The Effect of Chronic Pain on Human Cognitive and Sensorimotor Systems

  • Author / Creator
    Siddiqi, Anwer Zohaib
  • Chronic pain (CP) is a debilitating disorder that has a multitude of potential etiologies as well as numerous effects on the central and peripheral nervous systems. Even though CP is highly prevalent, these etiologies and effects are often misunderstood, which has led to a lack of adequate treatments for the disorder. In this thesis, we sought to investigate the effect that CP has on the cognitive and sensorimotor systems in the human brain. In the first project, we examined whether CP has a disruptive effect on cognition and if so, what effect this would have on quality of life and disability. We used a battery of neuropsychological as well as clinical measures to show that patients with CP do indeed have cognitive dysfunction and that this dysfunction predicts a lower quality of life and higher pain related disability. This knowledge could increase focus on therapies that target improving cognitive function and emotional health in addition to physical treatments for CP. In the second part of this thesis, we investigated a specific CP disorder, Complex Regional Pain Syndrome (CRPS). CRPS is unique in that it has motor, as well as neurocognitive, abnormalities. Using a paired pulse protocol of Transcranial Magnetic Stimulation (TMS), we examined if participants with CRPS have changes in the excitability of inhibitory circuitry within the primary motor cortex (M1). In addition, we piloted the efficacy of an innovative therapy, known as Graded Motor Imagery (GMI), and examined its potential neuroplastic mechanisms. In our preliminary results from five participants with CRPS, there appeared to be normal recruitment of inhibitory circuitry in M1compared to sex and age-matched controls. In the two participants with CRPS that were tested, GMI produced a reduction of pain and also an increase in the maximum amount of M1 inhibition activated by TMS. This pilot project provides introductory evidence that reductions in pain from GMI may be associated with increases in the excitability of inhibitory circuits in M1. Further research in a larger group of participants with CRPS is needed to make definitive conclusions. The results of these studies demonstrate that CP can have widespread cortical effects, which should be taken into account in the diagnosis, treatment, and management of patients with the disorder.

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  • Degree
    Master of Science
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    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.