Diminished cerebrovascular reserve in the cerebral white matter of elderly individuals with leukoaraiosis
Year: 2016
Type: dissertation
Study design: Observational Study
Abstract: The cerebral white matter contains millions of fibers that serve to connect different regions of the brain and supports sophisticated information processing. A sudden loss of these fibers in a brain region as seen in a stroke to a large blood vessel, can lead to severe loss of function especially when the affected fibers are in a strategic location. Little is known about the fine network of blood vessels supplying nutrition to the white matter that can become diseased with age, producing a very similar pattern of injury to the white matter termed "leukoaraiosis". Considerable research has been carried out studying the effects of injury to large vessels supplying the gray matter of the brain. However, understanding of the relationship between dysfunctional white matter blood vessels and injury to the white matter itself is limited. The purpose of the present research is to study this relationship in a unique way. The present work will use MRI and manipulation of blood carbon dioxide (CO2) levels for mapping the capacity of the cerebral vasculature to control blood flow, i.e. assessing cerebrovascular reactivity (CVR). CVR is a measure of the response of the arterial vasculature to respond to a vasoactive stimulus, such as CO2. The response to vasodilatory stimuli can fail in diseases that affect the integrity of the vasculature leading to interruption of blood supply, resulting in varying degrees of brain injury, including slowly progressive ischemic demyelination in the white matter. Research within this thesis has demonstrated that: CVR is reduced in leukoaraiosis compared to normal-appearing white matter (NAWM); (2) Cross-sectionally, abnormalities in diffusion and perfusion MRI metrics have been observed in the NAWM with steal physiology; (3) Reduced CVR is associated with the subsequent development of visible white matter injury when subjects completed a follow-up MRI scan separated 12-months apart from baseline and (4) The speed of the vascular response is also abnormal in leukoaraiosis compared to NAWM. This thesis provides insight into the mechanism of white matter injury and highlights a novel method for predicting injury in susceptible individuals.
Source: TSpace (University of Toronto)
Author: Kevin Sam
Language: English
Subfield: Clinical Neurology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2603744264