Thèses sur le sujet « Intracerebral haemorrhage »

Spontaneous (non-traumatic) intracerebral haemorrhage accounts for ~10% of all strokes in Western populations. Investigations may identify intracerebral haemorrhage (ICH) as ‘secondary’ to underlying causes such as tumours or aneurysms, but ~80% of ICHs which have no apparent underlying cause (so-called ‘primary’ ICH) tend to be attributed to small vessel vasculopathies such as arteriolosclerosis or cerebral amyloid angiopathy (CAA), on the basis of an adult’s risk factors and clinical and radiographic features of the ICH. The commonly accepted hypothesis is that CAA contributes to lobar ICH and arteriolosclerosis causes non-lobar ICH. In the following thesis, I set out to explore whether (a) the baseline demographic, clinical features and apolipoprotein E genotype of adults with lobar and non-lobar ICH differ, (b) the prognosis of adults with lobar and non-lobar ICH differ and (c) the neuroimaging correlates of small vessel disease in adults with lobar and non-lobar ICH differ since this might provide clues to the vasculopathies underlying lobar and non-lobar ICH. I explored (d) the strength of the association between CAA and ICH by systematically reviewing neuropathological case control studies and (e) the radiological and pathological features of lobar ICH to examine the nature of CAA in persons with lobar ICH and whether any computed tomography (CT) features of ICH are associated with CAA-related lobar ICH. I set up a prospective, community-based inception cohort study of adults with ICH in South East Scotland. Adults with spontaneous primary definite ICH had the opportunity to consent to participate in the Lothian Study of IntraCerebral Haemorrhage, Pathology, Imaging and Neurological Outcome (LINCHPIN), an ethically-approved, prospective community-based research study examining the causes of ICH using apolipoprotein E genotyping, brain MRI and research autopsy in case of death. Of 128 adults with first-ever spontaneous primary definite ICH diagnosed during 2010- 2011, age and pre-morbid hypertension did not differ by ICH location but a history of dementia was more common in adults with lobar ICH. The proportion of adults with one or more non-lobar brain microbleed (BMB) was significantly higher in adults with non-lobar ICH but I did not find any other differences in the severity or distribution of other neuroimaging correlates of small vessel disease between lobar and non-lobar ICH. The apolipoprotein e4 allele was more common in participants with lobar ICH in comparison to those with non-lobar ICH but the frequency of the e2 allele did not differ by ICH location. Adults with lobar ICH were significantly more likely to survive one year after their ICH in comparison to those with non-lobar ICH after adjustment for other known predictors of outcome. From a systematic review of neuropathological case control studies of CAA and ICH, stratified by ICH location, I found a significant association between CAA and lobar ICH but not with ICH in other locations. I examined the radiological and pathological features of 33 adults with first-ever lobar ICH. The presence of CAA or vasculopathy and the severity of CAA in a lobe affected by ICH was concordant with that of the corresponding contralateral unaffected lobe. Capillary CAA was associated with severe CAA. Subarachnoid extension of the ICH tended to be more frequent in those with CAA-related strictly lobar ICH. Having explored the incidence, risk factors and prognosis of lobar and non-lobar ICH, in future work I would aim to establish the strength of the association between CAA and ICH in different brain locations in a neuropathological case control study. Future work should examine the radiopathological features of lobar ICH in a larger cohort and the coexistence of other small vessel diseases, in particular arteriolosclerosis in persons with ICH.

Intracerebral haemorrhage (ICH) is a significant healthcare concern worldwide. Following ICH, primary injury occurs due to physical injury to neurones and glia as a result of mass effect from the haematoma. Secondary mechanisms of injury include haematoma expansion, toxic effects of the products of coagulation and blood breakdown products and sterile inflammation. Perihaematomal oedema can exacerbate mass effect in the acute and sub-acute phase of ICH. At present, the pathophysiology behind the secondary mechanisms of injury following ICH is not fully understood and this has led to inability to translate new treatments from bench to bedside. Haematoma expansion is a significant contributor to neurological deterioration in the acute phase; however, understanding of the factors leading to a third of patients developing haematoma expansion is limited. This thesis presents the results of work aiming to develop a reproducible model of haematoma expansion in preclinical ICH. Using this model we found that a systemic inflammatory stimulus failed to induce haematoma expansion in spontaneously hypertensive rats or their healthy controls. We gained further insight into factors that may contribute to haematoma expansion in ICH by studying the proteomic profile of patients in clinical ICH. We demonstrate the feasibility of multi-modality brain imaging in sub-acute ICH, which we propose will be a useful tool to monitor neuro-inflammation in the acute stages if the disease. Finally, we investigated the association between peripheral markers of inflammation (white blood cell count and C-reactive protein) and perihaematomal oedema at baseline and clinical outcome (mortality at 30 days). Our findings suggest that acute inflammation may drive acute perihaematomal oedema and interestingly, we found a negative association between C-reactive protein at baseline and 30-day mortality. Our findings are significant in the field of clinical ICH, and suggest that the inflammatory response is important. We will take our findings forward in future work with the goal of understanding why haematoma expansion occurs, with the aim of developing a test to identify patients at highest risk and interventions to improve outcome after ICH.

Primary Intracerebral haemorrhage is a severe form of stroke with poor prognosis attributed to haematoma characteristics. High blood pressure is present during the acute phase of intracerebral haemorrhage and associated with poor outcome in part through expansion of haematoma. Data from the ‘Efficacy of Nitric Oxide in Stroke trial’ (ENOS) was used to analyse the performance characteristics of qualitative and quantitative descriptors of intracerebral haematoma. The results showed that formal measurement of haemorrhage characteristics and visual estimates are reproducible. Intracerebral haemorrhage volumes measured using the modified ABC/2 formula were significantly lower compared to standard ABC/2 and computer assisted semi-automatic segmentation. In 629 patients with intracerebral haemorrhage presenting within 48 hours, the effect of blood pressure lowering with transdermal glyceryl trinitrate was assessed. Glyceryl trinitrate lowered blood pressure, was safe but did not improve functional outcome. In a small group of patients treated within 6 hours, glyceryl trinitrate improved functional outcome. Analysis of 246 patients with acute intracerebral haemorrhage from ENOS was undertaken to assess whether there were any differences in functional outcome among those who continued prior antihypertensive drugs during the immediate stroke period compared to those assigned to stop temporarily for 7 days. The results were neutral indicating that there was no benefit in those who continued treatment. Data of 1,011 patients with intracerebral haemorrhage in hyperacute trials from the VISTA collaboration showed differences in baseline characteristics and functional outcomes among patients from various ethnic backgrounds. A systematic review was updated to assess the effect of 26 randomised controlled trials that aimed to alter blood pressure within one week of acute stroke. The results showed that blood pressure reduction did not improve functional outcome irrespective of stroke type. When examined by time, treatment within 6 hours appeared to benefit but the number of patients were small and more studies are needed. The analysis also showed that continuing prestroke antihypertensive drugs in the immediate period after stroke did not benefit and might be harmful. In summary, this thesis provides new information on parameters used to estimate intracerebral haematoma, relationship between management of blood pressure and outcomes after haemorrhagic stroke. The work supports testing of whether very early blood pressure lowering after ictus is beneficial as is being undertaken in ongoing randomised controlled trials. Adjusting for ethnic differences may further identify patients in whom treatment may confer measurable advantage.

Intracerebral Haemorrhage (ICH) exhibits the worst mortality and morbidity of any stroke subtype. There are no efficacious treatments for this condition and little improvement in patient outcome has been noted despite advancements in medical science over the previous three decades. Furthermore, current available data is increasingly obsolete as the population suffering the disease burden rapidly ages and develops co-morbidities. It is thought that future therapies for this condition may be able to target neuroinflammatory response triggered by the formation of brain haemorrhage however there is little published evidence that has examined this aspect of ICH pathophysiology. This study therefore examines the current prognosis of a large cohort of patients with ICH to determine the key factors which result in mortality. We find that patients treated at a specialist centre have a surprising and significantly improved survival advantage. Since clinical practice in the United Kindgom is widely influential, the second part of the study focuses on whether the optimal cases are currently being transferred to these centres. The next part of the study then uses MRI/PET brain imaging for the first time in patients with ICH to establish an important link between the processes of neuroinflammation and Blood-Brain-Barrier breakdown. Finally, the concluding part of the thesis presents functional and radiological data from a rat model of ICH in which the inflammatory cascade has been modulated by the use of an antagonist against IL-1. The thesis thus presents a novel and important contribution in our present understanding of the preclinical and clinical disease process.

Sporadic cerebral amyloid angiopathy is a common small vessel disease that preferentially involves small cortical and leptomeningeal arteries due to progressive amyloid-β deposition in their walls. Cerebral amyloid angiopathy occurs frequently in elderly people, and is a common and important cause of symptomatic lobar intracerebral haemorrhage and cognitive impairment. There is currently a growing interest in cerebral amyloid angiopathy, at least partly thanks neuroimaging, which now allows an unprecedented ability to investigate the disease dynamics in vivo using MRI to reveal complex patterns of cerebral bleeding and ischaemia. The detection of CAA during life is becoming an increasingly important challenge, since approaches of prevention or treatment (disease-modification) are now emerging as realistic possibilities. Determining the most promising treatments requires development of reliable biomarkers, the goal of my research. The main objective of this PhD thesis is to provide new insights into potential clinical and applied clinical neuroimaging biomarkers in patients with cerebral amyloid angiopathy. This is accomplished by a portfolio of research studies investigating: (a) the clinical and radiological spectrum of transient focal neurological episodes as a potential clinical clue for cerebral amyloid angiopathy; (b) cortical superficial siderosis, a distinct pattern on bleeding in the brain, as both a diagnostic and a prognostic marker of cerebral amyloid angiopathy; (c) MRI-visible perivascular spaces topography, as a new marker of small vessel disease and cerebral amyloid angiopathy; (d) potential pathological, neuroimaging and genetic differences in patients with pathology-proven CAA with and without intracerebral haemorrhage and presents evidence for different disease phenotypes; (e) the evidence whether the presence and burden of cerebral microbleeds on MRI scans is associated with an increased risk of recurrent spontaneous ICH, and if this risk is different according to MRI-defined microangiopathy subtype, in a meta-analysis.

This current PhD Thesis in Neuropathology focuses on the development and assessment of in vitro simulation approaches to intracerebral haemorrhage. The PhD Thesis provides a clinical and experimental neuropathological overview of intracerebral haemorrhage as well as an account of the in vitro simulation approaches to the disease, before proceeding to the presentation of the experimental work designed and performed by the author. The development of the herein presented in vitro simulation approaches to intracerebral haemorrhage was based on the use of an immortalized embryonic murine hippocampal cell-line (mHippoE-14) and its response to oligomycin-A and ferrum or haemin under appropriately selected conditions (aiming to simulate the natural history of the disease in a more reliable manner). The PhD Thesis provides a characterization of the mHippoE-14 cell-line (through a real-time cellular response analysis and a cytomorphological characterization), before proceeding to the actual experimental justification of the conditions chosen for the development of the herein presented in vitro simulation approaches to intracerebral haemorrhage, and their assessment. The latter was performed through the undertaking of: (a) real-time cellular response analysis, (b) cytomorphological assessment, (c) profiling of neuronal markers’ expression, (d) neurochemical assessment, and (e) proteomic profiling. All experiments were performed at the University of Glasgow. The current PhD Thesis also provides a critical appraisal of: (a) the utility, novelty and limitations of the developed in vitro simulation approaches, and (b) the positioning of the developed in vitro simulation approaches within the neuropathopoietic context.

Background Stroke is the second most common cause of premature death worldwide, and the leading cause of death and disability in China. Stroke is a clinical syndrome that includes three distinct pathological types (i.e., ischaemic stroke [IS], intracerebral haemorrhage [ICH] and subarachnoid haemorrhage [SAH]) that have a different underlying pathophysiology. Previous observational studies and randomised trials have reported conflicting results on the associations of major blood lipids, including low-density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), and triglycerides with stroke pathological types. Moreover, the causal relevance of many of these associations is still not fully understood. Methods The China Kadoorie Biobank (CKB) prospective study collected questionnaire, physical measurement data, and blood samples on 512 891 adults from 10 diverse regions in China in 2004-2008. By 1st January 2016, over 32 000 incident IS, and 8000 ICH cases were recorded. A nested case-control study of stroke included 16 541 adults (5475 IS, 4776 ICH, and 6290 controls), with measurements of baseline plasma concentrations of LDL-C, HDL-C, and triglycerides, and genotyping of known lipid-related genetic variants. Repeat measurements of blood lipids were obtained in random samples of participants at resurveys (2008 and 2013-2014) to correct for regression dilution bias. The associations of major blood lipids with stroke pathological types were examined after adjustment for confounders and correction for regression dilution bias. The causal relevance of these associations was assessed by Mendelian randomisation (MR) using genetic risk scores (GRSs) involving lipid-related genetic variants identified in Western populations. Multivariable logistic and Cox regressions were used to yield odds ratios (ORs) and hazard ratios (HRs), respectively, relating major blood lipids or genetic variants with risks of stroke pathological types. Results Overall, the incidence rates of first IS and ICH were 761 and 187 cases per 100 000 person-years, respectively, with ~20% of the incident strokes attributable to ICH. The mean (SD) plasma concentrations of LDL-C, HDL-C, and triglycerides were 2.3 (0.8) mmol/L, 1.3 (0.3) mmol/L, and 1.6 (1.1) mmol/L, respectively. The regression dilution ratios at the mid-point of follow-up (around 3.7 years after baseline) were 0.68 for LDL-C, 0.72 for HDL-C, and 0.62 for triglycerides, respectively. Throughout the range of LDL-C examined (1.7-3.2 mmol/L), there was a positive log-linear association of usual LDL-C with risk of IS (HR 1.17; 95% CI 1.10-1.25 per 1 mmol/L higher LDL-C), and an inverse association with ICH (0.86; 0.80-0.92). Likewise, after adjusting for non-lipid vascular risk factors, usual plasma triglycerides were positively associated with risk of IS (1.02; 1.00-1.04 per 30% higher triglycerides), albeit weaker than for LDL-C, and were inversely associated with risk of ICH (0.94; 0.92-0.96), independent of LDL-C. HDL-C was inversely associated with risk of IS (0.93; 0.89-0.97 per 0.3 mmol/L higher HDL-C), but not with ICH. The proportional relevance of LDL-C, triglycerides, and HDL-C with IS differed significantly from those for ICH (p _{heterogeneity}: <0.00001, <0.00001, 0.0006, respectively). In the MR analyses, an externally weighted GRS of 8 known LDL-C related genetic variants was associated with plasma LDL-C (p=1.15x10^-272), but not associated with other lipid fractions or non-lipid major vascular risk factors. Each 1 mmol/L higher genetically-determined LDL-C was associated with an OR of 1.28 (1.05-1.56) for IS, similar to the risk estimates in both observational studies and randomised trials. There was no significant association of genetically-determined LDL-C with ICH (OR 1.04; 0.87-1.25), but the estimates did not differ significantly from those in the observational studies (p _{heterogeneity}=0.06), and randomised trials (p _{heterogeneity}=0.8). Neither genetically-determined HDL-C nor triglycerides were significantly associated with either IS or ICH. Conclusion The associations of major blood lipids with stroke differed qualitatively between pathological types. Lower LDL-C is causally associated with lower risk of IS, and probably, higher risk of ICH. Better genetic instruments are needed to assess the causal relevance, if any, of the observed associations of HDL-C, and of triglycerides for stroke pathological types presented in this thesis.

Patients with mechanical heart valves who present with intracranial haemorrhage are initially treated by reversing their coagulopathy. However, these patients will ultimately require that their oral anticoagulant be restarted. The time at which oral anticoagulants are restarted is critical since restarting too early may increase the risk of recurrent bleeding, while withholding anticoagulants increases the patient’s risk of thromboembolic events. The ideal time to restart patients on their oral anticoagulant medication is defined as the time at which all these risks are minimized. This thesis includes a systematic review and meta-analysis of the literature. The main outcomes were recurrent haematoma, valve thrombosis, stroke and peripheral emboli. Results were stratified by types of intracranial haemorrhage. We also conducted a survey to gain insight into current practices of neurosurgeons and thrombosis experts in Canada and USA when they are faced with deciding on anticoagulant restart times in patients with ICH. Results were stratified by type of intracranial bleed and participants’ characteristics and demographics. The systematic review identified that the ideal time for restarting anticoagulant therapy in patients following an ICH is unknown. Meta-analysis was limited by the heterogeneity of the studies. The survey results indicated that physicians had a wide range of practice and that their practice was dependent on the patient’s clinical features, but many physicians would restart oral anticoagulants between 4 and 14 days after the haemorrhage. For this reason we have proposed a multi centre cohort study to investigate the safety and efficacy of restarting patients on anticoagulation therapy between day 5 and 9 post haemorrhage. A full study protocol is presented in this thesis.

Background: Cerebral small vessel disease (SVD) causes substantial cognitive, psychiatric and physical disabilities. Despite its common nature, SVD pathogenesis and molecular mechanisms remain poorly understood, and prevention and treatment are probably suboptimal. Identifying the genetic determinants of SVD will improve understanding and may help identify novel treatment targets. The aim of this thesis is to better understand genetic associations with SVD through investigating its pathological, radiological and clinical phenotypes. Methods: To unravel the genetic associations with SVD, I used three complementary approaches. First, I performed a systematic review looking at existing intracerebral haemorrhage (ICH) classification systems and their reliability, to help inform future studies of ICH genetics. Second, I performed a series of systematic reviews and meta-analyses, investigating associations between genetic polymorphisms and histopathologically confirmed cerebral amyloid angiopathy (CAA). Third, I performed meta-analyses of existing genome-wide datasets to determine associations of >1000 common single nucleotide polymorphisms (SNP) in the COL4A1/COL4A2 genomic region with clinico-radiological SVD phenotypes: ICH and its subtypes, ischaemic stroke and its subtypes, and white matter hyperintensities. Results: The reliability of existing ICH classification systems appeared excellent in eight studies conducted in specialist centres with experienced raters, although these existing systems have several limitations. In my systematic evaluation of CAA genetics, meta-analyses of 24 studies including 3520 participants showed robust evidence for a dose-dependent association between APOE ɛ4 and histopathological CAA. There was, however, no convincing association between APOE ɛ2 and presence of CAA in a meta-analysis of 11 studies including 1640 participants. Meta-analyses of five studies including 497 participants showed, contrary to an existing popular hypothesis, that while APOE 4 may increase the risk of developing severe CAA vasculopathy, there is no clear evidence to support a role of ɛ2. There were few data about the role of APOE in hereditary CAA, but in the three studies that had looked at this, there was no evidence for an association between APOE ɛ4 and CAA severity. There were too few studies and participants to draw firm conclusions about the effect of non-APOE ε2/ε3/ε4 genetic polymorphisms on CAA, but there were positive associations with TGF-β1, TOMM40 and CR1 genes in four studies. Finally, in my meta-analyses of the COL4A1/COL4A2 genomic region, three intronic SNPs in COL4A2 were associated with SVD phenotypes: significantly with deep ICH, and suggestively with lacunar ischaemic stroke and WMH. Conclusions: I have shown that while existing ICH classification systems appear to have very good reliability, further research is needed to determine their performance in different settings. For large population-based prospective studies of ICH genetics, anatomical systems are likely to be more feasible, scalable and appropriate, although they have limitations and will need to be further developed. Using systematic reviews and meta-analyses, I have confirmed a dose-related association between APOE ɛ4 and histopathological CAA, but also demonstrated that, despite popular acceptance, there is insufficient data to draw firm conclusions about the association with APOE ɛ2. I found some positive associations with CAA in other genes, which merit replication in further larger studies, and showed that there is currently insufficient data about the role of APOE in hereditary CAA. Finally, I identified a novel association between a locus in a known hereditary SVD gene – COL4A2 – and sporadic SVD. This highlights a new and successful approach for selecting candidate genes and can be expanded in future studies to include other known hereditary SVD genes.

L'hémorragie intracérébrale spontanée (HIC) est associée à un pronostic dramatique et reste dépourvue de traitement spécifique. Par conséquent, une meilleure compréhension de ses mécanismes physiopathologiques et de ses conséquences est impérative. La zone péri-hémorragique, communément appelée "oedème péri-hémorragique" (OPH), pourrait faire l’objet de thérapies ciblées. Cependant, ses mécanismes, son évolution naturelle et sa valeur pronostique restent encore à préciser. Cette thèse avait pour but d'étudier les mécanismes et les conséquences de cet OPH. Pour ce faire, nous avons combiné une approche expérimentale (modèle animal d'HIC) et une approche neuropathologique (étude post-mortem sur tissu humain). Nous avons utilisé le modèle de double injection de sang autologue pour reproduire une HIC chez une large cohorte de rats mâles et femelles. Dans une première étude, nous avons montré à quel point l'IRM multimodale est un outil fiable pour suivre la progression dynamique des lésions péri-hémorragiques et nous avons caractérisé la cinétique des différents composants de l'OPH (densité en eau, atteinte [micro-]vasculaire, neuro-inflammation et dépôts de fer). Dans une deuxième étude, nous avons examiné les conséquences à court et à long terme de l'HIC. Nous avons montré qu'une HIC profonde provoque une atteinte cognitive hippocampique et non hippocampique à long terme, contrastant avec une récupération locomotrice spontanée précoce. Nous avons par ailleurs montré qu’une HIC striatale focale induit une atrophie et un hypométabolisme cérébral à distance, impliquant les structures du système limbique et les zones corticales. Nous avons mené une étude post-mortem sur 19 cas de patients décédés d’HIC. Nous avons prouvé l'infiltration de Neutrophil extracellular Traps (NETs) dans le coeur de l’HIC mais également dans l’OPH. Nous avons également étudié la cinétique naturelle du processus de résorption du sang après une HIC, en nous concentrant sur la voie du récepteur scavenger des monocytes-macrophages (CD163) / hème oxygénase-1 (HO-1). Nos résultats contribuent à affiner notre perception de l’OPH, à renforcer les liens entre recherche clinique et pré-clinique, et, nous l’espérons, à identifier des stratégies thérapeutiques innovantes pour l'HIC
Spontaneous intracerebral haemorrhage (ICH) is associated with a dramatic prognosis and remains devoid of specific treatment. Therefore, understanding the mechanisms of ICH pathology and repair is a matter of high priority. The peri-haemorrhagic zone, commonly called "peri-haematomal oedema" (PHE), might be a promising candidate for therapeutic interventions. However, its underlying mechanisms, natural evolution and prognostic value remain to date unclear. This thesis aimed at studying the mechanisms and consequences of this PHE. To do so, we combined an experimental (animal model of ICH) and a neuropathological (post-mortem study on human tissue) approach.We used the double autologous blood injection model to reproduce ICH in a large cohort of male and female rats. In a first study, we showed how multimodal MRI is a reliable tool to track the dynamic progression of peri-haematomal injuries and we characterized the kinetics of different PHE components (water content, [micro]-vessel injuries, neuro-inflammation and iron deposits). In a second study, we investigated the short and long-term consequences of ICH. We reported that a deep ICH provokes long term cognitive impairments in rats that affects both hippocampal and non hippocampal aspects of cognition contrasting with early spontaneous locomotor recovery. We also showed that focal striatal ICH induces distant brain atrophy and hypometabolism involving limbic system structures and cortical areas. We included 19 cases of patients who died from ICH in a post-mortem study. We provided evidence for Neutrophil extracellular Traps (NETs) infiltration within the haematoma core but also and within the PHE. We also investigated the natural kinetic of natural blood clearance process after ICH in human brain tissue with a focus on the monocyte-macrophage scavenger receptor (CD163)/hemoxygenase-1 (HO-1) pathway. Our findings contribute to refine our perception of PHE, to optimize the translational pipeline and, hopefully, to identify innovative therapeutic strategies for ICH

La barrière hémato-encéphalique (BHE) contrôle le passage des médicaments, en partie par la présence d’ATP Binding Cassette (ABC) transporteurs. Dans de nombreuses pathologies cérébrales, la BHE est altérée. Parmi elles, les hémorragies intracérébrales (HIC), qui sont un effet iatrogène des anticoagulants. Des analyses cliniques montrent que les patients sous Anticoagulants Oraux Directs (AODs) présentent moins d’HIC que les patients traités avec les anticoagulants de référence, les anti-vitamine K (AVK), sans que les mécanismes cellulaires soient élucidés. Une des différences entre les AODs et les AVK résident dans leur profil pharmacocinétique, effectivement, les AODs sont des substrats des ABC transporteurs contrairement aux AVKs. Au cours des HIC, la thrombine est activée et entraine une altération de la BHE par clivage et des récepteurs protease activated receptor (PAR). Les objectifs de ce travail de thèse ont été de mettre en place un modèle in vitro de BHE afin d’étudier les interactions des médicaments avec les ABC transporteurs. Ensuite, le modèle est utilisé pour étudier les interactions des AODs en condition pathologique. Le modèle développé est basé sur la lignée HBEC-5i, peu décrite dans la littérature. Les cellules ont été cultivées en monocouche sur insert avec milieu conditionné issu d’astrocytes humains. Le modèle permet l’étude de l’interaction de thérapeutiques avec des ABC transporteurs par des mesures d’efflux ratios. Le modèle a été validé par des études de transport de molécules pharmacologiques. Ensuite, nous avons comparé, sur notre modèle, les effets de l’exposition à la thrombine avec ou sans prétraitement d’anticoagulants (rivaroxaban, dabigatran, apixaban, warfarine et héparine). Les AODs limitent l’ouverture de la BHE induite par la thrombine contrairement aux autres anticoagulants. Nos résultats ont montré que l’altération de la BHE est médiée par le clivage du récepteur PAR-1 par la thrombine. Ce clivage n’est pas le même en fonction de la classe d’anticoagulants utilisée, les AODs minimisant ce clivage. L’ensemble de ce travail de thèse a permis de donner des premières explications cellulaires quant aux mécanismes d’ouverture de la BHE consécutifs aux HIC sous AODs
The blood-brain barrier (BBB) controls the passage of drugs, in part through the expression of the ATP Binding Cassette (ABC) transporters. In many brain diseases, the BBB is altered. Among them, intracerebral haemorrhages (ICH), which are an iatrogenic effect of anticoagulants. Clinical analyses show that patients with Direct Oral Anticoagulants (DOACs) treatment have less HIC than patients treated with the reference anticoagulants, Vitamin K Antagonist (VKA), without understanding the cellular mechanisms. One of the differences between DOACs and VKA lies in their pharmacokinetic profile, indeed, DOACs are substrates of ABC transporters unlike VKA. During HIC, thrombin, is activated and causes alterations in the BBB by the cleavage of the protease activated receptor (PAR). The objectives of this thesis work were first to set up an in vitro model of the BBB in order to study the passage of drugs and their interactions with ABC transporters. In a second step, the model is used to study the interactions of DOACs in pathological conditions. The model developed is based on the HBEC-5i cell line seldom described in the literature. The cells were cultured in monolayer on insert with conditioned medium from human astrocytes. It allows the study of the interaction of therapeutics with ABC transporters by measuring efflux ratios. The model has been validated by transport studies of pharmacological molecules. In order to meet our second objective, we compared the effect of thrombin exposure with or without pretreatment with anticoagulants (rivaroxaban, dabigatran, apixaban, warfarin and heparin sodium) on our model. DOACs limit the BBB damage induced by the thrombin unlike other anticoagulants. Our results showed that alteration of the BBB is mediated by the cleavage of the PAR-1 receptor by thrombin. This cleavage is not the same depending on the class of anticoagulants used, DOACs minimizing this cleavage. All this thesis work made it possible to provide the first cellular explanations of the opening mechanisms of the BBB following HIC under DOACs

Intracerebral haemorrhage is a form of haemorrhagic stroke that is associated with significant morbidity and mortality. Its clinical course can be fulminant, meaning that the early diagnosis and management of this condition is particularly time critical. Early diagnosis through computed tomography (CT) imaging and implementation of interventions such as blood pressure control and reversal of coagulopathy can improve outcomes in this patient cohort. Prolonged time to hospital presentation or imaging diagnosis can delay delivery of appropriate care. Factors associated with delays to care are not currently well defined, and identification of a modifiable factor could enhance management of patients with this condition. An increase in the volume of haematoma following initial diagnosis can be associated with precipitous neurological decline, and occurs in a significant subset of patients. The presence of a spot sign on CT angiography imaging represents a site of active contrast extravasation and is associated with an increased risk of haematoma expansion. More recently, the presence of spot signs on delayed contrast imaging sequences such as post contrast CT and CT perfusion have emerged as alternate predictors of haematoma expansion, as have certain non contrast CT imaging signs. It is currently not clear which is the imaging sign with the greatest level of diagnostic accuracy in predicting haematoma expansion in patients with intracerebral haemorrhage. Aims of this thesis: To characterise through a systematic review the diagnostic accuracy of various types of delayed CT spot signs in predicting rates of haematoma expansion in patients with intracerebral haemorrhage. To characterise in patients with intracerebral haemorrhage the average time taken from ictus to hospital presentation and diagnosis, along with factors associated with delayed presentation. To directly compare the diagnostic accuracy of non contrast, first pass angiography and perfusion CT signs in predicting haematoma expansion.
Thesis (MPhil.) -- University of Adelaide, Adelaide Medical School, 2022

Background: Elevated levels of substance P (SP) have previously been found following ischaemic stroke and traumatic brain injury. Inhibiting the main SP receptor (neurokinin-1 (NK1)) reduces oedema and improves functional outcome in both settings. As this thesis details, we hypothesised that SP plays a similarly deleterious role following intracerebral haemorrhage (ICH). We further hypothesised that the post-ICH effects of intracerebral thrombin (which is known to play a major role in post-ICH secondary injury) are at least partly SP-mediated. Thrombin, similarly to SP, is known to play a deleterious role following both ischaemic stroke and traumatic brain injury. Previous research has also demonstrated that thrombin causes cutaneous oedema by an SP-dependent mechanism. Methods: Three hundred and forty three male Sprague-Dawley rats were used, and variously subjected to collagenase ICH, autologous ICH, intracerebral thrombin injection and intracerebral injection of SP. The sequelae of these various injuries was assessed, as well as the effect of antagonists to the main substance P receptor (NK1R), using functional testing, histological analysis, ELISA, real-time RT-PCR, wet-weight dry weight (for assessment of oedema) and Evans blue (for assessment of blood-brain barrier integrity). The effect of prior splenectomy on oedema following ICH was also assessed. Results: Elevated levels of SP were demonstrated post-ICH in the two different ICH models, and localised to astrocytes. Following collagenase ICH, two structurally unrelated NK1R antagonists reduced oedema and blood-brain barrier (BBB) dysfunction, but failed to reduce cellular inflammation, brain lesion volume and functional deficits. Stereotactic thrombin injections caused both oedema and elevated intracerebral SP, however, NK1R antagonism post-intracerebral thrombin failed to reduce brain oedema, largely disproving the hypothesis that thrombin causes intracerebral oedema post-ICH by a SP-dependent mechanism. Supraphysiological levels of SP injected stereotactically caused surprisingly little oedema and BBB dysfunction. Additional exploratory experiments demonstrated that NK1R antagonism did not reduce oedema caused by autologous ICH and also that the oedema-reducing effects of NK1R antagonism following collagenase ICH were abrogated by prior splenectomy. Conclusion: These results demonstrate that the oedematogenic actions of substance P following ICH are complex, and may predominantly be peripherally-mediated. Future experiments are planned to characterise further the role of SP in neuroinflammatory conditions.
Thesis (Ph.D.) -- University of Adelaide, School of Medical Sciences, 2010

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2020
Introdução: Crises epiléticas precursoras de acidente vascular cerebral (“heraldic seizures”) têm sido descritas como podendo representar um sinal de alarme para um evento cerebrovascular major subsequente. Este trabalho tem como objetivo a descrição de um caso clínico e a revisão sistemática de casos de crises epiléticas precursoras de hemorragia intracerebral (HIC) como apresentação inicial de angiopatia amiloide cerebral (AAC). Métodos: Pesquisa no PubMed e análise das referências cruzadas. Caso clínico: Mulher de 82 anos apresentou três episódios transitórios de hemiparésia esquerda com evolução para episódios paroxísticos de postura tónica e movimentos clónicos do membro superior esquerdo, seguidos por sinais focais pós-ictais prolongados, pelo que iniciou terapêutica antiepilética. Apresentou ainda dois episódios de estado confusional prolongado, que responderam à otimização da terapêutica antiepilética. Vários eletroencefalogramas (EEG) mostraram atividade lenta focal e atividade epileptiforme frequente nas regiões temporo-parieto-occipitais direitas. A TC-CE e a RM-CE 0,5T excluíram uma lesão cerebral e o líquor não mostrou alterações. Trinta e dois meses após as primeiras manifestações, um novo episódio de prostração e hemiparesia esquerda revelou uma hemorragia aguda do lobo frontal direito. Foram excluídas causas traumáticas e hipertensivas, e a angio-TC não apresentou alterações. O EEG revelou atividade epileptiforme na região temporal direita, bem como na região fronto-temporal esquerda. Três meses depois foi internada por crise epilética com generalização e hemiparesia direita, tendo sido diagnosticado um extenso hematoma lobar temporoparietal esquerdo. A doente faleceu duas semanas depois. Resultados da revisão sistemática: Foram encontrados três casos clínicos de HIC primária em doentes com AAC precedidos de crises epiléticas como sua primeira manifestação clínica. Conclusão: Estes casos exemplificam o conceito de “crises precursoras”, sugerindo que a AAC é a causa subjacente das crises epiléticas e da HIC subsequente. As crises epiléticas e as alterações eletroencefalográficas podem representar um marcador para uma condição oculta, podendo antecipar uma HIC iminente relacionada com AAC.
Introduction: The term “heraldic seizures” has been used to describe epileptic seizures occurring prior to a stroke being a warning sign for a major cerebrovascular event. We aimed to describe one case and perform a systematic review of case-reports of epileptic seizures heralding an intracerebral haemorrhage (ICH) as the initial presentation of cerebral amyloid angiopathy (CAA). Methods: We searched PubMed and screened cross-references. Case report: An 82-year-old female presented three transient episodes of left side weakness. They evolved to paroxysmal episodes of tonic posturing and clonic jerks of the left arm, followed by prolonged post-ictal focal signs, leading to the introduction of anti-epileptic therapy. She also had two episodes of protracted confusional state which responded to anti-epileptic therapy optimization. Several EEGs showed focal slow activity and frequent epileptiform activity over the right temporo-parieto-occipital regions. Cranial CT scans and a 0.5T-brain MRI excluded a brain lesion and CSF was unremarkable. Thirty-two months after the first symptom, a new episode of prostration and left hemiparesis disclosed an acute right frontal lobe haemorrhage. Traumatic and hypertensive causes were excluded, and CT angiography did not show any abnormality. EEG revealed epileptiform activity over the right temporal region but also over left fronto-temporal regions. Three months later, she was admitted with seizures and persistent right hemiparesis and an extensive left temporo-parietal lobar haematoma was diagnosed. The patient died two weeks later. Systematic review results: We found three case-reports of primary ICH in CAA-patients preceded by epileptic seizures as its first clinical manifestation. Conclusion: These cases exemplify the concept of "heraldic seizures", suggesting that CAA is the underlying cause of both seizures and subsequent ICH. Epileptic seizures and electroencephalographic changes might be a biomarker for an otherwise occult condition, and they might be a predicting sign for an impending CAA-related ICH.

Univerzita Karlova v Praze 1. lékařská fakulta Autoreferát disertační práce Optimalizace indikací chirurgického a endovaskulárního ošetření intrakraniálních aneurysmat Anna Štekláčová 2018 2 Doktorské studijní programy v biomedicíně Univerzita Karlova v Praze a Akademie věd České republiky Obor: Neurovědy Předseda oborové rady: Prof. MUDr. Karel Šonka, DrSc. Školicí pracoviště: Neurochirurgická a neuroonkologická klinika 1. LF UK a ÚVN, Praha Školitel: Prof. MUDr. Vladimír Beneš, DrSc. Disertační práce bude nejméně pět pracovních dnů před konáním obhajoby zveřejněna k nahlížení veřejnosti v tištěné podobě na Oddělení pro vědeckou činnost a zahraniční styky Děkanátu 1. lékařské fakulty. 3 Obsah Abstrakt - Česky ..................................................................................... 4 Abstract - English ................................................................................... 5 Úvod........................................................................................................ 6 Hypotézy a cíle studie............................................................................. 6 Materiál a metody ................................................................................... 7 Výsledky...