Méthodes et principaux résultats. Dans une revue systématique des études sur les facteurs déclenchants des infarctus cérébraux, nous n’avons identifié qu’une seule étude, négative, consacrée aux événements de vie. Nous avons montré, dans une étude prospective portant sur 247 patients admis pour un infarctus cérébral, qu’une exposition à au moins 1 évènement de vie était plus fréquente dans le mois précédant l’infarctus cérébral que dans les 5 périodes témoins (OR=2,96 ; IC à 95% 2,19-4,00). L’exposition à des évènements de vie était aussi un facteur prédictif des dépressions survenant dans les 6 mois suivant un infarctus cérébral. Les autres facteurs prédictifs de dépression post-AVC étaient un score de Rankin > 2, un antécédent de dépression, une lésion caudée et/ou lenticulaire gauche, le sexe féminin et des pleurs pathologiques. Conclusion et perspectives. Ce travail de thèse apporte des arguments en faveur d’un rôle des évènements de vie d’une part, dans la survenue à court terme d’un infarctus cérébral, d’autre part dans la survenue d’une dépression dans les 6 mois suivant un AVC. Il souligne aussi les difficultés spécifiques de l’étude des événements de vie concernant leur définition, l’évaluation de leur sévérité, les biais de rappel et la définition de la période à risque. Nos résultats doivent être confirmés et précisés avant d’évaluer le bénéfice d’une stratégie préventive. / Methods and main results. In our systematic review of potential triggers of ischemic stroke, the only study that examined stressful life events didn’t show any association with stroke onset. In a prospective study of 247 consecutive patients admitted for ischemic stroke, exposure to at least one stressful life event was significantly more common during the first month preceding stroke onset than during the five control periods (OR=2.96 ; 95% CI 2.19-4.00). Stressful life events exposure also predicted depression occurring within six months after ischemic stroke onset. The other predictors of post-stroke depression were a modified Rankin score > 2, a prior history of depression, a left caudate and/or lenticular lesion, the female sex and pathologic crying.Conclusion and perspectives. Our results support the role of stressful life events as triggers of ischemic stroke and predictors of post-stroke depression. Our research also highlights the difficulty of studying stressful life events, due to potential influence of memory biases and lack of precise definitions of stressful life events, severe vs. minor events and hazard period durations. These preliminary results should be confirmed in order to assess benefits of preventive strategies.

Base teórica: O Acidente Vascular Cerebral (AVC) é a causa mais comum de novos diagnósticos de epilepsia no idoso. Embora a epilepsia pós-AVC seja um fenômeno clínico reconhecido há muito tempo, seguem muitas questões não resolvidas. Além disso, nas últimas duas décadas, o tratamento do AVC isquêmico sofreu mudanças radicais com a introdução da trombólise e da hemicraniectomia descompressiva (HD) para o tratamento do infarto maligno de artéria cerebral média (ACM). As consequências destas duas novas abordagens terapêuticas nas características da epilepsia pós-AVC ainda são pouco exploradas. Objetivo: Estudar as características e estimar fatores de risco para as crises epilépticas ou a epilepsia pós-AVC em pacientes submetidos ao tratamento agudo (Estudo 1) ou HD para infarto maligno de ACM (Estudo 2). Métodos: O estudo 1 é uma coorte de 153 pacientes submetidos a trombólise. Variáveis estudadas incluiram fatores de risco para o AVC e variáveis associadas ao AVC isquêmico agudo e trombólise. Utilizamos a análise de regressão de Cox para o estudo das variáveis que se associaram de forma independente com crises epilépticas, epilepsia pós-AVC e o desfecho do AVC. O estudo 2 é também uma coorte que retrospectivamente avaliou 36 pacientes com infarto maligno de ACM tratados com HD. Tempo, incidência e fatores de risco para crises epilépticas e desenvolvimento de epilepsia foram analisados. Resultados: Estudo 1: 74 pacientes (48,4%) eram mulheres; média de idade foi 67,2 anos (DP=13,1). Média do NIHSS na chegada foi 10,95 (DP=6,25) e 2,09 (DP=3,55) após 3 meses. Transformação hemorrágica ocorreu em 22 (14,4%) dos pacientes. Foi considerado desfecho bom classificação na escala modificada de Rankin (mRS) 0-1, sendo encontrado em 87 (56,9%) dos pacientes. Vinte e um pacientes (13,7%) tiveram crises epilépticas e 15 (9,8%) desenvolveram epilepsia após a trombólise. Crises epilépticas foram associadas de forma independente com transformação hemorrágica e desfecho não favorável (mRS ≥ 2) em três meses após o AVC. Transformação hemorrágica e mRS ≥ 2 avaliados em 3 meses, associaram-se de forma independente com epilepsia pós-AVC. Crises epilépticas surgiram como um fator de risco independente para desfecho pobre. Estudo 2. A média de seguimento dos pacientes foi de 1.086 (DP= 1.172) dias. Nove pacientes morreram antes de receberem alta hospitalar e no período de um ano, 11 pacientes haviam morrido. Quase 60% alcançaram mRS ≤ 4. Treze pacientes desenvolveram crises dentro da primeira semana após o AVC. No total, crises epilépticas ocorreram em 22 (61%) dos 36 pacientes. Dezenove pacientes (56%) dos 34, sobreviveram ao período agudo e desenvolveram epilepsia após infarto da ACM e HD. Questionamos aos pacientes ou responsáveis se eles se arrependeram de terem autorizado a HD no momento do AVC. Também foi perguntado se eles autorizariam a HD novamente. Trinta e dois (89%) não se arrependeram de ter autorizado a HD no momento do infarto agudo da ACM, e autorizaria novamente em retrospecto. Conclusão: Confirmamos que as frequências de crises ou epilepsia pós-AVC e trombolítico são comparáveis com as frequências das décadas da era pré-trombólise e confirmamos a alta incidência de crises epilépticas e epilepsia após infartos malignos de ACM submetidos a HD. Em nosso estudo, as crises epilépticas associaram-se de forma independente com pior prognóstico após terapia trombolítica. / Background: The most common cause of newly diagnosed epilepsies in the elderly is stroke. Although post-stroke epilepsy is a well-studied stroke complication, many questions remain unsolved. In addition, during the past two decades, the treatment of stroke has changed dramatically with the introduction of thrombolysis for treatment of acute ischemic stroke (AIS) and decompressive hemicraniectomy (DHC) for malignant middle cerebral artery infarction (MCA). The consequences of these two new therapeutic approaches for characteristics of post-stroke epilepsy remains poorly explored. Objective: To study characteristics and estimate risk factors for acute seizures or post-stroke epilepsy in patients submitted to thrombolysis for treatment of acute stroke (Study 1) or DHC for malignant MCA infarction. Methods: Study 1 is a cohort study of 153 patients submitted to thrombolysis. Variables studied included risk factors for stroke, and variables related to acute stroke and thrombolysis. Variables independently associated with seizures, pos-stroke epilepsy or stroke outcome were defined using Cox regression analysis. Study 2 is also a cohort study that retrospectively assessed 36 patients with malignant stroke of the MCA submitted to DHC. Timing, incidence and plausible risk factors for seizure and epilepsy development were analyzed in these patients. Results: Study 1. Seventy-four patients (48.4%) were female; mean age of patients was 67.2 years-old (SD=13.1). Initial NIHSS mean score was 10.95 (SD=6.25) and 2.09 (SD=3.55) after three months. Hemorrhagic transformation occurred in 22 (14.4%) patients. A good outcome, as defined by a modified Rankin Scale (mRS) of 0-1, was observed in 87 (56.9%) patients. Twenty one (13.7%) patients had seizures and 15 (9.8%) patients developed epilepsy after thrombolysis. Seizures were independently associated with hemorrhagic transformation and with mRS ≥ 2 three months after stroke. Hemorrhagic transformation and unfavorable outcome, as measured by mRS ≥ 2 after three months, were variables independently associated with post-stroke epilepsy. Seizures emerged as an independent factor for poor outcome in stroke thrombolysis. Study 2. Mean patient follow-up time was of 1.086 (SD=1.172) days. Nine patients died before being discharged and after one year eleven patients died. Almost 60% had the modified Rankin score ≤ 4. Thirteen patients developed seizures within the first week after stroke. In total, seizures occurred in 22 (61%) of 36 patients. Nineteen patients (56%) out of 34 patients who survived the acute period developed epilepsy after MCA infarcts and DHC. Also, we asked patients or the person responsible for them whether they regretted, in retrospect, having authorized DHC at the time of the stroke. It was also asked whether they would authorize DHC again. Thirty- two (89%) did not regret having authorized DHC at the time of acute MCA infarct, and would authorize DHC again in retrospect. Conclusion: We confirm that seizures or post-stroke epilepsy rates after thrombolysis are comparable with rates from pre-thrombolysis decades and a high incidence of seizures and epilepsy after malignant MCA infarcts submitted to DHC. In our study, seizures were an independent risk factor associated with worst outcome after thrombolysis therapy.

Base teórica: O Acidente Vascular Cerebral (AVC) é a causa mais comum de novos diagnósticos de epilepsia no idoso. Embora a epilepsia pós-AVC seja um fenômeno clínico reconhecido há muito tempo, seguem muitas questões não resolvidas. Além disso, nas últimas duas décadas, o tratamento do AVC isquêmico sofreu mudanças radicais com a introdução da trombólise e da hemicraniectomia descompressiva (HD) para o tratamento do infarto maligno de artéria cerebral média (ACM). As consequências destas duas novas abordagens terapêuticas nas características da epilepsia pós-AVC ainda são pouco exploradas. Objetivo: Estudar as características e estimar fatores de risco para as crises epilépticas ou a epilepsia pós-AVC em pacientes submetidos ao tratamento agudo (Estudo 1) ou HD para infarto maligno de ACM (Estudo 2). Métodos: O estudo 1 é uma coorte de 153 pacientes submetidos a trombólise. Variáveis estudadas incluiram fatores de risco para o AVC e variáveis associadas ao AVC isquêmico agudo e trombólise. Utilizamos a análise de regressão de Cox para o estudo das variáveis que se associaram de forma independente com crises epilépticas, epilepsia pós-AVC e o desfecho do AVC. O estudo 2 é também uma coorte que retrospectivamente avaliou 36 pacientes com infarto maligno de ACM tratados com HD. Tempo, incidência e fatores de risco para crises epilépticas e desenvolvimento de epilepsia foram analisados. Resultados: Estudo 1: 74 pacientes (48,4%) eram mulheres; média de idade foi 67,2 anos (DP=13,1). Média do NIHSS na chegada foi 10,95 (DP=6,25) e 2,09 (DP=3,55) após 3 meses. Transformação hemorrágica ocorreu em 22 (14,4%) dos pacientes. Foi considerado desfecho bom classificação na escala modificada de Rankin (mRS) 0-1, sendo encontrado em 87 (56,9%) dos pacientes. Vinte e um pacientes (13,7%) tiveram crises epilépticas e 15 (9,8%) desenvolveram epilepsia após a trombólise. Crises epilépticas foram associadas de forma independente com transformação hemorrágica e desfecho não favorável (mRS ≥ 2) em três meses após o AVC. Transformação hemorrágica e mRS ≥ 2 avaliados em 3 meses, associaram-se de forma independente com epilepsia pós-AVC. Crises epilépticas surgiram como um fator de risco independente para desfecho pobre. Estudo 2. A média de seguimento dos pacientes foi de 1.086 (DP= 1.172) dias. Nove pacientes morreram antes de receberem alta hospitalar e no período de um ano, 11 pacientes haviam morrido. Quase 60% alcançaram mRS ≤ 4. Treze pacientes desenvolveram crises dentro da primeira semana após o AVC. No total, crises epilépticas ocorreram em 22 (61%) dos 36 pacientes. Dezenove pacientes (56%) dos 34, sobreviveram ao período agudo e desenvolveram epilepsia após infarto da ACM e HD. Questionamos aos pacientes ou responsáveis se eles se arrependeram de terem autorizado a HD no momento do AVC. Também foi perguntado se eles autorizariam a HD novamente. Trinta e dois (89%) não se arrependeram de ter autorizado a HD no momento do infarto agudo da ACM, e autorizaria novamente em retrospecto. Conclusão: Confirmamos que as frequências de crises ou epilepsia pós-AVC e trombolítico são comparáveis com as frequências das décadas da era pré-trombólise e confirmamos a alta incidência de crises epilépticas e epilepsia após infartos malignos de ACM submetidos a HD. Em nosso estudo, as crises epilépticas associaram-se de forma independente com pior prognóstico após terapia trombolítica. / Background: The most common cause of newly diagnosed epilepsies in the elderly is stroke. Although post-stroke epilepsy is a well-studied stroke complication, many questions remain unsolved. In addition, during the past two decades, the treatment of stroke has changed dramatically with the introduction of thrombolysis for treatment of acute ischemic stroke (AIS) and decompressive hemicraniectomy (DHC) for malignant middle cerebral artery infarction (MCA). The consequences of these two new therapeutic approaches for characteristics of post-stroke epilepsy remains poorly explored. Objective: To study characteristics and estimate risk factors for acute seizures or post-stroke epilepsy in patients submitted to thrombolysis for treatment of acute stroke (Study 1) or DHC for malignant MCA infarction. Methods: Study 1 is a cohort study of 153 patients submitted to thrombolysis. Variables studied included risk factors for stroke, and variables related to acute stroke and thrombolysis. Variables independently associated with seizures, pos-stroke epilepsy or stroke outcome were defined using Cox regression analysis. Study 2 is also a cohort study that retrospectively assessed 36 patients with malignant stroke of the MCA submitted to DHC. Timing, incidence and plausible risk factors for seizure and epilepsy development were analyzed in these patients. Results: Study 1. Seventy-four patients (48.4%) were female; mean age of patients was 67.2 years-old (SD=13.1). Initial NIHSS mean score was 10.95 (SD=6.25) and 2.09 (SD=3.55) after three months. Hemorrhagic transformation occurred in 22 (14.4%) patients. A good outcome, as defined by a modified Rankin Scale (mRS) of 0-1, was observed in 87 (56.9%) patients. Twenty one (13.7%) patients had seizures and 15 (9.8%) patients developed epilepsy after thrombolysis. Seizures were independently associated with hemorrhagic transformation and with mRS ≥ 2 three months after stroke. Hemorrhagic transformation and unfavorable outcome, as measured by mRS ≥ 2 after three months, were variables independently associated with post-stroke epilepsy. Seizures emerged as an independent factor for poor outcome in stroke thrombolysis. Study 2. Mean patient follow-up time was of 1.086 (SD=1.172) days. Nine patients died before being discharged and after one year eleven patients died. Almost 60% had the modified Rankin score ≤ 4. Thirteen patients developed seizures within the first week after stroke. In total, seizures occurred in 22 (61%) of 36 patients. Nineteen patients (56%) out of 34 patients who survived the acute period developed epilepsy after MCA infarcts and DHC. Also, we asked patients or the person responsible for them whether they regretted, in retrospect, having authorized DHC at the time of the stroke. It was also asked whether they would authorize DHC again. Thirty- two (89%) did not regret having authorized DHC at the time of acute MCA infarct, and would authorize DHC again in retrospect. Conclusion: We confirm that seizures or post-stroke epilepsy rates after thrombolysis are comparable with rates from pre-thrombolysis decades and a high incidence of seizures and epilepsy after malignant MCA infarcts submitted to DHC. In our study, seizures were an independent risk factor associated with worst outcome after thrombolysis therapy.

Base teórica: O Acidente Vascular Cerebral (AVC) é a causa mais comum de novos diagnósticos de epilepsia no idoso. Embora a epilepsia pós-AVC seja um fenômeno clínico reconhecido há muito tempo, seguem muitas questões não resolvidas. Além disso, nas últimas duas décadas, o tratamento do AVC isquêmico sofreu mudanças radicais com a introdução da trombólise e da hemicraniectomia descompressiva (HD) para o tratamento do infarto maligno de artéria cerebral média (ACM). As consequências destas duas novas abordagens terapêuticas nas características da epilepsia pós-AVC ainda são pouco exploradas. Objetivo: Estudar as características e estimar fatores de risco para as crises epilépticas ou a epilepsia pós-AVC em pacientes submetidos ao tratamento agudo (Estudo 1) ou HD para infarto maligno de ACM (Estudo 2). Métodos: O estudo 1 é uma coorte de 153 pacientes submetidos a trombólise. Variáveis estudadas incluiram fatores de risco para o AVC e variáveis associadas ao AVC isquêmico agudo e trombólise. Utilizamos a análise de regressão de Cox para o estudo das variáveis que se associaram de forma independente com crises epilépticas, epilepsia pós-AVC e o desfecho do AVC. O estudo 2 é também uma coorte que retrospectivamente avaliou 36 pacientes com infarto maligno de ACM tratados com HD. Tempo, incidência e fatores de risco para crises epilépticas e desenvolvimento de epilepsia foram analisados. Resultados: Estudo 1: 74 pacientes (48,4%) eram mulheres; média de idade foi 67,2 anos (DP=13,1). Média do NIHSS na chegada foi 10,95 (DP=6,25) e 2,09 (DP=3,55) após 3 meses. Transformação hemorrágica ocorreu em 22 (14,4%) dos pacientes. Foi considerado desfecho bom classificação na escala modificada de Rankin (mRS) 0-1, sendo encontrado em 87 (56,9%) dos pacientes. Vinte e um pacientes (13,7%) tiveram crises epilépticas e 15 (9,8%) desenvolveram epilepsia após a trombólise. Crises epilépticas foram associadas de forma independente com transformação hemorrágica e desfecho não favorável (mRS ≥ 2) em três meses após o AVC. Transformação hemorrágica e mRS ≥ 2 avaliados em 3 meses, associaram-se de forma independente com epilepsia pós-AVC. Crises epilépticas surgiram como um fator de risco independente para desfecho pobre. Estudo 2. A média de seguimento dos pacientes foi de 1.086 (DP= 1.172) dias. Nove pacientes morreram antes de receberem alta hospitalar e no período de um ano, 11 pacientes haviam morrido. Quase 60% alcançaram mRS ≤ 4. Treze pacientes desenvolveram crises dentro da primeira semana após o AVC. No total, crises epilépticas ocorreram em 22 (61%) dos 36 pacientes. Dezenove pacientes (56%) dos 34, sobreviveram ao período agudo e desenvolveram epilepsia após infarto da ACM e HD. Questionamos aos pacientes ou responsáveis se eles se arrependeram de terem autorizado a HD no momento do AVC. Também foi perguntado se eles autorizariam a HD novamente. Trinta e dois (89%) não se arrependeram de ter autorizado a HD no momento do infarto agudo da ACM, e autorizaria novamente em retrospecto. Conclusão: Confirmamos que as frequências de crises ou epilepsia pós-AVC e trombolítico são comparáveis com as frequências das décadas da era pré-trombólise e confirmamos a alta incidência de crises epilépticas e epilepsia após infartos malignos de ACM submetidos a HD. Em nosso estudo, as crises epilépticas associaram-se de forma independente com pior prognóstico após terapia trombolítica. / Background: The most common cause of newly diagnosed epilepsies in the elderly is stroke. Although post-stroke epilepsy is a well-studied stroke complication, many questions remain unsolved. In addition, during the past two decades, the treatment of stroke has changed dramatically with the introduction of thrombolysis for treatment of acute ischemic stroke (AIS) and decompressive hemicraniectomy (DHC) for malignant middle cerebral artery infarction (MCA). The consequences of these two new therapeutic approaches for characteristics of post-stroke epilepsy remains poorly explored. Objective: To study characteristics and estimate risk factors for acute seizures or post-stroke epilepsy in patients submitted to thrombolysis for treatment of acute stroke (Study 1) or DHC for malignant MCA infarction. Methods: Study 1 is a cohort study of 153 patients submitted to thrombolysis. Variables studied included risk factors for stroke, and variables related to acute stroke and thrombolysis. Variables independently associated with seizures, pos-stroke epilepsy or stroke outcome were defined using Cox regression analysis. Study 2 is also a cohort study that retrospectively assessed 36 patients with malignant stroke of the MCA submitted to DHC. Timing, incidence and plausible risk factors for seizure and epilepsy development were analyzed in these patients. Results: Study 1. Seventy-four patients (48.4%) were female; mean age of patients was 67.2 years-old (SD=13.1). Initial NIHSS mean score was 10.95 (SD=6.25) and 2.09 (SD=3.55) after three months. Hemorrhagic transformation occurred in 22 (14.4%) patients. A good outcome, as defined by a modified Rankin Scale (mRS) of 0-1, was observed in 87 (56.9%) patients. Twenty one (13.7%) patients had seizures and 15 (9.8%) patients developed epilepsy after thrombolysis. Seizures were independently associated with hemorrhagic transformation and with mRS ≥ 2 three months after stroke. Hemorrhagic transformation and unfavorable outcome, as measured by mRS ≥ 2 after three months, were variables independently associated with post-stroke epilepsy. Seizures emerged as an independent factor for poor outcome in stroke thrombolysis. Study 2. Mean patient follow-up time was of 1.086 (SD=1.172) days. Nine patients died before being discharged and after one year eleven patients died. Almost 60% had the modified Rankin score ≤ 4. Thirteen patients developed seizures within the first week after stroke. In total, seizures occurred in 22 (61%) of 36 patients. Nineteen patients (56%) out of 34 patients who survived the acute period developed epilepsy after MCA infarcts and DHC. Also, we asked patients or the person responsible for them whether they regretted, in retrospect, having authorized DHC at the time of the stroke. It was also asked whether they would authorize DHC again. Thirty- two (89%) did not regret having authorized DHC at the time of acute MCA infarct, and would authorize DHC again in retrospect. Conclusion: We confirm that seizures or post-stroke epilepsy rates after thrombolysis are comparable with rates from pre-thrombolysis decades and a high incidence of seizures and epilepsy after malignant MCA infarcts submitted to DHC. In our study, seizures were an independent risk factor associated with worst outcome after thrombolysis therapy.

Ce mémoire décrit la conception d’un dispositif, communicant sans fil, estimant la dépense énergétique liée à une activité physique (DEAP) de patients présentant de faibles niveaux d’activité physique (post-AVC) dans un milieu sensible comme les hôpitaux en associant fiabilité et sécurité. La nécessité d’une nouvelle conception s’appuie sur les résultats d’études préalables et de tests des dispositifs commercialisés dans ce domaine basés sur des accéléromètres. Pour limiter l’impact des radiofréquences, nous utilisons une technologie optique sans fil avec un émetteur porté par le patient en mouvement (plateforme existante associée à un accéléromètre et un système d’émission par diode infrarouge) et des récepteurs fixés au plafond reliés via Ethernet à un ordinateur distant permettant l’analyse des données. La probabilité de coupure d’un lien mobile en optique sans fil par transmission diffuse a été établie théoriquement en considérant un débit faible et une haute qualité de service classique dans le domaine médical. La mesure du nombre de pertes de trame durant la communication a permis de valider les performances théoriques de la technologie optique sans fil et d’établir la fiabilité de ce type de transmission infrarouge en fonction du nombre de récepteurs. Le calcul de la DEAP a été effectué à partir d’un pré-étalonnage sur deux personnes en comparant les résultats obtenus avec ceux donnés par calorimétrie et ceux donnés par un dispositif commercial. Nous avons optimisé l’étalonnage en réalisant un protocole d’essais avec un échantillon de personnes plus vaste puis avec un échantillon de onze personnes post-AVC pour valider le prototype. / This thesis describes the design of a wireless device, communicating and estimating the energy expenditure (EE) related to physical activity of patients with low levels of physical activity (post stroke) in a sensitive environment such as hospitals by combining reliability and safety. The necessity of a new device is based on the results of preliminary studies and tests of commercially available devices (for the same use) based on accelerometers. To limit the impact of radio frequencies, we use optical technology with a wireless transmitter worn by a mobile patient (existing platform combined with an accelerometer and a system of transmission with infrared diode) and receiver fixed on the ceiling and connected via Ethernet to a remote computer for data analysis. The outage probability of a mobile wireless diffuse optical transmission was theoretically established by considering a low speed and a high quality of service in the conventional medical area. Measuring the number of frame losses during communication validates the theoretical performance of the optical wireless technology and proves the reliability of this type of mobile infrared transmission according to the number of receivers. The calculation of the EE has been performed on a pre-calibration from two people by comparing the results with those given by calorimetry and those given by a commercial device. We optimized the calibration by performing a test protocol with a larger sample of people and with a sample of eleven stroke people to validate the prototype.

La recherche de prédicteurs d’habilités langagières en aphasie post-accident vasculaire cérébral (AVC) basés sur la matière blanche a récemment vu un élan. Cela a été motivé par l’émergence du modèle à double-voie où des faisceaux de matière blanche dorsaux et ventraux jouent un rôle important dans le langage, ainsi que par l’avènement de la tractographie basée sur l’imagerie par résonance magnétique (IRM) de diffusion permettant l’étude in-vivo des faisceaux de matière blanche et de leurs propriétés structurelles. Les caractéristiques structurelles et la charge lésionnelle des faisceaux de matière blanche ont permis de prédire les troubles langagiers dans la phase chronique dans quelques études. Cependant, les prédicteurs aigus de matière blanche des habilités syntaxiques en aphasie post-AVC chronique sont méconnus. L’exploitation de la tractographie dans l’étude des faisceaux langagiers de matière blanche a été limitée par plusieurs défis méthodologiques, dont la difficulté de reconstruire des faisceaux ayant une architecture complexe. Des progrès méthodologiques ont été récemment introduits afin d’adresser ces limites, dont le plus important est la tractographie basée sur l’imagerie à haute résolution angulaire (« HARDI »). Cependant, la fiabilité test-retest de la reconstruction et des propriétés structurelles d’une approche de tractographie HARDI de pointe n’a pas encore été évaluée. Le premier article de cette thèse visait à évaluer la fiabilité test-retest de la reconstruction et des propriétés structurelles (anisotropie fractionnelle, FA; diffusivité moyenne, axiale et radiale, MD, AD, RD; nombre d’orientations de fibres, NuFO; volume du faisceau; longueur moyenne des « streamlines ») de faisceaux langagiers majeurs (arqué, inférieur fronto-occipital, inférieur longitudinal, unciné, AF, IFOF, ILF, UF) obtenus avec une approche de tractographie HARDI de pointe. La majorité des mesures de propriétés structurelles ont montré une bonne ou excellente fiabilité. Ces résultats ont des implications importantes pour l’utilisation d’une telle approche pour l’étude des faisceaux langagiers de matière blanche, car ils renforcent la confiance dans la stabilité des reconstructions et les propriétés structurelles obtenus avec la tractographie HARDI. Le second article de cette thèse visait à déterminer si et quelles propriétés structurelles (FA, AD, volume du faisceau), et la charge lésionnelle, de l’AF et l’UF gauches dans la phase aigüe (≤ 3 jours), obtenus avec l’approche de tractographie HARDI utilisée dans le premier article, prédisent les habilités syntaxiques dans le discours spontané en aphasie post-AVC chronique (≥ 6 mois). Des régressions multiples ascendantes ont révélé que le volume de l’AF prédit la production des verbes, la complexité des phrases et la complexité de la structure argumentale du verbe. Le volume de l’UF a amélioré la prédiction de cette dernière. Ces résultats indiquent que le volume semble être un bon prédicteur précoce des habilités syntaxiques dans le discours spontané en aphasie post-AVC chronique. Mis ensemble, les résultats de cette thèse soulignent l’utilité d’une approche de tractographie HARDI de pointe et son potentiel pour le développement futur de biomarqueurs précoces pouvant améliorer le pronostic de patients ayant une aphasie post-AVC chronique. Cela pourrait promouvoir l’optimisation des soins et le développement de thérapies pour le bienfait des patients et leurs familles. / The search for white matter predictors of language abilities in post-stroke aphasia has gained momentum in recent years. This growing interest has been driven by the emergence of the dual-stream framework where dorsal and ventral white matter bundles play an important functional role in language, as well as the advent of diffusion magnetic resonance imaging (MRI)-based tractography which allows the in-vivo investigation of white matter bundles and their structural properties. Structural characteristics, as well as the lesion load, of white matter bundles have been previously found to predict language impairments in the chronic phase. However, little is known about acute white matter predictors of syntactic abilities in chronic post-stroke aphasia. Leveraging tractography to study white matter language bundles has been limited by several methodological challenges, such as the difficulty of reconstructing white matter bundles with a complex fiber architecture. A number of methodological advances have been introduced fairly recently to address these limitations, the most important of which is the advent of tractography based on High Angular Resolution Imaging (HARDI). However, the test-retest reliability of the reconstruction and structural properties of a state-of-the-art HARDI-based tractography pipeline has not been previously assessed. The first article of the present thesis aimed to assess the test-retest reliability of the reconstruction and structural properties (fractional anisotropy, FA; mean, axial, radial diffusivity, MD, AD, RD; number of fiber orientations, NuFO; bundle volume; mean length of streamlines) of major white matter language bundles (arcuate, inferior fronto-occipital, inferior longitudinal, and uncinate fasciculi, AF, IFOF, ILF, UF) obtained using a state-of-the-art HARDI-based tractography pipeline. Most measures of structural properties showed good to excellent test-retest reliability. These findings have important implications for the use of such a pipeline for the study of white matter language bundles, as they increase our confidence that the reconstructions and structural properties obtained from the tractography pipeline are stable and not due to random variations in measurement. The second article of the thesis aimed to determine whether and which structural properties (FA, AD, bundle volume), as well as the lesion load, of the left AF and UF in the acute phase post-stroke (≤ 3 days), obtained with the same state-of-the-art HARDI-based tractography pipeline used in the first article, predict syntactic abilities in connected speech in chronic post-stroke aphasia (≥ 6 months). Forward multiple regressions revealed that the left AF’s volume predicted the percentage of verbs produced, the structural complexity of sentences, as well as verb-argument structure complexity. The left UF’s volume improved the prediction of verbs with a complex argument structure. These findings indicate that the bundle volume may be a good early predictor of syntactic ability in connected speech in chronic post-stroke aphasia. Overall, the findings of this thesis highlight the usefulness of a state-of-the-art HARDI-based tractography approach and its potential for the future development of early biomarkers that could improve the prognosis and personalized care of patients with chronic post-stroke aphasia. This would promote the optimization of patient care and the development of therapies for the benefit of patients and their families.

Les interfaces cerveau-ordinateur basées sur l’imagerie mentale (MI-BCIs) offrent de nouvelles possibilités d’interaction avec les technologies numériques, telles que les neuroprothèses ou les jeux vidéo, uniquement en effectuant des tâches d’imagerie mentale, telles qu’imaginer d’un objet en rotation. La reconnaissance de la commande envoyée au système par l’utilisateur repose sur l’analyse de l’activité cérébrale de ce dernier. Les utilisateurs doivent apprendre à produire des patterns d’activité cérébrale reconnaissables par le système afin de contrôler les MI-BCIs. Cependant, les protocoles de formation actuels ne permettent pas à 10 à 30 % des personnes d’acquérir les compétences nécessaires pour utiliser les MI-BCIs. Ce manque de fiabilité des BCIs limite le développement de la technologie en dehors des laboratoires de recherche. Cette thèse a pour objectif d’examiner comment le feedback fourni tout au longde la formation peut être amélioré et adapté aux traits et aux états des utilisateurs. Dans un premier temps, nous examinons le rôle qui est actuellement donné au feedback dans les applications et les protocoles d’entraînement à l’utilisation des MI-BCIs. Nous analysons également les théories et les contributions expérimentales discutant de son rôle et de son utilité dans le processus d’apprentissage de contrôle de correlats neurophysiologiques. Ensuite, nous fournissons une analyse de l’utilité de différents feedback pour l’entraînement à l’utilisation des MI-BCIs. Nous nous concentrons sur trois caractéristiques principales du feedback, i.e., son contenu, sa modalité de présentation et enfin sa dimension temporelle. Pour chacune de ces caractéristiques, nous avons examiné la littérature afin d’évaluer quels types de feedback ont été testés et quel impact ils semblent avoir sur l’entraînement. Nous avons également analysé quels traits ou états des apprenants influaient sur les résultats de cet entraînement. En nous basant sur ces analyses de la littérature, nous avons émis l’hypothèse que différentes caractéristiques du feedback pourraient être exploitées afin d’améliorer l’entraînement en fonction des traits ou états des apprenants. Nous rapportons les résultats de nos contributions expérimentales pour chacune des caractéristiques du feedback. Enfin, nous présentons différentes recommandations et défis concernant chaque caractéristique du feedback. Des solutions potentielles sont proposées pour à l’avenir surmonter ces défis et répondre à ces recommandations. / Mental-Imagery based Brain-Computer Interfaces (MI-BCIs) present new opportunities to interact with digital technologies, such as neuroprostheses or videogames, only by performing mental imagery tasks, such as imagining an object rotating. The recognition of the command for the system is based on the analysis of the brain activity of the user. The users must learn to produce brain activity patterns that are recognizable by the system in order to control BCIs. However, current training protocols do not enable 10 to 30% of persons to acquire the skills required to use BCIs. The lack of robustness of BCIs limit the development of the technology outside of research laboratories. This thesis aims at investigating how the feedback provided throughout the training can be improved and adapted to the traits and states of the users. First, we investigate the role that feedback is currently given in MI-BCI applications and training protocols. We also analyse the theories and experimental contributions discussing its role and usefulness. Then, we review the different feedback that have been used to train MI-BCI users. We focus on three main characteristics of feedback, i.e., its content, its modality of presentation and finally its timing. For each of these characteristics, we reviewed the literature to assess which types of feedback have been tested and what is their impact on the training. We also analysed which traits or states of the learners were shown to influence BCI training outcome. Based on these reviews of the literature, we hypothesised that different characteristics of feedback could be leveraged to improve the training of the learners depending on either traits or states. We reported the results of our experimental contributions for each of the characteristics of feedback. Finally, we presented different recommendations and challenges regarding each characteristic of feedback. Potential solutions were proposed to meet these recommendations in the future.

<div>Background: Structural priming – a tendency to reuse previously encountered sentence structures – has been shown to facilitate production of sentences in persons with aphasia (PWA). However, the task-specific and person-specific factors that modulate the strength of priming effects in PWA remain largely unknown. This study examined (a) if PWA and healthy older adults (HOA) demonstrate improved production of passive sentences following comprehension of passive (as opposed to active) prime sentences, (b) whether repeated use of a verb between a prime and target sentence boosts priming effects, and (c) whether individual participants’ deficits in syntactic processing modulate degrees of priming effects.</div><div><br></div><div>Method: The participants (16 HOA and 13 PWA) completed a comprehension-to-production structural priming task. For prime sentences, they completed a sentence-to-picture matching comprehension task. Then, they described a target action picture, which could be described in an active or passive sentence structure. For half of the prime-target pairs, the verb was repeated to compare the priming effects in the same vs. different verb prime conditions (i.e., lexical boost). To analyze individual variability, we examined if PWA’s scores on clinical measures of syntactic comprehension and production were associated with a positive priming effect.</div><div><br></div><div>Results: Both HOA and PWA showed increased production of passive sentences following comprehension of passive primes, although the priming effect was reduced for PWA. A significant lexical boost was found in HOA, but not for PWA. Within PWA, individuals with higher scores on clinical measures of syntactic production, but not syntactic comprehension, showed a significant priming effect.</div><div><br></div><div>Conclusion: The findings suggest that implicit comprehension-to-production structural priming is preserved in aphasia and that lexically-mediated structural priming may not be critical to effectiveness of structural priming in aphasia. Preliminary results indicate that individuals’ syntactic skills in the domain of production may need to be considered when comprehension-to-production priming is used to improve sentence production.</div>

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Following a stroke, normal usage of the impaired limb guides spontaneous recovery across many months or even years; however, recovery is rarely complete. Pre-clinical tools are needed to investigate stroke-induced cortical reorganization over long periods. This thesis aims to characterize stroke impairment and spontaneous recovery in parallel with a battery of behaviour tasks in a mouse model of focal stroke. Young adult Thy1-ChR2 mice were implanted with a transcranial window over the intact skull permitting cortex visualization and enabling longitudinal assessments with light-based motor mapping and intrinsic signal optical imaging. Furthermore, mice were tested on sensorimotor behavioural tasks in parallel to the mapping experiments. These experiments allowed for the quantification of impairments in the sensorimotor cortex and forelimb function while identifying regions within the sensorimotor cortex that show re-mapping associated with behavioural recovery. Following primary motor cortex-stroke induction, both sensory and motor map impairments occurred. Sensory map transient impairments recovered within the same atlas-defined regions two weeks after a primary motor cortex stroke as identified by intrinsic signal optical imaging. In contrast, motor forelimb recovery was observed four weeks after the stroke in the peri-infarct region, the supplemental motor cortex, and the contralesional motor cortex. This recovery was identified through a combination of analyses, including changes in the mapped area and the amplitude of evoked forelimb movements using light-based motor mapping. Behavioural recovery occurred four to six weeks post-stroke, depending on the sensitivity of the task in forelimb impairment. Additionally, the contralesional hemisphere and forelimb did not show impairment acutely but evoked forelimb amplitude was significantly increased by post-stroke week four for both forelimbs. As the first study to conduct within-animal longitudinal spontaneous recovery sensory and motor map experiments using bilateral forelimb and hemispheric representations, we show that 1) photothrombotic stroke impacts both forelimb representations pertained within the ipsilesional hemisphere in LBMM experiments, 2) recovery of the impaired forelimb occurs ipsilesionally and contralesionally and, 3) impairments from stroke observed through motor mapping are functionally relevant and precede behavioural recovery ranging from zero to two or more weeks depending on the motor cortex's involvement in the behavioural task.