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 rehabilitation.

Application of arm support training in sub-acute stroke rehabilitation: first results on effectiveness and user experiences.

A multi-center randomized clinical trial was performed in 7 Dutch rehabilitation centers, in the context of an implementation project (ROBAR), to compare the effect of an arm support (AS) training device to equally intensive conventional reach training (CON) on recovery of arm-hand function in sub-acute stroke. The Fugl-Meyer assessment (FM) and user experiences of therapists and patients were examined in both groups. An improvement of 10 and 8 points on the FM was found for respectively the CON and AS group. Both therapists and patients reported positive experiences on several aspects of user acceptance. These findings indicate that a low-tech system for arm support results in similar gains in arm function as conventional reach training in equal intensity, and is suitable for application in clinical practice.

An explorative study into changes in circle drawing after gravity compensation training in chronic stroke patients.

A way to reduce the influence of abnormal synergies on range of motion after stroke directly is to support the arm by a robotic gravity compensation device. However, it is not known whether a period of training with arm support improves independent, unsupported circle drawing, and what the role of abnormal synergies is. Seven chronic stroke patients received three 30 minute robotic gravity compensation training sessions per week for a period of six weeks. During baseline and evaluation measurements, Fugl-Meyer (FM) scores and circle drawing performance (area and roundness) were determined. After training, FM had improved in some subjects. Circle area increased significantly across subjects, whereas roundness did not. This indicates an improved unsupported active range of motion, but the influence of (reduced) abnormal synergies on this change remains unclear. Despite the small number of subjects, the present explorative study suggests that robotic gravity compensation training has the potential to increase the work area of the affected arm of chronic stroke patients. Further research into the impact of robotic gravity compensation training is warranted, to enhance insight into underlying mechanisms and optimal applications in clinical practice.

Objective measurement of synergistic movement patterns of the upper extremity following stroke: an explorative study.

The majority of stroke survivors have to cope with deficits in arm function, which is often monitored with subjective clinical scales during stroke rehabilitation. The aim of this study is to examine whether robotic outcome measures obtained during circle drawing are suitable to objectively measure upper extremity function of stroke survivors, especially regarding synergistic movement patterns. Stroke survivors (n = 16) and healthy subjects (n = 20) drew circles, as big and as round as possible, above a table top. Joint angles and positions of the shoulder and elbow were measured. Synergistic movement patterns were identified based on simultaneous changes of the shoulder elevation angle and elbow angle. Stroke survivors moved significantly more within synergistic movement patterns, compared to healthy subjects. Strong correlations between the proximal upper extremity part of the Fugl-Meyer (FM) scale and the use of synergistic movement patterns were found. The proposed outcome measures seem to be suitable measures to objectively quantify the occurrence of synergistic movement patterns of the upper extremity following stroke.

Preliminary results of training with gravity compensation of the arm in chronic stroke survivors.

After stroke, arm function can be limited by a reduction in the selectivity of movements, due to involuntary coupling of shoulder abduction and elbow flexion, limiting the ability to reach. Gravity compensation of the arm reduces the required active shoulder abduction torques, which results in a larger range of motion instantaneously. Integration of a motivating rehabilitation game in the training program stimulates motor relearning processes during training. During 6 weeks, 8 chronic stroke survivors received 3 sessions of 30 minutes gravity compensated reach training per week using a rehabilitation game, which was evaluated by assessing motor status and a circle drawing task before and after training. After gravity compensation training, Fugl Meyer scores and the range of motion obtained from the circle drawing task had improved in a seven of the eight chronic stroke survivors. The present findings indicate that gravity compensation in combination with rehab games can be a valuable training modality for stroke rehabilitation.

Influence of gravity compensation on muscle activation patterns during different temporal phases of arm movements of stroke patients.

BACKGROUND: Arm support to help compensate for the effects of gravity may improve functional use of the shoulder and elbow during therapy after stroke, but gravity compensation may alter motor control. OBJECTIVE: To obtain quantitative information on how gravity compensation influences muscle activation patterns during functional, 3-dimensional reaching movements. METHODS: Eight patients with mild hemiparesis performed 2 sets of repeated reach and retrieval movements, with and without unloading the arm, using a device that acted at the elbow and forearm to compensate for gravity. Electromyographic (EMG) patterns of 6 upper extremity muscles were compared during elbow and shoulder joint excursions with and without gravity compensation. RESULTS: Movement performance was similar with and without gravity compensation. Smooth rectified EMG (SRE) values were decreased from 25% to 50% during movements with gravity compensation in 5 out of 6 muscles. The variation of SRE values across movement phases did not differ across conditions. CONCLUSIONS: Gravity compensation did not affect general patterns of muscle activation in this sample of stroke patients, probably since they had adequate function to complete the task without arm support. Gravity compensation did facilitate active arm movement excursions without impairing motor control. Gravity compensation may be a valuable modality in conventional or robot-aided therapy to increase the intensity of training for mildly impaired patients.

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 (p < or = 0.026). The muscle activation pattern did not differ between movements with and without gravity compensation (p > or = 0.662). 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.