Methodological advances in spinal cord and brainstem fMRI provide an unprecedented view of human pain processing and alterations to pain mechanisms in fibromyalgia
MetadataShow full item record
Functional MRI of the human spinal cord and brainstem has tremendous potential to enhance our basic understanding of healthy subcortical function, and impact our ability to accurately diagnose and treat injury and disease. Despite this potential, there are many challenges and limitations that must be overcome before this technique can be of clinical use. The objectives of this thesis are to develop spinal cord and brainstem functional imaging methods in order to sensitively characterize sensory and pain processing in healthy humans, and to assess changes in the function of these structures that arise from a prevalent chronic pain condition, fibromyalgia (FM). Therefore, we first conducted a rigorous assessment of acquisition parameters and analytical approaches in order to reduce the impact of physiological noise and optimize our sensitivity for detecting neural function in the spinal cord and brainstem. These methodological developments were then applied to characterize the fMRI response to sensory stimuli presented in block and stepwise paradigms designed to probe different aspects of the sensory response. Results of this study confirmed the sensitivity of our fMRI methods for detecting subtle changes in sensory processing and highlight the importance of careful paradigm selection. Building on these findings, we probed central pain processing mechanisms using a temporal summation of second pain (TSSP) paradigm in both healthy adults and patients with FM. Our results characterized the spinal cord and brainstem fMRI response to TSSP and revealed alterations to this response in the descending control pathways in FM patients. This is the first investigation of spinal cord functioning in a chronic pain population, specifically with FM, and we provide insight into the aberrant neural mechanisms that may underlie this disorder. Altogether the work presented in this thesis details the current state-of-the-art in spinal cord/brainstem imaging methods and provides an unprecedented view of pain processing in humans.