Rehabilitation robotics : stimulating restoration of arm function after stroke

Stroke is a major cause of permanent disability, due to neurological damage in the brain. As a consequence, arm and hand function may be compromised: 60% of stroke patients experiences serious limitations in daily life due to reduced arm and hand function. To minimize such limitations, patients receive rehabilitation care. Optimal rehabilitation treatment should include several key aspects: active initiation and execution of movement, high intensity of training and application of functional exercises. Technological innovations enable development of interventions that specifically address these key aspects. A promising innovation is the use of rehabilitation robots in addition to conventional therapy, since robotic devices can apply forces to the arm of a person in a smart way: imposing passive movements, assisting active movements, or resisting active movements. \ud In her PhD research, Gerdienke Prange investigated in which way rehabilitation robotics can provide a valuable addition to conventional rehabilitation care for people with limitations in arm function after stroke. Both rehabilitation robotics and the sole application of one of its basic features, gravity compensation (or arm support), have the ability to improve arm movement ability after stroke. Gravity compensation facilitates and enhances reaching movements by direct application using a custom designed, smart gravity compensating device, Freebal. This is translated to improvement of unsupported reaching movements after a longer term application of gravity compensation as training intervention, involving mainly an improved ability to activate prime mover muscles at the elbow and shoulder. \ud The potential of current robot-aided therapy and gravity compensation training to improve arm movement ability after stroke is comparable to conventional therapy, and to each other. Considering implementation in clinical practice, the relatively simple, low-tech application of gravity compensation is more suitable than complex, high-tech devices. As advantage over conventional therapy, gravity compensation training, using a low-tech device in combination with interactive games, allows automation of therapy, with one therapist supervising multiple patients training at the same time. This offers the possibility to increase productivity of the healthcare system and reduce costs

A feasibility study of the effect of multichannel electrical stimulation and gravity compensation on hand function in stroke patients: A pilot study

Many stroke patients have to cope with impaired arm and hand function. As a feasibility study, gravity compensation (GC) and multichannel electrical stimulation (ES) were applied to the forearm of eight stroke patients to study potential effects on dexterity. ES was triggered by positional data of the subject's hand relative to the objects that had to be grasped. Dexterity was evaluated by means of the Box and Blocks Test (BBT). The BBT was performed with four combinations of support; with and without GC and with and without ES. In all patients, it was possible to induce sufficient hand opening for grasping a block of the BBT by means of ES. There was no significant increase in dexterity as measured with the BBT. GC and/or ES did not improve instantaneous dexterity in a small sample of stroke patients although sufficient hand opening was reached in all patients. More research in a larger sample of stroke patients with more specific and more sophisticated control algorithms is needed to explore beneficial effects of GC and ES on hand function in post stroke rehabilitatio

Influence of gravity compensation on muscle activity during reach and retrieval in healthy elderly.

INTRODUCTION: Arm support like gravity compensation may improve arm movements during stroke rehabilitation. It is unknown how gravity compensation affects muscle activation patterns during reach and retrieval movements. Since muscle activity during reach is represented by a component varying with movement velocity and a component supposedly counteracting gravity, we hypothesized that gravity compensation decreases the amplitude of muscle activity, but does not affect the pattern. To examine this, we compared muscle activity during well defined movements with and without gravity compensation in healthy elderly. METHODS: Ten subjects performed reach and retrieval movements with and without gravity compensation. Muscle activity of biceps, triceps, anterior, middle and posterior parts of deltoid and upper trapezius was compared between the two conditions. RESULTS: The level of muscle activity was lower with gravity compensation in all muscles, reaching significance in biceps, anterior deltoid and trapezius (p0.026). The muscle activation pattern did not differ between movements with and without gravity compensation (p0.662). DISCUSSION: Gravity compensation only influenced the level of muscle activity but not the muscle activation pattern in terms of timing. Future studies should examine if the influence of gravity compensation is comparable for stroke patients. This may stimulate early and intensive training during rehabilitation

Effect of position feedback during task-oriented upper-limb training after stroke: Five-case pilot study

Feedback is an important element in motor learning during rehabilitation therapy following stroke. The objective of this pilot study was to better understand the effect of position feedback during task-oriented reach training of the upper limb in people with chronic stroke. Five subjects participated in the training for 30 minutes three times a week for 6 weeks. During training, subjects performed reaching movements over a predefined path. When deviation from this path occurred, shoulder and elbow joints received position feedback using restraining forces. We recorded the amount of position feedback used by each subject. During pre- and posttraining assessments, we collected data from clinical scales, isometric strength, and workspace of the arm. All subjects showed improvement on one or several kinematic variables during a circular motion task after training. One subject showed improvement on all clinical scales. Subjects required position feedback between 7.4% and 14.7% of training time. Although augmented feedback use was limited, kinematic outcome measures and movement performance during training increased in all subjects, which was comparable with other studies. Emphasis on movement errors at the moment they occur may possibly stimulate motor learning when movement tasks with sufficiently high levels of difficulty are applied