Neurology Commons^™

Shedding Light On Hearing In Coma: Investigating The Applicability Of Functional Near-Infrared Spectroscopy For Assessing Auditory Function And Aiding Prognosis In Patients With Acute Disorders Of Consciousness, Reza Moulavi Ardakani

Electronic Thesis and Dissertation Repository

There is a critical need for a bedside neuroimaging tool to aid in the prediction of functional recovery outcomes for patients with acute disorders of consciousness (DoC) in the early days following severe brain injury. Current neurobehavioral examinations and prognosis tools have limitations in predicting good outcomes, leading to potential mistreatment or premature withdrawal of life support. Functional near-infrared spectroscopy (fNIRS) is a viable candidate for such purposes due to its portability and cost-effectiveness. Auditory processing, viewed as a multi-level and multifaceted brain function, could provide a sensitive and specific marker of residual cognitive function in unresponsive patients. This study …

Regulatory Implications Of Inadequately Designed Pimavanserin Drug Trials Published With Risk Of Bias On Expedited Regulatory Approval Processes, Benson Law

Electronic Thesis and Dissertation Repository

The objective of this retrospective critical appraisal study was to determine if the trials submitted to the Food and Drug Administration for the expedited approval of pimavanserin was of sufficient methodological quality to ascertain its safety and efficacy. After the general metrics of the trials were assessed, the Risk of Bias 2 tool and the PRagmatic Explanatory Continuum Indicator Summary tool were employed to evaluate the risk of bias and the design suitability of the trials. This study suggests that the decision to approve pimavanserin for the treatment of Parkinson’s Disease Psychosis failed to meet the threshold of evidence normally …

The Clinical Value Of Oculomotor Assessments Across The Continuum Of Concussion, Dillon Richards

Electronic Thesis and Dissertation Repository

Concussions are complex conditions that are difficult to manage medically. Variations in symptom presentation, intricate neurophysiological processes, and the availability of a variety of possible assessment tools may contribute to this complexity. Clinicians must use a broad approach, employing both subjective symptom assessment and objective assessments to confirm a diagnosis and/or monitor progression and recovery. Oculomotor function after concussion may be an important indicator of injury, given the interconnectedness of oculomotor function, vestibulo-ocular and visual systems, and even cognition. Oculomotor function may be assessed objectively or indirectly using patient-reported symptom checklists as part of subjective assessments. One way of objectively …

Multimorbidity And Cognition Among Canadian Older Adults: A Three-Decade Perspective, Juan Camilo Vargas Gonzalez

Electronic Thesis and Dissertation Repository

Background: Scarce information exists about whether the relationship between multimorbidity and cognitive decline has changed over the past decades.

Objectives: 1) To summarize knowledge about the association of multimorbidity and cognitive decline by performing a systematic review. 2) To estimate the association between multimorbidity in two cohorts selected three decades apart. 3)To identify which multimorbidity combinations have the strongest associations with cognitive decline 4) To identify protective factors that reduce the risk of cognitive decline in the presence of multimorbidity.

Methods: We performed a systematic review following the PRISMA statement. We then addressed objectives 2-4 by analyzing data from two …

Exploring The Effects Of Spinal Cord Stimulation For Freezing Of Gait In Parkinsonian Patients, Olivia Samotus

Electronic Thesis and Dissertation Repository

Dopaminergic replacement therapies (e.g. levodopa) provide limited to no response for axial motor symptoms including gait dysfunction and freezing of gait (FOG) in Parkinson’s disease (PD) and Richardson’s syndrome progressive supranuclear palsy (PSP-RS) patients. Dopaminergic-resistant FOG may be a sensorimotor processing issue that does not involve basal ganglia (nigrostriatal) impairment. Recent studies suggest that spinal cord stimulation (SCS) has positive yet variable effects for dopaminergic-resistant gait and FOG in parkinsonian patients. Further studies investigating the mechanism of SCS, optimal stimulation parameters, and longevity of effects for alleviating FOG are warranted. The hypothesis of the research described in this thesis is …

Validation Of Arterial Spin Labeling For Longitudinal Monitoring And Differential Diagnosis Of Frontotemporal Dementia, Tracy Ssali

Electronic Thesis and Dissertation Repository

Frontotemporal dementia (FTD) is a devastating neurodegenerative disease characterized by a rapid decline in behavioural, language, and motor abilities. Advances in the understanding of FTD genetics and pathophysiology, and the subsequent development of novel disease modifying treatments have highlighted the need for tools to assess their efficacy. While structural magnetic resonance imaging (MRI) and functional imaging with ¹⁸F-flurodeoxyglucose (FDG) positron emission tomography (PET) are used for clinical diagnosis, structural changes are subtle at the early stages and PET imaging is expensive and access limited. Given the coupling of cerebral blood flow (CBF) to energy metabolism, an attractive alternative is …

Association Between Air Pollution And Incidence Of Dementia: A Systematic Review And Meta-Analysis Of Cohort Studies, Ehsan Abolhasani

Electronic Thesis and Dissertation Repository

Objective. To estimate the risk of dementia in association with exposure to air pollutants.

Methods. Six databases were searched. Cohort studies that reported the hazard ratio (HR) of dementia in association with exposure to air pollutants in adults > 40y were included. For all meta-analyses, the random-effects model was used.

Results. A total of 16 and 13 studies were included in the systematic review and the meta-analysis, respectively. Risk of dementia increased by 4% per 1μg/m³ increase in fine particulate matter level (HR, 1.04; 95%CI, [1.02, 1.06]), which was statistically significant. The risk of dementia increased by 3% per 10μg/m …

Neurodevelopmental Outcomes Of Infantile Hydrocephalus: An Fmri Case Study, Ikhlas Ahmed Hashi

Electronic Thesis and Dissertation Repository

Ventricle dilatation caused by infantile hydrocephalus may result in extensive damage of the posterior cortex (parietal and occipital lobes). We hypothesize that pathological changes in the development of the posterior cortex can be linked to non-verbal learning disabilities in children with previous infantile hydrocephalus. This case study will investigate the neurodevelopmental outcomes of 3 treated hydrocephalus patients, when compared to a group of healthy control children (n = 12). Within the hydrocephalus group, patients displayed differences in non-verbal test performance as well as parietal brain activation during an fMRI number comparison task. We associated these differences with clinical variables such …

Improving The Assessment And Understanding Of Neurogenic Orthostatic Hypotension, Jacquie Baker

Electronic Thesis and Dissertation Repository

Neurogenic Orthostatic Hypotension (NOH) is a cardinal feature of autonomic failure. Patients with NOH experience a persistent and consistent drop in blood pressure when standing due to failure of the autonomic nervous system to reflexively increase sympathetic outflow. NOH affects individuals worldwide, presenting as both a primary feature (i.e. Multiple Systems Atrophy, Pure Autonomic Failure) and secondary to several common disorders including diabetes and Parkinson’s Disease. However, there are still several gaps in our overall understanding and assessment of patients with NOH. Therefore, the six studies presented in this thesis aimed to address some of these gaps in our current …

White Matter Inflammation And Executive Dysfunction: Implications For Alzheimer Disease And Vascular Cognitive Impairment, Alexander Levit

Electronic Thesis and Dissertation Repository

White matter integrity is crucial to healthy executive function, the cognitive domain that enables functional independence. However, in the ageing brain, white matter is highly vulnerable. White matter inflammation increases with age and Alzheimer disease (AD), which disrupts the normal function of white matter. This may contribute to executive dysfunction, but the relationship between white matter inflammation and executive function has not been directly evaluated in ageing nor AD. White matter is also particularly vulnerable to cerebrovascular disease, corresponding with the common presentation of executive dysfunction in vascular cognitive impairment (VCI). Thus, white matter may be an important substrate by …

Interactive Visualization Of Multimodal Brain Connectivity: Applications In Clinical And Cognitive Neuroscience, Saeed Mahdizadeh Bakhshmand

Electronic Thesis and Dissertation Repository

Magnetic resonance imaging (MRI) has become a readily available prognostic and diagnostic method, providing invaluable information for the clinical treatment of neurological diseases. Multimodal neuroimaging allows integration of complementary data from various aspects such as functional and anatomical properties; thus, it has the potential to overcome the limitations of each individual modality. Specifically, functional and diffusion MRI are two non-invasive neuroimaging techniques customized to capture brain activity and microstructural properties, respectively. Data from these two modalities is inherently complex, and interactive visualization can assist with data comprehension.

The current thesis presents the design, development, and validation of visualization and computation …

Investigating The Acute Levodopa Response In Early To Advanced Parkinson’S Disease, Marcus M. Pieterman

Electronic Thesis and Dissertation Repository

Parkinson’s disease (PD) is a neurogenerative movement disorder that often requires surgical interventions such as deep brain stimulation (DBS) when motor complications arise from long term levodopa therapy. Understanding the level of motor improvement received by patients from levodopa (levodopa response; LR) at each stage of disease duration is integral to optimizing both current treatment and DBS implementation. In this study, the levodopa challenge test was employed to investigate the LR in early to advanced stages of disease in 70 PD participants. The LR only moderately correlated with disease duration, suggesting large interindividual variability in the LR between patients of …

Nutrition Screening In The Adult Stroke Population Using The Canadian Nutrition Screening Tool In Comparison With The Subjective Global Assessment, Tess Coutu

Electronic Thesis and Dissertation Repository

Although the Canadian Best Practice Recommendations for Stroke Care recommend all acute stroke patients be screened for malnutrition within 48 hours of admission to hospital using a valid screening tool, none have been validated for use in adult acute stroke patients. The Canadian Nutrition Screening Tool (CNST) tool has been validated within medicine and surgery patients. The purpose of this study is to estimate the level of agreement between the CNST and the Subjective Global Assessment (SGA), a nutrition assessment tool, in a cohort of 58 acute adult stroke patients at the Southwestern Ontario Regional Stroke Centre in London. In …

Design Of Radio-Frequency Arrays For Ultra-High Field Mri, Ian R O Connell

Electronic Thesis and Dissertation Repository

Magnetic Resonance Imaging (MRI) is an indispensable, non-invasive diagnostic tool for the assessment of disease and function. As an investigational device, MRI has found routine use in both basic science research and medicine for both human and non-human subjects.

Due to the potential increase in spatial resolution, signal-to-noise ratio (SNR), and the ability to exploit novel tissue contrasts, the main magnetic field strength of human MRI scanners has steadily increased since inception. Beginning in the early 1980’s, 0.15 T human MRI scanners have steadily risen in main magnetic field strength with ultra-high field (UHF) 8 T MRI systems deemed to …

Quantitative Mri Correlates Of Hippocampal And Neocortical Pathology In Intractable Temporal Lobe Epilepsy, Maged Goubran

Electronic Thesis and Dissertation Repository

Intractable or drug-resistant epilepsy occurs in over 30% of epilepsy patients, with many of these patients undergoing surgical excision of the affected brain region to achieve seizure control. Advances in MRI have the potential to improve surgical treatment of epilepsy through improved identification and delineation of lesions. However, validation is currently needed to investigate histopathological correlates of these new imaging techniques. The purpose of this work is to investigate histopathological correlates of quantitative relaxometry and DTI from hippocampal and neocortical specimens of intractable TLE patients. To achieve this goal I developed and evaluated a pipeline for histology to in-vivo MRI …

Managing Uncertainty In Young-Onset Parkinson's Disease, Michael J. Ravenek

Electronic Thesis and Dissertation Repository

Typically considered a disease of old-age, Parkinson’s disease can affect those younger in life, i.e., before the age of 55, when it is referred to as young-onset Parkinson’s disease (YOPD). Using constructionist grounded theory, this research sought to understand how, and why, individuals with YOPD became informed about their disease over time. A total of 39 individuals, who self-identified as living with YOPD, took part in this study which was organized according to four cycles of data collection. These cycles utilized focus groups, in-depth interviews and a private online discussion board, supplemented by 14 autobiographies written by individuals living with …

Ultra High Field (7t) Magnetic Resonance Imaging Of Intracranial Vessel Wall, Pablo Lopez-Ojeda

Electronic Thesis and Dissertation Repository

Intracranial vessel wall imaging may be accomplished with high-field (7T) magnetic resonance (MRI). To determine its feasibility, a 7T MR protocol was defined using Polyvinyl-alcohol cryogel (PVA-C) phantom vessels and healthy subjects.

A 2D matrix construct of PVA-C vessel phantoms of different diameters and wall thicknesses was scanned. Three observers measured the phantom images, one of which three times. Physical measurements were performed using a digital caliper. Ten volunteers were scanned using three different MRI sequences (TSE-3D, FLAIR, MPRAGE). Imaging assessment was performed in different circle of Willis (COW) segments. Reliability and accuracy of the measurements was analyzed by inter …

Secular Trends In Ischemic Stroke Subtypes, Chrysi Bogiatzi

Electronic Thesis and Dissertation Repository

Background: With an aging population and an increasing prevalence of therapy for atherosclerosis, it might be expected that stroke subtypes would be changing over time. Limited information exists on the ischemic stroke subtypes in adults in Canada.

Methods: Patients referred to the Urgent TIA Clinic, in London, Ontario, between 2002-2012 were included. Secular trends were analyzed using Poisson regression with spline trend function. Ischemic stroke subtype classification was validated.

Results: 3,445 consecutive patients (mean age + SD 64.8 + 14.9) were included. Cardioembolic strokes/TIAs increased from 21% in 2002 to 56% in 2012, whereas all other ischemic stroke subtypes …

Causes Of Post Stroke Falls Along The Care Continuum: Implications For Improving Patient Safety, Mona Madady

Electronic Thesis and Dissertation Repository

In Western countries stroke is responsible for 10-12% of all deaths. In 2000, strokes cost $3.6 billion for the Canadian healthcare system and lost productivity due to premature death and long-term disability. Falls are a frequent occurrence at all stages of post-stroke recovery and can have significant negative impacts. While information about the incidence and risk factors of falling among stroke survivors is available, considerably less is known about the specific factors contributing to falls and the circumstances surrounding these adverse events. The purpose of this project was to identify similarities between systemic factors of falls in stroke survivors across …

The Effect Of Selective Hypothermia On Stroke Volume, Thomas K. Mattingly

Electronic Thesis and Dissertation Repository

Hypothermia is a well-established neuroprotectant. Selective hypothermia to the ischemic area may eliminate side effects while improving induction time. We studied the effect of selective hypothermia on stroke volumes in adult domestic swine. Under general anesthesia, one MCA was occluded transcranially for 3 hours followed by 3 hours of reperfusion. In half the animals, hypothermia was induced during reperfusion via a dual-lumen balloon occlusion catheter placed in the carotid ipsilateral to the ischemic region. Following reperfusion, the animals were sacrificed. Brain MRI and histology were evaluated blinded to the intervention. In a series of animals, the mean temperature achieved was …