Cardiovascular and cerebrovascular consequences of spinal cord injury

Spinal cord injury (SCI) has profound effects on motor, sensory, and autonomic function. The autonomic repercussions of SCI are widespread and demand life-long management and care. Cardiovascular problems are particularly common after high-level SCI that disrupts spinal sympathetic pathways to the heart and blood vessels. In this thesis I investigated the effect of damage to autonomic pathways on cardiovascular control during routine activities of daily living. In Chapter 2, I showed that moderate changes in wheelchair seating positions could challenge or bolster blood pressure and cerebral blood flow in individuals with damage to autonomic pathways. This shows that positional changes can be used as physical manoeuvres to maintain blood pressure. Chapter 3 documented the progression of autonomic function over time in the acute post-injury period, demonstrating the wide range of trajectories of cardiovascular function after injury. This work also highlighted how motor, sensory and autonomic function can be affected differently by SCI; damage to motor and sensory pathways cannot always predict autonomic deficits. Next, in Chapter 4, I examined cerebrovascular control, and found that individuals with damage to autonomic pathways have a reduced cerebral blood flow response to low oxygen. While the aetiology of this difference is unclear, the results suggest that exposure to low oxygen, for example during sleep apnea, may be particularly detrimental in this population. Finally, in Chapter 5, I conducted a survey examining bowel care and cardiovascular function after SCI that identified a significant need for ongoing support to improve bowel management. It also revealed the major limitations that bowel care can have on social participation and employment. A knowledge gap was also identified regarding blood pressure control and cardiovascular symptoms triggered by bowel care. This work reiterates the importance of autonomic assessment after SCI and the value of combining physiological recording with symptom assessments. Autonomic dysfunctions have significant ramifications for blood pressure control, cerebrovascular control, and quality of life after SCI. The integrity of the autonomic nervous system should be incorporated into research outcomes and stratification and be used to help guide clinical decision-making and self-management.