world concussive events. Peak resultant linear acceleration, peak resultant rotational acceleration and rotational velocity of the headform were measured. The University College Dublin Brain Trauma Model (UCDBTM) was used to calculate maximum principal strain (MPS) and von Mises stress in the cerebrum. The results demonstrated the importance of assessing the protective capacity of ice hockey goaltenders masks for each accident, as each event created a unique response. A comparison of unhelmeted and helmeted impacts revealed ice hockey goaltender masks are effective at reducing the risk of both concussion and TBI for falls and projectiles, but less so for collisions. Further, the risk of more serious injuries was found to increase for falls and collisions as impact velocity increased. The results highlight the importance of impacting multiple locations when assessing the protective capacity of ice hockey goaltenders masks, as different impact locations result in unique responses. Overall this study demonstrated ice hockey goaltenders masks capacity to reduce the risk of concussion across three accident events.

M.A. (Psychology) / The Post Traumatic Amnesic Syndrome, which follows a mild closed head injury, seems to be a common occurrence in the field of neuropsychology. The syndrome is primarily characterised by a transient memory loss of daily events, normally commencing within days after the injury. The symptoms include absent-mindedness, an inability to remember names, dates, numbers and faces, commands and orders given at work. Due to the relatively uncomplicated nature of a mild closed head injury, the syndrome is often overlooked and underestimated in terms of its intensity and psychological damage. Patients are sent home after a brief observation period and medical staff are of the opinion that the patients will recover successfully, without experiencing much psychological or cognitive strain. It is usually thought that the syndrome does not last for more than three to four months. The aim of the research was to determine the nature of the experience of not being able to remember daily events, as part of the post traumatic amnesic syndrome. The influence of the syndrome on the patients' support persons was also investigated