PRALINE: study protocol for a phase IIb inpatient stroke rehabilitation randomized controlled trial investigating longitudinal outcomes after progressive abduction loading therapy.

Background: Stroke is the leading cause of long-term disability with paucity of evidence-based interventions for individuals with severe upper extremity impairment in the affected arm. Loss of independent joint control limits reaching distance and velocity contributing to activity and participation limitations. Emerging evidence demonstrates improved independent upper extremity joint movement with training combining shoulder abduction loading during high repetition, task-specific reaching practice.

Test-Retest Reliability and Minimal Detectable Change of Body Function Impairment and Activity Limitation Outcomes Using a Mechatronic Evaluation Designed for Inpatient Stroke Research.

Objective: To determine the test-retest reliability and minimal detectable change (MDC) scores for 7 precision measures examining upper extremity strength, reaching ability, and the expression of flexion synergy after stroke. The measurements relied on a mechatronic evaluation designed for time efficiency facilitating implementation in inpatient translational research.

Design: Observational, analytical, cross-sectional study.

Human-in-the-Loop Myoelectric Pattern Recognition Control of an Arm-Support Robot to Improve Reaching in Stroke Survivors.

The objective of this study was to assess the feasibility and efficacy of using real-time human-in-the-loop pattern recognition-based myoelectric control to control vertical support force or vertical position to improve reach in individuals with chronic stroke. This work attempts to move proven lab-based static arm support paradigms towards a controllable wearable device. A machine learning (linear discriminant analysis)-based myoelectric pattern recognition system based on movement intent as determined by real-time muscle activation was used to control incremental changes in either vertical position or vertical support force during a reach and retrieve task, with the goal of improving reaching function.

Shear wave ultrasound elastography of the biceps brachii can be used as a precise proxy for passive elbow torque in individuals with 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 resistance to muscle elongation or joint torque under passive conditions. These effects likely compound neuromuscular impairments, exacerbating movement function.

Coupling of shoulder joint torques in individuals with chronic stroke mirrors controls, with additional non-load-dependent negative effects in a combined-torque task.

Background: After stroke, motor control is often negatively affected, leaving survivors with less muscle strength and coordination, increased tone, and abnormal synergies (coupled joint movements) in their affected upper extremity. Humeral internal and external rotation have been included in definitions of abnormal synergy but have yet to be studied in-depth.

Objective: Determine the ability to generate internal and external rotation torque under different shoulder abduction and adduction loads in persons with chronic stroke (paretic and non-paretic arm) and uninjured controls.

Feasibility of Two Different EMG-Based Pattern Recognition Control Paradigms to Control a Robot After Stroke - Case Study.

Stroke often results in chronic motor impairment of the upper-extremity yet neither traditional- nor robotics-based therapy has been able to affect this in a profound way. Supporting the weak affected shoulder against gravity improves reaching distance and minimizes abnormal co-contraction of the elbow, wrist, and fingers after stroke. However, it is necessary to assess the feasibility and efficacy of real-time controllers for this population as technology advances and a wearable shoulder device comes closer to reality.

Determining User Intent of Partly Dynamic Shoulder Tasks in Individuals With Chronic Stroke Using Pattern Recognition.

Stroke remains the leading cause of long-term disability in the US. Although therapy can achieve limited improvement of paretic arm use and performance, weakness and abnormal muscle synergies-which cause unintentional elbow, wrist, and finger flexion during shoulder abduction-contribute significantly to limb disuse and compound rehabilitation efforts. Emerging wearable exoskeleton technology could provide powered abduction support for the paretic arm, but requires a clinically feasible, robust control scheme capable of differentiating multiple shoulder degrees-of-freedom.

Therapeutic Systems and Technologies: State-of-the-Art Applications, Opportunities, and Challenges.

In this review, we present current state-of-the-art developments and challenges in the areas of thermal therapy, ultrasound tomography, image-guided therapies, ocular drug delivery, and robotic devices in neurorehabilitation. Additionally, intellectual property and regulatory aspects pertaining to therapeutic systems and technologies are addressed.

Applying LDA-based pattern recognition to predict isometric shoulder and elbow torque generation in individuals with chronic stroke with moderate to severe motor impairment.

Background: Abnormal synergy is a major stroke-related movement impairment that presents as an unintentional contraction of muscles throughout a limb. The flexion synergy, consisting of involuntary flexion coupling of the paretic elbow, wrist, and fingers, is caused by and proportional to the amount of shoulder abduction effort and limits reaching function. A wearable exoskeleton capable of predicting movement intent could augment abduction effort and therefore reduce the negative effects of distal joint flexion synergy.

Application of an LDA Classifier for Determining User-Intent in Multi-DOF Quasi-Static Shoulder Tasks in Individuals with Chronic Stroke: Preliminary Analysis.

Abnormal synergies commonly present after stroke, limiting function and accomplishment of ADL's. They cause co-activation of sets of muscles spanning multiple joints across the affected upper-extremity. These synergies present proportionally to the amount of shoulder effort, thus the effects of the synergy reduce with reduced effort of shoulder muscles.

Neuromodulatory Inputs to Motoneurons Contribute to the Loss of Independent Joint Control in Chronic Moderate to Severe Hemiparetic Stroke.

In chronic hemiparetic stroke, increased shoulder abductor activity causes involuntary increases in elbow, wrist, and finger flexor activation, an abnormal muscle coactivation pattern known as the flexion synergy. Recent evidence suggests that flexion synergy expression may reflect recruitment of contralesional cortico-reticulospinal motor pathways following damage to the ipsilesional corticospinal tract. However, because reticulospinal motor pathways produce relatively weak post-synaptic potentials in motoneurons, it is unknown how preferential use of these pathways could lead to robust muscle activation.

Altered Neuromodulatory Drive May Contribute to Exaggerated Tonic Vibration Reflexes in Chronic Hemiparetic Stroke.

Exaggerated stretch-sensitive reflexes are a common finding in elbow flexors of the contralesional arm in chronic hemiparetic stroke, particularly when muscles are not voluntarily activated prior to stretch. Previous investigations have suggested that this exaggeration could arise either from an abnormal tonic ionotropic drive to motoneuron pools innervating the paretic limbs, which could bring additional motor units near firing threshold, or from an increased influence of descending monoaminergic neuromodulatory pathways, which could depolarize motoneurons and amplify their responses to synaptic inputs. However, previous investigations have been unable to differentiate between these explanations, leaving the source(s) of this excitability increase unclear.

Progressive Abduction Loading Therapy with Horizontal-Plane Viscous Resistance Targeting Weakness and Flexion Synergy to Treat Upper Limb Function in Chronic Hemiparetic Stroke: A Randomized Clinical Trial.

Background: Progressive abduction loading therapy has emerged as a promising exercise therapy in stroke rehabilitation to systematically target the loss of independent joint control (flexion synergy) in individuals with chronic moderate/severe upper-extremity impairment. Preclinical investigations have identified abduction loading during reaching exercise as a key therapeutic factor to improve reaching function. An augmentative approach may be to additionally target weakness by incorporating resistance training to increase constitutive joint torques of reaching with the goal of improving reaching function by "overpowering" flexion synergy.

Progressive recruitment of contralesional cortico-reticulospinal pathways drives motor impairment post stroke.

Key Points: Activation of the shoulder abductor muscles in the arm opposite a unilateral brain injury causes involuntary increases in elbow, wrist and finger flexion in the same arm, a phenomenon referred to as the flexion synergy. It has been proposed that flexion synergy expression is related to reduced output from ipsilesional motor cortex and corticospinal pathways. In this human subjects study, we provide evidence that the magnitude of flexion synergy expression is instead related to a progressive, task-dependent recruitment of contralesional cortex.

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

Objective: Pharmaceutical intervention targets arm flexor spasticity with an often-unsuccessful goal of improving function. Flexion synergy is a related motor impairment that may be inadvertently neglected. Here, flexor spasticity and flexion synergy are disentangled to determine their contributions to reaching dysfunction.

Progressive abduction loading therapy targeting flexion synergy to regain reaching function in chronic stroke: Preliminary results from an RCT.

Reaching function is impaired following stroke due to abnormal coupling of shoulder abduction and elbow flexion. This phenomenon is commonly referred to as flexion synergy, loss of independent joint control, or impaired joint individuation. We have been successful in treating individuals with chronic stroke with moderate to severe motor impairments through the employment of targeted rehabilitation robotics and identified progressive abduction loading as a key element to the rehabilitation of reaching.

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.

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.

Neck rotation modulates flexion synergy torques, indicating an ipsilateral reticulospinal source for impairment in stroke.

The effect of reticular formation excitability on maximum voluntary torque (MVT) generation and associated muscle activation at the shoulder and elbow was investigated through natural elicitation (active head rotation) of the asymmetric tonic neck reflex (ATNR) in 26 individuals with stroke and 9 age-range-matched controls. Isometric MVT generation at the shoulder and elbow was quantified with the head rotated (face pointing) contralateral and ipsilateral to the paretic (stroke) and dominant (control) arm. Given the dominance of abnormal torque coupling of elbow flexion with shoulder abduction (flexion synergy) in stroke and well-developed animal models demonstrating a linkage between reticular formation and ipsilateral elbow flexors and shoulder abductors, we hypothesized that constituent torques of flexion synergy, specifically elbow flexion and shoulder abduction, would increase with contralateral head rotation.

Quantifying loss of independent joint control in acute stroke with a robotic evaluation of reaching workspace.

Early recovery after stroke is significant for slow emergence of volitional movement. Initial movements are constrained by stereotypical co-activation of muscle groups such as shoulder abductors and distal limb flexors resulting in the loss of independent joint control. The objective of this study was to utilize new quantitative methods to evaluate the emergence and progression of the loss of independent joint control in the acute phase of recovery from stroke.

Effects of body orientation on maximum voluntary arm torques.

Introduction: Increased reliance on bulbospinal motor systems has been implicated in individuals with chronic stroke during maximum voluntary arm joint torque generation.

Methods: Maximum isometric single-joint and multi-joint arm strength was observed in two body orientations (sitting and supine) while maintaining identical head/neck/trunk/extremity joint configurations in order to identify bulbospinal contributions to maximum joint torque generation in 11 individuals with stroke and 10 individuals without stroke.

Results: During sitting, shoulder flexion was greater for both groups, whereas shoulder extension and elbow flexion, part of the "flexion synergy," were greater only in individuals with stroke.

Impairment-Based 3-D Robotic Intervention Improves Upper Extremity Work Area in Chronic Stroke: Targeting Abnormal Joint Torque Coupling With Progressive Shoulder Abduction Loading.

The implementation of a robotic system (ACT(3D)) that allowed for a quantitative measurement of abnormal joint torque coupling in chronic stroke survivors and, most importantly, a quantitative means of initiating and progressing an impairment-based intervention, is described. Individuals with chronic moderate to severe stroke (n = 8) participated in this single-group pretest-posttest design study. Subjects were trained over eight weeks by progressively increasing the level of shoulder abduction loading experienced by the participant during reaching repetitions as performance improved.

Progressive shoulder abduction loading is a crucial element of arm rehabilitation in chronic stroke.

Background: Total reaching range of motion (work area) diminishes as a function of shoulder abduction loading in the paretic arm in individuals with chronic hemiparetic stroke. This occurs when reaching outward against gravity or during transport of an object.

Objectives: This study implements 2 closely related impairment-based interventions to identify the effect of a subcomponent of reaching exercise thought to be a crucial element in arm rehabilitation.

Evidence for increased activation of persistent inward currents in individuals with chronic hemiparetic stroke.

Despite the prevalence of hyperactive stretch reflexes in the paretic limbs of individuals with chronic hemiparetic stroke, the fundamental pathophysiological mechanisms responsible for their expression remain poorly understood. This study tests whether the manifestation of hyperactive stretch reflexes following stroke is related to the development of persistent inward currents (PICs) leading to hyperexcitability of motoneurons innervating the paretic limbs. Because repetitive volleys of 1a afferent feedback can elicit PICs, this investigation assessed motoneuronal excitability by evoking the tonic vibration reflex (TVR) of the biceps muscle in 10 awake individuals with chronic hemiparetic stroke and measuring the joint torque and electromyographic (EMG) responses of the upper limbs.