Paretic Arm Research Articles

Limited capacity for ipsilateral secondary motor areas to support hand function post-stroke.

Ipsilateral-projecting corticobulbar pathways, originating primarily from secondary motor areas, innervate the proximal and even distal portions, although they branch more extensively at the spinal cord. It is currently unclear to what extent these ipsilateral secondary motor areas and subsequent cortical projections may contribute to hand function following stroke-induced damage to one hemisphere. In the present study, we provide both structural and functional evidence indicating that individuals increasingly rely on ipsilateral secondary motor areas, although at the detriment of hand function. Increased activity in ipsilateral secondary motor areas was associated with increased involuntary coupling between shoulder abduction and finger flexion, most probably as a result of the low resolution of these pathways, making it increasingly difficult to open the hand. These findings suggest that, although ipsilateral secondary motor areas may support proximal movements, they do not have the capacity to support distal hand function, particularly for hand opening. Recent findings have shown connections of ipsilateral cortico-reticulospinal tract (CRST), predominantly originating from secondary motor areas to not only proximal, but also distal muscles of the arm. Following a unilateral stroke, CRST from the ipsilateral side remains intact and thus has been proposed as a possible backup system for post-stroke rehabilitation even for the hand. We argue that, although CRST from ipsilateral secondary motor areas can provide control for proximal joints, it is insufficient to control either hand or coordinated shoulder and hand movements as a result of its extensive spinal branching compared to contralateral corticospinal tract. To address this issue, we combined magnetic resonance imaging, high-density EEG, and robotics in 17 individuals with severe chronic hemiparetic stroke and 12 age-matched controls. We tested for changes in structural morphometry of the sensorimotor cortex and found that individuals with stroke demonstrated higher grey matter density in secondary motor areas ipsilateral to the paretic arm compared to controls. We then measured cortical activity when participants were attempting to generate hand opening either supported on a table or when lifting against a shoulder abduction load. The addition of shoulder abduction during hand opening increased reliance on ipsilateral secondary motor areas in stroke, but not controls. Crucially, the increased use of ipsilateral secondary motor areas was associated with decreased hand opening ability when lifting the arm as a result of involuntary coupling between the shoulder and wrist/finger flexors. Taken together, this evidence implicates a compensatory role for ipsilateral (i.e. contralesional) secondary motor areas post-stroke, although with no apparent capacity to support hand function.

Quantifying Altered Neural Connectivity of the Stretch Reflex in Chronic Hemiparetic Stroke.

Post-stroke flexion synergy limits arm/hand function and is also linked to hyperactive stretch reflexes or spasticity. It is implicated in the increased role of indirect motor pathways following damage to direct corticospinal projections. We hypothesized that this maladaptive neuroplasticity also affects stretch reflexes. Specifically, multi-synaptic interactions in indirect motor pathways may increase nonlinear neural connectivity and time lag between stretch and reflex muscle response. Continuous position perturbations were applied to the elbow joint when eleven participants with stroke generated two levels of shoulder abduction (SABD) torques with their paretic arm to induce synergy-related spasticity. Likewise, the perturbations were applied to eleven control subjects while performing SABD and elbow flexion levels matching the synergy torques in stroke. We quantified linear and non-linear connectivity and the corresponding time lags between perturbations and muscle activity. Enhanced nonlinear connectivity with a prolonged time lag was found in stroke as compared to controls. Non-linear connectivity and time lag also increased with the expression of the flexion synergy, as induced by greater SABD load levels, in stroke. This study provides new evidence of changes in neural connectivity and long-latency time lag in the stretch reflex response post-stroke. The results suggest the contribution of indirect motor pathways to synergy-related spasticity.

Treatment of Upper Limb Paresis With Repetitive Peripheral Nerve Sensory Stimulation and Motor Training: Study Protocol for a Randomized Controlled Trial.

Background: Repetitive peripheral nerve sensory stimulation (RPSS) has emerged as a potential adjuvant strategy to motor training in stroke rehabilitation. The aim of this study is to test the hypothesis that 3 h sessions of active RPSS associated with functional electrical stimulation (FES) and task-specific training (TST) distributed three times a week, over 6 weeks, is more beneficial to improve upper limb motor function than sham RPSS in addition to FES and TST, in subjects with moderate to severe hand motor impairments in the chronic phase (>6 months) after stroke.Methods: In this single-center, randomized, placebo controlled, parallel-group, double-blind study we compare the effects of 18 sessions of active and sham RPSS as add-on interventions to FES and task-specific training of the paretic upper limb, in 40 subjects in the chronic phase after ischemic or hemorrhagic stroke, with Fugl-Meyer upper limb scores ranging from 7 to 50 and able to voluntarily activate any active range of wrist extension. The primary outcome measure is the Wolf Motor Function Test (WMFT) after 6 weeks of treatment. The secondary outcomes are the WMFT at 3, 10, and 18 weeks after beginning of treatment, as well as the following outcomes measured at 3, 6, 10, and 18 weeks: Motor Activity Log; active range of motion of wrist extension and flexion; grasp and pinch strength in the paretic and non-paretic sides (the order of testing is randomized within and across subjects); Modified Ashworth Scale; Fugl-Meyer Assessment-Upper Limb in the paretic arm; Barthel Index; Stroke Impact Scale.Discussion: This project represents a major step in developing a rehabilitation strategy with potential to have impact on the treatment of stroke patients with poor motor recovery in developing countries worldwide. The study preliminarily evaluates a straightforward, non-invasive, inexpensive intervention. If feasibility and preliminary efficacy are demonstrated, further investigations of the proposed intervention (underlying mechanisms/ effects in larger numbers of patients) should be performed.Trial Registration: NCT02658578.

Feasibility of using acceleration-derived jerk to quantify bimanual arm use

BackgroundAccelerometers have become common for evaluating the efficacy of rehabilitation for patients with neurologic disorders. For example, metrics like use ratio (UR) and magnitude ratio (MR) have been shown to differentiate movement patterns of children with cerebral palsy (CP) compared to typically-developing (TD) peers. However, these metrics are calculated from “activity counts” – a measure based on proprietary algorithms that approximate movement duration and intensity from raw accelerometer data. Algorithms used to calculate activity counts vary between devices, limiting comparisons of clinical and research results. The goal of this research was to develop complementary metrics based on raw accelerometer data to analyze arm movement after neurologic injury.MethodWe calculated jerk, the derivative of acceleration, to evaluate arm movement from accelerometer data. To complement current measures, we calculated jerk ratio (JR) as the relative jerk magnitude of the dominant (non-paretic) and non-dominant (paretic) arms. We evaluated the JR distribution between arms and calculated the 50th percentile of the JR distribution (JR50). To evaluate these metrics, we analyzed bimanual accelerometry data for five children with hemiplegic CP who underwent Constraint-Induced Movement Therapy (CIMT) and five typically developing (TD) children. We compared JR between the CP and TD cohorts, and to activity count metrics.ResultsThe JR50 differentiated between the CP and TD cohorts (CP = 0.578 ± 0.041 before CIMT, TD = 0.506 ± 0.026), demonstrating increased reliance on the dominant arm for the CP cohort. Jerk metrics also quantified changes in arm use during and after therapy (e.g., JR50 = 0.378 ± 0.125 during CIMT, 0.591 ± 0.057 after CIMT). The JR was strongly correlated with UR and MR (r = − 0.92, 0.89) for the CP cohort. For the TD cohort, JR50 was repeatable across three data collection periods with an average similarity of 0.945 ± 0.015.ConclusionsAcceleration-derived jerk captured differences in motion between TD and CP cohorts and correlated with activity count metrics. The code for calculating and plotting JR is open-source and available for others to use and build upon. By identifying device-independent metrics that can quantify arm movement in daily life, we hope to facilitate collaboration for rehabilitation research using wearable technologies.

P14 Non-compensatory paretic arm training in chronic stroke improves reaching performance and alters functional brain network

P14 Non-compensatory paretic arm training in chronic stroke improves reaching performance and alters functional brain network

Effects of Modified Constraint-Induced Movement Therapy in Real-World Arm Use in Young Children with Unilateral Cerebral Palsy: A Single-Blind Randomized Trial.

To determine whether modified constraint-induced movement therapy (mCIMT) with continuous restraint is feasible and effective in improving the use of the paretic arm in the real world among infants and toddlers with unilateral cerebral palsy (CP). Single-blind randomized controlled trial. Tertiary hospital. Children aged 7 to 36 months with unilateral CP (N = 24; 16 boys, 8 girls). The experimental group received 2-hour clinic-based mCIMT sessions (5 days per week for 3 weeks), and a continuous restraint was applied. Standardized assessments were conducted. Peabody Developmental Motor Scales-2 (PDMS-2), Gross Motor Function Measure-66, Pediatric Motor Activity Log (PMAL), and Pediatric Evaluation of Disability Inventory were measured pre- and postintervention. Children who agreed to participate in the accelerometer study additionally wore accelerometers on both their wrists for 3 days before and after the intervention. The mCIMT group exhibited greater improvement in PMAL-how often (p = 0.048; ηp2 = 0.173), PMAL-how well (p = 0.008; ηp2 = 0.289), and PDMS-2 visual motor integration (p = 0.014; ηp2 = 0.256) posttreatment than the control group. The percentage of time in moderate-to-vigorous physical activity (z = -2.24; p = 0.03) and vector magnitude average counts (z = -2.52; p = 0.01) significantly increased in children in who wore accelerometers (N = 8) after the 3-week mCIMT protocol. mCIMT with continuous restraint applied to infants and toddlers with unilateral CP appeared to have a positive effect on paretic hand use in the real world. NCT03418519.

Comparing Home Upper Extremity Activity With Clinical Evaluations of Arm Function in Chronic Stroke

ObjectiveTo determine if clinical evaluations of poststroke arm function correspond to everyday motor performance indexed by arm accelerometers. DesignCross-sectional study analyzing baseline data from a larger trial (NCT02665052). SettingOutpatient research center. ParticipantsCommunity-dwelling adults (N=20) with chronic arm motor deficits (stroke≥6mo). InterventionA total of 72 hours of home wrist-worn accelerometry during normal routine. Main Outcome MeasuresClinical evaluations included the Fugl-Meyer Assessment (FMA), Action Research Arm Test (ARAT), Wolf Motor Function Test (WMFT), and 2 self-assessments: the Motor Activity Log (MAL) and hand motor subscale of the Stroke Impact Scale (SIS). Accelerometer-derived variables included quantifications of movement intensity (magnitude) and duration of arm use. ResultsParticipants had moderate arm impairment (FMA, 36.1±9.4). The accelerometer-derived mean magnitude ratio correlated significantly with the FMA (ρ=0.60, P<.01), WMFT functional score (ρ=0.59, P<.01), and ARAT (ρ=0.50, P<.05). The hours of use ratio correlated with the MAL amount of use (ρ=0.58, P<.01) and quality of movement (ρ=0.61, P<.01). Total paretic hours did not correlate with the FMA, WMFT, or ARAT, and intensity variables did not correlate with the MAL or SIS. ConclusionsParticipants with higher baseline function had greater intensity of paretic arm movement at home; similarly, those who perceived they had less disability used their paretic arm more relative to their nonparetic arm. However, some participants with higher clinical scores did not exhibit greater arm use in everyday life, possibly because of neglect and learned nonuse. Therefore, individualized home accelerometry profiles could provide valuable insight to better tailor poststroke rehabilitation.

Immediate effects of noxious and innocuous thermal stimulation on brain activation in patients with stroke.

Case-control studies have shown that noxious thermal stimulation (TS) can improve arm function in patients with stroke. However, the neural mechanisms underlying this improvement are largely unknown. We explored functional neural activation due to noxious and innocuous TS intervention applied to the paretic arm of patients with stroke. Sixteen participants with unilateral cortical infarctions were allocated to one of two groups: noxious TS (8 patients; temperature combination: hot pain 46°C to 47°C, cold pain 7°C–8°C) or innocuous TS (n = 8; temperature combination: hot 40°C–41°C, cold 20°C–21°C). All subjects underwent fMRI scanning before and after 30 min TS intervention and performed a finger tapping task with the affected hand. Immediate brain activation effects were assessed according to thermal type (noxious vs. innocuous TS) and time (pre-TS vs post-TS). Regions activated by noxious TS relative to innocuous TS (P < .05, adjusted for multiple comparisons) were related to motor performance and sensory function in the bilateral primary somatosensory cortices, anterior cingulate cortex, insula, thalamus, hippocampus and unilateral primary motor cortex, secondary somatosensory cortex at the contralateral side of lesion, and unilateral supplementary motor area at the ipsilateral side of lesion. Greater activation responses were observed in the side contralateral to the lesion, suggesting a significant intervention effect. Our preliminary findings suggest that noxious TS may induce neuroplastic changes unconstrained to the local area.Trial registration: NCT01418404

Ipsilateral primary motor cortex and behavioral compensation after stroke: a case series study.

Arm motor recovery after stroke is mainly attributed to reorganization of the primary motor cortex (M1). While M1 contralateral to the paretic arm (cM1) is critical for recovery, the role of ipsilateral M1 (iM1) is still inconclusive. Whether iM1 activity is related to recovery, behavioral compensation, or both is still far from settled. We hypothesized that the magnitude of iM1 activity in chronic stroke survivors will increase ordecrease in direct proportion to the degree that movements of the paretic arm are compensated. Movement kinematics (VICON, Oxford Metrics) and functional MRI data (3T MR system) were collected in 11 patients before and after a 4-week training designed to improve motor control of the paretic arm and decrease compensatory trunk recruitment. Twelve matched controls underwent similar evaluations and training. Relationships between iM1 activity and trunk motion were analyzed. At baseline, patients exhibited increased iM1 activity (p = 0.001) and relied more on trunk movement (p = 0.02) than controls. These two variables were directly and significantly related in patients (r = 0.74, p = 0.01) but not in controls (r = 0.28, p = 0.4). After training, patients displayed a significant reduction in iM1 activity (p = 0.008) and a trend toward decreased trunk use (p = 0.1). The relationship between these two variables remained significant (r = 0.66, p = 0.03) and different from controls (r = 0.26, p = 0.4). Our preliminary results suggest that iM1 may play a role in compensating for brain damage rather than directly gaining control of the paretic arm. However, we recommend caution in interpreting these results until more work is completed.

The “Exo hand-2” complex in the rehabilitation of the upper limb in cerebral palsy using the non-invasive interface “brain-computer”

Improving the function of the upper limb in cerebral palsy is one of the main tasks of rehabilitation treatment and socialization of the patient.The purpose of the study was to evaluate the effectiveness of the “Exo hand-2” complex with the non-invasive interface “brain-computer” for correcting the motor function of the upper limb in cerebral palsy.The study involved 50 male and female with cerebral palsy (main group n = 30, control group n = 20) aged 12–18 years old. The level of motor activity according to the criteria of classification of large motor functions (GMFCS) was not more than III. All patients received a standard course of spa rehabilitation for 21 days. Patients of the main group were additionally rehabilitated using the “Exo hand-2” complex with the non-invasive interface “brain-computer”. As a result of treatment in the main group, spasticity in the paretic hand on the Modified Ashworth Scale decreased from 3 (2; 3) to 2 (1; 2) points (p &lt;0.002); according to Tardieu, spasticity decreased from the level of 3 (2; 3) to 2 (1; 2) (p &lt;0.002). Half of the patients had paretic arm muscle strength in the Medical Research Counsil Weakness Scale sums core from 2.3 (2; 3) to 3 (2; 3) points after treatment (p = 0.002); assessment of household skills on the Modified Franchay Scale showed an improvement from 37 (22.75; 63.75) to 45 (30; 72.75) points after therapy.

Phase I/II parallel double-blind randomized controlled clinical trial of perispinal etanercept for chronic stroke: improved mobility and pain alleviation

ABSTRACT Background Previous open-label studies showed that chronic post-stroke pain could be abated by treatment with perispinal etanercept, although these benefits were questioned. A randomized double-blind placebo controlled clinical trial was conducted to test perispinal etanercept for chronic post-stroke pain. Research design and methods Participants received two treatments, either perispinal etanercept (active) or saline (control). Primary outcomes were the differences in daily pain levels between groups analyzed by SPSS. Results On the 0–100 points visual analog scale, perispinal etanercept reduced mean levels for worst and average daily pain from baseline after two treatments by 19.5 – 24 points (p < 0.05), and pain alleviation was maintained in the etanercept group, with no significant change in the control group. Thirty percent of etanercept participants had near complete pain abatement after first treatment. Goniometry of the paretic arm showed improved mean shoulder rotation by 55 degrees in active forward flexion for the etanercept group (p = 0.003) only. Conclusions Perispinal etanercept can provide significant and ongoing benefits for the chronic post-stroke management of pain and greater shoulder flexion by the paretic arm. Effects are rapid and highly significant, supporting direct action on brain function. Trial registration ACTRN12615001377527 and Universal Trial Number U1111-1174-3242.

Direction-specific Disruption of Paretic Arm Movement in Post-stroke Patients.

ABSTRACTObjective:This study aimed to characterize reaching movements of the paretic arm in different directions within the reachable workspace in post-stroke patients. Methods:A total of 12 post-stroke patients participated in this study. Each held a ball with a tracking marker and performed back-and-forth reaching movements from near the middle of the body to one of two targets in front of them located on the ipsilateral and contralateral sides of the arm performing the movement. We recorded and analyzed the trajectories of the tracking marker. The stability of arm movements was evaluated using areas and minimum Feret diameters to assess the trajectories of both the paretic and non-paretic arms. The speed of the arm movement was also calculated. Results:For the paretic arm, contralateral movement was more impaired than ipsilateral movement, whereas for the non-paretic arm, no difference was observed between the directions. The maximum speed of the contralateral movement was significantly slower than that of the ipsilateral movement in both the paretic and non-paretic arms. Conclusion:The paretic arm shows direction-specific instability in movement toward the contralateral side of the arm.

Self-Support Biofeedback Training for Recovery From Motor Impairment After Stroke

Unilateral arm paralysis is a common symptom of stroke. In stroke patients, we observed that self-guided biomechanical support by the nonparetic arm unexpectedly triggered electromyographic activity with normal muscle synergies in the paretic arm. The muscle activities on the paretic arm became similar to the muscle activities on the nonparetic arm with self-supported exercises that were quantified by the similarity index (SI). Electromyogram (EMG) signals and functional near-infrared spectroscopy (fNIRS) of the patients (n=54) showed that self-supported exercise can have an immediate effect of improving the muscle activities by 40-80% according to SI quantification, and the muscle activities became much more similar to the muscle activities of the age-matched healthy subjects. Using this self-supported exercise, we investigated whether the recruitment of a patient's contralesional nervous system could reactivate their ipsilesional neural circuits and stimulate functional recovery. We proposed biofeedback training with self-supported exercise where the muscle activities were visualized to encourage the appropriate neural pathways for activating the muscles of the paretic arm. We developed the biofeedback system and tested the recovery speed with the patients (n=27) for 2 months. The clinical tests showed that self-support-based biofeedback training improved SI approximately by 40%, Stroke Impairment Assessment Set (SIAS) by 35%, and Functional Independence Measure (FIM) by 20%.

Comparison of self-reported vs observational clinical measures of improvement in upper limb capacity in patients after stroke.

Recovery of the paretic arm post-stroke can be assessed using observational and self-reported measures. The aim of this study was to determine whether the correspondence (match) or non-correspondence (mismatch) between observational and self-reported improvements in upper limb capacity are significantly different at 0-3 months compared with 3-6 months post-stroke. A total of 159 patients with ischaemic stroke with upper limb paresis were included in the study. Recovery of arm capacity was measured with observational (Action Research Arm Test; ARAT) and self-reported measures (Motor Activity Log Quality of Movement; MAL-QOM and Stroke Impact Scale Hand; SIS-Hand) at 0-3 and 3-6 months post-stroke. The proportion of matches was defined (contingency tables and Fisher's exact test) and compared across the different time-windows using McNemar's test. The proportion of matches was not significantly different at 0-3 months compared with 3-6 months post-stroke for the ARAT vs MAL-QOM and SIS-Hand (all p > 0.05). In case of mismatches, patients' self-reports were more often pessimistic (86%) in the first 3 months post-stroke compared with the subsequent 3 months (39%). The match between observational and self-reported measures of upper limb capacity is not dependent on the timing of assessment post-stroke. Assessment of both observational and self-reported measures may help to recognize possible over- or under-estimation of improvement in upper limb capacity post-stroke.

Musical Sonification of Arm Movements in Stroke Rehabilitation Yields Limited Benefits.

Neurologic music therapy in rehabilitation of stroke patients has been shown to be a promising supplement to the often strenuous conventional rehabilitation strategies. The aim of this study was threefold: (i) replicate results from a previous study with a sample from one clinic (henceforth called Site 1; N = 12) using an already established recording system, and (ii) conceptually replicate previous findings with a less costly hand-tracking system in Site 2 (N = 30), and (iii) compare both sub-studies’ outcomes to estimate the efficiency of neurologic music therapy. Stroke patients in both sites were randomly assigned to treatment or control groups and received daily training of guided sequential upper limb movements additional to their standard stroke rehabilitation protocol. Treatment groups received sonification (i.e., changes in musical pitch) of their movements when they moved their affected hand up and down to reproduce a sequence of the first six notes of a C major scale. Controls received the same movement protocol, however, without auditory feedback. Sensors at the upper arm and the forearm (Xsens) or an optic sensor device (Leapmotion) allowed to measure kinematics of movements and movement smoothness. Behavioral measures pre and post intervention included the Fugl-Meyer assessment (FMA) and the Stroke Impact Scale (SIS) and movement data. Bayesian regression did not show evidence supporting an additional effect of sonification on clinical mobility assessments. However, combined movement data from both sites showed slight improvements in movement smoothness for the treatment group, and an advantage for one of the two motion capturing systems. Exploratory analyses of EEG-EMG phase coherence during movement of the paretic arm in a subset of patients suggested increases in cortico-muscular phase coherence specifically in the ipsilesional hemisphere after sonification therapy, but not after standard rehabilitation therapy. Our findings show that musical sonification is a viable treatment supplement to current neurorehabilitation methods, with limited clinical benefits. However, given patients’ enthusiasm during training and the low hardware price of one of the systems it may be considered as an add-on home-based neurorehabilitation therapy.

Bimanual Coordination Functions between Paretic and Nonparetic Arms: A Systematic Review and Meta-analysis

BackgroundBimanual coordination is essential for performing many everyday interlimb actions that require successful spatiotemporal interactions between the 2 arms. This systematic review and meta-analysis investigates bimanual coordination function of the upper extremities in patients with stroke. MethodsSeventeen studies that compared bimanual coordination functions in patients with stroke and age-matched healthy controls qualified for this meta-analysis. We categorized 25 comparisons from the 17 qualified studies into 6 types of bimanual actions based on 3 task constraints: (1), symmetry versus asymmetry movements, (2) parallel versus cooperative movements, and (3) independent goals versus a common goal. ResultsRandom effects meta-analysis revealed that patients with stroke had impaired kinematic (Hedges's g = −1.232 and P < .0001) and kinetic (Hedges's g = −.712 and P = .001) control of bimanual coordination as compared with the age-matched healthy controls. The moderator variable analysis on the 6 types of bimanual actions showed that bimanual coordination impairments after stroke appeared while performing both asymmetrical bimanual movements and symmetrical bimanual movements to achieve a common goal. Moreover, we observed a potential relationship between greater time since stroke onset and increased interlimb coordination impairments for chronic patients. ConclusionsThese findings suggest that restoring interlimb coordination functions after stroke may be a crucial rehabilitation goal for facilitating progress toward stroke motor recovery.

Actigraphic measurement of the upper limbs movements in acute stroke patients

BackgroundStroke units provide patients with a multiparametric monitoring of vital functions, while no instruments are actually available for a continuous monitoring of patients motor performance. Our aim was to develop an actigraphic index able both to identify the paretic limb and continuously monitor the motor performance of stroke patients in the stroke unit environment.MethodsTwenty consecutive acute stroke patients (mean age 69.2 years SD 10.1, 8 males and 12 females) and 17 bed-restrained patients (mean age 70.5 years SD 7.3, 7 males and 10 females) hospitalized for orthopedic diseases of the lower limbs, but not experiencing neurological symptoms, were enrolled. This last group represented our control group. The motor activity of arms was recorded for 24 h using two programmable actigraphic systems showing off as wrist-worn watches. The firmware segmented the acquisition in epochs of 1 minute and for each epoch calculates two motor activity indices: MAe1 (Epoch-related Motor Activity index) and MAe2 (Epoch-related Motor Activity index 2). MAe1 is defined as the standard deviation of the acceleration module and MAe2 as the module of the standard deviation of acceleration components. To describe the 24 h motor performance of each limb, we calculated the mean value of MAe1 and MAe2 (respectively MA1_24h and MA2_24h). Then we obtained two Asymmetry Rate Indices: AR1_24h and AR2_24h to show the motor activity prevalence. AR1_24h refers to the asymmetry index between the values of MAe1 of both arms and AR2_24h to MAe2 values.The stroke patients were clinically evaluated by NIHSS at the beginning (NIHSST0) and at the end (NIHSST1) of the 24 h actigraphic recordings.ResultsBoth MA1_24h and MA2_24h indices were smaller in the paretic than in the unaffected arm (respectively p = 0.004 and p = 0.004). AR2_24h showed a better capability (95% of paretic arms correctly identified, Phi Coefficient: 0.903) to discriminate the laterality of the clinical deficit than AR1_24h (85% of paretic arms correctly identified, Phi Coefficient: 0,698). We also found that AR1_24h did not differ between the two groups of patients while AR2_24h was greater in stroke patients than in controls and positively correlated with NIHSS total scores (r: 0.714, p < 0.001 for NIHSS, IC95%: 0.42–0.90) and with the sub-score relative to the paretic upper limb (r: 0.812, p < 0.001, IC95%: 0.62–0.96).ConclusionsOur data show that actigraphic monitoring of upper limbs can detect the laterality of the motor deficit and measure the clinical severity. These findings suggest that the above described actigraphic system could implement the existing multiparametric monitoring in stroke units.

Determining User Intent of Partly Dynamic Shoulder Tasks in Individuals With Chronic Stroke Using Pattern Recognition.

Stroke remains the leading cause of long-term disability in the US. Although therapy can achieve limited improvement of paretic arm use and performance, weakness and abnormal muscle synergies-which cause unintentional elbow, wrist, and finger flexion during shoulder abduction-contribute significantly to limb disuse and compound rehabilitation efforts. Emerging wearable exoskeleton technology could provide powered abduction support for the paretic arm, but requires a clinically feasible, robust control scheme capable of differentiating multiple shoulder degrees-of-freedom. This study examines whether pattern recognition of sensor data can accurately identify user intent for 9 combinations of 1- and 2- degree-of-freedom shoulder tasks. Participants with stroke (n = 12) used their paretic and non-paretic arms, and healthy controls (n = 12) used their dominant arm to complete tasks on a lab-based robot involving combinations of abduction, adduction, and internal and external rotation of the shoulder. We examined the effect of arm (paretic, non-paretic), load level (25% vs 50% maximal voluntary torque), and dataset (electromyography, load cell, or combined) on classifier performance. Results suggest that paretic arm, lower load levels, and using load cell or EMG data alone reduced classifier accuracy. However, this method still shows promise. Further work will examine classifier-user interaction during active control of a robotic device and optimization/minimization of sensors.

Effects of arm weight support on neuromuscular activation during reaching in chronic stroke patients.

To better understand how arm weight support (WS) can be used to alleviate upper limb impairment after stroke, we investigated the effects of WS on muscle activity, muscle synergy expression, and corticomotor excitability (CME) in 13 chronic stroke patients and 6 age-similar healthy controls. For patients, lesion location and corticospinal tract integrity were assessed using magnetic resonance imaging. Upper limb impairment was assessed using the Fugl-Meyer upper extremity assessment with patients categorised as either mild or moderate-severe. Three levels of WS were examined: low = 0, medium = 50 and high = 100% of full support. Surface EMG was recorded from 8 upper limb muscles, and muscle synergies were decomposed using non-negative matrix factorisation from data obtained during reaching movements to an array of 14 targets using the paretic or dominant arm. Interactions between impairment level and WS were found for the number of targets hit, and EMG measures. Overall, greater WS resulted in lower EMG levels, although the degree of modulation between WS levels was less for patients with moderate-severe compared to mild impairment. Healthy controls expressed more synergies than patients with moderate-severe impairment. Healthy controls and patients with mild impairment showed more synergies with high compared to low weight support. Transcranial magnetic stimulation was used to elicit motor-evoked potentials (MEPs) to which stimulus-response curves were fitted as a measure of corticomotor excitability (CME). The effect of WS on CME varied between muscles and across impairment level. These preliminary findings demonstrate that WS has direct and indirect effects on muscle activity, synergies, and CME and warrants further study in order to reduce upper limb impairment after stroke.

Influence of bimanual exercise on muscle activation in post-stroke patients

Brain damage due to stroke often leaves survivors with lateral functional motor deficits. Bimanual rehabilitation of the paretic arm is an active field of research aimed at restoring normal functionality by making use of the complex neural bindings that exist between the arms. In search of an effective rehabilitation method, we introduced a group of post-stroke rehabilitation patients to a set of bimanual motion tasks with inter-manual coupling and phasing. The surface EMG profiles of the patients were compared in order to understand the effect of the motion conditions. The paretic arms of the patients were more strongly affected by the task conditions compared with the non-paretic arms. These results suggest that in-phase motion may activate neural circuits that trigger recovery. Coupling also had an effect on behavior, but the response of patients was divided between those whom coupling helped or hindered.