Development of an integrated conceptual model of multiple sclerosis spasticity.

PURPOSE: Spasticity is common in multiple sclerosis (MS), often leading to functional limitations and disability. We developed a conceptual model of spasticity in MS integrating expert opinion, recent literature, and experiences of clinicians and people with MS spasticity. METHODS: A conceptual model was developed based on a targeted literature review of articles published between 2014 and 2019, followed by input from clinicians, then input from participants with MS spasticity. Multidisciplinary experts on spasticity provided guidance at each step. RESULTS: Key concepts of the integrated spasticity conceptual model included: moderators; triggers; modifiers; treatment; objective manifestations; subjective experience; physical, functional, social, and emotional/psychological impacts; and long-term consequences. Participants with MS spasticity most frequently endorsed spasms, tightness, and pain as descriptors of spasticity. Some participants with MS spasticity had difficulty distinguishing spasticity from other MS symptoms (e.g. muscle weakness). Some triggers, emotional/psychological impacts, and long-term consequences of spasticity reported by participants with MS spasticity were not previously identified in the published literature. CONCLUSIONS: This conceptual model of spasticity, integrating published literature with the experience of clinicians, people with MS spasticity, and experts, demonstrates the complex, multidimensional nature of MS spasticity. This model may be used to improve clinician-patient dialogue, research, and patient care.

Many people with multiple sclerosis (MS) have spasticity, generally in the lower limbs, but this symptom is complex and multidimensional and therefore difficult to characterize.MS spasticity may be influenced by moderators, triggers, modifiers, and treatment, all of which can affect objective measures and the subjective experience of spasticity.MS spasticity can have physical, functional, social, and emotional/psychological impacts as well as long-term consequences that can affect rehabilitation and ultimately reduce health-related quality of life for people with MS.Given that people with MS may view spasticity differently than their rehabilitation providers, providers should ask patients about their spasticity, including their moderators, triggers, modifiers, experience, impacts, long-term consequences, and effects on quality of life.This conceptual model provides a framework to improve clinician-patient dialogue, research, and rehabilitation for MS spasticity.

Gait asymmetry, and bilateral coordination of gait during a six-minute walk test in persons with multiple sclerosis.

Gait impairments in persons with multiple sclerosis (pwMS) leading to decreased ambulation and reduced walking endurance remain poorly understood. Our objective was to assess gait asymmetry (GA) and bilateral coordination of gait (BCG), among pwMS during the six-minute walk test (6MWT), and determine their association with disease severity. We recruited 92 pwMS (age: 46.6 ± 7.9; 83% females) with a range of clinical disability, who completed the 6MWT wearing gait analysis system. GA was assessed by comparing left and right swing times, and BCG was assessed by the phase coordination index (PCI). Several functional and subjective gait assessments were performed. Results show that gait is more asymmetric and less coordinated as the disease progresses (p < 0.0001). Participants with mild MS showed significantly better BCG as reflected by lower PCI values in comparison to the other two MS severity groups (severe: p = 0.001, moderate: p = 0.02). GA and PCI also deteriorated significantly each minute during the 6MWT (p < 0.0001). GA and PCI (i.e., BCG) show weaker associations with clinical MS status than associations observed between functional and subjective gait assessments and MS status. Similar to other neurological cohorts, GA and PCI may be important parameters to assess and target in interventions among pwMS.

Turning is an important marker of balance confidence and walking limitation in persons with multiple sclerosis.

The standard functional tool for gait assessment in multiple sclerosis (MS) clinical trials has been the 25-Foot Timed Walk Test, a measure of gait speed. Straight-line gait assessment may not reflect adequately upon balance and coordination. Walking tests with turns may add additional information towards understanding gait and balance status, and be more reflective of ambulation in the community. Understanding the impact of turn parameters on patient-reported outcomes of balance and walking would help MS clinicians better formulate treatment plans for persons with gait limitations. In this study, ninety-one persons with MS (Expanded Disability Status Score; EDSS, range: 0-6.5) were enrolled in an initial cross-sectional study. Twenty-four subjects (EDSS, range:1.0-6.0) completed a follow-up visit an average of 12 months later. Spatiotemporal gait analysis was collected at both visits using APDM Opal wireless body-worn sensors while performing the Timed-Up-and-Go (TUG) and 6-Minute Walk Test (6MWT). For both cross-sectional and longitudinal data, regression analyses determined the impact on the addition of turning parameters to stride velocity (SV), in the prediction of self-reported balance confidence (Activities-Specific Balance Confidence Scale (ABC)) and walking limitation (12-item Multiple Sclerosis Walking Scale (MSWS-12)). The addition of 6MWT peak turn velocity (PTV) to 6MWT SV increased the predictive power of the 6MWT for the ABC from 20% to 33%, and increased the predictive power from 28% to 41% for the MSWS-12. TUG PTV added to TUG SV also strengthened the relationship of the TUG for the ABC from 19% to 28%, and 27% to 36% for the MSWS-12. For those with 1 year follow-up, percent change in turn number of steps (TNS%Δ) during the 6MWT added to 6MWT SV%Δ improved the modeling of ABC%Δ from 24% to 33%. 6MWT PTV%Δ added to 6MWT SV%Δ increased the predictive power of MSWS-12%Δ from 8% to 27%. Conclusively, turn parameters improved modeling of self-perceived balance confidence and walking limitations when added to the commonly utilized measure of gait speed. Tests of longer durations with multiple turns, as opposed to shorter durations with a single turn, modeled longitudinal change more accurately. Turn speed and stability should be qualitatively assessed during the clinic visit, and use of multi-faceted tests such as the TUG or 6MWT may be required to fully understand gait deterioration in persons with MS.

Exploring the feasibility and acceptability of sensor monitoring of gait and falls in the homes of persons with multiple sclerosis.

Gait parameters variability and falls are problems for persons with MS and have not been adequately captured in the home. Our goal was to explore the feasibility and acceptability of monitoring of gait and falls in the homes of persons with MS over a period of 30 days. To test the feasibility of measuring gait and falls for 30days in the home of persons with MS, spatiotemporal gait parameters stride length, stride time, and gait speed were compared. A 3D infrared depth imaging system has been developed to objectively measure gait and falls in the home environment. Participants also completed a 16-foot GaitRite electronic pathway walk to validate spatiotemporal parameters of gait (gait speed (cm/s), stride length (cm), and gait cycle time(s)) during the timed 25 foot walking test (T25FWT). We also documented barriers to feasibility of installing the in-home sensors for these participants. The results of the study suggest that the Kinect sensor may be used as an alternative device to measure gait for persons with MS, depending on the desired accuracy level. Ultimately, using in-home sensors to analyze gait parameters in real time is feasible and could lead to better analysis of gait in persons with MS.

Prevalence of Walking-Related Motor Fatigue in Persons With Multiple Sclerosis: Decline in Walking Distance Induced by the 6-Minute Walk Test.

OBJECTIVE: To investigate the individual occurrence of walking-related motor fatigue in persons with multiple sclerosis (PwMS), according to disability level and disease phenotype.Study design This was a cross-sectional, multinational study.Participants They were 208 PwMS from 11 centers with Expanded Disability Status Scale (EDSS) scores up to 6.5. METHODS: The percentage change in distance walked (distance walked index, DWI) was calculated between minute 6 and 1 (DWI(6-1)) of the 6-Minute Walk Test (6MWT). Its magnitude was used to classify participants into 4 subgroups: (1) DWI(6-1)[≥5%], (2) DWI(6-1)[5%; -5%], (3) DWI(6-1)[-5%; > -15%], and (4) DWI(6-1)[≤-15%]. The latter group was labeled as having walking-related motor fatigue. PwMS were stratified into 5 subgroups based on the EDSS (0-2.5, 3-4, 4.5-5.5, 6, 6.5) and 3 subgroups based on MS phenotype (relapsing remitting [RR], primary progressive [PP], and secondary progressive [SP]). RESULTS: The DWI6-1was ≥5% in 16 PwMS (7.7%), between 5% and -5% in 70 PwMS (33.6%), between -5% and -15% in 58 PwMS (24%), and ≤-15% in 64 PwMS (30.8%). The prevalence of walking-related motor fatigue (DWI(6-1)[≤-15%]) was significantly higher among the progressive phenotype (PP = 50% and SP = 39%; RR = 15.6%) and PwMS with higher disability level (EDSS 4.5-5.5 = 48.3%, 6 = 46.3% and 6.5 = 51.5%, compared with EDSS 0-2.5 = 7.8% and 3-4 = 16.7%;P< .05). Stepwise multiple regression analysis indicated that EDSS, but not MS phenotype, explained a significant part of the variance in DWI(6-1)(R(2)= 0.086;P< .001). CONCLUSION: More than one-third of PwMS showed walking-related motor fatigue during the 6MWT, with its prevalence greatest in more disabled persons (up to 51%) and in those with progressive MS phenotype (up to 50%). Identification of walking-related motor fatigue may lead to better-tailored interventions.

Dynamometer-based measure of spasticity confirms limited association between plantarflexor spasticity and walking function in persons with multiple sclerosis.

The literature shows inconsistent evidence regarding the association between clinically assessed plantar-flexor (PF) spasticity and walking function in ambulatory persons with multiple sclerosis (pwMS). The use of a dynamometer-based spasticity measure (DSM) may help to clarify this association. Our cohort included 42 pwMS (27 female, 15 male; age: 42.9 +/- 10.1 yr) with mild clinical disability (Expanded Disability Status Scale score: 3.6 +/- 1.6). PF spasticity was assessed using a clinical measure, the modified Ashworth Scale (MAS), and an instrumented measure, the DSM. Walking function was assessed by the timed 25-foot walk test (T25FWT), the 6-minute walk test (6MWT), and the 12-item Multiple Sclerosis Walking Scale (MSWS-12). Spearman rho correlations were used to evaluate relationships between spasticity measures, measures of walking speed and endurance, and self-perceived limitations in walking. The correlation was small between PF spasticity and the T25FWT (PF maximum [Max] MAS rho = 0.27, PF Max DSM rho = 0.26), the 6MWT (PF Max MAS rho = -0.20, PF Max DSM rho = -0.21), and the MSWS-12 (PF Max MAS rho = 0.11, PF Max DSM rho = 0.26). Our results are similar to reports in other neurologic clinical populations, wherein spasticity has a limited association with walking dysfunction.

Does dance-based therapy increase gait speed in older adults with chronic lower extremity pain: a feasibility study.

A decreased gait speed in older adults can lead to dependency when the individuals are no longer able to participate in activities or do things for themselves. Thirty-seven senior apartment residents (31 females; Mean age=80.6 years; SD=8.9) with lower extremity pain/stiffness participated in a feasibility and preliminary efficacy study of 12 weeks (24 sessions). Healthy-Steps dance therapy compared to a wait-list control group. Small improvements in gait speed ([ES]=0.33) were noted for participants completing 19-24 dance sessions. Improvements in gait speed measured by a 10 Meter Walk Test (0.0517 m/s) exceeded 0.05 m/s, a value deemed to be meaningful in community dwelling older adults. These feasibility study findings support the need for additional research using dance-based therapy for older adults with lower extremity pain.

Plantarflexor weakness negatively impacts walking in persons with multiple sclerosis more than plantarflexor spasticity.

OBJECTIVES: To determine whether plantarflexor (PF) spasticity or ankle strength best predicts variance in walking capacity or self-perceived limitations in walking in persons with multiple sclerosis (MS) and whether persons with MS with PF spasticity are weaker and have greater walking dysfunction than do persons with MS without PF spasticity. DESIGN: Cross-sectional study. SETTING: University research laboratory. PARTICIPANTS: Forty-two adults with MS (mean age, 42.9±10.1y; Expanded Disability Status Scale score, median=3.0, range=0-6) and 14 adults without disability (mean age, 41.9±10.1y). INTERVENTION: Not applicable. MAIN OUTCOME MEASURES: PF spasticity and dorsiflexion and PF maximum voluntary isometric torque were assessed using the modified Ashworth Scale and a computerized dynamometer, respectively. The Timed 25-Foot Walk Test was the primary outcome measure of walking capacity. Secondary measures included the 6-Minute Walk Test and the 12-item Multiple Sclerosis Walking Scale. RESULTS: PF strength was the most consistent predictor of variance in walking capacity (Timed 25-Foot Walk Test: R(2) change=.23-.29, P≤.001; 6-Minute Walk Test: R(2) change=.12-.29, P≤.012), and self-perceived limitations of walking (12-item Multiple Sclerosis Walking Scale: R(2) change=.04-.14, P<.18). There were no significant differences (P>.05) between persons with MS with PF spasticity and persons with MS without PF spasticity for any of the outcome measures. CONCLUSIONS: Our study suggests a unique contribution of PF weakness to walking dysfunction in persons with MS, and highlights the importance of evaluating PF strength in this clinical population.

2nd International Symposium on Gait and Balance in Multiple Sclerosis: interventions for gait and balance in MS.

PURPOSE: To provide a review of the 2nd International Symposium on Gait and Balance in Multiple Sclerosis (MS), emphasizing interventions in gait and balance for people with MS. METHOD: Review of current research on interventions used with people having MS and with people having other disorders that may provide novel insights into improving gait and balance and preventing falls in people with MS (pwMS). RESULTS: Nine speakers provided evidence-based recommendations for interventions aimed at improving gait and balance dysfunction. Speaker recommendations covered the following areas: balance rehabilitation, self-management, medications, functional electrical stimulation, robotics, sensory augmentation, gait training with error feedback and fall prevention. CONCLUSIONS: The causes of gait and balance dysfunction in pwMS are multifactorial and therefore may benefit from a wide range of interventions. The symposium provides avenues for exchange of evidence and clinical experience that is critical in furthering physical rehabilitation including gait and balance dysfunction in MS. Implications for Rehabilitation Approaches to improve Gait and Balance dysfunction in Multiple Sclerosis. Balance exercises that include training of sensory strategies. Self-management and self-management support. Pharmacologic intervention, such as Dalfampradine. Functional electrical stimulation that may provide the extra stimulation to influence coordinated leg movements needed for walking.

Spinal cord tract diffusion tensor imaging reveals disability substrate in demyelinating disease.

OBJECTIVE: This study assessed the tissue integrity of major cervical cord tracts by using diffusion tensor imaging (DTI) to determine the relationship with specific clinical functions carried by those tracts. METHODS: This was a cross-sectional study of 37 patients with multiple sclerosis or neuromyelitis optica with remote cervical cord disease. Finger vibratory thresholds, 25-foot timed walk (25FTW), 9-hole peg test (9HPT), and Expanded Disability Status Scale were determined. DTI covered cervical regions C1 through C6 with 17 5-mm slices (0.9 × 0.9 mm in-plane resolution). Regions of interest included posterior columns (PCs) and lateral corticospinal tracts (CSTs). Hierarchical linear mixed-effect modeling included covariates of disease subtype (multiple sclerosis vs neuromyelitis optica), disease duration, and sex. RESULTS: Vibration thresholds were associated with radial diffusivity (RD) and fractional anisotropy (FA) in the PCs (both p < 0.01), but not CSTs (RD, p = 0.29; FA, p = 0.14). RD and FA in PCs, and RD in CSTs were related to 9HPT (each p < 0.0001). 25FTW was associated with RD and FA in PCs (p < 0.0001) and RD in CSTs (p = 0.008). Expanded Disability Status Scale was related to RD and FA in PCs and CSTs (p < 0.0001). Moderate/severe impairments in 9HPT (p = 0.006) and 25FTW (p = 0.017) were more likely to show combined moderate/severe tissue injury within both PCs and CSTs by DTI. CONCLUSIONS: DTI can serve as an imaging biomarker of spinal cord tissue injury at the tract level. RD and FA demonstrate strong and consistent relationships with clinical outcomes, specific to the clinical modality.

Four Square Step Test in ambulant persons with multiple sclerosis: validity, reliability, and responsiveness.

The aim of this study was to establish the concurrent validity and relative and absolute reliability, define the minimal detectable change, and evaluate the floor and ceiling effects of the Four Square Step Test (FSST) in ambulant persons with multiple sclerosis (pwMS). Twenty-five pwMS performed the FSST on two occasions, 8.1±4.1 days apart. During the first testing, session participants also reported their fall history, performed the Berg Balance Scale, Dynamic Gait Index, and completed the Activities-Specific Balance Confidence Scale. Performance on the FSST was significantly (P<0.001) and strongly associated with performance on the Berg Balance Scale (rs=-0.84), Dynamic Gait Index (rs=-0.81), and Activities-Specific Balance Confidence Scale (rs=-0.78). Relative reliability of the FSST was excellent (ICC2,1=0.922). The minimal detectable change estimate for the FSST was 4.6 s. The FSST is a valid and reliable measure of dynamic standing balance in ambulant pwMS. However, because a substantial change (43%) is required to demonstrate a real change in individual performance, the FSST is unlikely to be sensitive in detecting longitudinal change in dynamic standing balance.

An evaluation of the Wolf Motor Function Test in motor trials early after stroke.

OBJECTIVE: To examine the internal consistency, validity, responsiveness, and advantages of the Wolf Motor Function Test (WMFT) and compare these results to the Action Research Arm Test (ARAT) in participants with mild to moderate hemiparesis within the first few months after stroke. DESIGN: Data were collected as part of the Very Early Constraint-Induced Therapy for Recovery from Stroke (VECTORS) trial, an acute, single-blind randomized controlled trial of constraint-induced movement therapy. Subjects were studied at baseline (day 0), after treatment (day 14), and after 90 days (day 90) poststroke. SETTING: Inpatient rehabilitation hospital; follow-up 3 months poststroke. PARTICIPANTS: Hemiparetic subjects (N=51) enrolled in the VECTORS trial. INTERVENTION: None. MAIN OUTCOME MEASURES: At each time point, subjects were tested on (1) the WMFT and ARAT, (2) clinical measures of sensorimotor impairments, (3) reach and grasp movements performed in the kinematics laboratory, and (4) clinical measures of disability. Blinded raters performed all evaluations. Analyses at each time point included calculating effect size as indicators of responsiveness, and correlation analyses to examine relationships between WMFT scores and other measures. RESULTS: The WMFT is internally consistent, valid, and responsive in the early stages of stroke recovery. Sensorimotor and kinematic measures of reach and grasp support the construct validity of the WMFT. CONCLUSIONS: In an acute stroke population, the WMFT has acceptable reliability, validity, and responsiveness to change over time. However, when compared with the ARAT, the higher training and testing burdens may not be offset by the relatively small psychometric advantages.

Assessing the gap between current movement ability and preferred movement ability as a measure of disability.

BACKGROUND: If disability is the gap between what an individual can do and what that individual would like to be able to do, then measures that assess only current ability fall short of describing the impact of disability on the individual. OBJECTIVE: The aim of this study was to examine a potential measure of disability, the gap between current movement ability and preferred movement ability, as recorded with the Movement Ability Measure (MAM). This investigation was performed by establishing the relationship between self-perceived current ability and other measures and examining the evidence of convergence or divergence between the gap and other measures. DESIGN: This investigation was a descriptive study. METHODS: Thirty people who had multiple sclerosis and were ambulatory completed the MAM and 18 other measures of bodily function, activity, and participation. Item response theory methods were used to generate logit estimates of average current movement ability and separate abilities in the 6 dimensions of movement on the MAM. Pearson correlations were calculated between estimated abilities from the MAM and scores from measures expected to be associated with these estimated abilities, as well as between the MAM and additional measures in exploratory analyses of relationships. RESULTS: The average current ability and the separate dimensions correlated moderately to strongly (.5-.8) with many of the measures expected to be related and showed additional moderately strong correlations in exploratory analyses. The average gap between current ability and preferred ability correlated moderately with pain (-.56) and a scale of current ability (.46) but diverged from many of the measures. LIMITATIONS: The limitations of this study included the lack of an intervention to assess the response of the gap to therapy and the use of multiple statistical tests with a small sample. CONCLUSIONS: The evidence supports the convergent validity for current ability on the MAM but mostly the divergence of the gap. Additional research should compare the gap specifically with measures that assess patients' preferences when determining disability.

Gait abnormalities in multiple sclerosis: pathogenesis, evaluation, and advances in treatment.

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system characterized by episodic decline in various neurologic functions. Gait dysfunction in MS is distinguished by decreased gait speed, walking endurance, step length, cadence and joint motion, as well as increased metabolic cost of walking and increased variability of gait. Standardized clinical, timed, and patient-based measures can identify MS patients with gait dysfunction, and observational gait analysis, instrumented walkways, or three-dimensional gait analysis can help determine which problem underlies their gait dysfunction to help direct effective treatment. Exercise may ameliorate all types of gait dysfunction. In addition, gait dysfunction due to weakness may be alleviated by orthoses or functional electrical stimulation; gait dysfunction due to spasticity may be relieved by oral, intrathecal, or intramuscular medications. Assistive devices and balance training may reduce gait dysfunction from imbalance, and dalfampridine may accelerate gait in people with MS who walk slowly.

Reproducibility and minimal detectable change of three-dimensional kinematic analysis of reaching tasks in people with hemiparesis after stroke.

BACKGROUND AND PURPOSE: Three-dimensional kinematic analysis of reaching has emerged as an evaluative measure of upper-extremity motor performance in people after stroke. However, the psychometric properties supporting the use of kinematic data for evaluating longitudinal change in motor performance have not been established. The objective of this study was to determine, in a test-retest reliability manner, the reproducibility and minimal detectable change for reaching kinematics in people after stroke. SUBJECTS AND METHODS: Fourteen participants with hemiparesis after stroke performed forward reaching tasks on 2 occasions 37.3 (SD=9.8) days apart. At each session, participants performed 4 forward reaching tasks produced by the combination of 2 target heights (low and high [109 and 153 cm from the floor, respectively]) and 2 instructed movement speeds (self-selected and as fast as possible). Two analytical methods were used to calculate kinematic parameters. RESULTS: Relative reliability (intraclass correlation coefficient) ranged from .04 to .99, and absolute reliability (standard error of measurement) ranged from 2.7% to 76.8%, depending on the kinematic variable, the demands of the motor task (target height and movement speed), and the analytical method. Bland-Altman analysis, a statistical method used to assess the repeatability of a method, revealed few systematic errors between sessions. The minimal detectable change ranged from 7.4% to 98.9%. DISCUSSION AND CONCLUSION: Depending on the demands of the motor task and the analytical method, most kinematic outcome measures (such as peak hand velocity, endpoint error, reach extent, maximum shoulder flexion range of motion, and minimum elbow extension range of motion) are reliable measures of motor performance in people after stroke. However, because of the magnitude of within-subject measurement error, some variables (such as peak hand velocity, time to peak hand velocity, and movement time) must change considerably (>50%) to indicate a real change in individual participants. The results of our reliability analysis, which are based on our cohort of participants with hemiparesis after stroke and our specific paradigm, may not be generalizable to different subpopulations of people with hemiparesis after stroke or to the myriad movement tasks and kinematic variables used for the assessment of reaching performance in people after stroke.

Upper extremity use in people with hemiparesis in the first few weeks after stroke.

The purposes of this report were to: 1) determine the amount of upper extremity use in people with hemiparesis post stroke during their inpatient rehabilitation stay, and 2) to examine the relationships between upper extremity use and impairments and activity limitations at this early time point after stroke. We studied 34 subjects with mild-to-moderate acute hemiparesis (mean time since stroke = 9.3 days) and 10 healthy control subjects. Upper extremity use was measured over 24 hours using bilateral wrist accelerometers. Upper extremity impairments and activity limitations were measured using standard clinical techniques and tests. We found that healthy control subjects use their dominant and nondominant upper extremities 8-9 hours per day. Hemiparetic subjects used their affected and unaffected upper extremities substantially less than control subjects, 3.3 and 6.0 hours per day, respectively. Seven of ten impairment level measures and each of the activity level measures were related to affected upper extremity use. The impairment measures that were related to upper extremity use were those measures that assessed the ability to activate muscles (ie active range of motion and force production) and the measurement of shoulder pain. Our data show that affected upper extremity use is minimal during the inpatient rehabilitation stay, especially given that patients in this setting are required to have 3 hours of therapy per day. We speculate that accelerometer measurements of upper extremity use could be used in a variety of settings and that the objective information they provide would be of great value to clinicians as they select treatments and evaluate progress.

Sensorimotor impairments and reaching performance in subjects with poststroke hemiparesis during the first few months of recovery.

BACKGROUND AND PURPOSE: Little is known about the relationship between upper-extremity (UE) sensorimotor impairment and reaching performance during the first few months after stroke. The purpose of this study was to examine: (1) how measures of UE sensorimotor impairment are related to the speed, accuracy, and efficiency of reaching in subjects with hemiparesis during the subacute phase after stroke and (2) how impairments measured during the acute phase after stroke may predict the variance in reaching performance a few months later. SUBJECTS AND METHODS: Upper-extremity sensorimotor impairments and reaching performance were evaluated in 39 subjects with hemiparesis at 2 time points: during the acute phase (8.7+/-3.6 [X+/-SD] days) and the subacute phase (108.7+/-16.5 days) after stroke. Ten subjects who were healthy (control subjects) were evaluated once. Regression analyses were used to determine which impairments were the best predictors of variance in reaching performance in the subacute phase after stroke. RESULTS: Only a small amount of variance (<30%) in reaching performance was explained at the subacute time point, using either acute or subacute impairments as predictor variables. Of the impairments measured, UE strength deficits were the strongest, most consistent predictors of the variance in reaching performance during the first 3 months after stroke. DISCUSSION AND CONCLUSION: Surprisingly, the detailed clinical assessment of UE sensorimotor impairment, measured at the acute or subacute phase after stroke, did not explain much of the variance in reaching performance during the subacute phase after stroke. The findings that UE strength deficits (ie, decreased active range of motion and isometric force production) were the most common predictors of the variance in reaching performance during the first 3 months after stroke are consistent with the current viewpoint that impaired volitional muscle activation, clinically apparent as UE weakness, is a prominent contributing factor to UE dysfunction after stroke.

Upper extremity muscle activation during recovery of reaching in subjects with post-stroke hemiparesis.

OBJECTIVE: To investigate upper extremity muscle activation and recovery during the first few months after stroke. METHODS: Subjects with hemiparesis following stroke were studied performing a reaching task at an acute time point (mean=9 days post-stroke) and then again at a subacute time point (mean=109 days post-stroke). We recorded kinematics and electromyographic activity of six upper extremity muscles. RESULTS: At the acute time point, the hemiparetic group had delayed muscle onsets, lower modulation ratios, and higher relative levels of muscle activation (%MVIC) during reaching than controls. From the acute to the subacute time points, improvements were noted in all three variables. By the subacute phase, muscle onsets were similar to controls, while modulation ratios remained lower than controls and %MVIC showed a trend toward being greater in the hemiparetic group. Changes in muscle activation were differentially related to changes in reaching performance. CONCLUSIONS: Our data show that improvements in muscle timing and decreases in the relative level of volitional activation may underlie improved reaching performance in the early months after stroke. SIGNIFICANCE: Given that stroke is one of the leading causes of persistent physical disability, it is important to understand how the ability to activate muscles changes during the early phases of recovery after injury.

Measurement of upper-extremity function early after stroke: properties of the action research arm test.

OBJECTIVE: To examine the responsiveness and validity of the Action Research Arm Test (ARAT) in a population of subjects with mild-to-moderate hemiparesis within the first few months after stroke. DESIGN: Data were collected as part of the Very Early Constraint-Induced Therapy for Recovery from Stroke trial, an acute, single-blind randomized controlled trial of constraint-induced movement therapy. Subjects were studied at baseline (day 0), after treatment (day 14), and after 90 days (day 90) poststroke. SETTING: Inpatient rehabilitation hospital; follow-up 3 months poststroke. PARTICIPANTS: Fifty hemiparetic subjects. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: At each time point, subjects were tested on: (1) the ARAT, (2) clinical measures of sensorimotor impairments, (3) in the kinematics laboratory where they performed reach and grasp movements, and (4) clinical measures of disability. Blinded raters performed all evaluations. Analyses at each time point included calculating effect size as indicators of responsiveness, and correlation and regression analyses to examine relationships between ARAT scores and other measures. RESULTS: The ARAT is responsive to change, with effect sizes greater than 1.0 and responsiveness ratios of 7.0 at 3 months poststroke. ARAT scores were related to sensorimotor impairment measures, 3-dimensional kinematic measures of movement performance, and disability measures at all 3 time points. CONCLUSIONS: The ARAT is a responsive and valid measure of upper-extremity functional limitation and therefore may be an appropriate measure for use in acute upper-extremity rehabilitation trials.

Recovery of grasp versus reach in people with hemiparesis poststroke.

BACKGROUND AND OBJECTIVE: The authors recently found that grasping was not relatively more disrupted than reaching in people with acute hemiparesis. They now extend this work to the recovery of reach versus grasp. METHODS: Hemiparetic subjects were tested acutely, after 90 days, and then after 1 year poststroke, and a control group was evaluated once. Using kinematic techniques, subjects were studied performing reach and reach-to-grasp movements. The authors quantified 3 characteristics of performance for each movement: speed, accuracy, and efficiency, where an efficient movement was defined as a movement directly to the target without extraneous or abnormally circuitous movements. To evaluate the relative deficits and recovery in reach versus grasp, performance measures were converted to z scores using control group means and standard deviations. RESULTS: The authors' results showed that, starting with small deficits in speed acutely, both reach speed and grasp speed improved over time. Deficits in accuracy were greater in the reach than the grasp acutely, and these deficits lessened such that by the 90-day time point, the relative accuracy of the 2 movements was the same. In contrast, deficits in efficiency were greater in the grasp than the reach acutely, and grasp efficiency did not recover. The majority of recovery in reaching and grasping occurred by the 90-day time point, with little change occurring between the 90-day and 1-year time points. CONCLUSIONS: The authors hypothesize that, in chronic hemiparesis, purposeful movements requiring distal control may be more impaired than purposeful movements requiring proximal control, not because of the initial lesion, but because, over the course of recovery, spared components of the descending motor systems may be able to compensate for the accuracy deficits in reaching (proximal control) but not the efficiency deficits in grasping (distal muscular control).