Abstract TP143: Evaluation of Knee Extensor Muscle Strength and Femoral Artery Blood Flow in Subacute Stroke Patients Admitted to Inpatient Rehabilitation - a Feasibility Study

Abstract

Introduction: Weakness of the contralateral leg muscles commonly occurs following unilateral stroke. We and others have also shown that the femoral artery is atrophied in the paretic (P) limb of chronic stroke subjects (>6 months post-stroke) compared to the non-paretic (NP) limb, and that both resting and hyperemic blood flow to the exercising muscle are dramatically reduced. Further, the hyperemic response positively correlates with leg strength and clinical measures of leg function. It is unknown if these changes in femoral artery diameter and peripheral blood flow are present in the subacute phase of stroke (<30 days post-stroke). Hypothesis: Femoral artery diameter is smaller, and resting and hyperemic blood flow to exercising muscle is reduced in the P limb in subjects in the subacute phase of stroke admitted to inpatient rehabilitation. Methods: Stroke patients were tested within three days of admission to inpatient rehabilitation in a hospital setting. Isometric knee extensor maximal voluntary contractions (MVCs) were measured in both legs using a Biodex dynamometer. Superficial femoral artery diameter and blood flow were measured at rest and immediately following MVCs using Doppler ultrasound. Results: A pilot group of four subjects (1 male, 3 female) aged 68 ± 4 years (range 56-75 years) completed all study procedures on average 13 ± 5 days post ischemic stroke (range 7-24 days). All subjects had infarcts of the middle cerebral artery (3 right, 1 left). P leg knee extensor MVCs were lower compared to the NP leg (93.8 ± 25.5 Nm vs. 160.4 ± 33.2 Nm, respectively; p<0.05). Superficial femoral artery diameter was smaller in the P leg compared to the NP leg (5.7 ± 0.4 mm vs. 6.0 ± 0.5 mm, respectively; p=0.06), and resting blood flow was reduced (172 ± 46 ml/min vs. 206 ± 54 ml/min, respectively; p<0.05). Hyperemic blood flow in response to knee extensor MVCs was also lower in the P limb compared to the NP limb (239 ± 62 ml/min vs. 435 ± 67 ml/min, respectively; p<0.05). Conclusions: We show feasibility of testing knee extensor muscle strength and peripheral blood flow in subacute stroke inpatients. Our preliminary data indicates that femoral artery atrophy has occurred in the P leg and that both resting and hyperemic blood flow to the P muscle are reduced.