Hemiparetic Stroke Patients Research Articles

Early post-stroke physical conditioning in hemiplegic patients: A preliminary study

ObjectiveTo establish the value of an early post-stroke evaluation of cardiorespiratory fitness in hemiparetic patients using a one-leg cycling exercise test and to analyze the impact of an adapted physical activity programme 12weeks after the stroke. ProtocolEighteen hemiparetic stroke patients participated in the study. The subjects were randomly assigned to one of two groups: the control group (CG) underwent 4weeks of conventional rehabilitation, whereas the training group (TG) performed additional physical exercises. The initial evaluation (T1) was carried out after 1week of exercise and the final evaluation (T2) was performed after 28 days. Both evaluations consisted of maximal graded tests performed with the valid leg, followed by completion of a questionnaire on personal autonomy in activities of daily living (ADL). ResultsIn the CG group, we recorded a 4 to 8% increase in peak oxygen uptake (VO2 peak). There was no significant increase in peak power output (Wpeak). However, the TG displayed significantly (P<0.05) greater peak values than those recorded on study entry (Wpeak: +30%, VO2 peak: +20%). The TG showed a statistically significant improvement in the Barthel and Katz ADL scale scores, whereas the pre- and post-rehabilitation values did not differ significantly in the CG. However, there was no correlation between the Barthel/Katz scale scores and Wpeak. ConclusionEvaluation of cardiorespiratory fitness by using the valid leg seems to be feasible in hemiplegic patients 1month post-stroke. Early post-stroke physical training appears to be needed to limit the negative effects of functional hypoactivity.

Effects of Wrist Tendon Vibration on Targeted Upper-Arm Movements in Poststroke Hemiparesis

Background. Impaired motor control of the upper extremity after stroke may be related to lost sensory, motor, and integrative functions of the brain. Artificial activation of sensory afferents might improve control of movement by adding excitatory drive to sensorimotor control structures. The authors evaluated the effect of wrist tendon vibration (TV) on paretic upper-arm stability during point-to-point planar movements. Methods. TV (70 Hz) was applied to the forearm wrist musculature of 10 hemiparetic stroke patients as they made center-out planar arm movements. End-point stability, muscle activity, and grip pressure were compared as patients stabilized at the target position for trials completed before, during, and after the application of the vibratory stimulus. Results. Prior to vibration, hand position fluctuated as participants attempted to maintain the hand at the target after movement termination. TV improved arm stability, as evidenced by decreased magnitude of hand tangential velocity at the target. Improved stability was accompanied by a decrease in muscle activity throughout the arm as well as a mean decrease in grip pressure. Conclusions. These results suggest that vibratory stimulation of the distal wrist musculature enhances stability of the proximal arm and can be studied further as a mode for improving end-point stability during reaching in hemiparetic patients.

A neurophysiological and clinical study of Brunnstrom recovery stages in the upper limb following stroke

Primary objective: To determine the extent to which the Brunnstrom recovery stages of upper limb in hemiparetic stroke patients are correlated to neurophysiological measures and the spasticity measure of Modified Modified Ashworth Scale (MMAS).Research design: A concurrent criterion-related validity study.Interventions: Not applicable.Methods and procedures: Thirty patients (15 men and 15 women; mean ± SD = 58.8 ± 11.5 years) with upper limb spasticity after stroke were recruited. Wrist flexor spasticity was rated using the MMAS. The neurophysiological measures were Hslp/Mslp ratio, Hmax/Mmax ratio and Hslp.Main outcomes and results: There was a significant moderate correlation between the Brunnstrom recovery stages and the neurophysiological measures. The Brunnstrom recovery stages were highly correlated to the MMAS scores (r = −0.81, p < 0.0001).Conclusions: The Brunnstrom recovery stages are moderately correlated with neurophysiological measures and highly correlated with the MMAS regarding the evaluation of motor recovery in stroke patients. The Brunnstrom recovery stages can be used as a valid test for the assessment of patients with post-stroke hemiplegia.

Clinical Characteristics and Brain Activation Patterns of Mirror Movements in Patients with Corona Radiata Infarct

Objective: Mirror movements (MMs) are a phenomenon of involuntary movements that accompany physically intended movements of the opposite side of the body. In the current study, we investigated the clinical characteristics and cortical activation patterns of MMs in patients with corona radiata (CR) infarct, using functional MRI. Subjects and Methods: We recruited 31 consecutive hemiparetic stroke patients with CR infarct. Functional MRI was performed to verify brain activation patterns during grasp-release movements of the affected hand, and MM of the unaffected hand was observed simultaneously. Results: The prevalence of MMs was 54.8% (17 out of 31 patients), and the intensity of MMs ranged from mild to moderate. The severity of MM in the unaffected hand is closely related to the poor motor function of the affected upper extremity and to activations of the unaffected motor cortex and both supplementary motor areas (SMAs) during the movement of the affected hand. In addition, the activations of unaffected motor cortex and both SMAs were closely related to poor motor function of the affected upper extremity. Conclusions: The results suggest that MMs, poor motor function, and the activations of ipsilateral motor cortex and both SMAs are closely interconnected in patients with CR infarct.

Transcranial Magnetic Stimulation May Provide Benefit in Acute Ischemic Stroke

Recently, high-frequency repetitive transcranial magnetic stimulation (HF-rTMS) and low-frequency rTMS (LF-rTMS) are reported to improve motor function significantly in chronic hemiparetic stroke patients. However, few studies have investigated the safety and efficacy of these rTMS modalities introduced during the early phase of stroke. The purpose of this study was to clarify the rTMS modality that is more beneficial for upper limb hemiparesis in the early phase of stroke using a randomized controlled trial.Twenty-nine patients with a hemispheric stroke lesion in the early phase of stroke were examined. Patients were randomly assigned into 3 groups: the HF-rTMS group (10 Hz rTMS to the lesional hemisphere [n = 9]), the LF-rTMS group (1 Hz rTMS to the nonlesional hemisphere [n = 11]), and the sham stimulation group [n = 9]). Patients received sessions for 5 consecutive days. Grip strength and tapping frequency were assessed before and after the intervention. Motor improvement of the affected upper limb after intervention was compared among the 3 groups.All patients completed the 5-day protocol. Both the HF-rTMS and LF-rTMS groups had significant increases in both grip strength and tapping frequency. Comparison of the extent of improvement showed a more significant increase in grip strength and tapping frequency in the HF-rTMS group compared to the sham stimulation group (each P < .05), and no difference between the LF-rTMS group and the sham stimulation group.HF-rTMS applied to the lesional hemisphere in the early phase of stroke was more beneficial for motor improvement of the affected upper limb than LF-rTMS.

Master of engineering program in biomedical engineering at Cornell University: Collaboration with external sponsors to prove concepts in assistive devices

As a biomedical engineer, one seldom gets the opportunity to help patients return to health in areas in which the magnitude of the need, or the adoption of the approach, is unproven. Returning to my alma mater, Cornell University in Ithaca, New York, in late 2004, I was given the opportunity to coordinate the master of engineering program in biomedical engineering. Teaching students about the biomedical engineering arts and the Food and Drug Administration environment, and using projects proposed by external companies and physicians, we began to build a new Department of Biomedical Engineering. Professor Michael Shuler, our chairman, has had a distinguished career in chemical engineering. After a long process, he established a new program in biomedical engineering as part of the College of Engineering. The scientific orientation for the department is to understand disease mechanisms from a molecules-to-man perspective. Our engineering strategy was to develop a 1-year master of engineering program with an engineering project as the focal experience. Real projects are a demanding first experience and permit an engineering student to learn four key dimensions: How to-- 1. Understand customer needs. 2. Reduce needs to a concept and design. 3. Fabricate and test the design. 4. Deliver a documented prototype that can be reproduced. As the Program Coordinator, I solicit student-appropriate projects from sponsors that are presented to the students each year. Most projects are with my Cornell colleagues in their respective research laboratories. The remainder are with external sponsors. Early on, I realized we needed an exemption from University policy concerning intellectual property. With help from corporate and foundation relations in the College, we were permitted an exemption, primarily because our master of engineering students are not employees and pay full tuition for our program. External sponsors have been companies and individual physicians hoping to develop a prototype of a clinical concept. Remarkably, several of these have been in assistive technologies and surgical systems, including-- * A lower-cost stroke rehabilitation system. * An assisted walker. * A blink restoration device. Clients pay no fee for work performed on the project, but we do ask for reimbursement of direct expenses, such as student travel, etc. STROKE REHABILITATION SYSTEM Bruce T. Volpe, Professor of Neurology & Neuroscience from the Burke Rehabilitation Hospital in White Plains, New York, came to Ithaca to present a seminar (to our master of engineering students) on his work with Neville Hogan and H. I. Krebs on a robotic system for stroke rehabilitation that had remarkable results. After the seminar, we discussed a concept for a portable and lightweight system that could be used on a kitchen table as an alternative to his Massachusetts Institute of Technology-Weill Robot. With the help and laboratory space provided by Professor Andy Ruina, Professor of Mechanics in Mechanical Engineering, four enthusiastic students signed up for the project. After serious effort, the project met with technical difficulties centering on the need to secure the position of the patient with respect to the device (reported in their master of engineering project report, Home recovery robotic device for hemiparetic stroke patients, by Ian Colahan, Derek Stillwell, and Paula Wang, Cornell University, May 11, 2007). Even with the difficulty, the project had an upside. A doctor of philosophy (PhD) student, Michael A. Sherback, was not only a great resource to the team, he used his knowledge of oscillators and his keen ability to build a prototype of a novel and usable device that was relatively lightweight and could be portable (Figure 1) [1]. We used our college infrastructure and a grant to Volpe and Sherback from Cornell's Clinical Translational Science Center Program to fabricate additional prototypes. …

Effects of visual feedback of center-of-pressure displacements on undisturbed upright postural control of hemiparetic stroke patients

To assess whether insights from postural control without additional visual feedback (VFB) could be gained to explain the possible VFB effects (or non-effects) on upright stance performance. The center-of-pressure (CP) displacements of 39 patients with a recent hemispheric stroke (93 days ± 56; mean ± s.d.) were analyzed in two conditions (eyes open and VFB) through various classical parameters and fractional Brownian motion (fBm) modeling. Correlations between their ability to use the VFB technique appropriately and parameters assessing the eyes open condition were also computed. The fBm modeling showed that the VFB technique improves the control of the CP trajectories over the longer time intervals. In both conditions, the patients with right hemiparesis, compared to those with left hemiparesis, demonstrated improved control of their CP displacement along the AP axis over the shortest time intervals. Overall, 28% of the patients did not use the VFB technique. The correlation analysis indicated that the larger the spontaneous CP movements in the eyes open condition, the greater the effect of the VFB technique. By emphasizing its particular effects and the profile of the patients who used the technique, these data specify the conditions allowing hemiparetic patients to use the VFB technique appropriately and immediately.

Cortical activation pattern of compensatory movement in stroke patients

Little is known about the cortical activation pattern of compensatory movement (CM) in stroke patients. We attempted to investigate the cortical activation pattern of compensatory movement in stroke patients, using functional MRI (fMRI). Eight hemiparetic stroke patients were recruited for this study. We measured the shoulder abduction angle when each subject was simulating eating in a sitting position, which was considered as the degree of CM. The fMRI was performed at 1.5T using an elbow motor task at a frequency of 0.5 Hz. There was an inverse correlation between the shoulder abduction angle of the affected side and the LI (Laterality Index) (r=-0.745; p< 0.05). The shoulder abduction angle of the affected side was significantly related to the sum of activated voxels in all regions of interest (r=0.776; p< 0.05) and the activated voxels of the supplementary motor area (r=951; p< 0.05). However, we did not find any correlation between the shoulder abduction angle and the activated voxels of other brain areas. We demonstrated that a greater shoulder abduction angle on the affected side requires more cortical activation. Therefore, CM appears to be related to the change of the cortical motor control toward greater recruitment of cortical neurons.

Effect of auditory feedback differs according to side of hemiparesis: a comparative pilot study

BackgroundFollowing stroke, patients frequently demonstrate loss of motor control and function and altered kinematic parameters of reaching movements. Feedback is an essential component of rehabilitation and auditory feedback of kinematic parameters may be a useful tool for rehabilitation of reaching movements at the impairment level. The aim of this study was to investigate the effect of 2 types of auditory feedback on the kinematics of reaching movements in hemiparetic stroke patients and to compare differences between patients with right (RHD) and left hemisphere damage (LHD).Methods10 healthy controls, 8 stroke patients with LHD and 8 with RHD were included. Patient groups had similar levels of upper limb function. Two types of auditory feedback (spatial and simple) were developed and provided online during reaching movements to 9 targets in the workspace. Kinematics of the upper limb were recorded with an electromagnetic system. Kinematics were compared between groups (Mann Whitney test) and the effect of auditory feedback on kinematics was tested within each patient group (Friedman test).ResultsIn the patient groups, peak hand velocity was lower, the number of velocity peaks was higher and movements were more curved than in the healthy group. Despite having a similar clinical level, kinematics differed between LHD and RHD groups. Peak velocity was similar but LHD patients had fewer velocity peaks and less curved movements than RHD patients. The addition of auditory feedback improved the curvature index in patients with RHD and deteriorated peak velocity, the number of velocity peaks and curvature index in LHD patients. No difference between types of feedback was found in either patient group.ConclusionIn stroke patients, side of lesion should be considered when examining arm reaching kinematics. Further studies are necessary to evaluate differences in responses to auditory feedback between patients with lesions in opposite cerebral hemispheres.

Dissociation of initial trajectory and final position errors during visuomotor adaptation following unilateral stroke

Previous studies have demonstrated that following stroke, motor impairment can occur ipsilateral to the lesion. Such impairments have provided insight into the contributions of each hemisphere to movement control, showing that left and right hemisphere damage produce different effects on movement: Left hemisphere damage produces deficits in specifying features of movement trajectory, while right hemisphere damage produces deficits in achieving an accurate and stable final position. We now propose that left and right hemisphere damage should also produce different deficits in the adaptation of trajectory and position. To test this idea, we examined adaptation to visuomotor rotations in the ipsilesional arms of hemiparetic stroke patients with left (LHD) and right hemisphere damage (RHD). We found that LHD interfered with adaptation of initial direction, but not with the ability to adapt the final position of the limb. In contrast, RHD interfered with online corrections to the final position during the course of adaptation. These findings support our hypothesis that the control of trajectory and steady-state position may be lateralized to the left and right hemispheres, respectively.

Biorretroalimentação para treinamento do equilíbrio em hemiparéticos por acidente vascular encefálico: estudo preliminar

Como disfunções do equilíbrio são freqüentes nos pacientes hemiparéticos por acidente vascular encefálico (AVE), o treinamento do equilíbrio é meta fundamental em seu tratamento. O objetivo deste estudo preliminar foi verificar os efeitos da biorretroalimentação, por treinamento em plataforma instável computadorizada, em seis pacientes hemiparéticos por AVE (três homens e três mulheres, com idade média de 56,2 anos). Os pacientes foram avaliados, antes e após o tratamento, quanto a mobilidade funcional (pelo teste de levantar e caminhar cronometrado, TUGT na sigla em inglês), alcance funcional, qualidade de vida relacionada à saúde (pelo Perfil de Saúde de Nottingham) e equilíbrio sobre prancha instável. O treinamento foi feito na mesma prancha, em 23 sessões de cerca de 30 minutos cada, durante oito semanas. Os resultados indicam melhora do equilíbrio, em média, de 119,1% com pés separados e de 79,6% com pés juntos (p&lt;0,001); melhora média do alcance funcional de 15% (p&lt;0,001); melhora da mobilidade de 25,6% (p&lt;0,001); e discreta melhora nos escores da auto-avaliação de qualidade de vida. O programa de treinamento resultou pois em melhoras significativas na amostra estudada, sugerindo que a biorretroalimentação do equilíbrio pode ser uma ferramenta valiosa na reabilitação de pacientes hemiparéticos em decorrência de AVE.

A proteomics analysis of the effects of chronic hemiparetic stroke on troponin T expression in human vastus lateralis.

Stroke disability is attributed to upper motor neuron deficits resulting from ischemic brain injury. We have developed proteome maps of the Vastus lateralis to examine the effects of ischemic brain injury on paretic skeletal muscle myofilament proteins. Proteomics analyses from seven hemiparetic stroke patients have detected a decrease of three troponin T isoforms in the paretic muscle suggesting that myosin-actin interactions may be attenuated. We propose that ischemic brain injury may prevent troponin T participation in complex formation thereby affecting the protein interactions associated with excitation-contraction coupling. We have also detected a novel skeletal troponin T isoform that has a C-terminal variation. Our data suggest that the decreased slow troponin T isoform pools in the paretic limb may contribute to the gait deficit after stroke. The complexity of the neurological deficit on Vastus lateralis is suggested by the multiple changes in proteins detected by our proteomics mapping.

The effect of botulinum toxin injections on gait control in spastic stroke patients presenting with a stiff-knee gait

Introduction Botulinum toxin type A (BoNT-A) injections are known to improve walking impairments and activity in spastic hemiparetic stroke patients presenting with a stiff-knee gait [Caty GD, Detrembleur C, Bleyenheuft C, Deltombe T, Lejeune TM. Effect of simultaneous botulinum toxin injections into several muscles on impairment, activity, participation, and quality of life among stroke patients presenting with a stiff knee gait. Stroke 2008;39(October (10)):2803–8]. The aim of the present study was to understand how the improvement of mechanical variables during gait is controlled by the central nervous system after BoNT-A injections. Therefore, we used Kinematic Segmental Coordination (KSC), i.e. the kinematic covariation law of elevation angles between lower limb segments, to assess their effect on gait control. As far as we know, this has never been studied before. Methods Twenty chronic hemiparetic stroke patients presenting with a stiff-knee gait performed an instrumented gait analysis at the same walking speed before and 2 months after BoNT-A injection in several spastic muscles. We used the kinematic recordings previously obtained by Caty et al. [Caty GD, Detrembleur C, Bleyenheuft C, Deltombe T, Lejeune TM. Effect of simultaneous botulinum toxin injections into several muscles on impairment, activity, participation, and quality of life among stroke patients presenting with a stiff knee gait. Stroke 2008;39(October (10)):2803–8] and computed KSC following Borghese's methodology. The treatment effect was tested using a repeated measures ANOVA. Results BoNT-A injections allowed a statistically significant improvement in KSC of both lower limbs ( p = 0.004). Moreover, the unaffected side KSC reached normal values after BoNT-A injections. Conclusion and discussion BoNT-A allowed an improvement in KSC of the affected lower limb and a normalization of KSC of the unaffected limb. This improvement could either be due to a mechanical effect or a central effect of BoNT-A via the spinal central pattern generators (CPGs).

Stabilometry is a predictor of gait performance in chronic hemiparetic stroke patients

In patients with spastic hemiparesis, centre of foot pressure (CoP) is shifted toward the unaffected limb during quiet stance. We hypothesised that abnormal gait features would correlate with the degree of asymmetry during stance. In 15 patients and 17 normals we recorded CoP and body sway by a force platform and measured spatial–temporal variables of gait with pedobarography. In patients CoP was shifted toward the unaffected limb and sway was larger than in normals. CoP position was associated with the decrease in strength of the affected lower-limb muscles. Spatio-temporal variables of gait were also affected by the disease. Cadence and velocity were decreased, duration of single support on the unaffected limb and of double support were increased with respect to normals. The degree of impairment of gait variables correlated with CoP. We found a negative relationship between velocity or cadence and CoP, and a positive relationship between duration of single support and CoP in the unaffected but not in the affected limb. Duration of double support correlated positively with CoP. CoP asymmetry during both standing and walking suggests that postural and gait problems share some common neural origin in hemiparetic patients. This asymmetry affects gait performance by increasing the time and effort needed to shift body weight toward the affected limb. The degree of postural asymmetry measured by stabilometry is associated with the level of impairment of gait variables.

Efficacy of EMG-triggered electrical arm stimulation in chronic hemiparetic stroke patients

EMG-triggered electrostimulation (EMG-ES) may improve the motor performance of affected limbs of hemiparetic stroke patients even in the chronic stage. This study was designed to characterize cortical activation changes following intensified EMG-ES in chronic stroke patients and to identify predictors for successful rehabilitation depending on disease severity. We studied 9 patients with severe residual hemiparesis, who underwent 8 weeks of daily task-orientated multi-channel EMG-ES of the paretic arm. Before and after treatment, arm function was evaluated clinically and cortical activation patterns were assessed with functional MRI (fMRI) and/or transcranial magnetic stimulation (TMS). As response to therapy, arm function improved in a subset of patients with more capacity in less affected subjects, but there was no significant gain for those with Box & Block test values below 4 at inception. The clinical improvement, if any, was accompanied by an ipsilesional increase in the sensorimotor cortex (SMC) activation area in fMRI and enhanced intracortical facilitation (ICF) as revealed by paired TMS. The SMC activation change in fMRI was predicted by the presence or absence of motor-evoked potentials (MEPs) on the affected side. The present findings support the notion that intensified EMG-ES may improve the arm function in individual chronic hemiparetic stroke patients but not in more severely impaired individuals. Functional improvements are paralleled by increased ipsilesional SMC activation and enhanced ICF supporting neuroplasticity as contributor to rehabilitation. The clinical score at inception and the presence of MEPs have the best predictive potential.

Sensory Deficits in the Unaffected Hand of Hemiparetic Stroke Patients

To evaluate sensory function in the unaffected hand of unilateral stroke patients. Ipsilateral motor deficits have been described in stroke patients, but sensory function has usually been reported to be normal in the unaffected limbs. Twenty-five patients (19 males, 6 females, 58.24+/-11.11 y old) with first-ever stroke, in the chronic phase (mean interval after stroke: 43.8+/-55.4 mo), who fulfilled the inclusion criteria, and 25 age-matched and sex-matched healthy control subjects (19 males, 6 females, 58.60+/-11.32 y old) participated in the study. Ipsilateral hand sensory function was assessed with a Moving Touch-Pressure test; motor performance was evaluated by the Box and Block test and grip strength. The examiner was not blinded to the subject's neurologic status. Stroke patients had a mean Moving Touch-Pressure score of 79.77%+/-10.74% whereas the control group had a mean score of 89.10%+/-8.09% (P<0.01). Mean Box and Block scores were 58.4+/-8.27 and 68.08+/-8.98, respectively (P<0.01). In addition to motor dysfunction, decreased sensitivity to moving tactile stimuli may contribute to clumsiness of the unaffected arm of unilateral stroke patients.

Motor unit properties of biceps brachii in chronic stroke patients assessed with high‐density surface EMG

The aim of this study was to investigate motor unit (MU) characteristics of the biceps brachii in poststroke patients using high-density surface electromyography (sEMG). Eighteen chronic hemiparetic stroke patients took part. The Fugl-Meyer score for the upper extremity was assessed. Subjects performed an isometric step contraction consisting of force levels from 5%-50% maximal voluntary contraction while sEMG of the biceps brachii was recorded with a two-dimensional 16-channel electrode array. This was repeated for both sides. Motor unit action potentials (MUAPs) were extracted from the EMG signals, and their root-mean-square value (RMS(MUAP), reflecting MU size) and mean frequency of the power spectrum (FMEAN(MUAP), reflecting recruitment threshold) were calculated. FMEAN(MUAP) was smaller on the affected than on the unaffected side, indicating an increased contribution of low-threshold MUs, possibly related to degeneration of high-threshold MUs. The ratio of RMS(MUAP) on the affected side divided by that on the unaffected side correlated significantly with the Fugl-Meyer score. This ratio may reflect the extent to which reinnervation has occurred on the affected side.

A neural tracking and motor control approach to improve rehabilitation of upper limb movements

BackgroundRestoration of upper limb movements in subjects recovering from stroke is an essential keystone in rehabilitative practices. Rehabilitation of arm movements, in fact, is usually a far more difficult one as compared to that of lower extremities. For these reasons, researchers are developing new methods and technologies so that the rehabilitative process could be more accurate, rapid and easily accepted by the patient. This paper introduces the proof of concept for a new non-invasive FES-assisted rehabilitation system for the upper limb, called smartFES (sFES), where the electrical stimulation is controlled by a biologically inspired neural inverse dynamics model, fed by the kinematic information associated with the execution of a planar goal-oriented movement. More specifically, this work details two steps of the proposed system: an ad hoc markerless motion analysis algorithm for the estimation of kinematics, and a neural controller that drives a synthetic arm. The vision of the entire system is to acquire kinematics from the analysis of video sequences during planar arm movements and to use it together with a neural inverse dynamics model able to provide the patient with the electrical stimulation patterns needed to perform the movement with the assisted limb.MethodsThe markerless motion tracking system aims at localizing and monitoring the arm movement by tracking its silhouette. It uses a specifically designed motion estimation method, that we named Neural Snakes, which predicts the arm contour deformation as a first step for a silhouette extraction algorithm. The starting and ending points of the arm movement feed an Artificial Neural Controller, enclosing the muscular Hill's model, which solves the inverse dynamics to obtain the FES patterns needed to move a simulated arm from the starting point to the desired point. Both position error with respect to the requested arm trajectory and comparison between curvature factors have been calculated in order to determine the accuracy of the system.ResultsThe proposed method has been tested on real data acquired during the execution of planar goal-oriented arm movements. Main results concern the capability of the system to accurately recreate the movement task by providing a synthetic arm model with the stimulation patterns estimated by the inverse dynamics model. In the simulation of movements with a length of ± 20 cm, the model has shown an unbiased angular error, and a mean (absolute) position error of about 1.5 cm, thus confirming the ability of the system to reliably drive the model to the desired targets. Moreover, the curvature factors of the factual human movements and of the reconstructed ones are similar, thus encouraging future developments of the system in terms of reproducibility of the desired movements.ConclusionA novel FES-assisted rehabilitation system for the upper limb is presented and two parts of it have been designed and tested. The system includes a markerless motion estimation algorithm, and a biologically inspired neural controller that drives a biomechanical arm model and provides the stimulation patterns that, in a future development, could be used to drive a smart Functional Electrical Stimulation system (sFES). The system is envisioned to help in the rehabilitation of post stroke hemiparetic patients, by assisting the movement of the paretic upper limb, once trained with a set of movements performed by the therapist or in virtual reality. Future work will include the application and testing of the stimulation patterns in real conditions.

Balance control in hemiparetic stroke patients: main tools for evaluation.

Balance problems in hemiparetic patients after stroke can be caused by different impairments in the physiological systems involved in postural control, including sensory afferents, movement strategies, biomechanical constraints, cognitive processing, and perception of verticality. Balance impairments and disabilities must be appropriately addressed. This article reviews the most common balance abnormalities in hemiparetic patients with stroke and the main tools used to diagnose them.

Tight Link Between Our Sense of Limb Ownership and Self-Awareness of Actions

Hemiparetic stroke patients with disturbed awareness for their motor weakness (anosognosia for hemiparesis/-plegia [AHP]) may exhibit further abnormal attitudes toward or perceptions of the affected limb(s). The present study investigated the clinical relationship and the anatomy of such abnormal attitudes and AHP. In a new series of 79 consecutively admitted acute stroke patients with right brain damage and hemiparesis/-plegia, different types of abnormal attitudes toward the hemiparetic/plegic limb (asomatognosia, somatoparaphrenia, anosodiaphoria, misoplegia, personification, kinaesthetic hallucinations, supernumerary phantom limb) were investigated. Ninty-two percent of the patients with AHP showed additional "disturbed sensation of limb ownership" (DSO) for the paretic/plegic limb. The patients had the feeling that their contralesional limb(s) do not belong to their body or even belong to another person. Analysis of lesion location revealed that the right posterior insula is a crucial structure involved in these phenomena. DSO for hemiparetic/-plegic limbs and AHP are tightly linked both clinically and anatomically. The right posterior insula seems to be a crucial structure involved in the genesis of our sense of limb ownership and self-awareness of actions.