Introduktion: Traumatisk hjärnskada är en av det ledande orsakerna till mortalitet och morbiditet globalt. Traumatisk hjärnskada graderas som mild, måttlig eller svår skada. Prognosen kan variera beroende på allvarlighetsgraden, långvarig medvetslöshet samt storleken på primär och sekundär skada. De förlorade eller nedsatta funktioner som hjärnskadan medfört kan i olika grad påverka individers livssituation. Syfte: Syftet med denna studie var att beskriva hur individer med en traumatisk hjärnskada upplever sin livssituation tiden efter den akuta fasen av skadan. Metod: En kvalitativ systematisk litteraturstudie med beskrivande design. Studiens resultat baserades på 10 vetenskapliga originalartiklar från databaserna PubMed och CINAHL. Resultat: Fyra huvudkategorier identifierades: komplikationer, ett annat liv, mötet med hälso- och sjukvården samt vardagen med traumatisk hjärnskada. De mest framträdande komplikationerna var fysiska, kognitiva och psykosociala svårigheter. En förändrad självbild och att acceptera skadan gav upphov till känslan av ett annat liv efter skadan. Information, kommunikation och stöd var viktiga delar i mötet med hälso- och sjukvården. Vardagen med traumatisk hjärnskada omfattade närståendes betydelse, arbetsliv och återhämtning vilket var viktiga delar för en fungerande vardag. Slutsats: Individer som drabbats av traumatisk hjärnskada upplever i olika grad att livet förändras efter skadan. Hur komplikationer inverkar på livet, känslan av ett annat liv, mötet med hälso- och sjukvården samt vardagen med traumatisk hjärnskada var dominerande upplevelser som alla påverkade och kunde förändra individens livssituation. Upplevelserna av en förändrad livssituation kan bidra till känslan av att inte fylla sin funktion i livet vilket kan resultera i en minskad känsla av sammanhang. För att tillmötesgå dessa individer och optimera förutsättningarna krävs god information, kommunikation, förståelse och planering från hälso- och sjukvården och samhället.  Nyckelord: traumatisk hjärnskada, vuxna, livsavgörande händelser, känsla av sammanhang, kvalitativ systematisk litteraturstudie / Introduction: Traumatic brain injury is a worldwide leading cause of death and disability. Traumatic brain injuries can be graded as mild, moderate and severe. The prognosis can vary depending on severity, length of unconsciousness and the size of the primary and/or secondary trauma. The reduced or lost functions that the brain injury brings can to various extents influence individuals’ life situation. Purpose: The purpose of this study was to describe how individuals with a traumatic brain injury experience their life situation following the acute phase of the injury.  Method: Qualitative systematic literature study with a descriptive design. The result of the study is based on 10 scientific original articles from the databases PubMed and CINAHL. Results: Four main categories were identified: Complications, Another life, Encounter with healthcare and Daily life with traumatic brain injury. The most prominent complications were physical, cognitive and psychosocial difficulties. A changed self-perception and to accept the injury contributed to the sense of another life after the injury. Information, communication and support were crucial factors in the encounter with healthcare. Daily life with traumatic brain injury included the importance of relatives, working life and recovery which were important factors for a functional daily life. Conclusion: Individuals with traumatic brain injury experience life changes in varying degrees after the injury. Important aspects of the individuals’ life situation included: impact of complications, a feeling of a different life, encounters with healthcare and perceptions of daily life. The experiences of life changes may contribute to a feeling of not being able to fulfill life's duties. That may result in a lower sense of coherence. Adjustment and improvement of the conditions for these individuals require adequate information, communication, understanding and planning from healthcare and society.  Keywords: traumatic brain injury, adults, life change events, sense of coherence, qualitative systematic literature study Introduction: Traumatic brain injury is a worldwide leading cause of death and disability. Traumatic brain injuries can be graded as mild, moderate and severe. The prognosis can vary depending on severity, length of unconsciousness and the size of the primary and/or secondary trauma. The reduced or lost functions that the brain injury brings can to various extents influence individuals’ life situation. Purpose: The purpose of this study was to describe how individuals with a traumatic brain injury experience their life situation following the acute phase of the injury.  Method: Qualitative systematic literature study with a descriptive design. The result of the study is based on 10 scientific original articles from the databases PubMed and CINAHL. Results: Four main categories were identified: Complications, Another life, Encounter with healthcare and Daily life with traumatic brain injury. The most prominent complications were physical, cognitive and psychosocial difficulties. A changed self-perception and to accept the injury contributed to the sense of another life after the injury. Information, communication and support were crucial factors in the encounter with healthcare. Daily life with traumatic brain injury included the importance of relatives, working life and recovery which were important factors for a functional daily life. Conclusion: Individuals with traumatic brain injury experience life changes in varying degrees after the injury. Important aspects of the individuals’ life situation included: impact of complications, a feeling of a different life, encounters with healthcare and perceptions of daily life. The experiences of life changes may contribute to a feeling of not being able to fulfill life's duties. That may result in a lower sense of coherence. Adjustment and improvement of the conditions for these individuals require adequate information, communication, understanding and planning from healthcare and society.  Keywords: traumatic brain injury, adults, life change events, sense of coherence, qualitative systematic literature study

Schädel-Hirn-Traumata sind die häufigste Ursache von Tod und Behinderung bei jungen Erwachsenen und oftmals ein Grund für Erwerbsunfähigkeit. Deshalb sind das Verständnis der zugrundeliegenden Pathomechanismen und die Entwicklung von Rehabilitationsstrategien von höchster Wichtigkeit. Einer der Hauptschädigungsmechanismen sind diffuse axonale Schädigungen. Diese treten insbesondere in frontalen Hirnregionen auf und führen entsprechend zu einer Beeinträchtigung exekutiver Funktionen und Veränderungen im Verhalten noch Jahre nach dem Ereignis. Unsere Studie mit Patienten im chronischen Stadium zielte auf eine genauere Charakterisierung frontaler Funktionen nach Schädel-Hirn-Trauma. In einem ersten behavioralen Experiment setzten wir zwei Paradigmen ein, die einerseits mit dem frontolateralen (Stroop-Interferenz-Aufgabe) und andererseits mit dem frontomedianen Kortex (Aufgabe zur Unterdrückung von Handlungsimitation) assoziiert sind (Schroeter et al., 2007). Die Patienten waren spezifisch in der Aufgabe zur Unterdrückung von Handlungsimitation als Hinweis auf eine Alteration des anterioren frontomedianen Kortex beeinträchtigt. Die Defizite waren hierbei eng mit Veränderungen des Verhaltens und der posttraumatischen Amnesie, die das Outcome nach Schädel-Hirn-Trauma vorhersagt, verbunden. In einem zweiten fMRT-Experiment überprüften wir die Hypothese einer frontomedianen Dysfunktion mittels eines Paradigmas, das spezifisch frontomediane Strukturen beansprucht. Hierbei wurden evaluative Urteile mit semantischen Gedächtnisinhalten kontrastiert („Angela Merkel ist eine gute Bundeskanzlerin“ vs. „Angela Merkel ist Bundeskanzlerin“). Die Ergebnisse bestätigen, dass Patienten nach Schädel-Hirn-Trauma durch persistierende frontomediane Beeinträchtigungen charakterisiert sind. Unsere Ergebnisse stimmen gut mit der Literatur überein, welche Defizite bei der „Theory of Mind“ und sozialen Kognition, die ebenfalls wesentlich mit dem frontomedianen Kortex verbunden sind, berichtet. Die Studie trägt zum Verständnis der Pathomechanismen nach Schädel-Hirn-Trauma bei. Frontomediane Alterationen scheinen wesentlich für die Langzeitfolgen verantwortlich zu sein. Deshalb sollten frontomediane Funktionen in der Diagnostik, insbesondere zur Einschätzung der Prognose, und der Rehabilitation eine stärkere Beachtung finden.

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This dissertation presents an investigation and design optimization of energy absorbent protective systems that protect the brain. Specifically, the energy absorption characteristics of the bighorn sheep skull-horn system were quantified and used to inform a topology optimization performed on a football helmet facemask leading to reduced values of brain injury indicators. The horn keratin of a bighorn sheep was experimentally characterized in different stress states, strain rates, and moisture contents. Horn keratin demonstrated a clear strain rate dependence in both tension and compression. As the strain rate increased, the flow stress increased. Also, increased moisture content decreased the strength and increased ductility. The hydrated horn keratin energy absorption increased at high strain rates when compared to quasi-static data. The keratin experimental data was then used to inform constitutive models employed in the simulation of bighorn sheep head impacts at 5.5 m/s. Accelerations values as high as 607 G’s were observed in finite element simulations for rams butting their heads, which is an order of magnitude higher than predicted brain injury threshold values. In the most extreme case, maximum tensile pressure and maximum shear strains in the ram brain were 245 kPa and 0.28, respectively. These values could serve as true injury metrics for human head impacts. Finally, a helmeted human head Finite Element (FE) model is created, validated, and used to recreate impacts from a linear impactor. The results from these simulations are used to train a surrogate model, which is in turn utilized in multi-objective design optimization. Brain injury indicators were significantly reduced by performing multi-objective design optimization on a football helmet facemask. In particular, the tensile pressure and maximum shear strain in the brain decreased 7.5 % and 39.5 %, respectively when comparing the optimal designs to the baseline design. While the maximum tensile pressure and maximum shear strain values in the brain for helmeted head impacts (30.2 kPa and 0.011) were far less than the ram impacts (245 kPa and 0.28), helmet impacts up to 12.3 m/s have been recorded, and could easily surpass these thresholds.

Traumatic brain injury is highly prevalent in the United States yet there is little understanding of how the brain responds during injurious loading. A confounding problem is that because testing conditions vary between assessment methods, brain biomechanics cannot be fully understood. Data mining techniques were applied to discover how changes in testing conditions affect the mechanical response of the brain. Data were gathered from literature sources and self-organizing maps were used to conduct a sensitivity analysis to rank considered parameters by importance. Fuzzy C-means clustering was applied to find any data patterns. The rankings and clustering for each data set varied, indicating that the strain rate and type of deformation influence the role of these parameters. Multivariate linear regression was applied to develop a model which can predict the mechanical response from different experimental conditions. Prediction of response depended primarily on strain rate, frequency, brain matter composition, and anatomical region.

Subconcussive (SC) impacts have become a growing concern within the neuroscience community regarding the immediate and long-lasting effects of sports-related injuries. While a single low-level impact, i.e., a subconcussion, may not cause cerebral perturbations, it has been increasingly recognized that repeated SC exposure can induce deleterious effects. Therefore, determining the lower limits of systematic perturbation resulting from multiple SC impacts is of critical importance in expanding our understanding of cerebral vulnerability and recovery. Currently, there is a lack of correlation between a mild traumatic brain injury (mTBI) and repeated SC impacts with respect to injury biomechanics. Moreover, the cumulative threshold for repetitive low-level impacts is currently undefined. Thus, this research was designed to determine the pathophysiological differences between a single impact of an mTBI and repeated SC impacts with a subdivided cumulative kinetic energy of the single mTBI impact. In order to address this gap in knowledge, the present investigation employed a surgery-free, closed-head, weight drop injury device capable of producing repeatable, head impacts within a rat model. General locomotion and anxiety-like behavior were assessed using an Open Field Test and motor coordination dysfunction was measured using the rotarod assay. Neuroinflammation was measured using immunohistochemical assessment of astrogliosis (GFAP) and microgliosis (Iba-1) within the hippocampus. Additionally, immunohistochemical assessment of neuronal loss (NeuN) was measured within the hippocampus. To investigate the tolerance and the persistence of cerebral vulnerability following a single mTBI and repeated subconcussive impacts, measurement outcomes were assessed over two-time points (3- and 7-days) post final impact. Although injury groups were not statistically different from their associated sham groups with respect to behavioral outcomes; on average, RSC injury rats displayed a significant increase in anxious-like behavior after 7-days of recovery compared to the single mTBI group. From an inflammatory perspective, both mTBI and RSC injury groups led to extensive microgliosis in the gray matter following 3-days post-impact. Overall, this work’s findings do not provide evidence in support of the notion that repeated subconcussive impacts do result in behavioral disturbances and neuroinflammation, that do not manifest following a single mTBI of the same energy input.

Thèse de doctorat présenté en vue de l'obtention du doctorat en psychologie - recherche intervention, option neuropsychologie clinique (Ph.D) / L’objectif principal de la thèse est d’outiller les cliniciens œuvrant auprès d’une population atteinte d’un traumatisme craniocérébral (TCC) dans l’établissement d’un profil compréhensif et un pronostic des fonctions exécutives (FE), ainsi que dans leur capacité à cibler les patients qui développeront des difficultés d’intégration sociale, sur la base des troubles cognitifs objectivés et plus précisément des troubles des FE. Afin de répondre à cet objectif, la présente thèse contient deux articles qui se basent sur le modèle théorique de Miyake (Miyake, Friedman, et al., 2000) afin de définir les FE. Le premier article s’intéresse à caractériser les associations entre des variables sociodémographiques, liées au TCC léger et des symptômes post TCC léger d’une part, et les performances des FE d’autre part. Le deuxième article vise à (1) mesurer la récupération des FE entre la phase aiguë et six mois post-TCC et (2) explorer la relation entre les FE et la participation sociale après un TCC. Les résultats des articles suggèrent principalement que les personnes ayant subi un TCC léger qui sont les plus éduquées et dont le QI estimé prémobide est plus élevé (réserve cognitive plus grande), sont susceptibles de présenter de meilleures performances aux mesures des FE à la suite de leur accident. Les résultats suggèrent aussi que la performance des patients sur certaines mesures des FE s’améliore significativement dans les six mois suivant leur accident et qu’elle peut être associée, notamment pour la fluence verbale alternée, avec le niveau de participation sociale des patients après leur accident. Globalement, les résultats de cette thèse nous permettent de statuer que certains facteurs sont importants à prendre en compte lorsque l’on évalue les FE chez des personnes atteintes d’un TCC, et ce, afin de mieux comprendre les différences inter-individuelles chez cette population. Ainsi, la thèse suggère qu’il est crucial de considérer la notion de réserve cognitive avec une population atteinte d’un TCC. Puisqu’il est postulé que la réserve cognitive permet de compenser les déficits cognitifs, les déficits des FE chez des patients présentant une haute réserve cognitive pourraient apparaitre comme plus préoccupant que chez des patients présentant un faible niveau de réserve cognitive. De surcroît, les résultats de la thèse mettent de l’avant l’importance du test de fluence verbale alternée qui s’avère suffisamment sensible auprès de cette population pour mesurer la récupération des FE dans le temps, mais également pour donner un portrait de l’atteinte exécutive qui pourrait aussi se manifester et être associée à certaines difficultés de participation sociale dans la vie de tous les jours. / The main objective of this thesis is to provide clinicians working with a population suffering from traumatic brain injury (TBI) in establishing an accurate comprehensive profile and prediction of executive functions (EF), as well as in their ability to target patients who will develop difficulties in social integration, based on objectified cognitive disorders and more specifically on EF disorders. In order to meet this objective, this thesis contains two articles that will use Miyake's theoretical model (Miyake, Friedman, et al., 2000) to define EF. The first paper is interested in characterizing the associations between sociodemographic variables, related to mild TBI and post- mild TBI symptoms on the one hand, and EF performance on the other. The second article aims to (1) measure the recovery of EF between the acute phase and six months post-TBI and (2) explore the relationship between EF and social participation after TBI. The results of the articles primarily suggest that individuals with mild TBI who are more educated and have higher premorbid estimated IQ (cognitive reserve), are likely to show better performance on EF measures following their accident. The results also suggest that patients' performance on some EF measures improves significantly in the six months following their accident and may be associated, particularly for alternating verbal fluency, with patients' level of social participation following their accident. Overall, the results of this thesis allow us to state that certain factors are important to consider when assessing cognitive functions, especially EF in people with TBI. Thus, the thesis suggests that it is crucial to consider the notion of cognitive reserve with a TBI population. Since cognitive reserve is postulated to compensate for cognitive deficits, EF deficits in patients with high cognitive reserve might appear to be of greater concern than in patients with low cognitive reserve. Furthermore, the results of the thesis highlight the importance of the alternate verbal fluency test, which is sufficiently sensitive in this population to measure the recovery of EFs over time, but also to give a picture of the executive impairment that could also occur and be association with some difficulties in social participation in everyday life.

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.

Moderate-to-severe traumatic brain injury (M/S TBI) is a growing public health concern with significant impact on the cognitive functioning of survivors. Cognitive control and deficits in awareness have been linked to poor recovery and rehabilitation outcomes. One way to research cognitive control is through awareness of errors using electroencephalogram and event-related potentials (ERPs). Both the error-related negativity and the post-error positivity components of the ERP are linked to error awareness and cognitive control processes. Attentional capacity and levels of apathy influence error awareness in those with M/S TBI. There are strong links between awareness, attention, and apathy. However, limited research has examined the role of attention, awareness, and apathy using electrophysiological indices of error awareness to further understand cognitive control in a M/S TBI sample. The current study sought to elucidate the role of apathy in error awareness in those with M/S TBI. Participants included 75 neurologically-healthy controls (divided randomly into two control groups) and 24 individuals with M/S TBI. All participants completed self-report measures of mood, apathy, and executive functioning, as well as a brief neuropsychological battery to measure attention and cognitive ability. To measure awareness, participants completed the error awareness task (EAT), a modified Stroop go/no-go task. Participants signaled awareness of errors committed on the previous trial. The M/S TBI group decreased accuracy while improving or maintaining error awareness compared to controls over time. There were no significant between-group differences for ERN and Pe amplitudes. Levels of apathy in the M/S TBI group were included in three multiple regression analyses predicting proportion of unaware errors, ERN amplitude, and Pe amplitude. Apathy was predictive of error awareness, although not in the predicted direction. Major analyses were replicated using two distinct control groups to determine potential sample effects. Results showed consistent results comparing both control groups to a M/S TBI group. Findings show variable levels of awareness and accuracy over time for those with M/S TBI when compared to controls. Conclusions include varying levels of attention and awareness from the M/S TBI group over time, evidenced by improving awareness of errors when they are happening, but an inability to regulate performance sufficiently to improve accuracy. Levels of apathy are playing a role in error awareness, however, not in predicted directions. The study provides support for the role of attentional impairments in error awareness and encourages future studies to look for varying levels of performance within a given task when using populations linked to elevated levels of apathy and attentional deficits.