Time course of arterial remodelling in diameter and wall thickness above and below the lesion after a spinal cord injury

Abstract

Physical inactivity in response to a spinal cord injury (SCI) represents a potent stimulus for conduit artery remodelling. Changes in conduit artery characteristics may be induced by the local effects of denervation (and consequent extreme inactivity below the level of the lesion), and also by systemic adaptations due to whole body inactivity. Therefore, we assessed the time course of carotid (i.e. above lesion) and common femoral artery (i.e. below lesion) lumen diameter and wall thickness across the first 24 weeks after an SCI. Eight male subjects (mean age 35 ± 14 years) with a traumatic motor complete spinal cord lesion between T5 and L1 (i.e. paraplegia) were included. Four subjects were measured across the first 6 weeks after SCI, whilst another four subjects were measured from 8 until 24 weeks after SCI. Ultrasound was used to examine the diameter and wall thickness from the carotid and common femoral arteries. Carotid artery diameter did not change across 24 weeks, whilst femoral artery diameter stabilised after the rapid initial decrease during the first 3 weeks after the SCI. Carotid and femoral artery wall thickness showed no change during the first few weeks, but increased both between 6 and 24 weeks (P < 0.05). In conclusion, SCI leads to a rapid and localised decrease in conduit artery diameter which is isolated to the denervated and paralyzed region, whilst wall thickness gradually increases both above and below the lesion. This distinct time course of change in conduit arterial diameter and wall thickness suggests that distinct mechanisms may contribute to these adaptations.

Fig. 1

Individual (thin lines) and averaged (thick line) carotid arterial wall thickness (a) and diameter (b) from SCI individuals from weeks 3–6 (n = 4, solid symbols) and weeks 6–24 (n = 4, open symbols) after a spinal cord injury. Data are presented as the relative change from week 3 or week 8 (set at 100 %). Average data is presented when ≥3 subjects were tested. P values from the linear mixed models (based on absolute values) are added for the effect of time

Fig. 2

Individual (thin lines) and averaged (thick line) femoral arterial wall thickness (a) and diameter (b) from SCI individuals from weeks 3–6 (n = 4, solid symbols) and weeks 6–24 (n = 4, open symbols) after a spinal cord injury. Data are presented as the relative change from week 3 or week 8 (set at 100 %). Average data is presented when ≥3 subjects were tested. P values from the linear mixed models (based on absolute values) are added for the effect of time