| Category: Article | |||
| G. Prange, M. Jannink, A. Stienen, H. Van der Kooij, M. IJzerman & H. Hermens (2009), "An explorative, cross-sectional study into abnormal muscle synergies during functional reach in chronic stroke patients", J Neuroeng Rehabil. Conditionally accepted. Impact factor: 2.1. | |||
| Abstract: Background. In many stroke patients, arm function is limited, which can be related to a reduced selectivity of movement due to abnormal coupling between different joints. The extent of abnormal coupling between shoulder and elbow movements in chronic stroke patients in terms of muscle activation during functional movements is rather unknown. Therefore, the present study compared synergistic patterns in muscle activation during functional reaching movements between chronic stroke patients and healthy persons. Methods. To provoke synergistic patterns during movement, upward reaching movements were performed with and without resistance against shoulder elevation. Differences in movement performance (joint angles) and muscle activation (amplitude of activity) due to shoulder elevation resistance were compared between healthy persons and stroke patients using a repeated measures ANOVA. Results. Changes in movement performance and muscle activation during upward reaching due to shoulder elevation resistance were not significantly different between chronic stroke patients and healthy persons. Conclusions. These findings suggest that tasks corresponding with daily activities, without near-maximal effort, do not elicit abnormal coupling between shoulder and elbow movements in mildly affected chronic stroke patients. This implies that for this group of patients it would not be necessary to focus rehabilitation on reducing abnormal synergies, but can be aimed at other impairments that may be more involved in limiting arm function. |
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| BibTeX:
@article{prange09b,
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| L. Miller, R. Ruiz Torres, A. Stienen & J. Dewald (2009), "A wrist and finger force sensor module for quantifying wrist/finger dysfunction during movements of the paretic upper limb in chronic hemiparetic stroke.", IEEE T Bio-Med Eng. Vol. epub Impact factor: 1.6. | |||
| Abstract: Previous studies using robotic devices that focus on the wrist/fingers provide an incomplete picture of movement dysfunction following stroke because they do not consider the abnormal joint torque coupling that occurs during progressive shoulder abduction loading in the paretic upper limb. This letter introduces a device designed to measure isometric flexion/extension forces generated by the wrist and fingers during robot mediated 3-D dynamic movements of the upper limb and presents validating data collected from 8 participants with chronic stroke. | |||
| BibTeX:
@article{miller09,
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| A. Stienen, E. Hekman, F. van der Helm & H. van der Kooij (2009), "Analysis of weight-support mechanisms in upper-extremity rehabilitation devices.", IEEE Trans Neural Syst Rehabil Eng. Conditionally accepted. Impact factor: 2.5. | |||
| Abstract: In most upper-extremity rehabilitation devices, the arm is supported against gravity. This weight support assists the patient in making more meaningful movements earlier in the rehabilitation process. For devices, it reduces actuator strains and limits mechanical stresses. Weight support is often provided by separate mechanisms, indicating its importance. Current rehabilitation devices can be classified as endpoint manipulators, exoskeletons, and cable suspensions. The goal of this report is to evaluate their performance for providing weight support, based on the ease of use, construction and maintenance, best application per mechanism, and features like scalable compensation, range of motion and interaction impedance. The force-application and force-generation mechanisms are covered separately. In conclusion, the best possible solution of implementing weight support will depend on the primary design, but careful considerations at the start of the design process will lead to better design choices. | |||
| BibTeX:
@article{stienen09c,
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| A. Stienen, E. Hekman, G. Prange, M. Jannink, F. van der Helm & H. van der Kooij (2009), "Freebal: design of a minimal weight-support system for upper-extremity rehabilitation.", ASME J Med Dev. In press. Impact factor: unknown. | |||
| Abstract: Most rehabilitation devices for the upper extremities include a weight-support system. In recent publications, weight support is shown to be effective for stroke rehabilitation, but current devices are often complex, have significant movement inertia, and/or limit the movement range. The goal of this study is to improve on current designs by introducing a novel, dedicated weight-support device, the Freebal. This passive mechanical device uses ideal-spring mechanisms for constant-but-scalable forces to support the arm. It has a large workspace of roughly 1 m3, low movement impedance, and independent support at the elbow and wrist of up to 5 kg. An explorative cross-sectional study with eight patients shows the Freebal to instantly extend the range of motion of the affected arm. In conclusion, the requirements are met for patients to benefit from therapy with the Freebal, potentially progressing earlier to more motivating, functional training. | |||
| BibTeX:
@article{stienen09d,
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| A. Stienen, E. Hekman, G. Prange, M. Jannink, A. Aalsma, F. van der Helm & H. van der Kooij (2009), "Dampace: design of an exoskeleton for force-coordination training in upper-extremity rehabilitation.", ASME J Med Dev. Vol. 3(3), pp. 1-10. Impact factor: unknown. | |||
| Abstract: The Dampace exoskeleton combines functional exercises resembling activities of daily living with impairment-targeted force-coordination training. The goal of this paper is to evaluate the performance of the Dampace. In the design, the joint rotations are decoupled from the joint translations; the robot axes align themselves to the anatomical axes, overcoming some of the traditional difficulties of exoskeletons. Setup times are reduced to mere minutes and static reaction forces kept to a minimum. The Dampace uses hydraulic disk brakes which can resist rotations with up to 50 Nm and have a torque bandwidth of 10 Hz for multi-sine torques of 20 Nm. The brakes provide passive control over movement; patients’ movements can be selectively resisted, but active movement assistance is impossible and virtual environments restricted. However, passive actuators are inherently safe and force active patient participation. In conclusion, the Dampace is well suited to offer force-coordination training with functional exercises. | |||
| BibTeX:
@article{stienen09e,
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| E. Asseldonk, M. Wessels, A. Stienen, F. van der Helm & H. van der Kooij (2009), "Influence of haptic guidance in learning a novel visuomotor task.", J Physiol (Paris). Vol. epub Impact factor: 1.6. | |||
| Abstract: In (re)learning of movements, haptic guidance can be used to direct the needed adaptations in motor control. Haptic guidance influences the main driving factors of motor adaptation, execution error and control effort, in different ways. Human control effort is dissipated in the interactions that occur during haptic guidance. Minimizing the control effort would reduce the interaction forces and as a consequence would result in adaptation. However, guidance also decreases the magnitude of the execution errors, which could inhibit motor adaptation. The aim of this study was to assess how different types of haptic guidance affect kinematic adaptation in a novel visuomotor task. Five groups of subjects adapted in a reaching task in which the visual representation of the hand was rotated 30°. Each group was guided by a different force field. The force fields differed in magnitude and direction, in order to discern the adaptation based on execution errors and control effort. The results demonstrated that the execution error did indeed play a key role in adaptation; the more the guiding forces restricted the occurrence of execution errors, the smaller the amount and rate of adaptation. However, the force field that enlarged the execution errors did not result in an increased rate of adaptation. The presence of a small amount of adaptation in the groups who did not experience execution errors during training suggested that adaptation could be driven on a much slower rate and on the basis of minimization of control effort as was evidenced by a gradual decrease of the interaction forces during training. Remarkably, also in the group in which the subjects were passive and completely guided a small but significant adaptation occurred. The conclusion is that both minimization of execution errors and control effort drives kinematic adaptation in a novel visuomotor task, but the latter at a much slower rate. | |||
| BibTeX:
@article{vanasseldonk09,
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| A. Stienen, E. Hekman, H. Ter Braak, A. Aalsma, F. van der Helm & H. van der Kooij (2009), "Design of a Rotational Hydro-Elastic Actuator for an Active Upper-Extremity Rehabilitation Exoskeleton.", IEEE T Bio-Med Eng. Vol. epub Impact factor: 1.6. | |||
| Abstract: The goal of this study was to validate the suitability of a novel rotational hydro-elastic actuator (rHEA) for use in our new rehabilitation exoskeleton for the upper limbs, the Limpact. The rHEA consists of a rotational hydraulic actuator and a custom-designed symmetric torsion spring in a serieselastic configuration. For rehabilitation therapy and impairment quantification both compliant impedance control and stiff admittance control modes are possible. In the validation experiments the torque bandwidth of the rHEA was limited to 18 Hz for a desired 20 Nm reference signal (multi sine, constant spectrum) due the transport delays in the long flexible tubes between the valve and cylinder. These transport delays also required changes to existing theoretical models to better fit the models on the measured frequency response functions. The (theoretical) measurable torque resolution was better than 0.01 Nm and the (validated) delivered torque resolution below 1 Nm. After the validation experiments further iterative improvements resulted in a spring design capable of a maximum output torque of 50 Nm with an intrinsic stiffness of 150 Nm/rad and a slightly higher bandwidth. With the design locked, the maximum measurable isometric torque is 100 Nm. In conclusion, the rHEA is suitable for upper-limb rehabilitation therapy as it matches the desired performance. | |||
| BibTeX:
@article{stienen09,
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| A. Stienen, E. Hekman, A. Schouten, F. van der Helm & H. van der Kooij (2009), "Suitability of hydraulic disk brakes for passive actuation of upper-extremity rehabilitation exoskeletons.", Appl Bionics Biomech. Vol. 6(2), pp. 103-114. Impact factor: unknown. | |||
| Abstract: Passive, energy-dissipating actuators are promising for force-coordination training in stroke rehabilitation, as they are inherently safe and have a high torque-to-weight ratio. The goal of this study is to determine if hydraulic disk brakes are suitable to actuate an upper-extremity exoskeleton, for application in rehabilitation settings. Passive actuation with friction brakes has direct implications for joint control. Braking is always opposite to the movement direction. During standstill, the measured torque is equal to the torque applied by the human. During rotations, it is equal to the brake torque. Actively assisting move- ments is not possible, nor energy-requiring virtual environments. The evaluated disk brake has a 20 Nm bandwidth (flat-spectrum, multi-sine) of 10 Hz; sufficient for torques required for conventional therapy and simple, passive virtual environments. The maximum static out- put torque is 120 Nm; sufficient for isometric training of the upper extremity. The minimal impedance is close zero, with only the inertia of the device felt. In conclusion, hydraulic disk brakes are suitable for rehabilitation devices. | |||
| BibTeX:
@article{stienen09a,
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| A. Stienen, E. Hekman, F. van der Helm & H. van der Kooij (2009), "Self-aligning exoskeleton axes through decoupling of joint rotations and translations.", IEEE T Robot. Vol. 25(3), pp. 628-633. Impact factor: 2.0. | |||
| Abstract: To automatically align exoskeleton axes to human anatomical axes, we propose to decouple the joint rotations from the joint translations. Decoupling can reduce setup times and painful misalignment forces, at the cost of increased mechanical complexity and movement inertia. The decoupling approach was applied to the Dampace and Limpact exoskeletons. | |||
| BibTeX:
@article{stienen09b,
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| G. Prange, M. Jannink, A. Stienen, H. van der Kooij, M. IJzerman & H. Hermens (2009), "Influence of Gravity Compensation on Muscle Activation Patterns During Different Temporal Phases of Arm Movements of Stroke Patients.", Neurorehabil Neural Repair. Vol. 23(5), pp. 478-85. Impact factor: 3.8. | |||
| Abstract: 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. | |||
| BibTeX:
@article{prange09,
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| G. Prange, L. Kallenberg, M. Jannink, A. Stienen, H. van der Kooij, M. IJzerman & H. Hermens (2009), "Influence of gravity compensation on muscle activity during reach and retrieval in healthy elderly.", J Electromyogr Kinesiol. Vol. 19(2), pp. e40-e49. Impact factor: 1.9. | |||
| Abstract: 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. | |||
| BibTeX:
@article{prange09a,
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| M. Jannink, G. Prange, J. Buurke, A. Stienen, E. Van Asseldonk & H. van der Kooij (2008), "State of the art. CVA-revalidatie van beperkte arm- en handfunctie: Virtual Reality en Robotica?", Ned Tijdschr Fysiother. Vol. 118(4), pp. 86-94. Impact factor: unknown. | |||
| Abstract: De vergrijzing in de westerse wereld neemt toe. Recente gegevens laten zien dat in Europa ongeveer 21% van de bevolking ouder dan 50 jaar is. Men verwacht dat dit percentage zal toenemen tot 26% in het jaar 2020. Door deze demografishce veranderingen neemt de druk op de gezondheidzorg substantieel toe. Met het ouder worden neemt ook de kans op een neurologische aandoening, zoals een cerebrovasculair accident (CVA, beroerte), sterk toe. Een beroerte leidt tot een (gedeeltelijke) afbraak van corticaal weefsel, resulterend in een verstoorde generatie en integratie van neurale commando's. Een verstoorde generatie en integratie van neurale commando's in de sensomotorische gebieden van de cortex kan leiden ott een vermindering of zelfs compelte afwezigheid van het vermogen om speiren selectief te activeren. dit heeft zijn weerslag op de uitvoering van de motorische taak. Optimal herstel va nde motorische functie is dan ook essentieel om zo zelfstandig mogelijk te kunnen functioneren. Uit de literatuur blijkt dat actieve initiatie en uitvoering van bewegingen in betekenisvolle trainingsomgevingen met een hoge intensiteit essentieel zijn voor optimaal motorisch herstel na een beroerte. Intensieve therapie heeft tot op heden voornamelijk vorm gekregen middels de inzet van menselijke arbeid (een-op-eenbehandeling/training). De inzet van zorgprofessionals (fysiotherapeuten en ergotherapeuten0 kan in principe in beperkte mate toenemen. Met de recente ontwikkelingen op het gebeid van robotica en virtual reality (VR) kunnen patienten op een intensieve, efficiente en veilige manier trainen in de revalidatiefase. Deze state of the art review geeft een overzich tvan de mogelijkheden en de effectiviteit van robotica, virtual reality en gaming op de arm- en handfunctie binnen de motorische revalidatiebehandeling na een beroerte. |
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| BibTeX:
@article{jannink08,
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| A. Stienen, A. Schouten, J. Schuurmans & F. van der Helm (2007), "Analysis of reflex modulation with a biologically realistic neural network.", J Comput Neurosci. Vol. 23(3), pp. 333-48. Impact factor: 1.9. | |||
| Abstract: In this study, a neuromusculoskeletal model was built to give insight into the mechanisms behind the modulation of reflexive feedback strength as experimentally identified in the human shoulder joint. The model is an integration of a biologically realistic neural network consisting of motoneurons and interneurons, modeling 12 populations of spinal neurons, and a one degree-of-freedom musculoskeletal model, including proprioceptors. The model could mimic the findings of human postural experiments, using presynaptic inhibition of the Ia afferents to modulate the feedback gains. In a pathological case, disabling one specific neural connection between the inhibitory interneurons and the motoneurons could mimic the experimental findings in complex regional pain syndrome patients. It is concluded that the model is a valuable tool to gain insight into the spinal contributions to human motor control. Applications lay in the fields of human motor control and neurological disorders, where hypotheses on motor dysfunction can be tested, like spasticity, clonus, and tremor. | |||
| BibTeX:
@article{stienen07b,
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| Category: Inproceedings | |||
| A. Stienen, E. Hekman, H. Van der Kooij, M. Ellis & J. Dewald (2009), "Aspects of Weight-Support Mechanisms in Rehabilitation Robotics", In Proc WCMPBE'09. Munich, Germany. Sep 7-12 2009. | |||
| BibTeX:
@inproceedings{stienen09g,
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| T. Krabben, G. Prange, A. Stienen, B. Molier, G. Renzenbrink, H. van der Kooij & M. Jannink (2009), "Decoupling of synergistic movement patterns with gravity compensation and virtual reality in chronic stroke patients: preliminary results", In Proc INRS'09. Zurich, Switzerland. Feb 12-13 2009. | |||
| BibTeX:
@inproceedings{krabben09,
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| A. Stienen, E. Hekman, H. Ter Braak, A. Aalsma, F. Van der Helm & H. van der Kooij (2008), "Rotational Hydro Elastic Actuator for a Torque Driven Exoskeleton for the Upper-Extremities.", In Proc Biorob'08. Scottsdale, Arizona, USA. Oct 19-22 2008. | |||
| Abstract: Our new Limpact exoskeleton is mechanically based on the design of the passive Dampace and will be powered by rotational hydro-elastic actuators (rHEAs), using impedance control. In this paper we describe the design of the rHEA, which is a novel, custom-designed combination of a rotational hydraulic actuator and a symmetric torsion spring. The rHEA can also be used as a springless hydraulic actuator for stiffer admittance control, or for isometric large-torque measurements of up to 100 Nm, by locking specific components in the design. Our implementation of HEA required alterations to the existing theoretical models to account for (1) our long flexible tubes between the valve and cylinder, and (2) the influence of the pressure feedback on the valve flow. These newly adapted models gave the best fits on the frequency response functions from our open- and closed-loop identification experiments, and might even provide a better fit for the data in the original publication of the theoretical models. Multi-sine identification showed the torque-tracking bandwidth restricted to 18 Hz for a constant spectral-density reference signal of 20 Nm, mostly due the transport delays in the long flexible tubes. The measured torque resolution was better then 0.01 Nm. The delivered torque resolution was below 1 Nm, although at those small amplitudes, the output signal was accompanied by significant phase lead indicating some unaccounted for non-linearities in the actuator. When manipulated manually by forefinger and thumb, almost no distortion torques were felt during minimal-impedance and virtual-spring control. The symmetric torsion spring proved difficult to model correctly, and finding the best design became an iterative process. The spring in the prototype, used for the measurements as reported in this study, had a stiffness and maximum torque below those theoretically calculated, limiting the desired output to 22 Nm. With our latest spring design for the actuators in the Limpact, the maximum output torque is increased to 50 Nm. | |||
| BibTeX:
@inproceedings{stienen08,
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| A. Stienen, T. Rupert, G. Prange, M. Jannink, F. Van der Helm & H. van der Kooij (2007), "Multi-joint force-coordination training of healthy subject with our energydissipating exoskeleton Dampace.", In Proc Dutch BME'07. Egmond aan Zee, The Netherlands. Jan 18-19 2007., pp. 174. | |||
| Abstract: To facilitate force-coordination training of upper extremities of stroke patients, we developed a computer controlled energy-dissipating exoskeleton, called the Dampace. As an addition to the intended application in functional training for stroke rehabilitation, further usability is investigated by implementing a training protocol for multi-joint force and position control. | |||
| BibTeX:
@inproceedings{stienen07a,
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| A. Stienen, M. Wessels, E. van Asseldonk & H. van der Kooij (2007), "Influence of therapeutic force fields on visuomotor learning.", In Proc VI Mot Cont'07. Santos, Brazil. Aug 9-12 2007. | |||
| BibTeX:
@inproceedings{stienen07e,
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| H. van der Kooij, M. Wessels, A. Stienen & E. van Asseldonk (2007), "Influence of therapeutic force fields on visuomotor learning.", In Int Workshop on Mot Learn in Stroke Recov. Rome, Italy. Mar 18-19 2007. | |||
| BibTeX:
@inproceedings{vanderkooij07a,
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| A. Stienen, E. Hekman, F. van der Helm, G. Prange, M. Jannink, A. Aalsma & H. van der Kooij (2007), "Freebal: dedicated gravity compensation for the upper extremities.", In Proc 10th ICORR'07. Noordwijk, the Netherlands. Jun 13-15 2007. | |||
| Abstract: In most upper-extremity rehabilitation robotics, several components affect the therapy outcome. A common component is gravity compensation which alleviates upperextremity movements. Gravity compensation by itself could improve motor control further or faster, separate from other effects of robotic therapy. To investigate the rehabilitation value of gravity compensation separately, we created the dedicated gravity compensation system, Freebal. The sling systems with ideal spring mechanisms in the Freebal are well suited for providing compensation forces. The device has steplessly scalable forces, a large range of motion with constant compensation forces, independent control of the compensation of the lower and upper arm, and low movement impedance. It also does not need external power, force sensors or active controllers. Finally, the Freebal can be easily moved, serviced and used in arm rehabilitation with either sitting or standing subjects. | |||
| BibTeX:
@inproceedings{stienen07c,
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| A. Stienen, E. Hekman, F. van der Helm, G. Prange, M. Jannink, A. Aalsma & H. van der Kooij (2007), "Dampace: dynamic force-coordination trainer for the upper extremities.", In Proc 10th ICORR'07. Noordwijk, the Netherlands. Jun 13-15 2007. | |||
| Abstract: According to reviews, training with upperextremities rehabilitation robotics is at least as good as regular stroke rehabilitation, probably because the robotics increase the training intensity for the patients. As an alternative to the functional approach mimicking activities of daily living, targeted force-coordination training may also have its benefits. Our passive exoskeleton, the Dampace, has controlled braking on the three rotational axes of the shoulder and one of the elbow. It is designed to combine functional training of activities of daily living with force-coordination training. The Dampace exoskeleton can assist in identifying causes behind the movement disorders of stroke patients, tackle these causes with isolated force-coordination training, possibly simultaneously over multiple joints, and then integrate the isolated training back into a functional, task-specific training protocol. Not needing to align the Dampace axes to the human shoulder and elbow axes overcome some of the difficulties traditionally associated with exoskeletons. Although it adds more complexity, the reduction of setup times to a few minutes and the absence of static reaction forces in the human joints, are major advantages and have been well received by therapists and physicians. Controlled braking instead of actively assisting actuators, has the advantage of inherent safety and always actively participating patients, at the cost of not being able to assist movements or create all virtual environments. | |||
| BibTeX:
@inproceedings{stienen07d,
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| M. Jannink, G. Prange, A. Stienen, H. van der Kooij, J. Kruitbosch, M. IJzerman & H. Hermens (2007), "Reduction of muscle activity during repeated reach and retrieval with gravity compensation in stroke patients", In Proc 10th ICORR'07. Noordwijk, the Netherlands. Jun 13-15 2007. | |||
| Abstract: Active movement of the affected arm is important in the training of arm function after stroke. By supporting the weight of the arm during movements, either in conventional treatment or in other approaches such as robotaided therapy, active arm movements can be facilitated. Studies into the influence of arm support display encouraging results for its use in post-stroke arm rehabilitation. The objective of the present study was to investigate the influence of gravity compensation on muscle activity during reach and retrieval movements of stroke patients. Eight stroke patients performed repeated reach and retrieval movements with and without gravity compensation. Comparison of muscle activity of shoulder and elbow muscles in both conditions showed that the level of muscle activity was reduced with gravity compensation, while movement execution was comparable. This implies that gravity compensation may facilitate active use of the arm during post-stroke rehabilitation. | |||
| BibTeX:
@inproceedings{jannink07,
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| G. Prange, A. Stienen, M. Jannink, H. van der Kooij, M. IJzerman & H. Hermens (2007), "Increased range of motion and decreased muscle activity during maximal reach with gravity compensation in stroke patients", In Proc 10th ICORR'07. Noordwijk, the Netherlands. Jun 13-15 2007. | |||
| Abstract: To stimulate restoration of arm function after stroke, active movement is important, which can be facilitated by supporting the weight of the hemiparetic arm, either in conventional treatment or in other approaches such as robotaided therapy. During arm support, the active range of motion during reach can increase with respect to unsupported movements. The present objective was to investigate the influence of gravity compensation on muscle activity and range of motion during maximal reach. Six stroke patients performed maximal reaching movements, once with and once without gravity compensation. When comparing these two conditions, muscle activity decreased while range of motion increased with gravity compensation. This implies that gravity compensation may facilitate active arm movements, by reducing the required muscle activity to maintain a particular arm orientation. This may be related to a reduction of an abnormal coupling between shoulder abduction and elbow flexion when arm movements are performed with gravity compensation. | |||
| BibTeX:
@inproceedings{prange07a,
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| A. Stienen, G. Prange, H. van der Kooij, M. Jannink & F. van der Helm (2006), "Dampace: A Energy-Dispersing Exoskeleton For Rehabilitation Research, Assessment And Training.", In Proc Biomed Eng Soc'06. Chicago (Il), USA. Oct 11-14 2006. | |||
| BibTeX:
@inproceedings{stienen06a,
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| A. Stienen, F. van der Helm, G. Prange, M. Jannink & H. van der Kooij (2006), "Effects of Gravity Compensation on the Range-of-Motion of the Upper Extremities in Robotic Rehabilitation after Stroke.", In Proc ISG'06. Chicago, Illinois, USA. Oct 9-10 2006. | |||
| Abstract: Gravity compensation has an effect on the movement executions of the upper extemities of stroke patients. Our basic gravity compensation system increased the range-of-motion work area of patients with below average Fugl-Meyer scores. Similarly, the horizontal shoulder-wrist linear stretching distance also increases. | |||
| BibTeX:
@inproceedings{stienen06,
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| A. Stienen, G. Prange, F. van der Helm & H. van der Kooij (2004), "Gravity Compensation by Stroke Rehabilitation Robotics.", In Proc Dutch IBME'04. Papendal, The Netherlands. Oct 4-5 2004., pp. 124-126. | |||
| Abstract: The neuromusculoskeletal model of this study was built to give insight into the mechanisms behind negative position and velocity feedback gains as experimentally identified in human postural control. Specifically, neural deficiencies were sought which could explain why complex regional pain syndrom (CRPS) patients with tonic dystonia are unable to set negative gains, although they are still to modulate the gains in the positive range. The model is an integration of a biological realistic neural network, modelling all relevant spinal neurons, and a one degree-of-freedom musculoskeletal model. Muscle proprioceptors provide the neural network with feedback. Literature suggests that the inability to set negative gains results from neurotransmitter deficiencies in inhibiting synapses in the spinal neural network. Two synaptic connections were selected for possible dysfunctioning: (1) the synapse which presynaptically inhibits the monosynaptic stretch reflex synapse, and (2) the synapse connecting the inhibitory interneuron to the motoneuron. A lack of presynaptic inhibition resulted in an overly dominant monosynaptic stretch reflex with high, positive feedback gains. Disabling the second prevented several major proprioceptive feedback paths from providing the motoneurons with negative stimulation, making the setting of negative feedback gains next to impossible. It is concluded that both synapses play an important role in obtaining negative feedback gains and that dysfunctioning of these synapses could account for the motor features in CRPS patients. However the presynaptically inhibiting of the monosynaptic stretch is a prerequisite for feedback gain modulation. | |||
| BibTeX:
@inproceedings{stienen04,
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| Category: Mastersthesis | |||
| A. Stienen (2003), "3D model of the layer 4C neural circuitry in the Macaque monkey primary visual cortex.". School: Technical University of Berlin. Berlin, Germany, Aug 27, 2003. | |||
| BibTeX:
@mastersthesis{stienen03a,
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| A. Stienen (2003), "Analysis of reflex modulation with a biologically realistic neural network.". School: Delft University of Technology. Delft, The Netherlands, Aug 27, 2003. Published in 2007. | |||
| BibTeX:
@mastersthesis{stienen03b,
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| Category: Phdthesis | |||
| A. Stienen (2009), "Development of Novel Devices for Upper Extremity Rehabilitation.". School: University of Twente. Enschede, The Netherlands, Jan 29, 2009. | |||
| BibTeX:
@phdthesis{stienen09f,
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Last updated on 07/10/2009