New scale for assessing spasticity based on the pendulum test.

Quantified assessment of spasticity is essential for the rehabilitation of persons with paralysis. We introduce the new SPAsticity Scale (SPAS), which we found highly correlated with the Modified Ashworth Score (MAS); yet, with a delicate gradation of spasticity compared to the MAS. The parameters defining the SPAS show the level and the type of spasticity (flexion or extension). The SPAS is based on a complex model of the pendulum type oscillations of the lower leg, which includes the spastic torques. The data to calculate SPAS were collected by a wearable instrument with two inertial measurement units and two EMG recording units in subjects with a complete chronic spinal cord injury.

A principal component analysis (PCA) based assessment of the gait performance.

The gait assessment is instrumental for evaluating the efficiency of rehabilitation of persons with a motor impairment of the lower extremities. The protocol for quantifying the gait performance needs to be simple and easy to implement; therefore, a wearable system and user-friendly computer program are preferable. We used the Gait Master (instrumented insoles) with the industrial quality ground reaction forces (GRF) sensors and 6D inertial measurement units (IMU). WiFi transmitted 10 signals from the GRF sensors and 12 signals from the accelerometers and gyroscopes to the host computer. The clinician was following in real-time the acquired data to be assured that the WiFi operated correctly. We developed a method that uses principal component analysis (PCA) to provide a clinician with easy to interpret cyclograms showing the difference between the recorded and healthy-like gait performance. The cyclograms formed by the first two principal components in the PCA space show the step-to-step reproducibility. We suggest that a cyclogram and its orientation to the coordinate system PC1 vs. PC2 allow a simple assessment of the gait. We show results for six healthy persons and five patients with hemiplegia.

Hybrid Tongue - Myoelectric Control Improves Functional Use of a Robotic Hand Prosthesis.

OBJECTIVE: This study aims at investigating the functional performance of a novel prosthesis control scheme integrating an inductive tongue interface and myoelectric control. The tongue interface allowed direct selection of the desired grasp while myoelectric signals were used to open and close the robotic hand. METHODS: The novel method was compared to a conventional sequential on/off myoelectric control scheme using functional tasks defined by Assistive Hand Assessment protocol. Ten able-bodied participants were fitted with the SmartHand on their left forearm. They used both the conventional myoelectric control and the Tongue and Myoelectric Hybrid interface (TMH) to accomplish two activities of daily living (i.e., preparing a sandwich and gift wrapping). Sessions were video recorded and the outcome measure was the completion time for the subtasks as well as the full tasks. RESULTS: The sandwich task was completed significantly faster, with 19% decrease in the completion time, using the TMH when compared to the conventional sequential on/off myoelectric control scheme (p < 0.05). CONCLUSION: The results indicate that the TMH control scheme facilitates the active use of the prosthetic device by simplifying grasp selection, leading thereby to faster completion of challenging and relevant tasks involving bimanual activities.

EMG map image processing for recognition of fingers movement.

Electromyography (EMG) is the conventional noninvasive method for the estimation of muscle activities. We developed a new image processing method for the recognition of individual finger movements based on EMG maps. The maps were formed from the EMG recordings via an array electrode with 24 contacts connected to a multichannel wireless miniature digital amplifier. The task was to detect and quantify the high activity regions in the EMG maps in persons with no known motor impairment. The results show the temporal and spatial patterns within the images during well-defined finger movements. The average accuracy of the automatic recognition compared with the recognition by an expert clinician in persons involved in the tests was 97.87 ±â€¯0.92%. The application of the technique is foreseen for control for an assistive system (hand prosthesis and exoskeleton) since the interface is wearable and the processing can be implemented on a microcomputer.

Does galvanic vestibular stimulation decrease spasticity in clinically complete spinal cord injury?

The aim of this study was to determine changes in clinical and biomechanical measures of spasticity after administering galvanic vestibular stimulation in patients with a complete spinal cord injury (SCI). The spasticity in the lower limbs was assessed using the Modified Ashworth Scale and the pendulum test in seven SCI patients (grade A on the ASIA Impairment Scale) before (0), immediately after (0), and at 5 and 30 min after the real versus sham galvanic vestibular stimulation (15 s each, anode over the right mastoid). Overall, the changes in spasticity were not significantly different between the real and sham galvanic vestibular stimulation. However, the Modified Ashworth Scale and the pendulum test indicated a reduction in spasticity in two out of seven patients. The results suggest that galvanic vestibular stimulation may modify spasticity in some patients with complete SCI, presumably through the residual vestibulospinal influences. Future studies should determine clinical and neurophysiological profiles of responders versus nonresponders and optimize parameters of galvanic vestibular stimulation.

Assessment of Spasticity by a Pendulum Test in SCI Patients Who Exercise FES Cycling or Receive Only Conventional Therapy.

Increased muscle tone and exaggerated tendon reflexes characterize most of the individuals after a spinal cord injury (SCI). We estimated seven parameters from the pendulum test and used them to compare with the Ashworth modified scale of spasticity grades in three populations (retrospective study) to assess their spasticity. Three ASIA B SCI patients who exercised on a stationary FES bicycle formed group F, six ASIA B SCI patients who received only conventional therapy were in the group C, and six healthy individuals constituted the group H. The parameters from the pendulum test were used to form a single measure, termed the PT score, for each subject. The pendulum test parameters show differences between the F and C groups, but not between the F and H groups, however, statistical significance was limited due to the small study size. Results show a small deviation from the mean for all parameters in the F group and substantial deviations from the mean for the parameters in the C group. PT scores show significant differences between the F and C groups and the C and H groups and no differences between the F and C groups. The correlation between the PT score and Ashworth score was 0.88.

Posture in dentists: Sitting vs. standing positions during dentistry work--An EMG study.

INTRODUCTION: Adequate working posture is important for overall health. Inappropriate posture may increase fatigue, decrease efficiency, and eventually lead to injuries. OBJECTIVE: The purpose was to examine posture positions used during dentistry work. METHODS: In order to quantify different posture positions, we recorded muscle activity and positions of body segments. The position (inclination) data of the back was used to assess two postures: sitting and standing during standard dental interventions. RESULTS: During standard interventions, whether sitting or standing, a tilt of less than 20 degrees was most prevalent in the forward and lateral flexion directions. Amplitude of electromyography signals corresponding to the level of muscle activity were higher in sitting compared with the electromyography in standing position for all muscle groups on the left and right side of the body. Significant difference between muscle activity in two working postures was evident in splenius capitis muscle on the left (p = 0.032), on the right side of the body (p = 0.049) and in muscle activity of mastoid muscle on the left side (p = 0.029). CONCLUSION: These findings show that risk for increased fatigue and possible injures can be reduced by combining the sitting and standing occupational postures.

Stimulation map for control of functional grasp based on multi-channel EMG recordings.

Transcutaneous activation of muscles with electrical stimulation has limited selectivity in recruiting paralyzed muscles in stroke patients. However, the selectivity could be increased by the application of smaller electrodes and their appropriate positioning on the skin. We developed a method for selecting the appropriate positions of the stimulating electrodes based on electromyography (EMG). The EMG activity maps were estimated from signals recorded with two electrode arrays and two 24-channel wearable amplifiers positioned on the nonparetic and paretic forearms. The areas where the difference between the EMG maps obtained from the nonparetic and paretic arms was significant were identified as the stimulation sites. The stimulation was applied through array electrodes with magnetic holders and two wearable stimulators with four output channels each. The measures of functionality included joint angles measured with goniometers (hand opening) and grasp force measured with a multi-contact dynamometer (grasping). The stimulation protocol comprised co-activation of flexors and extensors to stabilize the wrist joint and prevent pronation/supination.

Control of a Robotic Hand Using a Tongue Control System-A Prosthesis Application.

OBJECTIVE: The aim of this study was to investigate the feasibility of using an inductive tongue control system (ITCS) for controlling robotic/prosthetic hands and arms. METHODS: This study presents a novel dual modal control scheme for multigrasp robotic hands combining standard electromyogram (EMG) with the ITCS. The performance of the ITCS control scheme was evaluated in a comparative study. Ten healthy subjects used both the ITCS control scheme and a conventional EMG control scheme to complete grasping exercises with the IH1 Azzurra robotic hand implementing five grasps. Time to activate a desired function or grasp was used as the performance metric. RESULTS: Statistically significant differences were found when comparing the performance of the two control schemes. On average, the ITCS control scheme was 1.15 s faster than the EMG control scheme, corresponding to a 35.4% reduction in the activation time. The largest difference was for grasp 5 with a mean AT reduction of 45.3% (2.38 s). CONCLUSION: The findings indicate that using the ITCS control scheme could allow for faster activation of specific grasps or functions compared with a conventional EMG control scheme. SIGNIFICANCE: For transhumeral and especially bilateral amputees, the ITCS control scheme could have a significant impact on the prosthesis control. In addition, the ITCS would provide bilateral amputees with the additional advantage of environmental and computer control for which the ITCS was originally developed.

A comparative study of virtual hand prosthesis control using an inductive tongue control system.

This study compares the time required to activate a grasp or function of a hand prosthesis when using an electromyogram (EMG) based control scheme and when using a control scheme combining EMG and control signals from an inductive tongue control system (ITCS). Using a cross-over study design, 10 able-bodied subjects used a computer model of a hand and completed simulated grasping exercises. The time required to activate grasps was recorded and analyzed for both control schemes. End session mean activation times (ATs; seconds) for the EMG control scheme grasps 1 -5 were 0.80, 1.51, 1.95, 2.93, and 3.42; for the ITCS control scheme grasps 1 ‒5 they were 1.19, 1.89, 1.75, 2.26, and 1.80. Mean AT for grasps 1 and 2 was statistically significant in favor of the EMG control scheme (p = 0.030; p = 0.004). For grasp 3 no statistical significance occurred, and for grasps 4 and 5 there was a statistical significance in favour of the ITCS control scheme (p = 0.048; p = 0.004). Based on the amount of training and the achieved level of performance, it is concluded that the proposed ITCS control scheme can be used as a means of enhancing prosthesis control.

Advances in functional electrical stimulation (FES).

This review discusses the advancements that are needed to enhance the effects of electrical stimulation for restoring or assisting movement in humans with an injury/disease of the central nervous system. A complex model of the effects of electrical stimulation of peripheral systems is presented. The model indicates that both the motor and sensory systems are activated by electrical stimulation. We propose that a hierarchical hybrid controller may be suitable for functional electrical stimulation (FES) because this type of controller acts as a structural mimetic of its biological counterpart. Specific attention is given to the neural systems at the periphery with respect to the required electrodes and stimulators. Furthermore, we note that FES with surface electrodes is preferred for the therapy, although there is a definite advantage associated with implantable technology for life-long use. The last section of the review discusses the potential need to combine FES and robotic systems to provide assistance in some cases.

Microsoft kinect-based artificial perception system for control of functional electrical stimulation assisted grasping.

We present a computer vision algorithm that incorporates a heuristic model which mimics a biological control system for the estimation of control signals used in functional electrical stimulation (FES) assisted grasping. The developed processing software acquires the data from Microsoft Kinect camera and implements real-time hand tracking and object analysis. This information can be used to identify temporal synchrony and spatial synergies modalities for FES control. Therefore, the algorithm acts as artificial perception which mimics human visual perception by identifying the position and shape of the object with respect to the position of the hand in real time during the planning phase of the grasp. This artificial perception used within the heuristically developed model allows selection of the appropriate grasp and prehension. The experiments demonstrate that correct grasp modality was selected in more than 90% of tested scenarios/objects. The system is portable, and the components are low in cost and robust; hence, it can be used for the FES in clinical or even home environment. The main application of the system is envisioned for functional electrical therapy, that is, intensive exercise assisted with FES.

GammaKey system for improved diagnostics with gamma cameras.

We designed the GammaKey system for the acquisition, storage and analysis of images from semi-analogue gamma scintillation cameras (GSCs). The GammaKey system, operating on a standard PC, replicates the functionality of earlier dedicated computer systems, allows the exchange of data in the DICOM format and has an open architecture enabling the development of new diagnostic techniques. The main purpose of the GammaKey is to enable the continued use of old GSCs which have functional scintillation crystals, but also to permit data exchange with new digital GSCs. The GammaKey has been technically validated by standards established by the National Electrical Manufacturers Association. The GammaKey has been used for seven years in two leading centres for nuclear medicine in Serbia (the Clinical Center of Serbia, Belgrade, and the Clinical Center of Vojvodina, Novi Sad) in approximately 30,000 patients. Clinical application proves that the GammaKey is a robust and reliable system with high-quality image output. Data processing can be upgraded with non-standard features added on request as shown in two examples: (1) the testing of splenectomy efficacy in the case of thrombocytopenia with normal production; and (2) the detection and localisation of parathyroid adenomas.

Muscle synergies with Walkaround® postural support vs. "cane/therapist" assistance.

BACKGROUND: The main clinical measures of walking recovery in stroke patients were compared for training assisted by Walkaround® postural support (WPS) and conventional (CON) support by a cane/therapist. OBJECTIVE: We attributed the differences between the trainings to modified muscular synergies that occurred during assistance by WPS. METHODS: We studied the muscle activities of the primary knee and ankle joint movers in the paretic and non-paretic legs of sub-acute stroke patients during assisted walking with WPS and CON. Recorded signals were compared to normative data that were recorded during speed-matched gait trials in healthy subjects. The specific measures were the relative contribution of individual muscles, levels of cocontraction, and the timing of the maximum electromyography (EMG) activity during the walking sessions. RESULTS: We found that, for most patients, the individual contribution of muscles were more similar to the healthy with the WPS assistance. In parallel, the cocontraction of the rectus femoris muscles in both legs was lower (by up to 39 %) during walking assisted by WPS than by cane/therapist gait support); the results from this case series (10 patients) showed that WPS might be the superior training scheme. CONCLUSIONS: These findings indicated that assistance by WPS changed the motor control output relative to CON assistance in most patients.

A method for assessing the arm movement performance: probability tube.

Quantification of motor performance is an important component of the rehabilitation of humans with sensory-motor disability. We developed a method for assessing arm movement performance of trainees (patients) termed "probability tube" (PT). PT captures the stochastic characteristics of a desired movement when repeated by an expert (therapist). The PT is being generated automatically from data recorded during point-to-point movement executed not more than 15 repetitions by the clinician and/or other non-expert programmer in just a few minutes. We introduce the index, termed probability tube score (PTS), as a single "goodness-of-fit" value allowing quantified analysis of the recovery and effects of the therapy. This index in fact scores the difference between the movement (velocity profile) executed by the trainee and the velocity profile of the desired movement (executed by the expert). We document the goodness of the automatic method with results from studies which included healthy subjects and show the use of the PTS in healthy and post-stroke hemiplegic subjects.

Multi-pad electrode for effective grasping: design.

We designed a new surface multi-pad electrode for the electrical stimulation of the forearm that is effective in controlling functional grasp in hemiplegic patients. The electrode shape and size were designed on the basis of the surface stimulation map of the forearm, determined from measurements in seven hemiplegic patients who had limited or absent voluntary movements of the fingers, thumb and wrist. The stimulation map for each patient was assessed with a conventional set of single pad Pals Platinum electrodes. Since the sites for the stimulation varied greatly between patients, the end result was a rather large multi-pad electrode. Modulating multi-pad electrode size, shape, position and individual pad stimulation parameters allows us to accommodate the diversity of the neural tissues in patients that need to be activated for functional grasp. This also allows asynchronous activation of different portions of the muscle and dynamic adaptation of the stimulation sites to appropriate underlying tissues during functional use. The validity of the determined stimulation map was tested in the same group of hemiplegic patients. The selected set of active pads resulted in fully functional and reproducible palmar and lateral grasps similar to healthy-like grasps.

Surface-distributed low-frequency asynchronous stimulation delays fatigue of stimulated muscles.

INTRODUCTION: One important reason why functional electrical stimulation (FES) has not gained widespread clinical use is the limitation imposed by rapid muscle fatigue due to non-physiological activation of the stimulated muscles. We aimed to show that asynchronous low-pulse-rate (LPR) electrical stimulation applied by multipad surface electrodes greatly postpones the occurrence of muscle fatigue compared with conventional stimulation (high pulse rate, HPR). METHODS: We compared the produced force vs. time of the forearm muscles responsible for finger flexion in 2 stimulation protocols, LPR (fL = 10 Hz) and HPR (fH = 40 Hz). RESULTS: Surface-distributed low-frequency asynchronous stimulation (sDLFAS) doubles the time interval before the onset of fatigue (104 ± 80%) compared with conventional synchronous stimulation. CONCLUSIONS: Combining the performance of multipad electrodes (increased selectivity and facilitated positioning) with sDLFAS (decreased fatigue) can improve many FES applications in both the lower and upper extremities.

A multi-pad electrode based functional electrical stimulation system for restoration of grasp.

BACKGROUND: Functional electrical stimulation (FES) applied via transcutaneous electrodes is a common rehabilitation technique for assisting grasp in patients with central nervous system lesions. To improve the stimulation effectiveness of conventional FES, we introduce multi-pad electrodes and a new stimulation paradigm. METHODS: The new FES system comprises an electrode composed of small pads that can be activated individually. This electrode allows the targeting of motoneurons that activate synergistic muscles and produce a functional movement. The new stimulation paradigm allows asynchronous activation of motoneurons and provides controlled spatial distribution of the electrical charge that is delivered to the motoneurons. We developed an automated technique for the determination of the preferred electrode based on a cost function that considers the required movement of the fingers and the stabilization of the wrist joint. The data used within the cost function come from a sensorized garment that is easy to implement and does not require calibration. The design of the system also includes the possibility for fine-tuning and adaptation with a manually controllable interface. RESULTS: The device was tested on three stroke patients. The results show that the multi-pad electrodes provide the desired level of selectivity and can be used for generating a functional grasp. The results also show that the procedure, when performed on a specific user, results in the preferred electrode configuration characteristics for that patient. The findings from this study are of importance for the application of transcutaneous stimulation in the clinical and home environments.

Nonlinear optimization for drift removal in estimation of gait kinematics based on accelerometers.

A new data processing method is described for estimation of angles of leg segments, joint angles, and trajectories in the sagittal plane from data recorded by sensors units mounted at the lateral side of leg segments. Each sensor unit comprises a pair of three-dimensional accelerometers which send data wirelessly to a PC. The accelerometer signals comprise time-varying and temperature-dependent offset, which leads to drift and diverged signals after integration. The key features of the proposed method are to model the offset by a slowly varying function of time (a cubic spline polynomial) and evaluate the polynomial coefficients by nonlinear numerical simplex optimization with the goal to reduce the drift in processed signals (angles and movement displacements). The angles and trajectories estimated by our method were compared with angles measured by an optical motion capture system. The comparison shows that the errors for angles (rms) were below 4° and the errors in stride length were below 2%. The algorithm developed is applicable for real-time and off-line analysis of gait. The method does not need any adaptation with respect to gait velocity or individuality of gait.

Wireless distributed functional electrical stimulation system.

BACKGROUND: The control of movement in humans is hierarchical and distributed and uses feedback. An assistive system could be best integrated into the therapy of a human with a central nervous system lesion if the system is controlled in a similar manner. Here, we present a novel wireless architecture and routing protocol for a distributed functional electrical stimulation system that enables control of movement. METHODS: The new system comprises a set of miniature battery-powered devices with stimulating and sensing functionality mounted on the body of the subject. The devices communicate wirelessly with one coordinator device, which is connected to a host computer. The control algorithm runs on the computer in open- or closed-loop form. A prototype of the system was designed using commercial, off-the-shelf components. The propagation characteristics of electromagnetic waves and the distributed nature of the system were considered during the development of a two-hop routing protocol, which was implemented in the prototype's software. RESULTS: The outcomes of this research include a novel system architecture and routing protocol and a functional prototype based on commercial, off-the-shelf components. A proof-of-concept study was performed on a hemiplegic subject with paresis of the right arm. The subject was tasked with generating a fully functional palmar grasp (closing of the fingers). One node was used to provide this movement, while a second node controlled the activation of extensor muscles to eliminate undesired wrist flexion. The system was tested with the open- and closed-loop control algorithms. CONCLUSIONS: The system fulfilled technical and application requirements. The novel communication protocol enabled reliable real-time use of the system in both closed- and open-loop forms. The testing on a patient showed that the multi-node system could operate effectively to generate functional movement.