Abstract 12557: The Impact of Spinal Cord Injury and Exercise Training on Cerebrovascular Function: Preliminary Results

Abstract

Background: Spinal cord injured (SCI) individuals are at higher risk of cerebrovascular disease, including stroke, suggesting that they cannot maintain steady cerebral perfusion. This may be due to disruption of nervous vascular control and/or prolonged inactivity and consequent deconditioning. If inactivity plays a significant role, appropriate exercise may reverse this decline. However, the relation between SCI and cerebrovascular function, and the impact of exercise is not well established. Methods: We studied cerebral blood flow responses to progressive increases in arterial CO 2 (via rebreathing) in 9 individuals with SCI (C5 - T10, >7 months post-injury). Vasoreactivity was derived from the relation between end-tidal CO 2 and cerebrovascular conductance. Five of the individuals were enrolled in 3-months hybrid-functional electrical stimulation-rowing exercise training program. Results: Vasoreactivity was somewhat lower in individuals with SCI compared to able-bodied controls (0.021±0.003 vs 0.030+0.009, p =0.28), and was related to the level of injury (R 2 =0.51, p =0.03), such that individuals with higher level injuries had lower vasoreactivity. Exercise training improved vasoreactivity (by ~25% overall), and the extent of improvement was strongly related to injury duration (R 2 =0.70, p =0.07) but not level (R 2 =0.06), such that longer injury duration was associated with a bigger improvement. Conclusions: Given that individuals with higher injuries are more inactive compared to those with lower injuries, these preliminary data suggest that the decline in cerebrovascular function after SCI may primarily be due to prolonged inactivity and may be reversed by appropriate exercise. These results may have implications for sustained physical inactivity and cumulative cerebrovascular risk in general population.