Racial differences in the distribution of cerebrovascular occlusive disease are well documented. Extracranial stenosis is more common in Caucasian while intracranial stenosis is more common in Asian, Hispanic and African-American. The prevalence of asymptomatic intracranial stenosis in middle age and elderly general population in China was about 7%. The frequency of intracranial atherosclerosis among patients with stroke and TIA is 40 to 50% in Chinese populations. Concurrent extracranial and intracranial stenoses is common in Asian, the incidence range from 10 to 39% in patients with stroke. The current population of China is 1.3 billion and it was estimated that 30% of the population will be aged 60 and above by 2050 in China. The incidence of stroke in China is 215 per 100000 which is one of the highest among the world and this burden is expected to escalate in the coming decades. However, studies of concurrent stenoses among Chinese are scarce. The aim of this precis is to present my studies that were conducted mainly among Chinese stroke patients on this particular field. The scope of the studies covers the following 4 areas: (1) Identification of Long-term prognosis of patients with concurrent stenoses; (2) Long-term prognosis of patients with concurrent stenoses and ischemic heart disease; (3) Lesion pattern and stroke mechanisms in concurrent stenoses; and (4) genetic polymorphisms of ischemic stroke patients with concurrent stenoses. The background, objectives, subjects, methods, results, and conclusions of these studies will be presented in this precis. / Man, Bik Ling. / Adviser: Lawrence K.S. Wong. / Source: Dissertation Abstracts International, Volume: 73-06, Section: B, page: . / Thesis (M.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 144-184). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.

Frontal lobe atrophy (FLA) is associated with late-life depression and cognitive impairment, although the pathogenesis of FLA in stroke is unclear. In an aim to ascertain whether FLA is affected by WMLs, we analyzed the MRIs of 471 Chinese ischemic stroke patients. Lobar atrophy was defined by a widely-used visual rating scale. WML severity was rated using the Fazekas scale. There was no correlation between PVH and DWMH and temporal and parietal atrophy. The results of this study suggest that FLA in ischemic stroke may be associated with SVD. / Poststroke depression (PSD) is the most common form of poststroke psychiatric morbidity. Small subcortical infarcts (SSIs) can result from small vessel disease (SVD) and large artery disease (LAD). No study has yet explored PSD in different etiological types of SSIs. To address this gap, 127 patients with SSIs resulting from LAD or SVD were examined. PSD was evaluated with the Geriatric Depression Scale (GDS) three months after stroke. The LAD group had a significantly higher frequency of PSD, and LAD was found to be a significant independent risk factor for PSD. This study suggests that cerebral blood perfusion may play an important role in PSD. / Post-stroke emotional lability (PSEL) is a distressing and embarrassing complaint among stroke survivors. Lesions located in various cortical and subcortical areas are thought to be involved in the pathophysiology of PSEL.The clinical significance of microbleeds (MBs) in the development of psychiatric conditions following stroke is unknown. We carried out a study to examine the association between PSEL and MBs in 519 Chinese patients with acute ischemic stroke admitted consecutively. PSEL was evaluated three months after the index stroke, and the number and location of MBs were evaluated with MRI. According to Kim's criteria, 74 (14.3%) of the patients had PSEL. Our results suggest that MBs in the thalamus may play a role in the development of PSEL. The importance of MBs in PSEL and other psychiatric conditions in stroke survivors warrants further investigation. / The first study reported in this thesis involved 328 Chinese ischemic stroke patients who were administered a series of neuropsychological tests covering seven domains three months after stroke. Two hundred and fifty-six of these patients were followed-up for one year. Volumetry of the infarcts, WMLs, and hippocampus atrophy on magnetic resonance imaging (MRI) was conducted. The prevalence of cognitive impairment was 54.9% at baseline and 52.4% at the one-year follow-up, although most of the patients (85.5%) remained cognitively stable. The evolution of cognitive impairment no dementia (CIND) at the one-year follow-up was bidirectional, with 11.2% progressing to dementia and 21.0% reverting to cognitive intact. WMLs volume rather than hippocampal volume was a significant predictor of cognitive impairment, cognitive decline, and delayed dementia. WMLs also had an independent effect on executive function, attention, visual memory, visuoconstruction, and visuomotor speed. / This thesis investigates the clinical and imaging characterization of cognitive impairment and psychiatric morbidity in Chinese stroke patients. The conclusions of the studies reported herein can be summarized as follows. (1) The prevalence of cognitive impairment is high among Chinese poststroke patients, but most remain cognitively stable at one year after stroke; WMLs rather than hippocampal atrophy predict cognitive impairment, longitudinal cognitive decline, and delayed dementia; (2) DLPFC atrophy is correlated with poor verbal fluency in elderly women with stroke, but not in their male counterparts; (3) LAD may be associated with PSD in patients with small subcortical infarcts; (4) MBs in the thalamus are associated with PSEL; (5) frontal lobe infarction and diabetes may be risk factors of insomnia symptoms in stroke patients; and (6) FLA in ischemic stroke may be associated with SVD. (Abstract shortened by UMI.) / Chen, Yangkun. / Adviser: Wai Kwong Tang. / Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 217-238). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

published_or_final_version / Speech and Hearing Sciences / Doctoral / Doctor of Philosophy

Persistent cerebrovascular dysfunction has been postulated as one mechanism that may contribute to divergent functional trajectories after ischemic stroke. However, how brain endothelial cells (BECs) acutely respond to ischemia and what endogenous signals subsequently regulate vascular normalization remain poorly understood. To spatiotemporally interrogate neuronal activity and hemodynamics in the acute period after ischemic brain injury we used wide-field imaging. Local ischemia consistently provoked a large-amplitude cortical spreading depolarization (CSD) accompanied by strong vasoconstriction, followed by subsequent diverse CSDs with varying hemodynamic responses. Small CSDs with slow depolarization induced vasodilation in well oxygenated cortical tissue. CSDs of larger amplitude with non-sustained depolarization induced biphasic vascular responses. CSDs of large amplitude, characterized by rapid and prolonged depolarization, drove vasoconstriction in deoxygenated cortical tissue with sustained neuronal depolarization. These observations support a model in which vascular responses after acute brain injury are dependent upon the local relationship between CSD features (i.e. slope, duration, and amplitude of depolarization) and the underlying cortical state (i.e. neuronal activity, perfusion, oxygenation). After this acute period, the ischemic brain is characterized by profound changes in immune cell composition and function. To understand how distinct immune signaling pathways regulate blood-brain barrier (BBB) repair and vascular remodeling after ischemic brain injury, I investigated a unique post-ischemic BEC type one interferon (IFN1) signature. Functional assays and single-cell transcriptomic analyses in IFN1 receptor (Ifnar1) inducible EC knockout (iECKO) mice revealed that loss of BEC IFN1 signaling exacerbated post-stroke barrier disruption and resulted in an expansion of BECs enriched in genes involved in angiogenic processes. Conversely, acute administration of exogenous IFNI ameliorated post stroke BBB disruption. In vitro assays supported that IFNI signaling modulates BEC junctional protein stabilization and vascular endothelial growth factor (VEGF) signaling to enhance BEC barrier properties and suppress angiogenic features, respectively. These findings suggest that endogenous BEC IFN signaling after ischemic brain injury restricts angiogenesis to potentially promote acute barrier function. These studies, which span from the systems to molecular level, demonstrate that brain ischemia and post-ischemic sequelae have a profound impact on cerebrovascular dysfunction and recovery. Furthermore, each study introduces a novel framework to investigate how differences in acute BEC responses may contribute to variable vascular trajectories and longitudinal brain function after ischemic insult.

Thesis (MScMedSc (Rehabilitation))--University of Stellenbosch, 2008. / Stroke is the second commonest cause of mortality worldwide and remains a leading cause of adult physical disability. It is estimated that sixty percent of South African stroke survivors require assistance with at least one activity of daily living. This burden is predominantly on the shoulders of mostly untrained caregivers. The process of enabling caregivers to make choices conducive to their own health as well as the health of the stroke survivors is multidimensional. One of the cornerstones of this process is the provision of information. In 1995, the Centre for Rehabilitation Studies of the University of Stellenbosch started to develop a training package for stroke care at home. The training takes the form of an interactive workshop and a booklet with practical information. The aim of this study was to refine and pilot this booklet for implementation with the training. The study found that existing guidelines to evaluate the appropriateness of written material for developing communities (measured by Hugo’s grading model), were inadequate. Consequently, a new checklist, based on twenty existing checklists, was compiled. This list, as well as the Suitability Assessment of Material (SAM), was used to evaluate the booklet and make recommendations for a pre-pilot refinement. Even though this checklist has not been validated, it revealed similar results to the SAM when applied to the booklet. After cosultation with the authors, improvements were effected to the booklet The booklet was tested with four samples of the target audience. The functional literacy of the participants was determined using a standardised literacy test. A fifth sample completed a questionnaire on their preference between the pre- and postrefined booklet. Experts in the field of rehabilitation and graphic design also commented on the booklet. This study confirmed the need of stroke survivors and their caregivers for written health information. The refined booklet was found to be an appropriate tool to address the needs of the target audience. The participants perceived the booklet as useful and comprehensible and the readability level was shown to correspond with the tested literacy level of the samples. However, there is a need for printed material on topics related to stroke not currently covered in the booklet, e.g. spasticity. This study showed that the checklist could be used to tailor written health information that is preferred by the target audience. It confirmed that the testing of printed material with stakeholders could expose additional gaps after applying the checklist. Recommendations for further improvements were made based on the comments of the participants. It is foreseen that the new checklist could be a valuable tool for developing future written health material. Finally, it is recommended that an interdisciplinary team that includes a graphic designer be involvement from the planning stages.

published_or_final_version / Social Work / Master / Master of Social Work

Although self-efficacy has long been established as an important variable for psychological wellbeing across a range of contexts, coping self-efficacy, a subtype of self-efficacy specific to the function of coping, has only recently begun to receive research attention. In addition, despite support from both self-efficacy theory and coping theory, the relationship between coping self-efficacy and coping behaviour in the face of stressful events has not previously been considered. This thesis explores the importance of coping self-efficacy for psychological wellbeing in a new context, recovery after stroke, and investigates the relationship between coping self-efficacy and coping behaviour in the face of this stressor. Stroke was selected as a suitable context for this exploration given its high incidence, lengthy recovery period and the prevalence of significant post stroke psychological distress. The thesis explores four key questions: (i) is coping self-efficacy related to psychological wellbeing for people recovering from stroke, (ii) what types of coping behaviours are related to coping self-efficacy during recovery, (iii) does coping behaviour mediate the relationship between coping self-efficacy and psychological outcomes, and (iv) what is the role of individual dispositional traits (optimism and trait anxiety) in these relations. The implications of these relationships for clinical intervention were a secondary focus of the project.

While dyspraxia has been studied from the neuro-anatomical aspects, few studies have explored the experience of adults with dyspraxia in the course of their everyday activities. This study reveals the unique and complex experiences of five adults as they struggle to live with dyspraxia.The research is underpinned by the phenomenological perspective. Participants were filmed performing everyday activities of their choice and were interviewed on their experiences of dyspraxia with everyday activities.The stories and videos reveal the struggle participants have with their unknowing and unwilling bodies, puzzled thinking, unfamiliar surroundings, and unhandy tools. Despite the enormity of their struggles, participants persevere, using individual strategies to overcome obstacles. The findings show that the lived-experience of dyspraxia tends to remain hidden from the person, as well as the clinician. Much of what is taken for granted during everyday activities is shattered in the lives of people with dyspraxia. The automatic, smooth, unconscious way activities are done, tools are handled and the world is experienced is altered. The path to recovery remains unclear as dyspraxia makes itself known one day and not the next. Sheer determination and a hope for the future helps participants carry on with trying to reclaim the person they lost as a result of the dyspraxia.The importance for understanding, by clinicians of the impact of dyspraxia on people's everyday lives cannot be underestimated. Implications for practice are discussed, as these relate to formal definitions of dyspraxia, client-centred practice, as well as diagnosis, assessment, intervention, and education.

PDSE are common (19.6%) in the local stroke population. Both premorbid factors as well as stroke-related factors contribute to the development of PRSD and PSDE. The application of different diagnostic criteria for PSDE will affect the frequency and the associated radiological characteristics. As regards the screening methods of PSDE, a more specific instrument should supplement the IQCODE or MDRS-IP in a two-stage screening procedure. / PSD is also common (16--17%) among local stroke survivors. Both psychosocial factors and the location of cerebrovascular lesions play an important role in the development of PSD. PSD in local Chinese seems to have a favorable short-term outcome in comparison with their Caucasian counterparts. With regard to the screening of PSD in Chinese, we found that both the GDS and HADS depression subscale have a satisfactory response rate and accuracy in detecting PSD. However, due to the relative low frequency of PSD in the local stroke population, a more specific instrument should supplement the GDS in a two-stage screening procedure. Finally, the familiarity of the rater with the subjects based on a preexisting therapeutic relationship did not influence the accuracy of screening for PSD in Chinese patients. / There has been a paucity of data on the frequency, clinical correlates and methods of screening of poststroke dementia (PSDE) and depression (PSD) in Chinese populations. The objective of this thesis is to examine the prevalence, diagnostic criteria and clinical correlates of PSDE and PSD in Chinese stroke patients in Hong Kong. A series of studies were all carried out; the author of the thesis had interviewed all the subjects 1--3 months after their index stroke and made the diagnosis of dementia and depression according to the DSM-IV criteria. / Tang Wai Kwong. / "July 2005." / Adviser: Gabor S. Ungvari. / Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0177. / Thesis (M.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 136-191). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / School code: 1307.

The neurophysiological basis of cognition changes with age is relatively unexplained, with most studies reporting weak relationships between cognition and measures of brain function, such as event related potentials, brain size and cerebral blood flow. Proton magnetic resonance spectroscopy (1H-MRS) is an in vivo method used to detect metabolites within the brain that are relevant to certain brain processes. Recent studies have shown that these metabolites, in particular N-acetyl aspartate (NAA), which is associated with neuronal viability, correlate with performance on neuropsychological tests or other measures of cognitive function in patients with a variety of cognitive disorders associated with ageing and in normal ageing subjects. We have studied the relationship between metabolites and cognitive function in elderly patients 3 months and 3 years after a stroke or transient ischemic attack (TIA) and in an ageing comparison group. Metabolites were no different between stroke/TIA patients and elderly controls, however, there were significant metabolite differences between stroke/TIA patients with cognitive impairment (Vascular Cognitive Impairment and Vascular Dementia) and those without. Frontal measures of NAA and NAA/Cr predicted cognitive decline over 12 months and 3 years in stroke/TIA patients and elderly controls, and these measures were superior predictors than structural MRI measures. Longitudinal stability of metabolites in ageing over 3 years was associated with stability of cognitive function. The results indicate that 1H-MRS is a useful tool in differentiating stroke/TIA patients with and without cognitive impairment, with possibly superior predictive ability than structural MRI for assessing future cognitive decline. The changes in 1H-MRS that occur with ageing and cognitive decline have implications for the neurophysiological mechanisms and processes that are occurring in the brain, as well as application to clinical diagnosis, the early detection of pathology and the examination of longitudinal change.