Impaired Microvascular Reactivity to Passive Limb Movement After Stroke Is Improved by a Single Session of Ischemic Conditioning.

BACKGROUND

Microvascular dysfunction post stroke remains insufficiently investigated and may contribute to impairments in physical function. Single passive limb movement (sPLM) provides a clinically relevant assessment of microvascular vasodilation. We hypothesized the response to sPLM would be attenuated in the paretic leg compared with age- and sex-matched controls (CON) and would improve following a single session of ischemic conditioning (IC), an intervention known to enhance vasodilation.

METHODS

In this randomized crossover trial, superficial femoral artery leg blood flow was measured during sPLM, using a Biodex dynamometer, which passively moved the leg 90° at 1 Hz. A thigh cuff was placed around the paretic leg (dominant leg in CON) and inflated to 225 mm Hg for IC or 25 mm Hg for sham-IC for 5 minutes, followed by 5 minutes deflation, repeated for 45 minutes. A blinded assessor remeasured the sPLM response, calculated as the percentage of change in peak leg blood flow relative to baseline.

RESULTS

Fifteen individuals post stroke (62±10 years old, 60% female, 8±6 years post stroke) and fifteen CON completed the study. The microvascular response to sPLM was lower in the paretic leg (x¯=47%±19%) compared with CON (x¯=65%±36%, P=0.04) but not the nonparetic leg (x¯=56%±34%, P=0.10). IC improved the microvascular response to sPLM in the paretic leg (P=0.02) but not the nonparetic leg or CON (P≥0.68).

CONCLUSIONS

Individuals post stroke exhibited impaired movement-induced microvascular vasodilation in the paretic leg. A single session of IC acutely improved the paretic leg's response, potentially supporting local IC as an adjunct therapy to enhance microvascular health before neurorehabilitation.