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Rehabilitation Engineering, IEEE Transactions on

Issue 1 • Date March 1997

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Displaying Results 1 - 14 of 14
  • Guest Editorial FES Control Strategies, Methods of Selective Activation, Applications, and Test Models

    Page(s): 1
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    Freely Available from IEEE
  • Call for papers

    Page(s): 116
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    Freely Available from IEEE
  • Threshold-distance measures from electrical stimulation of human brainstem

    Page(s): 70 - 74
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    Threshold current levels for electrical stimulation of a single human brainstem via an auditory prosthesis are compared with postmortem measures of the distance between the electrode and stimulated structures. The results compare well with the summary of threshold-distance measures from animal experiments compiled by J. Ranck (see Brain Res., vol. 98, p. 417-40, 1975). The correspondence between the human and animal data gives confidence that the extent of current spread (distance to stimulable neural units) can be well estimated from the current level at threshold for 200 μs/phase biphasic pulses. This is of particular interest in electrical stimulation of the human central nervous system, where localization of stimulation is of paramount importance View full abstract»

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  • Potential for use of a House of Quality matrix technique in rehabilitation engineering [wheelchair customized seating]

    Page(s): 106 - 115
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    This article describes a concept of using the House of Quality matrix tool to aid the process of designing customized seating. The work of a cross-function team in two seating clinics was videotaped. At a later date the information derived from the videotapes was analyzed using a House of Quality matrix. We were interested in the capacity of House of Quality to draw out customer requirements in a seating device and relate engineering requirements for manufacturing the seating. The scores for engineering features derived from the matrix were compared with the features the cross-function team treated with high priority and also the features which the team experienced most difficulty in satisfying as revealed in the video viewed. The matrix scores demonstrated the House of Quality's capacity to select key features 50% of the time. House of Quality was time-consuming to execute. Its application in everyday clinical settings is limited by this fact View full abstract»

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  • Automatic visual to tactile translation. II. Evaluation of the TACTile image creation system

    Page(s): 95 - 105
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    This is the second part of a two-part paper that develops a method for the automatic conversion of images from visual to tactile form. In Part I (see ibid. vol.5, no.1, p.81-94 (1997)), a variety of topics mere reviewed including issues in human factors, access technology for tactile graphics production, and image processing. In this part, the material presented in the first part is used to motivate, develop, and support the methods used in the development of a prototype visual-to-tactile translator called the TACTile Image Creation System (TACTICS). The specific choices made in the design of the system are discussed and justified, including selection of software platform, tactile output format, tactile image creation procedure, aggregate image processing sequences used, and principles from the discipline of psychophysics. The results of four experiments on tactile image discrimination, identification, and comprehension are reported and discussed, and future directions in this area are proposed View full abstract»

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  • Experimental evaluation of an adaptive feedforward controller for use in functional neuromuscular stimulation systems

    Page(s): 12 - 22
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    An adaptive feedforward control system has been evaluated for use in functional neuromuscular stimulation (FNS) systems. The control system, which utilizes neural network techniques, was used to generate isometric muscle contractions to track a periodic torque trajectory signal. The evaluation of the control system was performed using percutaneous intramuscular electrodes to stimulate the quadriceps muscles of spinal cord injured adolescents. Results of the evaluation indicate that the control system automatically customized its parameters for controlling isometric muscle torque in a particular muscle and that the parameters were adapted on-line to account for changes in muscle properties due to fatigue. This study demonstrates that this control system may play an important role in the development of practical FNS systems that are capable of automatically adjusting stimulation parameters to fit the needs of a particular individual at a given time View full abstract»

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  • A neuro-control system for the knee joint position control with quadriceps stimulation

    Page(s): 2 - 11
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    A neuro-control system was designed to control the knee joint to move in accordance with the desired trajectory of movement through stimulation of quadriceps muscle. This control system consisted of a neural controller and a fixed parameter proportional-integral-derivative (PID) feedback controller, which was designated as a neuro-PID controller. A multilayer feedforward time-delay neural network was used and trained as an inverse model of the functional electrical stimulation (FES)-induced quadriceps-lower leg system for direct feedforward control. The training signals for neural network learning were obtained from experimentation using a low-pass filtered random sequence to reveal the plant characteristics. The Nguyen-Widrow method was used to initialize the neural connection weights. The conjugate gradient descent algorithm was then used to modify these connection weights so as to minimize the errors between the desired outputs and the network outputs. The knee joint angle was controlled with only small deviations along the desired trajectory with the aid of the neural controller. In addition, the PID feedback controller was utilized to compensate for the residual tracking errors caused by disturbances and modeling errors. This control strategy was evaluated on one able-bodied and one paraplegic subject. The neuro-PID controller showed promise as a position controller of knee joint angle with quadriceps stimulation View full abstract»

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  • Automatic visual to tactile translation. I. Human factors, access methods and image manipulation

    Page(s): 81 - 94
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    This is the first part of a two-part paper that motivates and evaluates a method for the automatic conversion of images from visual to tactile form. In this part, a broad-ranging background is provided in the areas of human factors, including the human sensory system, tactual perception and blindness, access technology for tactile graphics production, and image processing techniques and their appropriateness to tactile image creation. In Part II, this background is applied in the development of the TACTile Image Creation System (TACTICS), a prototype for an automatic visual-to-tactile translator. The results of an experimental evaluation are then presented and discussed, and possible future work in this area is outlined View full abstract»

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  • Recruitment characteristics of nerve fascicles stimulated by a multigroove electrode

    Page(s): 40 - 50
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    The recruitment characteristics of fascicle-selective nerve stimulation by a multigroove electrode have been investigated both theoretically and in acute experiments. A three-dimensional (3-D) volume conductor model of fascicles in a multigroove device and a model of myelinated nerve fiber stimulation were used to calculate threshold stimuli of nerve fibers in these fascicles. After their exposition, fascicles from rat sciatic nerve were positioned in different grooves of appropriate sizes and stimulated separately. The device appeared to be suitable for fascicle-selective stimulation, because both computer simulations and acute animal experiments showed that crosstalk between neighboring fascicles is not a problem, even when monopolar stimulation was used. The threshold stimulus was lower for a small fascicle than for a large one. When the amount of (conducting) medium between contact and perineurium or its conductivity was reduced, threshold stimuli were lower. Moreover, simulations predict that the slopes of recruitment curves are smaller and inverse recruitment order is less pronounced. Simulations also showed that a small contact is preferable to a large one, because a small contact gives a slightly smaller slope of the recruitment curve. Both experimentally and theoretically a significantly smaller slope of recruitment curves was obtained by stimulation with a cathode and an anode at opposite sides of the fascicle, driven by two current sources giving simultaneous pulses with different, but linearly dependent amplitudes View full abstract»

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  • A methodology for definition of neuromuscular electrical stimulation sequences: an application toward overcoming small obstacles

    Page(s): 30 - 39
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    Neuromuscular electrical stimulation (NMES) is an important tool for research in the rehabilitation of lost movements in spinal cord injured patients. However, for NMES to be used outside the laboratory setup, the stimulation controller needs to be able to cope with challenging environmental conditions. A methodology to allow conversion of any specific motor task used to cope with one of these environmental conditions toward a control algorithm for NMES is proposed. The methodology was used in the definition of a stimulation sequence that allows overcoming small obstacles by the spinal cord injured patient. Simulations have proven the method feasibility, and clinical trials have confirmed these findings. Motor task conversion using the kinematic approach has shown better results than that of muscle activity View full abstract»

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  • Testing peripheral somatosensory neuroprostheses by recording from raccoon cortex

    Page(s): 75 - 80
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    A topologically organized representation of the body surface exists within the mammalian somatosensory cortical areas such that stimulation of a part of the body surface will produce a response in a localized region of the contralateral somatosensory cortex. Because of this topography, we propose that the selectivity of a peripheral somatosensory neuroprosthetic electrode array can be tested by noting whether the locus of maximum activation in the cortex moves in a consistent manner when differing portions of the array are stimulated. We further propose that the raccoon might well be the ideal animal in which to test this hypothesis, since the raccoon has a rather unique cortical somatosensory area where each digit is represented in individual subgyri around the tri-radiate sulcus. To demonstrate the feasibility of this concept, a pilot study was carried out in one raccoon under barbiturate anesthesia. The median nerve was stimulated via selective quadrants of a nerve cuff array of four tripolar electrodes implanted around the nerve. Cuff stimulation produced short-latency evoked surface potentials in the digit areas of the raccoon first somatosensory cortex. Response selectivity could be demonstrated, as could a separation between thresholds for producing movement or producing cortical evoked potentials. The sensory and motor responses elicited were consistent with the orientation of the median nerve within the cuff as determined by a postmortem identification of the muscle innervation pattern of the nerve View full abstract»

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  • Electrical stimulation-induced contraction to reduce blood stasis during arthroplasty

    Page(s): 62 - 69
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    Deep venous thrombosis and subsequent pulmonary embolism due to venous pooling/stasis commonly occur in patients during hip and/or knee arthroplasty (i.e., replacement). This problem may be alleviated by using techniques to promote lower limb blood flow. Electrical stimulation-induced contractions have been shown to activate the skeletal muscle pump, promote limb blood flow, and may be effective for reducing venous pooling/stasis and edema. Therefore, electrical stimulation may reduce the incidence of deep venous thrombosis (DVT) and pulmonary embolism (PE) during and following surgery. The overall goal of this project was to evaluate the clinical efficacy of sequential electrical stimulation-induced leg muscle contractions on the venous blood flow during surgery. The degree of venous pooling/stasis was monitored via electrical impedance changes in the thorax. The changes in the patient's central hemodynamics were then calculated. Thirty patients were recruited and randomly assigned to either a control group (n=15, mean age=66.4±7.3) or experimental group (n=15, age 60.7±9.7). Both groups received the standard medical treatment for prevention of DVT (i.e., coumadin, heparin, etc.) and compression stockings (TED, Kendall). The control group used the sequential compression device (SCD+TED) and the experimental group used electrical stimulation (ES+TED). Electrical stimulation was applied via surface electrodes to the lower-limb muscles (tibialis anterior and gastrocnemius) and upper limb muscles (quadriceps femoris and hamstrings). These muscles contracted sequentially, using an 8-channel electrical stimulator. Four seconds of calf (contraction/compression) were followed by 7-s of calf and thigh (contraction/compression) interspersed by 60-s rest period during both electrical stimulation or sequential compression device. This cycle continued throughout the surgery (60-75 min) for both groups. At 15 min intervals, venous return was monitored by impedance cardiograph. Physiologic responses including ventricular stroke volume (SV), cardiac output (CO), heart rate (HR), total peripheral resistance (TPR), as well as mean arterial pressure (MAP) were monitored. These responses were statistically analyzed and compared throughout the surgery within each group and between the 2 groups. The results show stroke volume and cardiac output to be higher throughout surgery in the electrical stimulation group as compared with the sequential compression device group. The heart rate was consistently lower during electrical stimulation for both groups. Total peripheral resistance did not change in the electrical stimulation group; but increased in the sequential compression device group View full abstract»

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  • A slowly penetrating interfascicular nerve electrode for selective activation of peripheral nerves

    Page(s): 51 - 61
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    To meet the future needs of functional electrical stimulation (FES) applications, peripheral nerve electrodes must be able to safely, selectively, and independently stimulate small subpopulations of the axons within a common nerve trunk. A new electrode has been designed to place contacts outside of the perineurium, but within the epineurium of the nerve. This slowly penetrating interfascicular nerve electrode (SPINE) combines the safety and simplicity of extraneural cuff electrodes with the intimate interface of intrafascicular wire and probe electrodes. The authors briefly discuss a mathematical method of quantifing performance of nerve electrodes based on the functional output of the intact neuromuscular system. The quantification involves three variables: (1) the functional recruitment trajectory (FRT), (2) functional overlap (O), and (3) overall functional selectivity (Λ). Second, the authors present results from six acute SPINE implants on the feline sciatic nerve. Quantification of stimulation results demonstrate interfascicular stimulation is functionally different than extraneural stimulation in 32 of 38 trials. In 19 of 28 trials, interfascicular stimulation is functionally selective based on depth of penetration and 52 of 58 trials demonstrate selectivity based on the side of the penetrating element. Third, tissue sections show that the SPINE electrode penetrates into the nerve within 24 h without evidence of edema or damage to the perineurium View full abstract»

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  • Muscle selection and walking performance of multichannel FES systems for ambulation in paraplegia

    Page(s): 23 - 29
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    A minimal set of muscles (8 to 16) were identified as candidates for implantation in a clinical system to provide walking function to individuals with complete paraplegia using functional electrical stimulation (FES). Three subjects with complete motor and sensory paraplegia had percutaneous intramuscular electrodes implanted in all major muscles controlling the trunk, hips, knees, and ankles. Stimulation patterns for walking with FES were generated for different sets of 8 and 16 muscles. The quality and repeatability of the resulting gait produced by walking patterns consisting of various combinations of muscles were determined. Most 8-channel stimulation patterns resulted in scissoring or insufficient hip flexion, preventing forward progression. One 8-channel system allowed a maximum speed of 0.1 m/s with a cadence of 22 steps/min and a stride length less than 0.3 m. Improved walking performance was observed with 16 channels of stimulation. This ranged from slow step to gait at 0.1 m/s to smooth reciprocal gait at 0.5 m/s. In all 3 subjects, the favored combination of 16 channels included erector spinae for trunk extension; gluteus maximus, posterior portion of adductor magnus and hamstrings for hip extension; tensor fasciae latae and either sartorius or iliopsoas for hip flexion; vastus lateralis/intermedius for knee extension; and tibialis anterior/peroneous longus for ankle dorsiflexion. In 1 subject the 16-channel FES system provided repeatable day-to-day gait averaging 0.4 m/s, 58 steps/min and a stride length at 0.8 m. A maximum repeatable walking distance with 16 channels was 34 m. Multiple 34-m trials were possible with minimal rests between walks. Fatigue of both the hip extensors and upper body was a limiting factor. The selection of target muscles for implantation is critical to the performance of FES systems. This study provides guidelines to muscle selection for walking with FES based on objective measures of gait performance. The findings indicate that a 16-channel FES system for total implantation is feasible for repeatable short distance, independent, walker-support walking in paraplegia View full abstract»

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Aims & Scope

This Transaction ceased publication in 2000. The current retitled publication is IEEE Transactions on Neural Systems and Rehabiliation Engineering.

Full Aims & Scope