Muscle spasticity associated with reduced whole-leg perfusion in persons with spinal cord injury

Objective: To determine the association between peripheral blood flow and spasticity in individuals with spinal cord injury (SCI). Design: A cross-sectional study with measurements of muscle spasticity and whole-limb blood flow in individuals with SCI. Setting: University of Texas at Austin and Brain & Spine Recovery Center, Austin, TX, USA. Participants: Eighteen individuals (14 males and 4 females) with SCI were classified into high (N = 7), low (N = 6), and no (N = 5) spasticity groups according to the spasticity levels determined by the modified Ashworth scale scores. Interventions: Whole-limb blood flow was measured in the femoral and brachial arteries using Doppler ultrasound and was normalized to lean limb mass obtained with dual-energy X-ray absorptiometry. Outcome measures: Limb blood flow and muscle spasticity. Results: Age, time post-SCI, and the American Spinal Injury Association impairment scale motor and sensory scores were not different among groups with different muscle spasticity. Femoral artery blood flow normalized to lean leg mass was different (P = 0.001) across the three spasticity groups (high 78.9 +/- 16.7, low 98.3 +/- 39.8, no 142.5 +/- 24.3 ml/minute/kg). Total leg muscle spasticity scores were significantly and negatively correlated with femoral artery blood flow (r = -0.59, P < 0.01). There was no significant difference in brachial artery blood flow among the groups. Conclusions: Whole-leg blood flow was lower in individuals with greater spasticity scores. These results suggest that a reduction in lower-limb perfusion may play a role, at least in part, in the pathogenesis leading to muscle spasticity after SCI.