How blood flow affects stroke risk after spinal cord injury

Image: Individuals with spinal cord injury can lose the ability to regulate involuntary functions, including blood pressure. In this blog post, Dr. Aaron Phillips describes his research into the impact of unstable blood pressure on the brain's susceptibility to stroke.

Dr. Aaron Phillips is a post-doctoral fellow at the University of British Columbia. He researches brain blood flow regulation and the clinical outcomes of dysfunction at the Centre for Heart, Lung, and Vascular Health, as well as the International Collaboration on Repair Discoveries (ICORD).

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Spinal cord injury (SCI) is undoubtedly devastating. What is not commonly appreciated is that in addition to devastating paralysis and loss of sensation, individuals with SCI also lose the ability to regulate many involuntary functions of the body controlled by the autonomic nervous system.

These changes to involuntary functions include extremely unstable blood pressure. Specifically, the majority of people with SCI experience massive drops in blood pressure when they sit up from lying down (referred to as orthostatic hypotension), as well as dangerous uncontrolled increases in blood pressure (referred to as autonomic dysreflexia).

High blood pressure is well understood to be unhealthy to the cardiovascular system, and we are beginning to understand that low blood pressure can also negatively impact health, particularly the health of the brain. We now recognize that in able-bodied individuals, brief but intense episodes of low and high blood pressure are associated with stroke. We have also recently become aware that those with SCI are two to three times more likely to suffer a stroke.

Further to this point, people with SCI find that these issues impact their lives so much that they ranked autonomic/involuntary issues above being able to walk again when ranking their preferences for future medical research.

Currently, with the support of MSFHR, we are in the in the initial stages of examining cerebral blood pressure and cerebral blood flow (using the most advanced techniques) during medically required procedures in humans with SCI, which induce orthostatic hypotension and autonomic dysreflexia.

This study will provide critical information regarding how susceptible the brain becomes to blood flow that is too high or too low, which can starve brain blood cells or rupture brain blood vessels (both related to stroke). Through this project, we will likely be able to detect how high blood pressure can rise before the brain blood vessels become susceptible to rupture (stroke).