Robotic quantification of upper extremity loss of independent joint control or flexion synergy in individuals with hemiparetic stroke: a review of paradigms addressing the effects of shoulder abduction loading

Abstract

Unsupported or “against-gravity” reaching and hand opening movements are greatly impaired in individuals with hemiparetic stroke. The reduction in reaching excursion and hand opening is thought to be primarily limited by abnormal muscle co-activation of shoulder abductors with distal limb flexors, known as flexion synergy, that results in a loss of independent joint control or joint individuation. Our laboratory employs several methods for quantifying this movement impairment, however the most documented techniques are sophisticated and laboratory-based. Here a series of robotic methods that vary in complexity from comprehensive (laboratory-based) to focused (clinically relevant) are outlined in detail in order to facilitate translation and make recommendations for utilization across the translational spectrum as part of Journal of NeuroEngineering and Rehabilitation thematic series, “Technically-advanced assessments in sensory motor rehabilitation.” While these methods focus on our published work utilizing the device, ACT3D, these methods can be duplicated using any mechatronic device with the appropriate characteristics. The common thread and most important aspect of the methods described is addressing the deleterious effects of abduction loading. Distal upper extremity joint performance is directly and monotonically modulated by proximal (shoulder abduction) joint demands. The employment of robotic metrics is the best tool for selectively manipulating shoulder abduction task requirements spanning the individual’s full range of shoulder abduction strength. From the series of methods and the concluding recommendations, scientists and clinicians can determine the ideal robotic quantification method for the measurement of the impact of loss of independent joint control on reaching and hand function.

Flexion synergy overshadows flexor spasticity during reaching in chronic moderate to severe hemiparetic stroke

“…The ACT 3D robotic device was employed to quantify reaching function under various abduction loading conditions (Figure 1A,B) (Sukal et al, 2007, Ellis et al, 2008, Ellis et al, 2016). The participant interface of the ACT 3D allows motion of the arm in the horizontal plane and is capable of imposing vertical forces upon its user, thus controlling the abduction loading experienced by the participant during an outward reach.…”

“…Participants were asked to make ballistic arm movements from an initial home position close by their body to an outward target in order to quantify reaching velocity (Ellis et al, 2016). The home position and reaching target were standardized to shoulder and elbow joint angles.…”

“…Concurrent quantification of each phenomena in a single controlled movement task, as performed in this study, allows for causative (effect of abduction loading) as opposed to relational hypotheses to be tested identifying key impairments of reaching dysfunction. The device, ACT 3D , (Sukal et al, 2005) is capable of systematically manipulating the amount of abduction loading required during outward reaching (Sukal et al, 2007, Ellis et al, 2008, Ellis et al, 2016). Muscle electromyography can be concurrently acquired and partitioned into time epochs prior to and just after the onset of elbow joint extension allowing for quantification of the contributions of synergy-related vs. spasticity-related flexor activation to reaching performance.…”

Technology-aided assessment of functionally relevant sensorimotor impairments in arm and hand of post-stroke individuals

“…Digital health metrics extracted from technology-aided assessments can provide objective and traceable descriptions of upper limb behaviour on sensitive, continuous scales without ceiling effects [17][18][19]. However, the majority of instrumented assessments focuses on characterizing impairments during isolated planar joint movements while supporting the arm against gravity [20][21][22][23].…”

“…However, the majority of instrumented assessments focuses on characterizing impairments during isolated planar joint movements while supporting the arm against gravity [20][21][22][23]. This neglects the importance of hand impairments and shadows the effect of certain deficits, such as weakness [19], which are both fundamental when performing daily activities. This questions the functional relevance of these assessments.…”