Vascular Remodeling after Spinal Cord Injury

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Abstract
Our purpose was to determine whether spinal cord injured (SCI) subjects have decreased femoral artery diameter and maximal hyperemic blood flow when expressed per unit of muscle volume compared with able-bodied (AB) individuals. A secondary purpose was to determine whether blood flow recovery rates were similar between groups. Blood flow was measured in the femoral artery using Doppler ultrasound after distal thigh cuff occlusion of 4 and 10 min. Muscle mass of the lower leg was determined by magnetic resonance imaging (MRI). SCI individuals had smaller muscle cross-sectional areas (37%, P = 0.001) and volumes (38%, P = 0.001) than AB individuals. Furthermore, femoral artery diameter (0.76 +/- 0.14 vs 0.48 +/- 0.06 cm, AB vs SCI, P < 0.001) and femoral artery maximal blood flow (2050 +/- 520 vs 1220 +/- 240 mL x min-1, AB vs SCI, P < 0.001) were lower in SCI than AB individuals. Femoral artery diameter and maximal blood flow per unit muscle volume did not differ between SCI and AB individuals (P = 0.418 and P = 0.891, respectively). Blood flow recovery after ischemia was prolonged in SCI compared with AB individuals for both cuff durations (P = 0.048). In summary, femoral artery diameter and maximal hyperemic blood flow response per unit muscle volume are not different between SCI and AB individuals. Vascular atrophy after SCI appears to be closely linked to muscle atrophy. Furthermore, the SCI compared with AB individuals had a prolonged time to recovery, which may suggest decreased vessel reactivity.