Upper-limb Motor Impairment Research Articles

Fugl-Meyer Assessment Scores Are Related With Kinematic Measures in People with Chronic Hemiparesis after Stroke

Background: Stroke often results in motor impairment and limited functional capacity. This study aimed to verify the relationship between widely used clinical scales and instrumented measurements to evaluate poststroke individuals with mild, moderate, and severe motor impairment. Methods: This cross-sectional study included 34 participants with chronic hemiparesis after stroke. Fugl-Meyer Assessment and Modified Ashworth Scale were used to quantify upper and lower limb motor impairment and the resistance to passive movement (i.e., spasticity), respectively. Upper limb Motor performance (movement time and velocities) and movement quality (range of motion, smoothness and trunk displacement) were analyzed during a reaching forward task using an optoelectronic system (instrumented measurement). Lower limb motor performance (gait and functional mobility parameters) was assessed by using an inertial measurement unit system. Findings: Fugl-Meyer Assessment correlated with motor performance (upper and lower limbs) and with movement quality (upper limb). Modified Ashworth scale correlated with movement quality (upper limb). Cutoff values of 9.0 cm in trunk anterior displacement and .57 m/s in gait velocity were estimated to differentiate participants with mild/moderate and severe compromise according to the Fugl-Meyer Assessment. Conclusions: These results suggest that the Fugl-Meyer Assessment can be used to infer about motor performance and movement quality in chronic poststroke individuals with different levels of impairment.

Feedback Error Learning with Sliding Mode Control for Functional Electrical Stimulation: Elbow Joint Simulation

Motivation: Upper-limb motor impairment is one of the most common consequences after Stroke. Limited capability for performing reaching and grasping movements hinders the execution of most activities of daily living. Consequently, the quality lives of the affected individuals are severely compromised. Due to these facts, the recovery of the upper limb functional capabilities is currently one of the keystones of the rehabilitation therapy. Background: Researchers are developing new methods and technologies to boost the outcomes of rehabilitation therapy. A hybrid robotic system has been proposed as a promising rehabilitation technology that combines a passive device (Armeo Spring exoskeleton) to support the arm weight against gravity with a Functional Electrical Stimulation (FES) system to execute the reaching task. This system provides to patients the possibility of training specifically and intensive exercises. Objective: The main objective of this paper is to investigate the performance and robustness of a Feedback Error learning (FEL) scheme mixed with sliding mode control (SMC) to control the FES. Methods: We implemented a nonlinear model describing the muscle response to FES and the dynamic behavior of the elbow joint. Using this model we carried out a simulation study to compare four control strategies: computed torque control (CTC), sliding mode Control (SMC), and adaptive feedback control using FEL: ANN+ CTC and FEL: ANN+SMC. We tested these controllers in two different simulation conditions: In the absence and presence of fatigue. To check the performance of the controllers, we compared the root means square (RMSE) of tracking error and the Normalized RMS of muscle stimulation for various range of movement (ROM). Results: All four controllers achieved good tracking performance in the absence of perturbations. When introducing muscle fatigue, good tracking performance is given essentially by the adaptive control ANN+SMC. Conclusion: Among the proposed approaches, we conclude that the adaptive control (FEL: ANN + SMC) is the most efficient and robust controller, which has been proven by calculating RMSE.

Elucidating the Structural and Functional Correlates of Upper-Limb Poststroke Motor Impairment.

Background and Purpose- Many studies have attempted to bring to light the neural correlates of poststroke motor impairment, but few have used multimodal approach to explain it. The aim of this study was to elucidate neural structural and functional correlates of upper limb motor impairment by combining electrophysiological, anatomic, and functional neuroimaging data. Methods- Forty ischemic stroke patients (median [min-max] age: 63 [33-82] years, time poststroke: 3.5 [1.1-58] months) with unilateral upper limb weakness were included. The upper limb motor impairment was defined by a motor composite score. Simple linear analysis followed by multiple linear regression analysis were performed to identify which variables (corticospinal excitability, laterality indices within the primary motor cortex or corticospinal [CST], and corpus callosum tracts integrity) were the best explaining factors of upper limb motor impairment. Results- There was a significant correlation between the resting motor threshold ratio and CST damage (r= -0.50 [95% CI, -0.70 to -0.22]; P<0.001) as well as the motor-evoked potentials amplitude (r= -0.73 [95% CI, -0.85 to -0.54]; P<0.001). Only the resting motor threshold ratio was retained by the multiple regression model and explained half of the variance (49%; P<0.001) of the upper limb motor impairment after stroke. Conclusions- The implementation of quantitative neurophysiological measurements such as the resting motor threshold as a surrogate marker of impairment could be considered in neurorehabilitation trials.

What the Proportional Recovery Rule Is (and Is Not): Methodological and Statistical Considerations

In 2008, it was proposed that the magnitude of recovery from nonsevere upper limb motor impairment over the first 3 to 6 months after stroke, measured with the Fugl-Meyer Assessment (FMA), is approximately 0.7 times the initial impairment (“proportional recovery”). In contrast to patients with nonsevere hemiparesis, about 30% of patients with an initial severe paresis do not show such recovery (“nonrecoverers”). Hence it was suggested that the proportional recovery rule (PRR) was a manifestation of a spontaneous mechanism that is present in all patients with mild-to-moderate paresis but only in some with severe paresis. Since the introduction of the PRR, it has subsequently been applied to other motor and nonmotor impairments. This more general investigation of the PRR has led to inconsistencies in its formulation and application, making it difficult to draw conclusions across studies and precipitating some cogent criticism. Here, we conduct a detailed comparison of the different studies reporting proportional recovery and, where appropriate, critique statistical methodology. On balance, we conclude that existing data in aggregate are largely consistent with the PRR as a population-level model for upper limb motor recovery; recent reports of its demise are exaggerated, as these excessively focus on the less conclusive issue of individual subject-level predictions. Moving forward, we suggest that methodological caution and new analytical approaches will be needed to confirm (or refute) a systematic character to spontaneous recovery from motor and other poststroke impairments, which can be captured by a mathematical rule either at the population or at the subject level.

Exergaming-Based Dexterity Training in Persons With Parkinson Disease: A Pilot Feasibility Study.

Many individuals with Parkinson disease (PD) suffer from impaired dexterity, which impacts activities of daily living and quality of life. Exergaming, video game-based training with augmented virtual reality, may have value for improving function. The aim of the present pilot study was to comprehensively evaluate the feasibility of a dexterity training program using exergaming, in individuals with PD. Ten participants with PD (aged between 55 and 75 years, Hoehn and Yahr stages II-IV) trained over a period of 4 weeks, twice a week for 30 minutes. Baseline (T0) and postintervention (T1) assessments were done. Primary outcomes with respect to feasibility were the adherence rate, open-end questions, the level of participation (Pittsburgh Rehabilitation Participation Scale), and the usability (System Usability Scale). Dexterous function was measured with the Nine-Hole Peg Test and the Dexterity Questionnaire-24. Upper limb motor impairment was assessed by a modified version of the Movement Disorders Society Unified Parkinson's Disease Rating Scale III. Finally, quality of life was assessed by the 39-item Parkinson's Disease Questionnaire (PDQ-39). Adherence rate was 99%, motivation increased significantly from 3.9 to 4.8 (Pittsburgh Rehabilitation Participation Scale, P = 0.03), and system usability of the exergaming system was acceptable to very good. Regarding potential efficacy, participants with impaired dexterity at T0 significantly improved in the Nine-Hole Peg Test and the PDQ-39. The outcomes of this pilot study suggest that exergaming is feasible and has potential to improve dexterity in individuals with PD. Its efficacy should be investigated in a properly powered randomized controlled trial.Video Abstract available for more insights from the authors (see Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A270).

Onset Detection to Study Muscle Activity in Reaching and Grasping Movements in Rats.

EMG signals reflect the neuromuscular activation patterns related to the execution of a certain movement or task. In this work, we focus on reaching and grasping (R&G) movements in rats. Our objective is to develop an automatic algorithm to detect the onsets and offsets of muscle activity and use it to study muscle latencies in R&G maneuvers. We had a dataset of intramuscular EMG signals containing 51 R&G attempts from 2 different animals. Simultaneous video recordings were used for segmentation and comparison. We developed an automatic onset/offset detector based on the ratio of local maxima of Teager-Kaiser Energy (TKE). Then, we applied it to compute muscle latencies and other features related to the muscle activation pattern during R&G cycles. The automatic onsets that we found were consistent with visual inspection and video labels. Despite the variability between attempts and animals, the two rats shared a sequential pattern of muscle activations. Statistical tests confirmed the differences between the latencies of the studied muscles during R&G tasks. This work provides an automatic tool to detect EMG onsets and offsets and conducts a preliminary characterization of muscle activation during R&G movements in rats. This kind of approaches and data processing algorithms can facilitate the studies on upper limb motor control and motor impairment after spinal cord injury or stroke.

A functional analysis-based approach to quantify upper limb impairment level in chronic stroke patients: a pilot study.

The accurate assessment of upper limb motion impairment induced by stroke - which represents one of the primary causes of disability world-wide - is the first step to successfully monitor and guide patients' recovery. As of today, the majority of the procedures relies on clinical scales, which are mostly based on ordinal scaling, operator-dependent, and subject to floor and ceiling effects. In this work, we intend to overcome these limitations by proposing a novel approach to analytically evaluate the level of pathological movement coupling, based on the quantification of movement complexity. To this goal, we consider the variations of functional Principal Components applied to the reconstruction of joint angle trajectories of the upper limb during daily living task execution, and compared these variations between two conditions, i.e. the affected and non-affected arm. A Dissimilarity Index, which codifies the severity of the upper limb motor impairment with respect to the movement complexity of the non-affected arm, is then proposed. This methodology was validated as a proof of concept upon a set of four chronic stroke subjects with mild to moderate arm and hand impairments. As a first step, we evaluated whether the derived outcomes differentiate between the two conditions upon the whole data-set. Secondly, we exploited this concept to discern between different subjects and impairment levels. Results show that: i) differences in terms of movement variability between the affected and nonaffected upper limb are detectable and ii) different impairment profiles can be characterized for single subjects using the proposed approach. Although provisional, these results are very promising and suggest this approach as a basis ingredient for the definition of a novel, operator-independent, sensitive, intuitive and widely applicable scale for the evaluation of upper limb motion impairment.

Automated Evaluation of Upper Limb Motor Impairment of Patient with Cerebellar Ataxia.

Upper limb impairment with various symptoms including incoordination, tremors and prolonged motion are important factors of motor disturbance in Cerebellar ataxia (CA). Accurate assessment is a key element in the diagnosis and progress monitoring of conditions such as CA. Often such assessments are mostly based on the observations of the clinicians and hence, are inherently subjective. In this paper, we propose a system that consists of two automated assessment schemes which employ a depth camera and an inertial measurement unit (IMU) sensor for the quantification of upper limb ataxia in the treatment of CA. The assessment includes an automated finger chase in which the patients were asked to follow a target point on the screen using their index finger and another assessment in which the patients were asked to tap their finger continuously on a surface at a comfortable rate. The overall system was tested for 44 CA patients and 14 age matched healthy individuals. The combination of features of the two tests provided us with an objective measurement which identifies CA patients to a higher degree of accuracy (Quadratic Discriminant Analysis, 93.1%) in addition to providing a high correlation (r = 0.8, p <; 0.001) with the the Scale for the Assessment and Rating of Ataxia (SARA) based severity evaluation of patients.

Bi-cephalic transcranial direct current stimulation combined with functional electrical stimulation for upper-limb stroke rehabilitation: A double-blind randomized controlled trial.

Stroke survivors often present poor upper-limb (UL) motor performance and reduced movement quality during reaching tasks. Transcranial direct current stimulation (tDCS) and functional electrical stimulation (FES) are widely used strategies for stroke rehabilitation. However, the effects of combining these two therapies to rehabilitate individuals with moderate and severe impairment after stroke are still unknown. Our primary aim was to evaluate the effects of concurrent bi-cephalic tDCS and FES on UL kinematic motor performance and movement quality of chronic post-stroke subjects with moderate and severe compromise. Our secondary aim was to verify the effects of combining these therapies on handgrip force and UL motor impairment. We randomized 30 individuals with moderate and severe chronic hemiparesis after stroke into tDCS plus FES (n=15) and sham tDCS plus FES (n=15) groups. Participants were treated 5 times a week for 2 weeks. Kinematic motor performance (movement cycle time, velocity profile) and movement quality (smoothness, trunk contribution, joint angles) were assessed during an UL reach-to-target task.Handgrip force and motor impairment were also recorded before and after the intervention. Participants allocated to the tDCS plus FES group improved movement cycle time (P=0.039), mean reaching velocity (P=0.022) and handgrip force (P=0.034). Both groups improved the mean returning phase velocity (P=0.018), trunk contribution (P=0.022), movement smoothness (P=0.001) and UL motor impairment (P=0.002). Concurrent bi-cephalic tDCS and FES slightly improved reaching motor performance and handgrip force of chronic post-stroke individuals with moderate and severe UL impairment. ClinicalTrials.gov (NCT02818608).

Relationship Between Clinical Measures of Upper Limb Movement Quality and Activity Poststroke

Background. Understanding the relationship between movement quality (impairment) and performance (activity) in poststroke patients is important for rehabilitation intervention studies. This has led to an interest in kinematic characterization of upper limb motor impairment. Since instrumented motion analysis is not readily clinically available, observational kinematics may be a viable alternative. Objective. To determine if upper limb movement quality during a reach-to-grasp task identified by observation could be used to describe the relationship between motor impairments and the time to perform functional tasks. Methods. Cross-sectional, secondary analysis of baseline data from 141 participants with stroke, age 18 to 85 years, who participated in a multicenter randomized controlled trial. Clinical assessment of movement quality using the Reaching Performance Scale for Stroke (RPSS–Close and Far targets) and of performance (activity) from the Wolf Motor Function Test (WMFT–7 items) was assessed. The degree to which RPSS component scores explained scores on WMFT items was determined by multivariable regression. Results. Clinically significant decreases (>2 seconds) in performance time for some of the more complex WMFT tasks involving prehension were predicted from RPSS–Close and Far target components. Trunk compensatory movements did not predict either increases or decreases in performance time for the WMFT tasks evaluated. Overall, the strength of the regression models was low. Conclusions. In lieu of kinematic analysis, observational clinical movement analysis may be a valid and accessible method to determine relationships between motor impairment, compensations and upper limb function in poststroke patients. Specific relationships are unlikely to generalize to all tasks due to kinematic redundancy and task specificity.

Boosting robot-assisted rehabilitation of stroke hemiparesis by individualized selection of upper limb movements \u2013 a pilot study

BackgroundIntensive robot-assisted training of the upper limb after stroke can reduce motor impairment, even at the chronic stage. However, the effectiveness of practice for recovery depends on the selection of the practised movements. We hypothesized that rehabilitation can be optimized by selecting the movements to be practiced based on the trainee’s performance profile.MethodsWe present a novel principle (‘steepest gradients’) for performance-based selection of movements. The principle is based on mapping motor performance across a workspace and then selecting movements located at regions of the steepest transition between better and worse performance.To assess the benefit of this principle we compared the effect of 15 sessions of robot-assisted reaching training on upper-limb motor impairment, between two groups of people who have moderate-to-severe chronic upper-limb hemiparesis due to stroke. The test group (N = 7) received steepest gradients-based training, iteratively selected according to the steepest gradients principle with weekly remapping, whereas the control group (N = 9) received a standard “centre-out” reaching training. Training intensity was identical.ResultsBoth groups showed improvement in Fugl-Meyer upper-extremity scores (the primary outcome measure). Moreover, the test group showed significantly greater improvement (twofold) compared to control. The score remained elevated, on average, for at least 4 weeks although the additional benefit of the steepest-gradients -based training diminished relative to control.ConclusionsThis study provides a proof of concept for the superior benefit of performance-based selection of practiced movements in reducing upper-limb motor impairment due to stroke. This added benefit was most evident in the short term, suggesting that performance-based steepest-gradients training may be effective in increasing the rate of initial phase of practice-based recovery; we discuss how long-term retention may also be improved.Trial registrationISRCTN, ISRCTN65226825, registered 12 June 2018 - Retrospectively registered,

Abstract WP189: Safety and Preliminary Efficacy of Cathodal Transcranial Direct Current Stimulation to Enhance Upper Limb Motor Function Early After Ischemic Stroke: a Double-blind, Randomized Clinical Trial

Introduction: Transcranial direct current stimulation (tDCS) has the potential to improve upper limb motor outcomes after stroke. Objective: To evaluate the safety and preliminary efficacy of active cathodal compared to sham tDCS of the primary motor cortex of the unaffected hemisphere (ctDCSM1 UH ), within 72 hours to 6 weeks post-ischemic stroke. Methods: In this randomized, double-blind study, 30 patients with unilateral hand paresis were assigned to either active or sham ctDCSM1 UH as add-on interventions to rehabilitation. The primary outcome was the frequency of adverse events. Secondary outcomes, compared before, immediately after treatment and three months later, included measures of upper limb motor performance and quality of life. Stroke volume was assessed before and after treatment. Results: Overall, tDCS was well tolerated and there were no serious adverse events. One subject in the active group reported paresthesias in the paretic arm during the first session of ctDCSM1 UH . Heart rate increased significantly after active and decreased significantly after sham ctDCSM1 UH but these changes were not clinically significant. Upper limb motor impairment and quality of life improved significantly more in the sham than in the active group at three months post-treatment according to intention-to-treat and per-protocol analyses. The between-group difference in motor impairment was not clinically relevant. There were no recurrent strokes and lesion volumes did not increase significantly in either group. Conclusions: Active ctDCSM1 UH was safe and well tolerated but the preliminary efficacy results do not support a beneficial role of this intervention within the first six weeks after stroke.

Abstract WP193: Genetic Polymorphisms Negatively Impact Upper Limb Motor Recovery After Stroke - A Meta-analysis

Upper limb (UL) hemiparesis is one of the most disabling consequences of a stroke. In addition to spontaneous recovery, post-stroke motor recovery is associated with adaptive neuroplasticity and motor learning. Factors affecting motor learning and adaptive neuroplasticity include the presence of genetic polymorphisms. Evidence is emerging that these polymorphisms can influence UL motor recovery. However, the implications of these polymorphisms on rehabilitation are unclear. Using a systematic review and meta analysis, we examined the influence of genetic polymorphisms on post-stroke UL motor recovery. We conducted a systematic review of the published literature in English language. The Down’s and Black checklist helped evaluate the quality of the published studies. We compared changes in UL motor impairment and activity levels between groups with and without the polymorphisms using standardized mean differences and derived summary effect sizes. Seven studies that examined the effects of genetic polymorphisms on UL motor recovery were obtained. The studies examined the effects of polymorphisms (presence of met alleles) in brain derived neurotrophic factor (BDNF, 5 studies) and Catechol- O -Methyltransferase (COMT, 1 study). One study assessed the effects of Apolipoprotein polymorphism (ApoE ε4). The Fugl Meyer Assessment and Wolf Motor Function Test outcomes assessed motor impairment and activity levels respectively. The quality of the published studies ranged from fair to good. The meta analysis revealed that presence of met allele in BDNF negatively influenced the recovery of motor impairment (moderate effect size -0.47). In addition, recovery of activity levels for people with moderate and high levels of motor ability (effect sizes -1.39 and -7.37 respectively) were also negatively impacted by the presence of met allele in BDNF. The met allele in COMT also negatively influenced recovery of motor impairment (effect size -2.66). Presence of ApoE ε4 did not influence UL motor recovery. In conclusion, the presence of genetic polymorphisms negatively influences the recovery of UL motor impairment and activity. These factors need to be considered while selecting rehabilitation interventions to maximize levels of UL motor recovery post-stroke.

Abstract 120: Peripheral Nerve Stimulation to Enhance Upper Limb Motor Function in Stroke

Introduction: Peripheral sensory stimulation (PSS) administered for 2 hours prior to intensive task-oriented motor training delivered for 4 hours, over 10 days, leads to clinically significant benefits in subjects with stroke and moderate to severe upper limb motor impairment, compared to sham PSS. Whether similar results can be obtained with less intensive training programs remains to be determined. Methods: Twenty subjects with stroke in the chronic phase (&gt;6m) and moderate to severe upper limb motor impairments were randomized to treatment with either 1.5h active PSS or sham, followed by functional electrical stimulation (FES) and task-specific training (TST) in sessions administered three times per week over six weeks. FES lasted for 30 minutes and TST, for 45 minutes. The primary outcome was the difference in performance in the Wolf Motor Function Test. The data were analyzed with a generalized estimating equations model with factors “group” (active or sham) and “time” (baseline, three and six weeks after starting treatment). Results: There were significant effects of “time” (Wald Chi-square = 16.5, p&lt;0.001) and interaction between “group” and “time” (Wald Chi-square = 10.4, p=0.005) for the Wolf Motor Function Test, Functional Ability Scale. Post-hoc Bonferroni-corrected analyses showed a statistically significant improvement in performance between baseline and three weeks after beginning of treatment in the active (p=0.001) but not in the sham group (p=0.912). The difference between performance at baseline and six weeks after beginning of treatment almost reached statistically significance in the active (p=0.058) but not in the sham (p&gt;0.999) group. Conclusions: These results are relevant for the design of larger clinical trials involving durations of interventions that are more easily implemented in clinical practice than rehabilitation protocols lasting for 6 hours per day. The study is ongoing.

A multimodal approach to understand upper-limb motor impairment after stroke in subacute and chronic phases

Purpose: Accumulated evidence supports motor evoked potential (MEP) status and neuroimaging measures of corticospinal tract (CST) integrity as useful biomarkers for understanding upper-limb motor outcome. Our aim was to determine which biomarkers among electrophysiological and MRI variables can accurately explain the motor impairment in subacute and chronic stroke patients.

Automated Assessment of Movement Impairment in Huntington's Disease.

Quantitative assessment of movement impairment in Huntington’s disease (HD) is essential to monitoring of disease progression. This paper aimed to develop and validate a novel low cost, objective automated system for the evaluation of upper limb movement impairment in HD in order to eliminate the inconsistency of the assessor and offer a more sensitive, continuous assessment scale. Patients with genetically confirmed HD and healthy controls were recruited to this observational study. Demographic data, including age (years), gender, and unified HD rating scale total motor score (UHDRS-TMS), were recorded. For the purposes of this paper, a modified upper limb motor impairment score (mULMS) was generated from the UHDRS-TMS. All participants completed a brief, standardized clinical assessment of upper limb dexterity while wearing a tri-axial accelerometer on each wrist and on the sternum. The captured acceleration data were used to develop an automatic classification system for discriminating between healthy and HD participants and to automatically generate a continuous movement impairment score (MIS) that reflected the degree of the movement impairment. Data from 48 healthy and 44 HD participants was used to validate the developed system, which achieved 98.78% accuracy in discriminating between healthy and HD participants. The Pearson correlation coefficient between the automatic MIS and the clinician rated mULMS was 0.77 with a p-value < 0.01. The approach presented in this paper demonstrates the possibility of an automated objective, consistent, and sensitive assessment of the HD movement impairment.

Functional and structural plasticity following action observation training in multiple sclerosis

Background: Hand motor deficits contribute to multiple sclerosis (MS)-related disability. Action observation training (AOT) is promising to improve upper limb function in neurologic patients. Objectives: In this preliminary study, we investigated AOT effects on dominant-hand motor performance in MS patients with upper limb motor impairment and performed an explorative analysis of their anatomical and functional magnetic resonance imaging (MRI) substrates. Methods: In total, 46 healthy controls (HC) and 41 MS patients with dominant-hand motor impairment were randomized to AOT (HC-AOT = 23; MS-AOT = 20; watching daily-life action videos and execution) or control-training (HC-Control = 23; MS-Control = 21; watching landscapes videos and execution). Behavioral, structural, and functional (at rest and during object manipulation) MRI scans were acquired before and after a 2-week training. Results: After training, MS groups improved in right upper limb functions, mainly in AOT group (p from 0.02 to 0.0001). All groups showed regional increased and decreased gray matter volume, with specific AOT effects in fronto-temporal areas in MS-AOT (p < 0.001), without white matter (WM) integrity modifications. Increased and reduced recruitments of the action observation matching system and its connections in MS-AOT were found (p < 0.001). Motor improvements were correlated with volumetric and functional MRI modifications (r from −0.78 to 0.77, p < 0.001). Conclusion: The 10-day AOT promotes clinical improvements in MS patients through structural and functional modifications of the action observation matching system.

Activation of elbow extensors during passive stretch of flexors in patients with post-stroke spasticity

ObjectivesDeficits in regulation of tonic stretch reflex thresholds (TSRTs) after stroke occur in elbow flexors and extensors leading to spasticity in specific joint ranges. Threshold deregulation may also be responsible for other deficits such as abnormal activation of passively shortening muscles. Goals were to characterize activation of shortening elbow extensors during passive elbow flexor stretch in individuals with stroke, and identify its relationship to upper-limb motor impairment. MethodsThirty-three participants with unilateral stroke participated. TSRTs in elbow flexors were measured by stretching passive elbow flexors at different velocities. EMG responses were recorded from stretched agonist (biceps) and shortened antagonist (triceps) muscles. ResultsTriceps activation during passive biceps stretch occurred in all but 4 participants simultaneously with, before or after biceps activation onset. Biceps and triceps activation onsets and durations decreased with stretch velocity. Biceps TSRT and triceps activation magnitude did not correlate with sensorimotor impairment but greater stroke chronicity tended to be related to higher biceps TSRTs (r = 0.406, p = 0.041). ConclusionsStroke may result in both limitations in reciprocal inhibition and excessive agonist-antagonist co-activation, likely from deficits in TSRT modulation in both muscle groups. SignificanceSince both reciprocal inhibition and co-activation are fundamental to normal motor control, their cooperative action should be considered in designing interventions to increase the ranges of regulation of TSRTs in flexors and extensors to enhance upper limb functional recovery.

Dose-response relationship during motor learning with bimanual-to-unimanual training

Few options exist for training arm movements in patients with little active movement in their affected arm after a stroke. The purpose of this study was to test the efficacy of bimanual-to-unimanual training in reducing upper limb motor impairment and active movement in the affected arm, and to examine the effect of training dose on motor learning. Twenty subjects with chronic post-stroke hemiparesis underwent 6 weeks of usual care. They then received 12 one-hour sessions of bimanual-to-unimanual training using the Bimanual Arm Trainer (BAT, Mirrored Motion Works, Inc.). The training consisted of bimanual training of both arms followed by unimanual training of the affected arm alone. Some patients received the 12 sessions over 4 weeks, whereas others received it within 6 weeks. Extent of motor impairment on the Fugl-Meyer scale and active movement at upper limb joints was examined at baseline and pre- and post-training. The degree of improvement in the affected arm was computed both within and between training sessions as well as pre- and post-training. Repeated measures ANOVA was performed on the variables of interest. Bimanual-to-unimanual training led to a significant improvement in upper limb Fugl-Meyer scores and active movement compared with usual care ( P < 0.05). The difference was significantly greater in patients who underwent 12 sessions of training within 4 weeks compared with those who underwent training over 6 weeks. Changes in within and between session learning curves enable characterization of patterns of motor learning across individuals that can facilitate the development of algorithms for precision rehabilitation for post-stroke motor learning and recovery. Bimanual-to-unimanual arm training can reduce motor impairment in patients with chronic post-stroke hemiparesis. Higher frequency of training leads to greater improvements despite the same total dose. The study provides a means for understanding dosing of treatment for motor learning post-stroke.

Effect of intensive motor training with repetitive transcranial magnetic stimulation on upper limb motor function in chronic post-stroke patients with severe upper limb motor impairment

Background Intensive motor training with low-frequency repetitive transcranial magnetic stimulation (rTMS) has efficacy as a therapeutic method for motor dysfunction of the affected upper limb in patients with mild to moderate stroke. However, it is not clear whether this combination therapy has the same effect in chronic post-stroke patients with severe upper limb motor impairment.Objectives The aim of this study was to test the treatment effects of intensive motor training with low-frequency rTMS in chronic post-stroke patients with severe upper limb motor impairment.Methods A convenience sample of 26 chronic post-stroke patients with severe upper limb motor impairment participated in this study with the non-randomized, non-controlled clinical trial. All subjects were hospitalized to receive intensive motor training with low-frequency rTMS. During 2 weeks in which Sundays were excluded, a total of 24 sessions (2 sessions per day) of the intervention were conducted. The Fugl–Meyer Assessment (FMA) and Wolf Motor Function Test (WMFT) were used to assess motor impairment and function of the affected upper limb, respectively, before and after intervention. Paired t-test was used to analyze the effects of the intervention.Results The FMA total score and WMFT log performance time significantly improved from before to after intervention (FMA: 12.6–18.0; WMFT: 3.6–3.3, p < 0.001).Conclusions The present results suggest that intensive motor training with low-frequency rTMS could improve motor impairment in chronic post-stroke patients with severe upper limb motor impairment and contribute to the expansion of the application range of this combination therapy.