Hemiplegic Limb Synergies in Stroke Patients

Baseline robot-measured kinematic metrics predict discharge rehabilitation outcomes in individuals with subacute stroke

Background: The literature on upper limb robot-assisted therapy showed that robot-measured metrics can simultaneously predict registered clinical outcomes. However, only a limited number of studies correlated pre-treatment kinematics with discharge motor recovery. Given the importance of predicting rehabilitation outcomes for optimizing physical therapy, a predictive model for motor recovery that incorporates multidirectional indicators of a patient's upper limb abilities is needed. Objective: The aim of this study was to develop a predictive model for rehabilitation outcome at discharge (i.e., muscle strength assessed by the Motricity Index of the affected upper limb) based on multidirectional 2D robot-measured kinematics. Methods: Re-analysis of data from 66 subjects with subacute stroke who underwent upper limb robot-assisted therapy with an end-effector robot was performed. Two least squares error multiple linear regression models for outcome prediction were developed and differ in terms of validation procedure: the Split Sample Validation (SSV) model and the Leave-One-Out Cross-Validation (LOOCV) model. In both models, the outputs were the discharge Motricity Index of the affected upper limb and its sub-items assessing elbow flexion and shoulder abduction, while the inputs were the admission robot-measured metrics. Results: The extracted robot-measured features explained the 54% and 71% of the variance in clinical scores at discharge in the SSV and LOOCV validation procedures respectively. Normalized errors ranged from 22% to 35% in the SSV models and from 20% to 24% in the LOOCV models. In all models, the movement path error of the trajectories characterized by elbow flexion and shoulder extension was the significant predictor, and all correlations were significant. Conclusion: This study highlights that motor patterns assessed with multidirectional 2D robot-measured metrics are able to predict clinical evalutation of upper limb muscle strength and may be useful for clinicians to assess, manage, and program a more specific and appropriate rehabilitation in subacute stroke patients.

The Emergence of Stereotyped Kinematic Synergies when Mice Reach to Grasp Following Stroke

Reaching tasks are commonly used in preclinical and clinical studies to assess the acquisition of fine motor skills and recovery of function following stroke. These tasks are often used to assess functional deficits in the absence of quantifying the quality of movement which requires kinematic analysis. To meet this need, this study uses a kinematic analysis in mice performing the Montoya staircase task at 5 and 14 days following a cortical photothrombosis-induced stroke. Following stroke, the mice had reaching impairments associated with sustained deficits including longer, unsmooth, and less individuated paw trajectories. Two weeks after stroke we also detected the emergence of abnormal elbow and shoulder angles, flexion/extensions, and stereotyped kinematic synergies. These data suggest that proximal and distal segments acting in concert is paramount during post-stroke reaching and encourage further analysis of synergies within the translational pipeline of preclinical to clinical studies.

Dimensionality and item-difficulty hierarchy of the Fugl-Meyer assessment of the upper extremity among Japanese patients who have experienced stroke

Background: The Fugl-Meyer Assessment of the Upper Extremity (FMA-UE) has been used in many clinical studies and in stroke rehabilitation. In studies evaluating psychometric properties, confirmatory factor analysis (CFA) indicated that the FMA-UE is a multidimensional tool. Item Response Theory One-Parameter Logistic (IRT1PL) supports that item-difficulty hierarchy can be used as a treatment index of upper extremity function for stroke recovery. However, studies on the psychometric properties of the FMA-UE in Asian populations are lacking.Objectives: To investigate the dimensionality and item-difficulty hierarchy of the FMA-UE for stroke rehabilitation in Japanese patients. Methods: This was a cross-sectional study. The participants comprised 268 individuals admitted for de novo stroke (median age, 70.0 years; median days since stroke onset, 78.5) in 22 hospitals in Japan. The dimensionality of the FMA-UE was evaluated using CFA of selected items. The item-difficulty hierarchy of the FMA-UE using the appropriately selected model was demonstrated using IRT1PL analysis after confirming dimensionality.Results:Two reflex items were removed by utilizing the floor and ceiling effects. The 31- and 30-item FMA-UE exhibited a good model fit of the unidimensionality in the CFA. The 30-item FMA-UE was found to be a good model by model comparison (the 31-item vs. the 30-item). The item-difficulty hierarchy of the 30-item FMA-UE was found not to be consistent with the expected item order.Conclusions:This study provides evidence that the FMA-UE has multidimensionality and the 30-item FMA-UE is a valid instrument for measuring upper-extremity impairment after stroke.

The effect of mirror therapy on lower extremity motor function and ambulation in post-stroke patients: A prospective, randomized-controlled study

Objectives

This study aims to evaluate the effects of mirror therapy (MT) on lower extremity motor function and ambulation in post-stroke patients.

Patients and methods

A total of 42 post-stroke patients (25 males, 17 females; mean age 58 years; range, 32 to 71 years) were included. All patients were randomly divided into two groups as the control group (n=21) receiving a conventional rehabilitation program for four weeks (60 to 120 min/day for five days a week) and as the MT group (n=21) receiving MT for 30 min in each session in addition to the conventional rehabilitation program. The Brunnstrom stages of stroke recovery, Functional Independence Measure (FIM), Berg Balance Scale (BBS) and Motricity Index (MI) scores, six-minute walking test (6MWT), Functional Ambulation Category (FAC), and the degree of ankle plantar flexion spasticity using the Modified Ashworth Scale (MAS) were evaluated at baseline (Day 0), at post-treatment (Week 4), and eight weeks after the end of treatment (Week 12).

Results

There were significant differences in all parameters between the groups, except for the degree of ankle plantar flexion spasticity, and in all time points between Week 0 and 4 and between Week 0 and 12 (p<0.05).

Conclusion

These results suggest that MT in addition to conventional rehabilitation program yields a greater improvement in the lower extremity motor function and ambulation, which sustains for a short period of time after the treatment.

Comparison of Therapeutic Ultrasound and Radial Shock Wave Therapy in the Treatment of Plantar Flexor Spasticity After Stroke: A Prospective, Single-blind, Randomized Clinical Trial

BACKGROUND

This study aimed to compare the effects of therapeutic ultrasound (US) and radial extracorporeal shock wave therapy (rESWT) in the treatment of plantar flexor spasticity after stroke.

MATERIALS AND METHODS

In this prospective, single-blind, randomized clinical trial, 32 patients (age range 42-78 years; male 19) with stroke were randomly divided into two groups: The US group (n = 16) received the continuous ultrasound, intensity 1.5 w/cm², frequency 1 MHz, and duration 10 minutes. The rESWT group (n = 16) was treated with rESWT, 0.340 mJ/mm², 2000 shots. Both groups received the treatments for 1 session. The H-reflex tests of H_max/M_max ratio and H-reflex latency, the Modified Modified Ashworth Scale (MMAS), active range of motion (AROM), passive range of motion (PROM), passive plantar flexor torque (PPFT), and the timed "up and go" test (TUG) were blinded assessed at baseline (T0), immediately post-treatment (T1), and one hour follow-up (T2).

RESULTS

The H-reflex tests did not improve across the groups. However, the MMAS spasticity scores, AROM and PROM, PPFT, and TUG improved significantly within groups. The results found no significant differences between groups for all outcome measures.

CONCLUSIONS

The US and rESWT had similar effects, and the rESWT was not more effective than the US in improving ankle plantar flexor spasticity after stroke.

Determining Levels of Upper Extremity Movement Impairment by Applying a Cluster Analysis to the Fugl-Meyer Assessment of the Upper Extremity in Chronic Stroke

OBJECTIVE

To quantitatively determine levels of upper extremity movement impairment by using a cluster analysis of the Fugl-Meyer Assessment of the Upper Extremity (FMA-UE) with and without reflex items.

DESIGN

Secondary analysis.

SETTING

University and research centers.

PARTICIPANTS

Individuals (N=247) with chronic stroke (>6mo poststroke).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Cutoff scores defined by FMA-UE total scores of clusters identified by 2 hierarchical cluster analyses performed on the full sample of FMA-UE individual item scores (with and without reflexes). Patterns of motor function defined by aggregate item scores of clusters.

RESULTS

FMA-UE scores ranged from 2 to 63 (mean, 26.9±15.7) with reflex items and from 0 to 57 (mean, 22.1±15.3) without reflex items. Three clusters were identified. The distributions of the FMA-UE scores revealed considerable overlap between the clusters; therefore, 4 distinct stroke impairment levels were derived.

CONCLUSIONS

For chronic stroke, the cluster analysis of the FMA-UE supports either a 3- or a 4-impairment level classification scheme.

Motor recovery of stroke patients after rehabilitation: one-year follow-up study

Purpose To investigate motor recovery of stroke patients 1 year after rehabilitation. Materials and Methods A cross-sectional study of 192 stroke patients discharged from rehabilitation wards in nine tertiary hospitals was conducted. Motor recovery was assessed using the Brunnstrom motor recovery stages (BMRS), at 6 and 12 months after discharge. Factors related to the BMRS of the hand, arm and leg were analyzed. Results The mean age of patients was 62.2 years (57.3% male). Significantly more patients presented improvement of at least one BMRS of the hand, arm and leg compared with those with decreasing BMRS (p < 0.001). The percentage of patients with BMRS III- VI at 6 months was greater than that at discharge, but the recovery at 12 months was slightly higher than that at 6 months. It seems that motor recovery from stroke was near maximal at six months. Regarding the factors related to motor recovery, only lengths of stay (LOS) <30 d during the first admission and Barthel index at discharge ≥10 were related to the improvement of BMRS of the hand, arm and leg on multivariate analysis. Additionally, no complication at discharge was associated with the improvement of BMRS of the leg. Conclusions Approximately half of our stroke patients had motor improvement of at least one stage of BMRS at one year. Motor recovery after stroke at the end of the first year was associated with shorter LOS during the first admission, higher discharge Barthel index score and absence of complications at discharge.

Gait post-stroke: Pathophysiology and rehabilitation strategies

We reviewed neural control and biomechanical description of gait in both non-disabled and post-stroke subjects. In addition, we reviewed most of the gait rehabilitation strategies currently in use or in development and observed their principles in relation to recent pathophysiology of post-stroke gait. In both non-disabled and post-stroke subjects, motor control is organized on a task-oriented basis using a common set of a few muscle modules to simultaneously achieve body support, balance control, and forward progression during gait. Hemiparesis following stroke is due to disruption of descending neural pathways, usually with no direct lesion of the brainstem and cerebellar structures involved in motor automatic processes. Post-stroke, improvements of motor activities including standing and locomotion are variable but are typically characterized by a common postural behaviour which involves the unaffected side more for body support and balance control, likely in response to initial muscle weakness of the affected side. Various rehabilitation strategies are regularly used or in development, targeting muscle activity, postural and gait tasks, using more or less high-technology equipment. Reduced walking speed often improves with time and with various rehabilitation strategies, but asymmetric postural behaviour during standing and walking is often reinforced, maintained, or only transitorily decreased. This asymmetric compensatory postural behaviour appears to be robust, driven by support and balance tasks maintaining the predominant use of the unaffected side over the initially impaired affected side. Based on these elements, stroke rehabilitation including affected muscle strengthening and often stretching would first need to correct the postural asymmetric pattern by exploiting postural automatic processes in various particular motor tasks secondarily beneficial to gait.

Prediction of functional outcomes in stroke patients: the role of motor patterns according to limb synergies

BACKGROUND AND AIMS

To address the relationships among motor patterns evaluated according to the limb synergies and functional outcomes in stroke patients and clarify which motor pattern was the most important predictor of functional outcomes.

METHODS

The study was conducted on 208 patients with primary diagnosis of stroke admitted for in-hospital rehabilitation. At entry, the Fugl-Meyer Scale was administered to assess motor function according to limb synergies. Pearson's correlation was used to assess the relationship between variables, and backward stepwise regression analysis was used to identify the outcome determinants. Final functional independence measure (FIM) scores and length of in-hospital stay were the outcome measures.

RESULTS

At the end of rehabilitation, motor-FIM scores of patients with extensor and flexor synergies, mixing synergies, and no dependence from the synergies were higher than those of no movements and flexor synergy. Multivariate regression analysis showed that extensor synergy of upper limb was an independent predictor of final motor-FIM, personal care and mobility, extensor synergy of lower limb of locomotion, while mixing synergies of upper limb was an independent predictor of length of in-hospital stay.

CONCLUSIONS

In stroke rehabilitation, the patients' motor patterns according to the synergies strongly relate with functional outcomes and are important outcome predictors.

Transcranial direct current stimulation improves ipsilateral selective muscle activation in a frequency dependent manner

Failure to suppress antagonist muscles can lead to movement dysfunction, such as the abnormal muscle synergies often seen in the upper limb after stroke. A neurophysiological surrogate of upper limb synergies, the selectivity ratio (SR), can be determined from the ratio of biceps brachii (BB) motor evoked potentials to transcranial magnetic stimulation prior to forearm pronation versus elbow flexion. Surprisingly, cathodal transcranial direct current stimulation (c-TDCS) over ipsilateral primary motor cortex (M1) reduces (i.e. improves) the SR in healthy adults, and chronic stroke patients. The ability to suppress antagonist muscles may be exacerbated at high movement rates. The aim of the present study was to investigate whether the selective muscle activation of the biceps brachii (BB) is dependent on altering frequency demands, and whether the c-tDCS improvement of SR is dependent on task frequency. Seventeen healthy participants performed repetitive isometric elbow flexion and forearm pronation at three rates, before and after c-tDCS or sham delivered to ipsilateral left M1. Ipsilateral c-tDCS improved the SR in a frequency dependent manner by selectively suppressing BB antagonist excitability. Our findings confirm that c-tDCS is an effective tool for improving selective muscle activation, and provide novel evidence for its efficacy at rates of movement where it is most likely to benefit task performance.

Asymmetric training using virtual reality reflection equipment and the enhancement of upper limb function in stroke patients: a randomized controlled trial

BACKGROUND

Asymmetric movements with both hands contributed to the improvement of spatially coupled motion. Thus, the aim of this study was to investigate the effects of an asymmetric training program using virtual reality reflection equipment on upper limb function in stroke patients.

METHODS

Twenty-four stroke patients were randomly allocated to an experimental group (n=12) or a control group (n=12). Both groups participated in conventional physical therapy for 2×30 min/d, 5 d/wk, for 4 weeks. The experimental group also participated in an asymmetric training program using virtual reality reflection equipment, and the control group participated in a symmetric training program. Both asymmetric and symmetric programs were conducted for 30 min/d, 5 d/wk, for 4 weeks. To compare upper limb function before and after intervention, the Fugl-Meyer Assessment (FMA), the Box and Block Test (BBT), grip strength, range of motion (ROM), and spasticity were assessed.

RESULTS

Both groups showed significant increases in upper limb function, excepting spasticity, after intervention (P<.05, 1-way repeated-measures analysis of variance [ANOVA]). A significant group-time interaction was demonstrated only for shoulder/elbow/wrist items of FMA, BBT, grip strength, and ROM of wrist flexion, extension, and ulnar deviation (P<.05, 2-way repeated-measures ANOVA).

CONCLUSIONS

This study confirms that the asymmetric training program using virtual reality reflection equipment is an effective intervention method for improving upper limb function in stroke patients. We consider that an additional study based on a program using virtual reflection, which is more functional than performing simple tasks, and consisting of tasks relevant to the activities of daily living be conducted.

Impairment in task-specific modulation of muscle coordination correlates with the severity of hand impairment following stroke

Significant functional impairment of the hand is commonly observed in stroke survivors. Our previous studies suggested that the inability to modulate muscle coordination patterns according to task requirements may be substantial after stroke, but these limitations have not been examined directly. In this study, we aimed to characterize post-stroke impairment in the ability to modulate muscle coordination patterns across tasks and its correlation with hand impairment. Fourteen stroke survivors, divided into a group with severe hand impairment (8 subjects) and a group with moderate hand impairment (6 subjects) according to their clinical functionality score, participated in the experiment. Another four neurologically intact subjects participated in the experiment to serve as a point of comparison. Activation patterns of nine hand and wrist muscles were recorded using surface electromyography while the subjects performed six isometric tasks. Patterns of covariation in muscle activations across tasks, i.e., muscle modules, were extracted from the muscle activation data. Our results showed that the degree of reduction in the inter-task separation of the multi-muscle activation patterns was indicative of the clinical functionality score of the subjects (mean value = 26.2 for severely impaired subjects, 38.1 for moderately impaired subjects). The values for moderately impaired subjects were much closer to those of the impaired subjects (mean value = 46.1). The number of muscle modules extracted from the muscle activation patterns of a subject across six tasks, which represents the degree of motor complexity, was found to be correlated with the clinical functionality score (R = 0.68). Greater impairment was also associated with a change in the muscle module patterns themselves, with greater muscle coactivation. A substantial reduction in the degrees-of-freedom of the multi-muscle coordination post-stroke was apparent, and the extent of the reduction, assessed by the stated metrics, was strongly associated with the level of clinical impairment.

Virtual walking training program using a real-world video recording for patients with chronic stroke: a pilot study

OBJECTIVE

The purpose of this study was to investigate the effectiveness of the virtual walking training program using a real-world video recording on walking balance and spatiotemporal gait parameters in patients with chronic stroke.

DESIGN

Fourteen patients with chronic stroke were randomly assigned to either the experimental group (n = 7) or the control group (n = 7). The subjects in both groups underwent a standard rehabilitation program; in addition, the experimental group participated in the virtual walking training program using a real-world video recording for 30 mins a day, three times a week, for 6 wks, and the control group participated in treadmill gait training for 30 mins a day, three times a week, for 6 wks. Walking balance was measured using the Berg Balance Scale (BBS) and the Timed Up and Go test. Gait performance was measured using an electrical walkway system.

RESULTS

In walking balance, greater improvement on the Berg Balance Scale (experimental group: 4.14 vs. control group: 1.85) and the Timed Up and Go test (-2.25 vs. -0.94) was observed in the experimental group compared with the control group (P <; 0.05). In the spatiotemporal gait parameters, greater improvement on velocity (25.40 vs. 9.74) and cadence (26.71 vs. 11.11) was observed in the experimental group compared with the control group (P <; 0.05).

CONCLUSIONS

This study demonstrated the positive effects of the virtual walking training program using a real-world video recording on gait performance. These findings suggest that the virtual walking training program using a real-world video recording may be a valid approach to enhance gait performance in patients with chronic stroke.

Spasticity after stroke: an overview of prevalence, test instruments, and treatments

The objective of this study was to present an overview of the prevalence of spasticity after stroke as well as of test instruments and treatments. Recent studies show that spasticity occurs in 20%-30% of all stroke victims and in less than half of those with pareses. Although spasticity may occur in paretic patients after stroke, muscle weakness is more likely to be the reason for the pareses. Spasticity after stroke is more common in the upper than the lower limbs, and it seems to be more common among younger than older people. To determine the nature of passive stretch, electromyographic equipment is needed. However, the Modified Ashworth Scale, which measures the sum of the biomechanical and neural components in passive stretch, is the most common instrument used to grade spasticity after stroke. Treatment of spasticity with physiotherapy is recommended, although its beneficial effect is uncertain. The treatment of spasticity with botulinum toxin in combination with physiotherapy is suggested to improve functioning in patients with severe spasticity. A task-specific approach rather than a neurodevelopmental approach in assessing and treating a patient with spasticity after stroke seems to be preferred.

Towards more effective robotic gait training for stroke rehabilitation: a review

Background

Stroke is the most common cause of disability in the developed world and can severely degrade walking function. Robot-driven gait therapy can provide assistance to patients during training and offers a number of advantages over other forms of therapy. These potential benefits do not, however, seem to have been fully realised as of yet in clinical practice.

Objectives

This review determines ways in which robot-driven gait technology could be improved in order to achieve better outcomes in gait rehabilitation.

Methods

The literature on gait impairments caused by stroke is reviewed, followed by research detailing the different pathways to recovery. The outcomes of clinical trials investigating robot-driven gait therapy are then examined. Finally, an analysis of the literature focused on the technical features of the robot-based devices is presented. This review thus combines both clinical and technical aspects in order to determine the routes by which robot-driven gait therapy could be further developed.

Conclusions

Active subject participation in robot-driven gait therapy is vital to many of the potential recovery pathways and is therefore an important feature of gait training. Higher levels of subject participation and challenge could be promoted through designs with a high emphasis on robotic transparency and sufficient degrees of freedom to allow other aspects of gait such as balance to be incorporated.

The loss of dexterity in the bilateral lower extremities in patients with stroke

The aim of this study was to examine the dexterity of both lower extremities in patients with stroke. Twenty patients with stroke and 20 age-matched control subjects participated in this study. To determine the dexterity of the lower extremities, we examined the ability to control muscle force during submaximal contractions in the knee extensor muscles using a force tracking task. The root mean square errors were calculated from the difference between the target and response force. The root mean square error was significantly greater in the affected limb of patients with stroke compared with those of the unaffected limb and the control subjects, and in the unaffected limb compared with that of the control subjects. Furthermore, the root mean square error of the affected limb was related significantly to motor function as determined by Fugl-Myer assessment. These results demonstrate impairment of the dexterity of both the affected and the unaffected lower extremities in patients with stroke.

An explorative, cross-sectional study into abnormal muscular coupling during reach in chronic stroke patients

Background

In many stroke patients arm function is limited, which can be related to an abnormal coupling between shoulder and elbow joints. The extent to which this can be translated to activities of daily life (ADL), in terms of muscle activation during ADL-like movements, is rather unknown. Therefore, the present study examined the occurrence of abnormal coupling on functional, ADL-like reaching movements of chronic stroke patients by comparison with healthy persons.

Methods

Upward multi-joint reaching movements (20 repetitions at a self-selected speed to resemble ADL) were compared in two conditions: once facilitated by arm weight compensation and once resisted to provoke a potential abnormal coupling. Changes in movement performance (joint angles) and muscle activation (amplitude of activity and co-activation) between conditions were compared between healthy persons and stroke patients using a repeated measures ANOVA.

Results

The present study showed slight changes in joint excursion and muscle activation of stroke patients due to shoulder elevation resistance during functional reach. Remarkably, in healthy persons similar changes were observed. Even the results of a sub-group of the more impaired stroke patients did not point to an abnormal coupling between shoulder elevation and elbow flexion during functional reach.

Conclusions

The present findings suggest that in mildly and moderately affected chronic stroke patients ADL-like arm movements are not substantially affected by abnormal synergistic coupling. In this case, it is implied that other major contributors to limitations in functional use of the arm should be identified and targeted individually in rehabilitation, to improve use of the arm in activities of daily living.

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, H(max)/M(max) 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.

Brunnstrom recovery stage and motricity index for the evaluation of upper extremity in stroke: analysis for correlation and responsiveness

The aim of this study was to find out first whether Brunnstrom recovery stage (BRS) and motricity index (MI) were correlated with each other and second to observe whether the two assessment tools were sensitive to changes regarding the rehabilitation outcome. Forty-six stroke patients who were admitted to the Stroke Rehabilitation Unit at our Rehabilitation Centre were recruited. All measurements were made within the first 72 h of admission and on the last day of discharge. A physiotherapist performed all MI evaluations and a physiatrist blind to the results performed all BRS evaluations. Both upper extremity (UE) and hand BRS scores were found to be positively correlated with those of UE-MI; moreover, correlations between the discharge values were stronger than those between the admission values. The responsiveness of both the total scores of the BRS and UE-MI were strong (effect size d = 0.97, Wilcoxon Z=5.33, P<0.001 for the UE-BRS; d=0.81, Z=5.09, P<0.001 for the hand BRS; d=0.91, Z=5.45, P<0.001 for the UE-MI). BRS and MI scores were found to be increased on discharge when compared with those of admission and the differences in between were statistically significant (P<0.001). BRS and MI seem to be well correlated and responsive concerning the evaluation of UEs in early stage stroke patients. Being convenient tests, they may easily be applied repetitively for close follow-up during rehabilitation.

A mathematical approach to the mechanical capabilities of limbs and fingers

Neuromuscular function is the interaction between the nervous system and the physical world. Limbs and fingers are, therefore, the ultimate mechanical filters between the motor commands that the nervous system issues and the physical actions that result. In this chapter we present a mathematical approach to understanding how their anatomy (i.e., physical structure) defines their mechanical capabilities. We call them "mechanical filters" because they attenuate, amplify, and transform neural signals into mechanical output. We explicitly distinguish between limbs and fingers because their subtle anatomical differences have profound effects on their mechanical properties. Our main message is that many aspects of neuromuscular function such as co-contraction, posture selection, muscle redundancy, optimality of motor command, are fundamentally affected (if not defined) by the physical structure of limbs and fingers. We attempt to present the fundamental filtering properties of limbs and fingers in a unified manner to allow for a direct and useful application of powerful mathematical concepts to the study of neuromuscular function. Every researcher of motor control is well advised to consider these filtering properties to properly understand the co-evolution and synergistic interactions between brain and body. At the end of the day, every inquiry in neuromuscular function can be reduced to the fundamental question whether and how the nervous system can perform the necessary sensorimotor functions to exploit and reach the mechanical capabilities of limbs and fingers.

Intrinsic muscle strength and voluntary activation of both lower limbs and functional performance after stroke

The objective of this study was to assess the nature of muscle weakness in both legs after stroke compared with able-bodied control individuals and to examine whether there is a relationship between the degree of muscle weakness and coactivation of knee extensors and flexors as well as voluntary activation capacity of knee extensors of both paretic and non-paretic legs and indices of functional performance. Maximal voluntary isometric torques of knee extensors (MVCe) and flexors (MVCf) were determined in 14 patients (bilaterally) and 12 able-bodied controls. Simultaneous measurements were made of torque and surface EMG from agonist and antagonist muscles. Coactivation was calculated. Supramaximal triplets were evoked with electrical stimulation to estimate maximal torque capacity and degree of voluntary activation of knee extensors. MVCs, activation and coactivation parameters were correlated to scores of seven functional performance tests. MVCe, MVCf and voluntary activation were lower in paretic lower limb (PL) compared with both non-paretic lower limb (NL) and control. Besides, all these parameters of NL were also lower than control. Electrically evoked torque capacity of knee extensors of PL was about 60% of both NL and control, which were not significantly different from each other. Strong significant correlations between strength, as well as voluntary activation, and functional performance were found. Coactivation did not correlate well with functional performance. Thus, whereas for NL activation failure can explain weakness, for PL both activation failure and reduced intrinsic torque capacity are responsible for the severe weakness. Activation capacity and muscle strength correlated strongly to functional performance, while coactivation did not.

Systematic review of progressive strength training in children and adolescents with cerebral palsy who are ambulatory

PURPOSE

To capture and analyze the evidence concerning the effects of progressive strength training on function and gait in children and adolescents with cerebral palsy (CP) who are ambulatory.

METHOD

A language-inclusive search was conducted for controlled or noncontrolled studies of strength training for subjects with CP who were ambulatory and aged 4 to 20 years, using objective outcome measures. Quality was assessed with the Maastricht-Amsterdam List. Data were extracted and analyzed.

RESULTS

The 13 included articles favored treatment without significant adverse effects. Function and gait improved more following isotonic rather than isokinetic training, and in younger rather than older subjects.

CONCLUSIONS

Function and gait improvements were greater in preadolescents.

Shoulder abduction-induced reductions in reaching work area following hemiparetic stroke: neuroscientific implications

A stroke-related loss of corticospinal and corticobulbar pathways is postulated to result in an increased use of remaining neural substrates such as bulbospinal pathways as individuals with stroke are required to generate greater volitional shoulder abduction torques. The effect of shoulder abduction on upper extremity reaching range of motion (work area) was measured in 18 individuals with stroke using the Arm Coordination Training 3-D (ACT(3D)) device. This robotic system is capable of quantifying movement kinematics when a subject attempts to reach while simultaneously generating various levels of active shoulder abduction torque. We have provided data demonstrating an incremental increase of abnormal coupling of elbow flexion for greater levels of shoulder abduction in the paretic limb that results in a reduction in available work area as a function of active limb support. The progressive increase in the expression of abnormal shoulder/elbow coupling can be explained by a progressive reliance on the indirect cortico-bulbospinal connections that remain in individuals following a stroke-induced brain injury.

Dimensionality and Construct Validity of the Fugl-Meyer Assessment of the Upper Extremity

OBJECTIVE

To investigate the dimensionality and construct validity of the Fugl-Meyer Assessment of the upper extremity by using Rasch analysis.

DESIGN

Secondary analysis of pooled data from 2 existing datasets: a randomized therapeutic exercise clinical trial and a cohort longitudinal study of stroke recovery.

SETTING

University research center.

PARTICIPANTS

A total of 512 subjects, ages 69.8+/-11.1 years, who were 0 to 145 days poststroke.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Dimensionality was examined with principal components analysis and Rasch item-fit statistics. The Rasch-derived item hierarchy was examined for consistency with the expected course of poststroke upper-extremity recovery suggested by the reflex-hierarchical conceptual model underlying the assessment.

RESULTS

Factor loadings and item infit statistics suggested that the 3 reflex items were empirically disconnected from other assessment items. The reflex items were removed. The modified 30-item assessment showed a unidimensional structure. The Rasch-item-difficulty order was not consistent with the expected item order.

CONCLUSIONS

The items testing resting-state reflexes may threaten the assessment's dimensionality. With reflex items removed, the assessment is a unidimensional measure of volitional movement. The Rasch-generated item-difficulty order challenges the hierarchical structure implied by the instrument's underlying conceptual framework.

Knee Muscle Strength, Gait Performance, and Perceived Participation After Stroke

OBJECTIVE

To assess the relation between knee muscle strength, gait performance, and perceived participation in subjects with chronic mild to moderate poststroke hemiparesis.

DESIGN

Descriptive analysis of convenience sample.

SETTING

University hospital.

PARTICIPANTS

Fifty men and women (mean age, 58+/-6.4y) 6 to 46 months poststroke.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Isokinetic concentric knee extension and flexion strength was measured at 60 degrees /s. Gait performance was assessed by Timed Up & Go, comfortable and fast gait speed, stair climbing ascend and descend, and 6-minute walk test. Perceived participation was assessed with the Stroke Impact Scale.

RESULTS

There was a significant correlation (P < .01) between knee muscle strength and gait performance for the paretic but not for the nonparetic lower limb. Strength for the paretic limb explained 34% to 50% of the variance in gait performance; the addition of strength for the nonparetic limb explained at most a further 11% of the variance in gait performance. There was a significant correlation (P < .01) between gait performance and perceived participation; gait performance explained 28% to 40% of the variance in perceived participation.

CONCLUSIONS

Knee muscle strength is a moderate to strong predictor of walking ability in individuals with chronic mild to moderate poststroke hemiparesis. Walking ability influences perceived participation, but the strengths of the relations indicate that other factors are also important.