Upper motor neuron lesions: their effect on muscle performance and appearance in stroke patients with minor motor impairment

Stroke-induced excess in capillarization relative to oxidative capacity in rats is muscle specific

Stroke is not only associated with muscle weakness, but also associated with reduced muscle fatigue resistance and reduced desaturation during exercise that may be caused by a reduced oxidative capacity and/or microvasculature. Therefore, the objective of the present study was to determine the effects of stroke on muscle mass, fiber size and shape, capillarization and oxidative capacity of the rat m. extensor carpi radialis (ECR) and m. flexor carpi ulnaris (FCU) after a photothrombotic stroke in the forelimb region of the primary sensorimotor cortex. The main observation of the present study was that 4 weeks after induction of stroke there were no significant changes in muscle fiber size and shape. Although there was no significant capillary rarefaction, there was some evidence for remodeling of the capillary bed as reflected by a reduced heterogeneity of capillary spacing (p = 0.006) that may result in improved muscle oxygenation. In the ECR, but not in the FCU, this was accompanied by reduction in muscle fiber oxidative capacity as reflected by reduced optical density of sections stained for succinate dehydrogenase (p = 0.013). The reduced oxidative capacity and absence of significant capillary rarefaction resulted in a capillary to fiber ratio per unit of oxidative capacity that was higher after stroke in the ECR (p = 0.01), but not in the FCU. This suggests that at least during the early stages, stroke is not necessarily accompanied by muscle fiber atrophy, and that stroke-induced reductions in oxidative capacity resulting in relative excess of capillarization are muscle specific.

Differences in Skeletal Muscle Fiber Characteristics Between Affected and Nonaffected Limbs in Individuals With Stroke: A Scoping Review

OBJECTIVE

The objective of this scoping review was to characterize and identify knowledge gaps about the changes in skeletal muscle fiber type proportion and cross-sectional area (CSA) after stroke.

METHODS

This scoping review followed previously proposed frameworks. A systematic search was conducted for articles examining muscle fiber type proportion and CSA in individuals with stroke in EMBASE, MEDLINE, PsycINFO, CINAHL, SPORTDiscus, and Web of Science databases from inception to December 20, 2022. Two independent authors screened and extracted the data. Results were discussed using theories proposed by the authors of the included studies.

RESULTS

Of 13 studies (115 participants), 6 (46%) were case studies or case series, 6 (46%) were cross-sectional studies, and 1 (8%) was an experimental study. Studies had small sample sizes (1-23 participants) and various muscle sampling sites (6 different muscles). All 13 studies examined muscle fiber type distributions, and 6 (46%) examined CSA. Ten (77%) studies examined differences between paretic and nonparetic muscles, and 5 (38%) compared people with stroke to people without stroke. Results from 9 of 13 studies (69%) supported a greater proportion of type II muscle fibers in the paretic limb. Of those, 4 studies (42 participants), 3 studies (17 participants), and 1 study (1 participant) saw no differences, preferential type II and type I CSA loss between limbs, respectively.

CONCLUSION

Of the limited available evidence, stroke appears to result in a shift to a higher proportion of type II muscle fibers in the paretic muscles. There are mixed results for effects on muscle fiber CSA, but there is some evidence of specific atrophy of type II muscle fibers.

IMPACT

Changes in paretic skeletal muscle fibers of individuals with stroke may explain, in part, the substantial losses in strength and power in this population. Interventions to restore type II muscle fiber size may benefit people with stroke.

Assessment of changes in muscle mass, strength, and quality and activities of daily living in elderly stroke patients

Whether poststroke rehabilitation improves muscle mass and quality along with the recovery of muscle strength is not clear. In this study, we examined the changes in muscle strength, muscle mass, and muscle quality in patients undergoing poststroke rehabilitation and assessed the relationship of these variables with improvement in activities of daily living (ADL). This prospective study was conducted at stroke rehabilitation unit in Japan. Muscle mass and quality were assessed using bioelectrical impedance analysis (BIA). ADLs were assessed using the functional independence measure (FIM). Grip strength of the nonaffected and affected sides was measured using hand dynamometer. All measurements were performed at admission to the stroke rehabilitation unit and at 4 weeks thereafter. We assessed changes in motor FIM items and examined the relationships among the measured variables. This study included 179 patients. Patients received stroke rehabilitation 7 days a week individually. Muscle strength and quality significantly increased after 4 weeks on both the sides. Muscle mass decreased after 4 weeks; however, there was no significant difference between the two time points. Changes in muscle strength and quality showed a significant correlation with improvement in ADLs [r = 0.66 (male), 0.45 (female) and 0.55 (male), 0.31 (female), respectively]; however, muscle mass showed no correlation with improvement in ADLs. Poststroke rehabilitation improves muscle strength and quality, as well as ADLs. Muscle mass is not an appropriate measure to assess the effects of stroke rehabilitation; it is desirable to instead use muscle strength and quality to assess stroke rehabilitation.

Correlation of Body Composition and Nutritional Status with Functional Recovery in Stroke Rehabilitation Patients

Previous studies have suggested that the nutritional status after stroke is independently associated with long-term outcomes and that sarcopenia delays poststroke rehabilitation and worsens the prognosis. However, many stroke patients have a deteriorated nutritional status and a decreased muscle mass in the acute phase. This prospective study included 179 patients who were admitted to the stroke rehabilitation unit. We performed bioelectrical impedance analysis and determined the Geriatric Nutritional Risk Index (GNRI) to assess muscle mass and the nutritional status on admission. Furthermore, we analyzed the activities of daily living using the Functional Independence Measure (FIM) at the time of admission and four weeks later. Furthermore, we evaluated the change in motor FIM items and examined the relationship with the data. Multiple regression analysis revealed that a high muscle rate (skeletal muscle mass/body weight) (odds ratio OR = 2.43), high phase angle (OR = 3.32), and high GNRI (OR = 2.57) were significantly associated with motor FIM items at four weeks in male and female patients. Muscle mass maintenance through nutritional management and early rehabilitation in the acute period of stroke is essential for functional recovery in stroke patients.

Peripheral Electrical Stimulation Paired With Movement-Related Cortical Potentials Improves Isometric Muscle Strength and Voluntary Activation Following Stroke

Background

Endogenous paired associative stimulation (ePAS) is a neuromodulatory intervention that has potential to aid stroke recovery. ePAS involves pairing endogenous electroencephalography (EEG) signals known as movement-related cortical potentials (MRCPs), with peripheral electrical stimulation. Previous studies have used transcranial magnetic stimulation (TMS) to demonstrate changes in corticomotor excitability following ePAS. However, the use of TMS as a measure in stroke research is limited by safety precautions, intolerance, and difficulty generating a measurable response in more severely affected individuals. We were interested in evaluating the effect of ePAS using more feasible measures in people with stroke. This study asks whether ePAS produces immediate improvements in the primary outcomes of maximal voluntary isometric contraction (MVIC) and total neuromuscular fatigue of the dorsiflexor muscles, and in the secondary outcomes of muscle power, voluntary activation (VA), central fatigue, peripheral fatigue, and electromyography activity.

Method

In this repeated-measures cross-over study, 15 participants with chronic stroke completed two interventions, ePAS and sham, in a randomized order. During ePAS, 50 repetitions of visually cued dorsiflexion were completed, while single pulses of electrical stimulation were delivered to the deep branch of the common peroneal nerve. Each somatosensory volley was timed to arrive in the primary motor cortex at the peak negativity of the MRCP. Univariate and multivariate linear mixed models were used to analyze the primary and secondary data, respectively.

Results

There was a statistically significant increase in dorsiflexor MVIC immediately following the ePAS intervention (mean increase 7 N), compared to the sham intervention (mean change 0 N) (univariate between-condition analysis p = 0.047). The multivariate analysis revealed a statistically significant effect of ePAS on VA of the tibialis anterior muscle, such that ePAS increased VA by 7 percentage units (95% confidence interval 1.3–12.7%). There was no statistically significant effect on total neuromuscular fatigue, muscle power, or other secondary measures.

Conclusion

A single session of ePAS can significantly increase isometric muscle strength and VA in people with chronic stroke. The findings confirm that ePAS has a central neuromodulatory mechanism and support further exploration of its potential as an adjunct to stroke rehabilitation. In addition, the findings offer alternative, feasible outcome measures for future research.

Clinical trial registration

Australia New Zealand Clinical Trials Registry ACTRN12617000838314 (www.anzctr.org.au), Universal Trial Number U111111953714.

The Comparison between Isokinetic Knee Muscles Strength in the Ipsilateral and Contralateral Limbs and Correlating with Function of Patients with Stroke

Objective The aim of this study is to compare the isokinetic knee muscles peak torque measurements and proprioception between the affected and intact limbs of patients with stroke, in addition to finding the correlation between knee muscles strength and lower limb function. Methods Twelve patients with stroke (mean age 64.33 ± 6.140 years), with 3 to 7 months poststroke who can walk 25 feet independently without using or using assistive devices and full passive range of motion were included in the study. Biodex isokinetic dynamometer was used for measuring isokinetic strength at 90°/s, 120°/s, and 150°/s and isometric strength at 60°/s in both flexors and extensors of the knee, whereas proprioception was measured at 45°/s knee flexion, all for affected and intact limbs. Functional measurements were assessed using the Fugl-Meyer Assessment for Lower Limb scale and Barthel Index (BI). Results The differences shown were found to be statistically significant between affected and intact limbs in isokinetic 90°/s flexion ( p = 0.005), extension ( p = 0.0013), and isometric at 60°/s flexion ( p < 0.0001) knee muscle strengths and also the proprioception ( p = 0.05). Significant positive correlation was found between isokinetic affected side knee flexion at 90°/s ( r = 0.903) with BI ( r = 0.704). Conclusion There is a significant difference in peak torque measurements between affected and normal lower limbs of poststroke patients, as well as a significant correlation between the knee strength and lower limb functions. Furthermore, it can also be concluded that the differences in knee proprioception between the affected and intact limbs were shown to be significant.

Cross-sectional study of quadriceps properties and postural stability in patients with chronic stroke and limited vs. non-limited community ambulation

Background: Changes in the paretic-side metabolism post-stroke and quadriceps muscle mechanical properties favour muscle wasting, affecting postural instability and walking impairment. Further clarification is needed in subjects post-stroke who show limited or non-limited community ambulation. Objectives: To analyze between-limb differences in quadriceps muscle thickness, strength and thigh cutaneous temperature, as well as investigate postural stability in subjects with chronic stroke and limited vs. non-limited community ambulation and compared against healthy controls. Methods: In this controlled cross-sectional study, 26 participants with chronic hemiparesis post-stroke (divided in a slow gait group (SG<0.8 m/s) (n = 13) and a fast gait group with full community ambulation speed (FG≥0.8 m/s)) and 18 healthy people were recruited. Thigh surface temperature, rectus femoris (RF) and vastus intermedius (VI) muscles thickness, quadriceps' isometric maximal voluntary contraction and postural stability were measured. Results: The SG presented significantly lower RF (P = .019) and VI (P = .006) muscle thickness, less peak force (P < .001) and lower temperature (P = .002) in the paretic vs the non-paretic limb. The FG showed significantly lower VI thickness (P = .036) and peak force (P < .001) in the paretic vs the non-paretic limb. Regarding balance, all indices were worse in the SG versus the FG and CG. Conclusions: Subjects of the FG, despite showing full community ambulation speed, had less quadriceps strength and VI muscle thickness but not RF muscle wasting in the paretic limb. The paretic VI muscle wasting may be an important factor to reach normal walking. The SG showed between-limb differences in all the studied variables and the worst postural stability.

Motor Unit Activity during Fatiguing Isometric Muscle Contraction in Hemispheric Stroke Survivors

Enhanced muscle weakness is commonly experienced following stroke and may be accompanied by increased susceptibility to fatigue. To examine the contributions of central and peripheral factors to isometric muscle fatigue in stroke survivors, this study investigates changes in motor unit (MU) mean firing rate, and action potential duration during, and directly following, a sustained submaximal fatiguing contraction at 30% maximum voluntary contraction (MVC). A series of short contractions of the first dorsal interosseous muscle were performed pre- and post-fatigue at 20% MVC, and again following a 10-min recovery period, by 12 chronic stroke survivors. Individual MU firing times were extracted using surface EMG decomposition and used to obtain the spike-triggered average MU action potential waveforms. During the sustained fatiguing contraction, the mean rate of change in firing rate across all detected MUs was greater on the affected side (-0.02 ± 0.03 Hz/s) than on the less-affected side (-0.004 ± 0.003 Hz/s, p = 0.045). The change in firing rate immediately post-fatigue was also greater on the affected side than less-affected side (-13.5 ± 20 and 0.1 ± 19%, p = 0.04). Mean MU firing rates increased following the recovery period on the less-affected side when compared to the affected side (19.3 ± 17 and 0.5 ± 20%, respectively, p = 0.03). MU action potential duration increased post-fatigue on both sides (10.3 ± 1.2 to 11.2 ± 1.3 ms on the affected side and 9.9 ± 1.7 to 11.2 ± 1.9 ms on the less-affected side, p = 0.001 and p = 0.02, respectively), and changes in action potential duration tended to be smaller in subjects with greater impairment (p = 0.04). This study presents evidence of both central and peripheral fatigue at the MU level during isometric fatiguing contraction for the first time in stroke survivors. Together, these preliminary observations indicate that the response to an isometric fatiguing contraction differs between the affected and less-affected side post-stroke, and may suggest that central mechanisms observed here as changes in firing rate are the dominant processes leading to task failure on the affected side.

POWER training in chronic stroke individuals: differences between responders and nonresponders

BACKGROUND

Lower extremity muscle weakness is a primary contributor to post-stroke dysfunction. Resistance training is an effective treatment for hemiparetic weakness and improves walking performance. Post-stroke subject characteristics that do or do not improve walking speed following resistance training are unknown.

OBJECTIVE

The purpose of this paper was to describe baseline characteristics, as well as responses to training, associated with achieving a minimal clinically important difference (MCID) in walking speed (≥0.16 m/s) following Post-stroke Optimization of Walking Using Explosive Resistance (POWER) training.

METHODS

Seventeen participants completed 24 sessions of POWER training, which included intensive progressive leg presses, jump training, calf raises, sit-to-stands, step-ups, and over ground fast walking. Outcomes included SSWS, FCWS, DGI, FMA-LE, 6-MWT, paretic knee power, non-paretic knee power, and paretic step ratio.

RESULTS

Specific to those who reached MCID in SSWS (e.g. "responders"), significant improvements in SSWS, FCWS, 6-MWT, paretic knee power, and non-paretic knee power was realized. Paretic knee power and non-paretic knee power significantly improved in those who did not achieve MCID for gait speed (e.g. "non-responders").

CONCLUSION

The potential for POWER training to enhance general locomotor function was confirmed. Baseline paretic knee strength/power may be an important factor in how an individual responds to this style of training. The lack of change within the non-responders emphasizes the contribution of factors other than lower extremity muscle power improvement to locomotor dysfunction.

Skeletal muscle changes following stroke: a systematic review and comparison to healthy individuals

BACKGROUND

Despite extensive study of the impact of stroke on muscle and functional performance, questions remain regarding the extent to which changes are due to the neurological injury vs. age-related loss of morphology and force production.

OBJECTIVES

To synthesize available evidence describing post-stroke changes in lower extremity muscle size and strength compared to healthy adults.

METHODS

Scientific literature was searched up to April 2016 to identify studies that included lower extremity muscle size and strength measures in individuals with chronic stroke. Lower extremity muscle size and strength data from healthy controls were sought for comparison. Relative differences were calculated between paretic, nonparetic, and control limbs.

RESULTS

Fifteen studies with 375 participants (61% male; age = 62 ± 5 years; time since stroke = 60 ± 42 months) were included. The paretic limb exhibited deficits of ~13% in thigh muscle size, ~5% in lower leg muscle size, and ~8% in lean leg mass compared to the nonparetic limb. Paretic plantarflexor and knee extensor strength were 52 and 36% lower, respectively, compared to the nonparetic limb. When compared to age-matched control data, both paretic and nonparetic limbs showed deficits in muscle size and strength.

CONCLUSIONS

Age-related differences support the impact of stroke-related sarcopenia as a contributor to hemiparetic muscle dysfunction. Understanding these muscular changes is necessary for designing appropriate exercise interventions aimed at restoring muscle function.

Longer-term impact of hemiparetic stroke on skeletal muscle metabolism-A pilot study

BACKGROUND

Hemiparetic stroke leads to structural and metabolic alterations of skeletal muscle tissue, thereby contributing to functional impairment associated with stroke. In situ metabolic processes at tissue level in skeletal muscle have not been investigated. We hypothesize that muscular metabolic capacity is limited after hemiparetic stroke, and that changes affect rather the paretic than non-paretic limb.

METHODS

Nine male hemiparetic stroke survivors (age, 62±8years; BMI, 28±4kg/m²; median stroke latency, 23months ranging from 7 to 34months poststroke) underwent dynamic in situ measurements of carbohydrate and lipid metabolism at fasting condition and during oral glucose tolerance testing, using bilateral microdialysis. Results were compared to 8 healthy male subjects of similar age and BMI.

RESULTS

Tissue perfusion, fasting and postprandial profiles of interstitial metabolites glucose, pyruvate, lactate and glycerol did not differ between paretic and non-paretic muscle. Patients displayed higher fasting and postprandial dialysate glycerol levels compared to controls (P<0.001) with elevated plasma FFA (fasting FFA; 0.63±0.23 vs. 0.29±0.17mmol/L; P=0.004). Glycolytic activity was higher in patients vs. controls, with increased lactate production upon glucose load (P<0.001).

CONCLUSIONS

An elevated lipolytic and glycolytic activity on tissue level suggests an impaired substrate metabolism with blunted oxidative metabolism in bilateral skeletal muscle in patients after hemiparetic stroke. Muscular metabolic properties did not differ between paretic and non-paretic leg. Further work is needed to investigate the clinical impact of this impaired muscular metabolic capacity in post-stroke patients.

Assessment of the strength of the lower limb muscles in subjects with stroke with portable dynamometry: a literature review

Abstract Introduction: Weakness of the lower limb muscles, which are the main impairments after stroke, is associated with reduced mobility and decreased performance in functional tasks. Therefore, the assessment of strength of these muscles is necessary, which is commonly assessed with portable dynamometry. Aims: To perform a literature review regarding the methods used to assess lower limb strength with portable dynamometry in subjects with stroke and to describe its investigated measurement properties with this population. Materials and Methods: An extensive search was performed on the MEDLINE, SCIELO, LILACS, and PEDro databases, by combining specific key words, followed by active manual search by two independent researchers. Results and Discussion: Thirty studies were included, and the muscular groups of the knee (90%) were the most assessed, followed by the ankle (66.7%) and hip (63.3%) joints. In 5% of the studies, there were not reported any descriptions related to the positioning of the subjects and the equipment, neither regarding the stabilization procedures. Only 50% provided information regarding the number of trials and only 46.7% regarding the contraction times, being three trials and 5s the most commonly applied. Only 10% provided feedback and 23.3% demonstrations, prior to data collection. Only seven studies (23.3%) investigated the measurement properties of portable dynamometry and reported moderate to high reliability levels. Final Considerations: The protocols used for the assessment of the strength of the lower limb muscles with portable dynamometry in subjects with stroke were not standardized. Moreover, only one measurement property was investigated: the reliability, which was considered adequate.

Factors that influence muscle weakness following stroke and their clinical implications: a critical review

PURPOSE

To provide a comprehensive review of changes that occur in the muscle after stroke and how these changes influence the force-generating capacity of the muscle.

METHODS

A literature search of PubMed, CINAHL, MEDLINE, and Embase was conducted using the search terms stroke, hemiparesis, muscle structure, cross sectional area, atrophy, force, velocity, and torque. There were 27 articles included in this review.

RESULTS

Three changes occur in the muscle after stroke: a decrease in muscle mass, a decrease in fibre length, and a smaller pennation angle. In addition, the tendon is stretched and becomes more compliant. All of these factors reduce the affected muscle's ability to generate forces similar to controls or to non-paretic muscles. The result is a leftward shift in the length-tension curve, a downward shift in the torque-angle curve, and a downward shift in the force-velocity curve.

CONCLUSION

Changes in muscle architecture contributing to weakness, such as muscle-fibre length, pennation angle, muscle atrophy, and tendon compliance, should be prevented or reversed by means of an appropriate rehabilitation programme.

Why use a connectivity-based approach to study stroke and recovery of function?

The brain is organized into a set of widely distributed networks. Therefore, although structural damage from stroke is focal, remote dysfunction can occur in regions connected to the area of lesion. Historically, neuroscience has focused on local processing due in part to the absence of tools to study the function of distributed networks. In this article we discuss how a more comprehensive understanding of the effects of stroke can be attained using resting state functional connectivity BOLD magnetic resonance imaging (resting state fcMRI). Resting state fcMRI has a number of advantages over task-evoked fMRI for studying brain network reorganization in response to stroke, including the ability to image subjects with a broad range of impairments and the ability to study multiple networks simultaneously. We describe our rationale for using resting state connectivity as a tool for investigating the neural substrates of stroke recovery in a heterogeneous population of stroke patients and discuss the main questions we hope to answer, in particular whether resting state fcMRI measures in the acute phase of stroke can predict subsequent recovery. Early results suggest that disruption of inter-hemispheric connectivity in the somatomotor network and the dorsal attention network is more strongly associated with behavioral impairment in those domains than is intra-hemispheric connectivity within either the lesioned or unaffected hemisphere. We also observe in the somatomotor network an interesting interaction between corticospinal tract damage and decreased inter-hemispheric connectivity that suggests that both processes combine to contribute to neuromotor impairment after stroke. A connectivity-based approach will provide greater insight into network reorganization in the acute and chronic phases after stroke and will contribute to improving prognostic ability and the development of therapeutic interventions.

Muscle atrophy and functional deficits of knee extensors and flexors in people with chronic stroke

BACKGROUND

Further clarification is needed with regard to the degree of atrophy in individual muscle groups and its possible relationship to joint torque deficit poststroke.

OBJECTIVE

The purpose of this study was to investigate quadriceps and hamstring muscle volume and strength deficits of the knee extensors and flexors in people with chronic hemiparesis compared with a control group.

DESIGN

This was a cross-sectional study.

METHODS

Thirteen individuals with hemiparesis due to chronic stroke (hemiparetic group) and 13 individuals who were healthy (control group) participated in this study. Motor function, quadriceps and hamstring muscle volume, and maximal concentric and eccentric contractions of the knee extensors and flexors were assessed.

RESULTS

Only the quadriceps muscle of the paretic limb showed reduced muscle volume (24%) compared with the contralateral (nonparetic) limb. There were no differences in muscle volume between the hemiparetic and control groups. The peak torque of the paretic-limb knee extensors and flexors was reduced in both contraction modes and velocities compared with the nonparetic limb (36%-67%) and with the control group (49%-75%). The nonparetic limb also showed decreased extensor and flexor peak torque compared with the control group (17%-23%). Power showed similar deficits in strength (12%-78%). There were significant correlations between motor function and strength deficits (.54-.67).

LIMITATIONS

Magnetic resonance imaging coil length did not allow measurement of the proximal region of the thigh.

CONCLUSIONS

There were different responses between quadriceps and hamstring muscle volumes in the paretic limb that had quadriceps muscle atrophy only. However, both paretic and nonparetic limbs showed knee extensor and flexor torque and power reduction.

Paretic muscle atrophy and non-contractile tissue content in individual muscles of the post-stroke lower extremity

Muscle atrophy is one of many factors contributing to post-stroke hemiparetic weakness. Since muscle force is a function of muscle size, the amount of muscle atrophy an individual muscle undergoes has implications for its overall force-generating capability post-stroke. In this study, post-stroke atrophy was determined bilaterally in fifteen leg muscles with volumes quantified using magnetic resonance imaging (MRI). All muscle volumes were adjusted to exclude non-contractile tissue content, and muscle atrophy was quantified by comparing the volumes between paretic and non-paretic sides. Non-contractile tissue or intramuscular fat was calculated by determining the amount of tissue excluded from the muscle volume measurement. With the exception of the gracilis, all individual paretic muscles examined had smaller volumes in the non-paretic side. The average decrease in volume for these paretic muscles was 23%. The gracilis volume, on the other hand, was approximately 11% larger on the paretic side. The amount of non-contractile tissue was higher in all paretic muscles except the gracilis, where no difference was observed between sides. To compensate for paretic plantar flexor weakness, one idea might be that use of the paretic gracilis actually causes the muscle to increase in size and not develop intramuscular fat. By eliminating non-contractile tissue from our volume calculations, we have presented volume data that more appropriately represents force-generating muscle tissue. Non-uniform muscle atrophy was observed across muscles and may provide important clues when assessing the effect of muscle atrophy on post-stroke gait.

Physical activity, ambulation, and motor impairment late after stroke

Objective. To assess walking capacity and physical activity using clinical measures and to explore their relationships with motor impairment late after stroke. Subjects. A nonrandomised sample of 22 men and 9 women with a mean age of 60 years, 7–10 years after stroke. Methods. Fugl-Meyer Assessment, maximum walking speed, 6 min walk test, perceived exertion, and heart rate were measured, and the Physiological Cost Index was calculated. Physical activity was reported using The Physical Activity Scale for the Elderly. Results. Mean (SD) 6 min walking distance was 352 (±136) m, and Physiological Cost Index was 0.60 (±0.41). Self-reported physical activity was 70% of the reference. Motor impairment correlated with walking capacity but not with the physical activity level. Conclusion. It may be essential to enhance physical activity even late after stroke since in fairly young subjects both walking capacity and the physical activity level were lower than the reference.

Loss of Skeletal Muscle Mass after Stroke: a Systematic Review

Loss of muscle mass after stroke has implications for strength and functional ability and may also contribute to impaired glucose metabolism. Therefore, prevention of muscle loss is desirable. Before interventions to prevent loss of muscle can be designed and evaluated, the expected rate, magnitude and timing of muscle loss need to be understood. A systematic search was undertaken to identify all studies that investigated changes in skeletal muscle mass, volume or cross-sectional area in people after stroke. Studies that used either direct measures of muscle size (computer tomography, magnetic resonance imaging or ultrasound) or measures of lean tissue mass (dual X-ray absorptiometry) were included. Fourteen trials were found and the results were pooled for differences in lean tissue mass between the paretic and the nonparetic leg and arm as well as differences in the midthigh cross-sectional area. In individuals at least 6-month post-stroke, there was significantly less lean tissue mass in the paretic compared with the nonparetic lower limb (MD 342.3 g, 95% confidence interval 247.0–437.6 g) and upper limb (MD 239.9 g, 95% confidence interval 181.7–298.2 g), and significantly less midthigh muscle cross-sectional area (MD 15.4 cm2, 95% confidence interval 13.8–16.9 cm2). There were insufficient data to pool with regard to change in muscle mass over time. There is a significant difference in the regional muscle mass in the paretic vs. the nonparetic limb in individuals greater than 6-months poststroke but little is known about how early and how quickly changes in muscle mass occur.

The surface electromyography analysis of the non-plegic upper limb of hemiplegic subjects

Many authors have studied physical and functional changes in individuals post-stroke, but there are few studies that assess changes in the non-plegic side of hemiplegic subjects. This study aimed to compare the electromyographic activity in the forearm muscles of spastic patients and clinically healthy individuals, to determine if there is difference between the non-plegic side of hemiplegics and the dominant member of normal individuals. 22 hemiplegic subjects and 15 clinically healthy subjects were submitted to electromyography of the flexor and extensor carpi ulnaris muscles during wrist flexion and extension. The flexor muscles activation of stroke group (average 464.6 u.n) was significantly higher than the same muscles in control group (mean: 106.3 u.n.) during the wrist flexion, what shows that the non affected side does not present activation in the standard of normality found in the control group.

The reliability of side to side measurements of upper extremity activity levels in healthy subjects

Background

In both clinical and occupational settings, ambulatory sensors are becoming common for assessing all day measurements of arm motion. In order for the motion of a healthy, contralateral side to be used as a control for the involved side, the inherent side to side differences in arm usage must be minimal. The goal of the present study was to determine the reliability of side to side measurements of upper extremity activity levels in healthy subjects.

Methods

Thirty two subjects with no upper extremity pathologies were studied. Each subject wore a triaxial accelerometer on both arms for three and a half hours. Motion was assessed using parameters previously reported in the literature. Side to side differences were compared with the intraclass correlation coefficient, standard error of the mean, minimal detectable change scores and a projected sample size analysis.

Results

The variables were ranked based on their percentage of minimal detectable change scores and sample sizes needed for paired t-tests. The order of these rankings was found to be identical and the top ranked parameters were activity counts per hour (MDC% = 9.5, n = 5), jerk time (MDC% = 15.8, n = 8) and percent time above 30 degrees (MDC% = 34.7, n = 9).

Conclusions

In general, the mean activity levels during daily activities were very similar between dominant and non-dominant arms. Specifically, activity counts per hour, jerk time, and percent time above 30 degrees were found to be the variables most likely to reveal significant difference or changes in both individuals and groups of subjects. The use of ambulatory measurements of upper extremity activity has very broad uses for occupational assessments, musculoskeletal injuries of the shoulder, elbow, wrist and hand as well as neurological pathologies.

Reduced skeletal muscle capillarization and glucose intolerance

OBJECTIVE

Reduced capillarization in hemiparetic skeletal muscle of chronic stroke patients can limit insulin, glucose, and oxygen supply to muscle, thereby contributing to impaired glucose metabolism and cardiovascular deconditioning. We hypothesized that compared to sedentary controls, stroke subjects have reduced skeletal muscle capillarization that is associated with glucose intolerance and reduced peak oxygen consumption (Vo(2peak)).

METHODS

Twelve chronic stroke subjects (ages, 62.1+/-2.8 years), and matched sedentary controls with impaired (n=12) or normal (n=12) glucose tolerance underwent oral glucose tolerance tests, exercise tests, and vastus lateralis biopsies.

RESULTS

Stroke subjects had lower capillarization in hemiparetic muscle than in nonparetic muscle and normal glucose tolerant controls ( approximately 22 and approximately 28%, respectively; P<0.05) and had similar bilateral capillarization, compared to controls with impaired glucose tolerance. Capillary density in hemiparetic muscle inversely correlated with 120-minute glucose (r=-0.70, P<0.01) and glucose area under the curve (r=-0.78, P<0.01). Vo(2peak) was approximately 40% lower in stroke subjects, compared to controls (P<0.001), but did not correlate with capillarization (P=n.s.).

CONCLUSIONS

Hemiparetic muscle capillarization is reduced after stroke, and reduced capillarization is associated with glucose intolerance in stroke and control subjects. Interventions to increase skeletal muscle capillarization may prove beneficial for improving glucose metabolism in chronic stroke patients.

Circuit training in community-living "younger" men after stroke

OBJECTIVES

We sought to assess a training program focused on muscle strength and endurance in persons with prior stroke.

METHODS

Thirty men with a slight hemiparesis caused by a first occurrence of stroke at least 6 months earlier were included with an average age of 54 years. The following was assessed before and after an 8-week period: muscle strength, endurance, work capacity, and activity level. The training group consisted of 21 persons and 9 served as control subjects. There were no differences between the groups in the various assessments from the start. The training was set up as circuit training with 5 stations aiming to strengthen the muscles and increase endurance in the bilateral lower limbs. The session lasted for 45 minutes, 3 times per week, for 8 weeks. On eligible persons in the training group, double-sided muscle biopsies were also performed before and after.

RESULTS

There was significance in improved muscle strength and improved peak oxygen uptake for the paretic leg, which was reflected in the muscle enzymes. The nonparetic side also showed improvement, but to a lesser extent. The control group remained unchanged.

CONCLUSIONS

Stroke survivors can improve muscle strength, endurance, and work capacity in both the paretic and nonparetic leg with a circuit training program.

The effect of poststroke impairments on brachialis muscle architecture as measured by ultrasound

OBJECTIVE

To evaluate the joint angle dependence of brachialis muscle architecture at rest and changes in brachialis muscle architecture during isometric voluntary contractions in people after stroke.

DESIGN

The pennation angle and fascicle length of the brachialis muscle were measured in the affected and unaffected sides of people after stroke at 9 different elbow angles ranging from 10 degrees to 90 degrees at the rest condition. Measurements were also carried out at a fixed joint angle of 90 degrees while the subjects were performing isometric muscle contractions at 5 incremental levels of maximal voluntary contraction (MVC) from 20% to 100% of MVC. The data obtained from the affected and unaffected sides of the subjects were compared.

SETTING

A research laboratory in a rehabilitation center.

PARTICIPANTS

Seven hemiplegic adults after stroke with passive range of motion in the elbow from 10 degrees to 90 degrees and Modified Ashworth Scale score larger than 1 were recruited.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Ultrasonography was used to measure brachialis muscle pennation angle and fascicle length at the rest condition and during isometric contractions.

RESULTS

The measured pennation angles and fascicle lengths were found to be joint-angle-dependent in both the affected and unaffected groups at the rest condition. Further comparisons found that the pennation angles of the affected brachialis muscle were significantly larger (P<.05) than the unaffected muscle in the most extended positions (<50 degrees ), whereas the affected fascicle lengths were significantly shorter (P<.05) than the unaffected muscle in most flexed positions (>20 degrees ). As the level of isometric voluntary contraction was increased incrementally from 20% to 100% of MVC, the results showed that pennation angle increased significantly (P<.05) while fascicle length decreased significantly (P<.01) in the unaffected muscle. However, the contraction level has a significant effect only on pennation angle (P<.05) but not on fascicle length in the affected side. In addition, the measured fascicle lengths in the unaffected group were significantly shorter than those in the affected group for isometric contractions above 40% MVC.

CONCLUSIONS

Our findings suggest that the architectural parameters of the brachialis muscle in people after stroke are elbow-joint-angle-dependent at the rest condition. In the affected side, pennation angle changed the most when the muscle was in an extension position and fascicle length changed the most in a flexed position when compared with the unaffected side. Immobilization and contracture might cause a shortening of the fascicle and an increase in pennation angle in the affected side. Smaller pennation angle and fascicle length changes in the affected side during isometric contraction might be due to weakness in the muscle after the onset of stroke.

One-legged bicycling as an assessment tool for patients with stroke

OBJECTIVE

To assess whether one-legged bicycling correlates with muscle strength and thereby could work as an outcome measure for persons with stroke.

METHODS

The study comprised 29 men (age 35-65) with a first occurrence of stroke 6-35 months earlier. Each leg was evaluated separately. A ramp protocol was used (10 W/min), with continuous recording of the ventilatory uptake (Vo(2)) and heart rate. An isokinetic dynamometer was used to assess strength and endurance. Enzyme assays were performed on muscle biopsy samples.

RESULTS

The peak isometric strength and isokinetic strength of the paretic leg correlated with the max. W on the bicycle. The oxidative enzyme citrate synthase correlated with the workload for both legs on the bicycle and lactate dehydrogenase correlated with peak isometric strength in both legs.

CONCLUSIONS

The one-legged bicycle exercise test can be used to assess endurance in persons with a previous stroke as it correlates with dynamometer testing and muscle biopsies.

Evaluation of upper-limb spasticity after stroke: A clinical and neurophysiologic study

OBJECTIVES

To assess upper-limb spasticity after stroke by means of clinical and instrumental tools and to identify possible variables influencing the clinical pattern.

DESIGN

Descriptive measurement study of a consecutive sample of patients with upper-limb spasticity after stroke.

SETTING

Neurorehabilitation hospital.

PARTICIPANTS

Sixty-five poststroke hemiplegic patients.

INTERVENTIONS

Not applicable. Main outcome measures Upper-limb spasticity, as assessed clinically (Modified Ashworth Scale [MAS], articular goniometry) and neurophysiologically (maximum H-reflex [Hmax], maximum M response [Mmax], Hmax/Mmax ratio).

RESULTS

Poorer MAS scores were associated with lower passive range of motion (PROM) values at the wrist ( P =.01) and elbow ( P =.002). The flexor carpi radialis Hmax/Mmax ratio correlated directly with MAS scores at the wrist ( P =.005) and correlated inversely with PROM. The presence of pain in the fingers, wrist, and elbow was significantly associated only with lower PROM values at the wrist.

CONCLUSIONS

Upper-limb spasticity is involved in the development of articular PROM limitation after a stroke. Pain appears to be related to PROM reduction as well, but the exact causal relationship between these 2 factors is still unclear. The MAS and the Hmax/Mmax ratio correlated when evaluating poststroke spasticity; they characterize 2 different aspects of spasticity, clinical and neurophysiologic, respectively, and they could be used as an integrated approach to study and follow poststroke patients.

Renforcement musculaire isocinétique excentrique des ischiojambiers chez des patients atteints de sclérose en plaque

OBJECTIVE

To assess the benefit of a program of rehabilitation involving eccentric isokinetic muscle strengthening for hamstrings of patient with multiple sclerosis.

PATIENTS AND METHODS

A total of 28 patients with multiple sclerosis and abnormalities when walking who underwent a program of rehabilitation involving eccentric isokinetic muscle strengthening associated with classical neurological rehabilitation. Assessment was by use of an isokinetic test, clinical examination and score on a visual analog scale (VAS) about quality of walking at the beginning and end of the rehabilitation program and three months later. The rehabilitation program involved eccentric isokinetic exercises during 12 sessions.

RESULTS

Patients with multiple sclerosis and difficulty walking showed weak hamstrings on manual muscular testing. After 12 sessions of isokinetic eccentric rehabilitation, hamstring and quadriceps strength increased, VAS score increased, and recurvatum of the knee improved in 26 cases. Three months later, the score for quality of walking remained the same, but that for strength returned to a previous level.

CONCLUSION

Hamstring strength in patients with multiple sclerosis can be improved without complication with use of eccentric isokinetic rehabilitation. This is an interesting way to improve the quality of walking in these patients.

Addition of intensive repetition of facilitation exercise to multidisciplinary rehabilitation promotes motor functional recovery of the hemiplegic lower limb

OBJECTIVE

To evaluate the effects of the intensive repetition of movements elicited by the facilitation technique to improve voluntary movement of a hemiplegic lower limb in patients with brain damage.

DESIGN

A multiple-baseline design (A-B-A-B: A without specific therapy, B with specific therapy) across individuals.

PATIENTS

The sample comprised 22 subjects with stroke and 2 brain tumour-operated subjects (age: 50.7 +/- 9.6 years, time after onset: 7.1 +/- 2.6 weeks). They were selected from among 165 patients with stroke who were admitted to our rehabilitation centre from September 1, 1995 to March 31, 1997.

METHODS

Two 2-week facilitation technique sessions (more than 100 repetitions a day for each of 5 kinds of movement) were applied at 2-week intervals in patients with hemiplegia, who were being treated with continuous conventional rehabilitation exercise without the facilitation technique for hemiplegia. Motor function of the affected lower limb (Brunnstrom Recovery Stage of hemiplegia, the foot-tap test and the strength of knee extension/flexion) and walking velocity were evaluated at 2-week intervals.

RESULTS

Significant improvements in Brunnstrom Stage, foot-tapping and the strength of knee extension/flexion of the affected lower limb were seen after the first conventional rehabilitation exercise session and after the first and second facilitation technique and conventional rehabilitation exercise sessions. The improvements after facilitation technique and conventional rehabilitation exercise sessions were significantly greater than those after the preceding conventional rehabilitation exercise sessions.

CONCLUSION

Intensive repetition of movement elicited by the facilitation technique (chiefly proprioceptive neuromuscural facilitation pattern, stretch reflex and skin-muscle reflex) improved voluntary movement of a hemiplegic lower limb in patients with brain damage.

Functional and locomotive characteristics of stroke survivors in Japanese community-based rehabilitation

OBJECTIVE

The purposes of this study were as follows: (1) to compare the characteristics of functional fitness of Japanese stroke survivors with those of control subjects of a similar age; and (2) to relate these characteristics to the extent of physical impairment and the period after stroke onset to better design community-based rehabilitation programs for stroke survivors.

DESIGN

One hundred fifty-three stroke survivors who participated in community-based rehabilitation and 119 control subjects were measured. Twelve performance test items were designed to assess functional fitness.

RESULTS

The average functional fitness score for the stroke survivors was significantly lower than that of the control group. However, some survivors had higher performance scores than the control group. Significant correlations were shown between some functional fitness items and Brunnstrom recovery stage in the stroke survivors.

CONCLUSION

The large variability in functional fitness scores for stroke survivors indicates a need to design variable rehabilitation programs so that survivors can be grouped according to their specific levels of functional fitness.

Reliability and comparison of weight-bearing ability during standing tasks for individuals with chronic stroke

OBJECTIVES

To determine the test-retest reliability over 2 separate days for weight-bearing ability during standing tasks in individuals with chronic stroke and to compare the weight-bearing ability among 5 standing tasks for the paretic and nonparetic limbs.

DESIGN

Prospective study using a convenient sample.

SETTING

Free-standing tertiary rehabilitation center.

PARTICIPANTS

Fifteen community-dwelling stroke individuals with moderate motor deficits; volunteer sample.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Weight-bearing ability as measured by the vertical ground reaction force during 5 standing tasks (rising from a chair, quiet standing, weight-shifting forward, backward, laterally).

RESULTS

The weight-bearing ability was less for the paretic limb compared with the nonparetic limb, but the intraclass correlation coefficients were high (.95-.99) for both limbs between the 2 sessions for all 5 tasks. The forward weight-shifting ability was particularly low in magnitude on the paretic side compared with the other weight-shifting tasks. In addition, the forward weight-shift ability of the nonparetic limb was also impaired but to a lesser extent. Large asymmetry was evident when rising from a chair, with the paretic limb bearing a mean 296N and the nonparetic side bearing a mean 458N. The weight-bearing ability during all 5 tasks correlated with one another (r range,.56-.94).

CONCLUSIONS

Weight-bearing ability can be reliably measured and may serve as a useful outcome measure in individuals with stroke. We suggest that impairments of the hemiparetic side during forward weight shifting and sit-to-stand tasks presents a challenge to the motor systems of individuals with stroke, which may account for the poor balance that is often observed in these individuals.

Magnetic resonance elastography of skeletal muscle

While the contractile properties of skeletal muscle have been studied extensively, relatively little is known about the elastic properties of muscle in vivo. Magnetic resonance elastography (MRE) is a phase contrast-based method for observing shear waves propagating in a material to determine its stiffness. In this work, MRE is applied to skeletal muscle under load to quantify the change in stiffness with loading. A mathematical model of muscle is developed that predicts a linear relationship between shear stiffness and muscle load. The MRE technique was applied to bovine muscle specimens (N = 10) and human biceps brachii in vivo (N = 5). Muscle stiffness increased linearly for both passive tension (14.5 +/- 1.77 kPa/kg) and active tension, in which the increase in stiffness was dependent upon muscle size, as predicted by the model. A means of noninvasively assessing the viscoelastic pro-perties of skeletal muscle in vivo may provide a useful method for studying muscle biomechanics in health and disease.