A Passive-State Comparison of Shear Wave Ultrasound Elastography of the Biceps Brachii with a Robotic Measurement of Elbow Extension Impedance in Chronic Hemiparetic Stroke

Muscle tissue is prone to changes in composition and architecture following stroke. Changes in muscle tissue of the extremities are thought to increase passive muscle stiffness and joint impedance. These effects likely compound neuromuscular impairments exacerbating movement function. Unfortunately, conventional rehabilitation is devoid of quantitative measures yielding to subjective assessment of passive joint mobility and end feel. Shear wave ultrasound elastography is a conventional tool used by ultrasonographers that may be readily available for use in the rehabilitation setting as a quantitative measure, albeit at the muscle-tissue level, filling the gap. To support this postulation, we evaluated the criterion validity of shear wave ultrasound elastography of the biceps brachii by investigating the relationship to a laboratory-based criterion measure for quantifying elbow joint impedance in individuals with moderate to severe chronic stroke. Measurements were performed under passive conditions at seven positions spanning the arc of elbow joint extension in both arms of twelve individuals with hemiparetic stroke. Surface electromyography was utilized for threshold-based confirmation of muscle quiescence. A significant moderate relationship was identified near end range of elbow extension and all metrics were greater in the paretic arm. Data supports the progression toward clinical application of shear wave ultrasound elastography in evaluating altered muscle mechanical properties in stroke stipulating the confirmation of muscle quiescence. Considering the lack of bedside robotics in clinical practice, shear wave ultrasound elastography will likely augment the conventional method of manually testing joint mobility. Tissue-level measurement may also assist in identifying new therapeutic targets for patient-specific impairment-based interventions. New & NoteworthyMethods for quantifying passive (non-reflex mediated) joint mobility are absent in stroke rehabilitation. Rehabilitation specialists are left to subjective assessment of the impact on function. Here, we compare the application of shear wave ultrasound elastography for estimating mechanical properties of muscle with a robotic method (criterion measure) of measuring passive elbow extension joint impedance. Data support the clinical application of shear wave ultrasound elastography, especially with the absence of bedside robotics.