Quadriceps muscle weakness following acute hemiplegic stroke

Factors influencing the reduction in quadriceps muscle thickness in the paretic limbs of patients with acute stroke

BACKGROUND & AIMS

Muscle atrophy is an early event that occurs after stroke, but there are few reports on the changes in skeletal muscle thickness in acute stroke. This study investigated the factors contributing to reduced muscle thickness in patients with acute stroke.

METHODS

In total, 51 patients with stroke and the National Institute of the Health Stroke Scale (NIHSS) > 3 were included in our study. They were admitted to our hospital between July 2017 and May 2020. The quadriceps muscle thickness was measured with an ultrasound device within 2 days after admission and 14 days later. The collected data included age, sex, body mass index, stroke type, neuromuscular electrical stimulation, NIHSS, serum albumin at admission, start of enteral nutrition, Functional Oral Intake Scale (FOIS), start of mobilization and ambulation, number of physical and occupational therapy units, C-reactive protein at admission and whether surgery had been performed. These data were retrospectively retrieved from medical documents. A dietician calculated energy intake, protein intake, and energy adequacy. Multiple regression analysis was used to identify the factors associated with reduced quadriceps muscle thickness. The independent variables were NIHSS, date of start of enteral feeding, protein intake, FOIS, date of mobilization, and date of start of ambulation training.

RESULTS

The rate of change in quadriceps muscle thickness of the paretic limb was -15.3 % (interquartile range, -46.1-14.8 %). Multiple regression analysis showed that the factors responsible for the decrease in muscle thickness on the paretic side were FOIS (β: 0.376; 95 % Cl, 0.999 to 4.541) and the start date of ambulation (β: -0.378; 95 % Cl, -2.575 to -0.543), with a multiple correlation coefficient of 0.456.

CONCLUSION

The FOIS and the start date of ambulation after acute stroke were related to the rate of reduction in muscle thickness on the paretic side.

Biochemical, biomechanical and imaging biomarkers of ischemic stroke: Time for integrative thinking

Stroke is one of the leading causes of adult disability affecting millions of people worldwide. Post-stroke cognitive and motor impairments diminish quality of life and functional independence. There is an increased risk of having a second stroke and developing secondary conditions with long-term social and economic impacts. With increasing number of stroke incidents, shortage of medical professionals and limited budgets, health services are struggling to provide a care that can break the vicious cycle of stroke. Effective post-stroke recovery hinges on holistic, integrative and personalized care starting from improved diagnosis and treatment in clinics to continuous rehabilitation and support in the community. To improve stroke care pathways, there have been growing efforts in discovering biomarkers that can provide valuable insights into the neural, physiological and biomechanical consequences of stroke and how patients respond to new interventions. In this review paper, we aim to summarize recent biomarker discovery research focusing on three modalities (brain imaging, blood sampling and gait assessments), look at some established and forthcoming biomarkers, and discuss their usefulness and complementarity within the context of comprehensive stroke care. We also emphasize the importance of biomarker guided personalized interventions to enhance stroke treatment and post-stroke recovery.

Treadmill training impacts the skeletal muscle molecular clock after ischemia stroke in rats

Objective

Stroke is frequently associated with muscle mass loss. Treadmill training is considered the most effective treatment for sarcopenia. Circadian rhythms are closely related to exercise and have been extensively studied. The skeletal muscle has its molecular clock genes. Exercise may regulate skeletal muscle clock genes. This study evaluated the effects of early treadmill training on the skeletal muscle molecular clock machinery in rats with stroke and determined the relationship of these changes with exercise-induced improvements in skeletal muscle health.

Materials and methods

Overall, 168 Sprague-Dawley rats were included in this study. We established an ischemic stroke rat model of sarcopenia. Finally, 144 rats were randomly allocated to four groups (36 per group): normal, sham, middle cerebral artery occlusion, and training. Neurological scores, rotating rod test, body weight, muscle circumference, wet weight, and hematoxylin-eosin staining were assessed. Twenty-four rats were used for transcriptome sequencing. Gene and protein expressions of skeletal muscles, such as brain muscle arnt-like 1, period 1, and period 2, were measured by quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assays.

Results

Neurological function scores and rotating rod test results improved after treadmill training. Nine differentially expressed genes were identified by comparing the sham group with the hemiplegic side of the model group. Seventeen differentially expressed genes were identified between the hemiplegic and non-hemiplegic sides. BMAL1, PER1, and PER2 mRNA levels increased on both sides after treadmill training. BMAL1 expression increased, and PER1 expression decreased on both sides, whereas PER2 expression decreased on the hemiplegic side but increased on the non-hemiplegic side.

Conclusion

Treadmill training can mitigate muscle loss and regulate skeletal muscle clock gene expression following ischemic stroke. Exercise affects the hemiplegic side and has a positive regulatory effect on the non-hemiplegic side.

Hospital-associated sarcopenia and the preventive effect of high energy intake along with intensive rehabilitation in patients with acute stroke

OBJECTIVES

Hospital-associated sarcopenia is prevalent and associated with poor outcomes in acutely admitted patients. Prevention of developing sarcopenia during hospitalization is an important factor in stroke management. Therefore, this study aimed to investigate whether energy intake and rehabilitation duration contribute to the prevention of hospital-associated sarcopenia in patients with acute stroke.

METHODS

Patients with acute stroke were included in this study. Energy intake during the first week of hospitalization was classified as "high" or "low" based on the reported cutoff value. Rehabilitation time during hospitalization was classified as "intense" or "mild" based on the median. The four groups were compared based on the combinations of high or low energy intake and intense or mild rehabilitation. The primary outcome was the development of sarcopenia during hospitalization. The secondary outcome was the Functional Independence Measure motor item gain during hospitalization. Multivariate analysis was performed with the primary or secondary outcome as the dependent variable and the effect of each group on the outcome was examined.

RESULTS

A total of 112 participants (mean age = 70.6 y; 63 men) were included in the study. Multivariate analysis found that high × intense (odds ratio = 0.113; P = 0.041) was independently associated with the development of sarcopenia during hospitalization (i.e., hospital-related sarcopenia). High × intense (β = 0.395; P < 0.001) was independently associated with the gain of Functional Independence Measure motor items.

CONCLUSIONS

In patients with acute stroke, the combination of high energy intake and adequate rehabilitation time is associated with prevention of hospital-associated sarcopenia.

Neuromuscular electrical stimulation during maximal voluntary contraction: a Delphi survey with expert consensus

PURPOSE

The use of electrical stimulation to assess voluntary activation of muscle/s is a popular method employed in numerous exercise science and health research settings. This Delphi study aimed to collate expert opinion and provide recommendations for best practice when using electrical stimulation during maximal voluntary contractions.

METHODS

A two-round Delphi study was undertaken with 30 experts who completed a 62-item questionnaire (Round 1) comprising of open- and closed-ended questions. Consensus was assumed if ≥ 70% of experts selected the same response; such questions were removed from the subsequent Round 2 questionnaire. Responses were also removed if they failed to meet a 15% threshold. Open-ended questions were analysed and converted into closed-ended questions for Round 2. It was assumed there was no clear consensus if a question failed to achieve a ≥ 70% response in Round 2.

RESULTS

A total of 16 out of 62 (25.8%) items reached consensus. Experts agreed that electrical stimulation provides a valid assessment of voluntary activation in specific circumstances, such as during maximal contraction, and this stimulation can be applied at either the muscle or the nerve. Experts recommended using doublet stimuli, self-adhesive electrodes, a familiarisation session, real-time visual or verbal feedback during the contraction, a minimum current increase of + 20% to ensure supramaximal stimulation, and manually triggering stimuli.

CONCLUSION

The results of this Delphi consensus study can help researchers make informed decisions when considering technical parameters when designing studies involving electrical stimulation for the assessment of voluntary activation.

Structural and pathophysiological muscle changes up to one year after post-stroke hemiplegia: a systematic review

INTRODUCTION

Muscle changes after stroke cannot be explained solely on the basis of corticospinal bundle damage. Muscle-specific changes contribute to limited functional recovery but have been poorly characterized.

EVIDENCE ACQUISITION

We conducted a systematic review of muscular changes occurring at the histological, neuromuscular and functional levels during the first year after the onset of post-stroke hemiplegia. A literature search was performed on PubMed, Embase and CINHAL databases up to November 2022 using a keyword combination comprising cerebral stroke, hemiplegic, atrophy, muscle structure, paresis, skeletal muscle fiber type, motor unit, oxidative stress, strength, motor control.

EVIDENCE SYNTHESIS

Twenty-seven trial reports were included in the review, out of 12,798 articles screened. Structural modifications described on the paretic side include atrophy, transformation of type II fibers into type I fibers, decrease in fiber diameter and apparent myofilament disorganization from the first week post-stroke up to the fourth month. Reported biochemical changes comprise the abnormal presence of lipid droplets and glycogen granules in the subsarcolemmal region during the first month post-stroke. At the neurophysiological level, studies indicate an early decrease in the number and activity of motor units, correlated with the degree of motor impairment. All these modifications were present to a lesser degree on the non-paretic side. Although only sparse data concerning the subacute stage are available, these changes seem to appear during the first two weeks post-stroke and continue up to the third or fourth month.

CONCLUSIONS

Considering these early pathophysiological changes on both the paretic and non-paretic sides, it seems crucial to promptly stimulate central and also peripheral muscular activation after stroke through specific rehabilitation programs focused on the maintenance of muscle capacities associated with neurological recovery or plasticity.

Electrical stimulation for investigating and improving neuromuscular function in vivo: Historical perspective and major advances

This historical review summarizes the major advances - particularly from the last 50 years - in transcutaneous motor-level electrical stimulation, which can be used either as a tool to investigate neuromuscular function and its determinants (electrical stimulation for testing; EST) or as a therapeutic/training modality to improve neuromuscular and physical function (neuromuscular electrical stimulation; NMES). We focus on some of the most important applications of electrical stimulation in research and clinical settings, such as the investigation of acute changes, chronic adaptations and pathological alterations of neuromuscular function with EST, as well as the enhancement, preservation and restoration of muscle strength and mass with NMES treatment programs in various populations. For both EST and NMES, several major advances converge around understanding and optimizing motor unit recruitment during electrically-evoked contractions, also taking into account the influence of stimulation site (e.g., muscle belly vs nerve trunk) and type (e.g., pulse duration, frequency, and intensity). This information is equally important both in the context of mechanistic research of neuromuscular function as well as for clinicians who believe that improvements in neuromuscular function are required to provide health-related benefits to their patients.

Determinants of in-hospital muscle loss in acute ischemic stroke - Results of the Muscle Assessment in Stroke Study (MASS)

BACKGROUND & AIMS

There is a change in the mass and composition of paretic and non-paretic skeletal muscles in the chronic phase of stroke. The multi-center, prospective, and observational Muscle Assessment in Stroke Study (MASS) was performed to evaluate the degree of muscle loss during the in-hospital acute stroke setting and determine factors contributing to this loss.

METHODS

Acute dysphagic ischemic stroke patients (n = 107) admitted to neuro-intensive care units were evaluated by computed tomography on days 1 and 14 after admission to determine the cross-sectional muscle area (CSMA) at the level of the mid-humerus, mid-thigh, and third lumbar vertebra. The percentage change in CSMA and variables associated with this change were evaluated by univariate and multivariate analyses.

RESULTS

There were significant reductions in CSMA in all the muscle groups analyzed; the most prominent change was observed in the arms (both: 14.2 ± 10.7%; paretic: 17.7 ± 11.6%; non-paretic: 10.1 ± 12.5%), followed by the muscles in the legs (both: 12.4 ± 8.7%; paretic: 12.9 ± 9.9%; non-paretic: 12.0 ± 9.3%) and L3-vertebra level (5.6 ± 9.8%) (P < 0.001 for all). Higher calorie (r = -0.378, P < 0.001) or protein (r = -0.352, P < 0.001) intake was negatively associated with the decrease in CSMA of upper extremities. A substantial protein (≥0.4 g/kg/d) or calorie (≥5 kcal/kg/d) gap between targeted or actual intake was related to a larger decrease in CSMA in all the anatomic regions (P ≤ 0.05 for all). Other significant predictors of muscle loss included history of diabetes mellitus, male sex, higher BMI, in-hospital infections, and the necessity for invasive mechanical ventilation.

CONCLUSIONS

There is a considerable degree of loss in the global muscle mass in acute ischemic stroke patients over a two-week period. Along with several factors, falling significantly behind the daily protein or calorie targets was related to the decrease in the muscle area. TRIAL REGISTRATION INFORMATION: clinicaltrials.gov identifier NCT03825419.

Strength Training of the Nonhemiplegic Side Promotes Motor Function Recovery in Patients With Stroke: A Randomized Controlled Trial

OBJECTIVE

To observe the effect of strength training of the nonhemiplegic side (NHS) on balance function, mobility, and muscle strength of patients with stroke.

DESIGN

A single-blinded (evaluator) randomized controlled trial.

SETTING

A tertiary hospital rehabilitation center.

PARTICIPANTS

139 patients with first stroke (N=139) were recruited and randomly separated into a trial (n=69) or control group (n=70).

INTERVENTIONS

The control group underwent usual rehabilitation training, including step training and trunk control training in standing position. The trial group underwent strength training of NHS on the basis of usual rehabilitation training. The strength training of NHS included lower limb stepping training with resisting elastic belt and upper limb pulling elastic belt training in standing position. The training for both groups was 45 min, once a day, 5 days a week for 6 weeks.

MAIN OUTCOME MEASURES

Balance evaluation was done with the Berg Balance Scale (BBS); mobility assessment with the 6-minute walk test (6-MWT); activities of daily life was examined via the modified Barthel Index (MBI); muscle strengths of the biceps brachii, iliopsoas, and quadriceps were measured via the isokinetic muscle strength testing system. All assessments were performed at baseline (T0) and after intervention (T1).

RESULTS

The trial group performed better than control group in BBS scores (adjusted mean difference: 6.83; 95% confidence interval [CI]: 4.71-8.94) and 6-MWT (adjusted mean difference: 50.32; 95% CI: 40.58-60.05) after intervention. In terms of muscle strength of the hemiplegic side, the trial group displayed greater gains in biceps brachii, iliopsoas, and quadriceps than control group after intervention.

CONCLUSION

Strength training of the NHS can promote recovery of balance, mobility, and muscle strength of the paretic side of patients with stroke.

Trajectories of the Prevalence of Sarcopenia in the Pre- and Post-Stroke Periods: A Systematic Review

Interventions for stroke-related sarcopenia in patients with stroke are needed, but the details of the target population are unclear. This systematic review aimed to identify trajectories of the prevalence of sarcopenia in the pre- and post-stroke periods and to determine the diagnostic criteria used in patients with stroke. We searched for literature in six databases: MEDLINE, EMBASE, Web of Science, Cochrane Central Register of Controlled Trials, CINAHL, and Ichushi-web (in Japanese). We included 1627 studies in the primary screening, and 35 studies were finally included. Of the 35 studies, 32 (91.4%) included Asian patients, and the criteria of the Asian Working Group for Sarcopenia was mainly used as the diagnostic criteria. Nineteen studies used muscle strength and muscle mass to diagnose sarcopenia, whereas a full assessment, including physical performance, was performed in five studies. The estimated prevalences of sarcopenia in pre-stroke, within 10 days of stroke, and from 10 days to 1 month after stroke were 15.8%, 29.5%, and 51.6%, respectively. Sarcopenia increased by approximately 15% from pre-stroke to 10 days, and increased by approximately 20% from 10 days to 1 month. Healthcare providers should note that the prevalence of sarcopenia increases during the acute phase in patients with stroke.

Quantitative Evaluation of Biceps Brachii Muscle by Shear Wave Elastography in Stroke Patients

Purpose

The present study aimed to investigate the differences in muscle size and shear wave speed (SWS) values of biceps brachii muscle (BBM) between stroke survivors and healthy controls.

Methods

This study comprised 61 stroke survivors and 24 healthy subjects, examined at Guangzhou First People's Hospital within one year. Each participant underwent ultrasonic examinations for recording some specific measurement indicators, including muscle thickness, cross-sectional area (CSA), and shear wave speed (SWS) of BBM. The muscular tension of the paretic arm was scored using the modified Ashworth scale (MAS). These above-mentioned indexes were compared between stroke survivors and healthy controls. Also, the correlations among SWS and MAS scores were assessed.

Results

When the lifting arm angle was set for 45°, the CSA and muscle thickness of BBM were obviously decreased in the paretic arms of stroke subjects compared to the non-paretic arms as well as the arms of healthy controls. Moreover, the paretic arms had obviously higher SWS than the non-paretic arms and the healthy arms at 45° or 90°. When the angles of paretic arms were lifted at 90° and 45°, respectively, a positive correlation was established between MAS and SWS.

Conclusion

Ultrasonic examination assessing muscle thickness, CSA, and SWS of the BBM could be used as a means of assessment of the paretic arms of stroke survivors.

Sarcopenia and nervous system disorders

Sarcopenia has an insidious start that can induce physical malfunction, raise the risk of falls, disability, and mortality in the old, severely impair the aged persons' quality of life and health. More and more studies have demonstrated that sarcopenia is linked to neurological diseases in recent years. This review examines the advancement of sarcopenia and neurological illnesses research.

Frailty in Stroke-A Narrated Review

This narrative review provides a summary introduction to the relationship between stroke and physical and cognitive frailty syndromes and the neuro-inflammatory similarities (including inflammaging) between the two. The review argues the potential effects of Post COVID-19 Neurological Syndrome (PCNS, also known as Long COVID) with similar pathophysiology. Many patients who have suffered from acute stroke experience long-lasting symptoms affecting several organs including fatigue, brain fog, reduced physical activity, loss of energy, and loss of cognitive reserve, culminating in the loss of independence and poor quality of life. This is very similar to the emerging reports of PCNS from different parts of the world. Stroke, particularly in older adults with comorbidities appears to impact the health and welfare of patients by reducing central neuronal input and neuromuscular function, with muscular atrophy and neuropsychiatric complications. The cumulative effects can potentially lead to a range of physical and cognitive frailty syndromes, which, in many cases may be attributed to persistent, maladapted, low grade, chronic inflammation. Meanwhile, post-COVID-19 Neurological Syndrome (also known as Long COVID Syndrome) appears to share a similar trajectory, adding further urgency for investigations into the mechanisms underlying this constellation of symptoms.

Ultrasound Evaluation of the Rectus Femoris for Sarcopenia in Patients with Early Subacute Stroke

We investigated the ultrasound characteristics of the rectus femoris for sarcopenia detected by dual-energy X-ray absorptiometry (DEXA) in the early subacute stroke phase. Physical features (age, sex, body mass index, and circumference of thigh) and performances (modified Barthel index in Korean, functional ambulation categories, and mini-mental state examination in Korean) were measured. The thickness of the fat layer, the thickness of the rectus femoris (TRF), echo intensity (EI), EI to TRF ratio, and strain ratio of elastography (SRE) were measured by ultrasound in 30 patients with first-ever stroke (male: n = 20). Appendicular lean body mass was measured by DEXA. Sarcopenia was defined according to the Foundation for the National Institutes of Health Sarcopenia Project. In total, 14 patients were in the sarcopenia group, and 16 were in the non-sarcopenia group. Clinical characteristics were similar between the two groups. In the sarcopenia group, TRF was significantly decreased in the paretic (p < 0.026) and non-paretic sides (p < 0.01), and the EI to TRF ratio on the paretic side was significantly increased (p < 0.049). Multivariate binary logistic regression showed that TRF on the non-paretic side was independently and significantly associated with sarcopenia (OR = 0.616, 95% CI: 0.381-0.996). The EI and SRE were not significant between the two groups. In the early subacute stroke phase, TRF on the non-paretic side is a key factor for quantitative evaluation of sarcopenia, and the EI to TRF ratio on the paretic side is also a meaningful qualitative evaluation of sarcopenia.

Lost in Translation: Simple Steps in Experimental Design of Neurorehabilitation-Based Research Interventions to Promote Motor Recovery Post-Stroke

Stroke continues to be a leading cause of disability. Basic neurorehabilitation research is necessary to inform the neuropathophysiology of impaired motor control, and to develop targeted interventions with potential to remediate disability post-stroke. Despite knowledge gained from basic research studies, the effectiveness of research-based interventions for reducing motor impairment has been no greater than standard of practice interventions. In this perspective, we offer suggestions for overcoming translational barriers integral to experimental design, to augment traditional protocols, and re-route the rehabilitation trajectory toward recovery and away from compensation. First, we suggest that researchers consider modifying task practice schedules to focus on key aspects of movement quality, while minimizing the appearance of compensatory behaviors. Second, we suggest that researchers supplement primary outcome measures with secondary measures that capture emerging maladaptive compensations at other segments or joints. Third, we offer suggestions about how to maximize participant engagement, self-direction, and motivation, by embedding the task into a meaningful context, a strategy more likely to enable goal-action coupling, associated with improved neuro-motor control and learning. Finally, we remind the reader that motor impairment post-stroke is a multidimensional problem that involves central and peripheral sensorimotor systems, likely influenced by chronicity of stroke. Thus, stroke chronicity should be given special consideration for both participant recruitment and subsequent data analyses. We hope that future research endeavors will consider these suggestions in the design of the next generation of intervention studies in neurorehabilitation, to improve translation of research advances to improved participation and quality of life for stroke survivors.

Accuracy and cut-off points of different models of knee extension strength analysis to identify walking performance in individuals with chronic stroke

BACKGROUND

Adequate muscle strength is essential for walking performance in individuals with stroke.

OBJECTIVE

To investigate the accuracy of different forms of muscle knee extension strength analysis to identify high or low walking performance in individuals with chronic stroke.

METHODS

Twenty-eight participants with a chronic stroke for more than six months participated. Independence for walking was judged by measurement of walking performance assessed for comfortable walking speed (CWS), maximum walking speed (MWS), and the Six Minute Walk Test (6MWT). Peak knee extension torque of the paretic side, non-paretic side, sum of the sides (SS), and difference in the sides (DS) was assessed during concentric movements using an isokinetic dynamometer.

RESULTS

The equation with greatest predictive capacity for CWS and MWS included the DS as the main predictor (R² of 0.65 and 0.71, respectively, p < 0.05). The variable with the greatest predictive capacity for 6MWT was time since injury (R² of 0.68, p < 0.05). The highest percentile for CWS in the receiver operating characteristic curve of DS was 25 Nm/kg (cut-off: -12.75 for CWS of 0.498 m/s). The 75th percentile of the 6MWT (324.3 m) was used as the cut-off for the SS (2.1 Nm/kg). The area under the curve for CWS was 0.76 (p < 0.05) on the DS and 0.75 (p < 0.05) for 6MWT on the SS.

CONCLUSION

The models of muscle knee extension strength analysis using the SS and DS presented moderate accuracy to identify walking performance in individuals with chronic stroke.

Malondialdehyde as a Useful Biomarker of Low Hand Grip Strength in Community-Dwelling Stroke Patients

The assessment of muscle strength by hand grip strength (HGS) is used to evaluate muscle weakness and wasting among stroke patients. This study aimed to investigate the association of oxidative stress/oxidative damage and inflammatory biomarkers with muscle strength and wasting, as evaluated by HGS, among community-dwelling post-stroke patients. The HGS of both paretic and non-paretic limbs was negatively associated with modified Rankin scale (mRS) values. The serum levels of catalase activity and malondialdehyde (MDA), and plasma tumor necrosis factor (TNF)-α levels were significantly increased in post-stroke patients compared with non-stroke controls. Further analysis highlighted that hydrogen peroxide was positively correlated with HGS in the paretic limbs. Interestingly, an elevated MDA level, excluding advanced age and high mRS, increased the risk of low HGS in the non-paretic limbs of stroke patients. This study suggests that there is a detrimental association between MDA and muscle strength and early muscle wasting among post-stroke patients. Hence, MDA is a potentially useful biomarker of muscle weakness and wasting in post-stroke patients living in the community.

Stroke and sarcopenia

Purpose of review

to evaluate recent scientific research studies related to the changes in skeletal muscle after stroke and the presence of sarcopenia in stroke survivors to establish its incidence and effects on function.

Recent Findings

Recently published findings on stroke-related sarcopenia are limited. This might be due to changes in the consensus definition of sarcopenia. Sarcopenia in stroke patients is estimated at 14 to 54%. The presence of sarcopenia at the time of a stroke can lead to worse recovery and functional outcomes.

Summary

Presence of sarcopenia prior to a stroke may be more common than suspected and can lead to worse functional recovery. Clinicians should be aware of this to better identify and treat stroke-related sarcopenia. Future research should focus on larger population studies to more accurately establish correlation between stroke and sarcopenia.

Focal brain ischemia in mice does not cause electrophysiological signs of critical illness neuropathy

OBJECTIVE

Critical illness polyneuropathy (CIP) is a common complication of severe systemic illness treated in intensive care medicine. Ischemic stroke leads to an acute critical injury of the brain with hemiparesis, immunosuppression and subsequent infections, all of which require extended medical treatment. Stroke-induced sarcopenia further contributes to poor rehabilitation and is characterized by muscle wasting and denervation in the paralytic, but also the unaffected limbs. Therefore, we asked whether stroke leads to an additional CIP-like neurodegeneration.

RESULTS

Focal brain ischemia was induced in adult mice by 60-min middle cerebral artery occlusion (MCAo) following reperfusion and led to functional deficits and marked hemispheric brain atrophy. Nerve conduction function and muscle potentials were measured in the ipsilateral sciatic nerve and gastrocnemius and quadriceps muscle with electroneurography/-myography on days 10, 22, 44 after stroke. An additional crush-injury to the sciatic nerve was included in two sham mice as positive control (sham +). We found no differences in nerve conduction function nor spontaneous electromyographic activity between MCAo and sham animals. Sham + mice developed marked reduction of the motor action potential amplitudes and conduction velocities with pathologic spontaneous activity. In conclusion, we found no peripheral nerve dysfunction/degeneration as signs of a CIP-like phenotype after MCAo.

Inclusion of People Poststroke in Cardiac Rehabilitation Programs in Canada: A Missed Opportunity for Referral

BACKGROUND

Evidence supports establishing a continuum of care from stroke rehabilitation (SR) to cardiac rehabilitation programs (CRPs). It is not known to what extent people poststroke are being integrated. This study aimed to determine the proportion of CRPs that accept referrals poststroke, barriers/facilitators, and eligibility criteria.

METHODS

A web-based questionnaire was sent to CRPs across Canada.

RESULTS

Of 160 questionnaires sent, 114 representatives (71%) of 130 CRPs responded. Of respondents, 65% (n = 74) reported accepting people with a diagnosis of stroke and doing so for a median of 11 years, 11 offering stroke-specific classes and an additional 6 planning inclusion. However, 62.5% of CRPs reported that < 11 patients participated in the last calendar year despite 88.5% reporting no limit to the number they could enroll. Among CRPs, 25% accepted only patients with concurrent cardiac diagnoses, living in the community (47.8%), and without severe mobility (70.1%), communication (80.6%), or cognitive (85.1%) deficits. The 2 most influential barriers and facilitators among all CRPs were funding and staffing. The fourth greatest barrier was lack of poststroke referrals, and third to sixth facilitators were SR/CRP collaboration to ensure appropriate referrals (third) and to increase referrals (sixth), toolkits for prescribing resistance (fourth), and aerobic training (fifth). CRP characteristics associated with accepting stroke were a hybrid program model, a medium program size, and having a falls prevention component.

CONCLUSIONS

Most CRPs accept patients poststroke, but few participate. Therefore, establishing SR/CRP partnerships to increase appropriate referrals, using a toolkit to help operationalize exercise components, and allocating funding/resources to CRPs may significantly increase access to secondary prevention strategies.

Correlation between lower limb muscle asymmetry during the sit-to-stand task and spatiotemporal gait asymmetry in subjects with stroke

The purpose of this study was to investigate the relationship between the both lower limb muscle asymmetry during sit-to-stand (STS) and spatiotemporal gait asymmetry in subjects with stroke. Twenty-nine patients were included in this study, lower limb muscle (rectus femoris, tibialis anterior, gastrocnemius) asymmetry during STS, five times sit-to-stand (FTSTS) and spatiotemporal (speed, step length, step time, swing time, stance time, single support time) gait asymmetry were measured. According to the results of the measurement, significant positive correlations between gastrocnemius and rectus femoris asymmetry during STS and step length asymmetry. Furthermore, significant positive correlations between rectus femoris asymmetry during STS and step time asymmetry. In addition, significant negative correlations between the FTSTS and gait speed. This study's results suggested that necessary to apply exercise that the gastrocnemius and rectus femoris symmetry during STS for improving step length and step time symmetry of gait, and necessary to apply exercise that increase STS speed for gait speed.

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.

Corticosterone-Mediated Body Weight Loss Is an Important Catabolic Process for Poststroke Immunity and Survival

Background and Purpose- Stroke-induced acute severe body weight (BW) loss is associated with a high rate of mortality during a critical poststroke period. Several interventions to reduce weight loss, however, have not been successful. Currently, the biological significance of this extraordinary catabolic process is not well understood. Spleen-derived monocytes/macrophages (MMs) are the major immune cells recruited to the injured brain. The trafficking of MMs has been shown to be important for tissue repair and recovery. The purpose of the study is to investigate whether the BW reduction is essential for MM-mediated immune response for mice to survive and whether a corticosterone-mediated catabolic event underlies the processes. Methods- C57BL/6 male mice (12-week-old) were subjected to transient middle cerebral artery occlusion. BW, total MMs, and their Ly-6Chigh and Ly-6Clow subsets were determined in the spleen, blood, and the brain in poststroke mice. Poststroke survival rate and MM subsets were determined in mice with adrenalectomy, sham-adrenalectomy, and adrenalectomy mice supplemented with corticosterone. Results- Stroke reduced BW with a maximum reduction at day 3 poststroke (17.2±5.2%). The reduction at day 3 was positively linked to injury severity and selective depletion of MMs, but no other types of immune cells, in the spleen. Notably, the splenic MM depletion was significantly greater in mice with severe BW reduction (≥18% at day 3). In the blood, stroke depleted circulating MMs to a similar degree in animals with moderate and severe BW loss. Ly-6C+ monocyte infiltration in the poststroke brain was greater in mice with severe BW loss. Blocking the catabolic process by adrenalectomy significantly increased poststroke mortality, but the mortality was partially rescued by corticosterone supplement in adrenalectomy mice. Conclusions- Stroke-induced BW loss facilitates MM-mediated immune response, and the adrenal corticosterone-mediated catabolic process is necessary for poststroke survival. Visual Overview- An online visual overview is available for this article.

Amino acids in post-stroke rehabilitation

Objectives: Patients with stroke are prone to disability due to muscle hypercatabolism. We aim to review this concept based on available data on benefits of amino acid supplementation in post-stroke rehabilitation.Method: The search was performed on Medline and Embase in January 2019. Randomized controlled studies, observational studies and case reports conducted in the last 15 years on the supplementation of amino acids in post-stroke rehabilitation patients were included.Result: Amino acids prevent muscle hypercatabolism in post stroke patients by suppressing myofibrillar protein and skeletal muscle degradation. Stroke patients supplemented with amino acids led to an improvement of functional and physical performance.Discussion: Muscle protein hypercatabolism and sequestration of amino acids from skeletal muscles occur cyclically in post-stroke patients to counter each other. There is a resultant deficit of amino acids which is unmet. Amino acids have antiproteolytic effect. Its supplementation prevents muscle wasting and improves rehabilitation by promoting physical performance, muscle strength, mass, and function.

Loss of selective wrist muscle activation in post-stroke patients

Purpose: Loss of selective muscle activation after stroke contributes to impaired arm function, is difficult to quantify and is not systematically assessed yet. The aim of this study was to describe and validate a technique for quantification of selective muscle activation of wrist flexor and extensor muscles in a cohort of post-stroke patients. Patterns of selective muscle activation were compared to healthy volunteers and test-retest reliability was assessed.Materials and methods: Activation Ratios describe selective activation of a muscle during its expected optimal activation as agonist and antagonist. Activation Ratios were calculated from electromyography signals during an isometric maximal torque task in 31 post-stroke patients and 14 healthy volunteers. Participants with insufficient voluntary muscle activation (maximal electromyography signal <3SD higher than baseline) were excluded.Results: Activation Ratios at the wrist were reliably quantified (Intraclass correlation coefficients 0.77-0.78). Activation Ratios were significantly lower in post-stroke patients compared to healthy participants (p < 0.05).Conclusion: Activation Ratios allow for muscle-specific quantification of selective muscle activation at the wrist in post-stroke patients. Loss of selective muscle activation may be a relevant determinant in assigning and evaluating therapy to improve functional outcome.Implications for RehabilitationLoss of selective muscle activation after stroke contributes to impaired arm function, is difficult to quantify and is not systematically assessed yet.The ability for selective muscle activation is a relevant determinant in assigning and evaluating therapy to improve functional outcome, e.g., botulinum toxin.Activation Ratios allow for reliable and muscle-specific quantification of selective muscle activation in post-stroke patients.

A Novel Interpretation of Sample Entropy in Surface Electromyographic Examination of Complex Neuromuscular Alternations in Subacute and Chronic Stroke

The objective of this paper was to develop sample entropy (SampEn) as a novel surface electromyogram (EMG) biomarker to quantitatively examine post-stroke neuromuscular alternations. The SampEn method was performed on surface EMG interference patterns recorded from biceps brachii muscles of nine healthy control subjects, fourteen subjects with subacute stroke, and eleven subjects with chronic stroke, respectively. Measurements were collected during isometric contractions of elbow flexion at different constant force levels. By producing diagnostic decisions for individual muscles, two categories of abnormalities in some paretic muscles were discriminated in terms of abnormally increased and decreased SampEn. The efficiency of the SampEn was demonstrated by its comparable performance with a previously reported clustering index (CI) method. Mixed SampEn (or CI) patterns were observed in paretic muscles of subjects with stroke indicating complex neuromuscular changes at work as a result of a hemispheric brain lesion. Although both categories of SampEn (or CI) abnormalities were observed in both subacute and chronic stages of stroke, the underlying processes contributing to the SampEn abnormalities might vary a lot in stroke stage. The SampEn abnormalities were also found in contralateral muscles of subjects with chronic stroke indicating the necessity of applying interventions to contralateral muscles during stroke rehabilitation. Our work not only presents a novel method for quantitative examination of neuromuscular changes, but also explains the neuropathological mechanisms of motor impairments and offers guidelines for a better design of effective rehabilitation protocols toward improved motor recovery.

Integrating Individuals With Stroke Into Cardiac Rehabilitation Following Traditional Stroke Rehabilitation: Promoting a Continuum of Care

Following stroke, people are at high risk for repeat strokes and for complications related to coronary artery disease (CAD). Indeed, stroke and CAD share many of the same risk factors. Unfortunately, patients become sedentary after stroke, which leads to cardiorespiratory deconditioning as well as muscle atrophy and weakness that in turn leads to deterioration in metabolic, cardiorespiratory, and functional health. Access to intensive secondary prevention programs with structured exercise components that include both aerobic and resistance training can help to prevent and reverse these health hazards. Traditional stroke rehabilitation programs face many barriers to providing exercise programming early post-stroke, such as lack of available therapy time and short length of stay, lack of equipment for exercise and assessments, and concerns for patient safety related to cardiac status. Building a partnership between traditional stroke rehabilitation programs and cardiac rehabilitation by operationalizing an automatic referral process has the potential to affect secondary prevention of stroke and cardiovascular risk significantly. It could also mitigate the tremendous burden on patients and their family members. This is an easily identified group that can achieve significant gains over multiple domains of recovery with the targeted exercise and risk-factor modification components offered by comprehensive cardiac rehabilitation programs.

A Soft-Inflatable Exosuit for Knee Rehabilitation: Assisting Swing Phase During Walking

In this paper, we present a soft-inflatable exosuit to assist knee extension during gait training for stroke rehabilitation. The soft exosuit is designed to provide 25% of the knee moment required during the swing phase of the gait cycle and is integrated with inertial measurement units (IMUs) and smart shoe insole sensors to improve gait phase detection and controller design. The stiffness of the knee joint during level walking is computed using inverse dynamics. The soft-inflatable actuators, with an I cross-section, are mechanically characterized at varying angles to enable generation of the required stiffness outputs. A linear relation between the inflatable actuator stiffness and internal pressure as a function of the knee angle is obtained, and a two-layer stiffness controller is implemented to assist the knee joint by providing appropriate stiffness during the swing phase. Finally, to evaluate the ability of the exosuit to assist in swing motion, surface-electromyography (sEMG) sensors are placed on the three muscle groups of the quadriceps and two groups of the hamstrings, on three healthy participants. A reduction in muscle activity of the rectus femoris, vastus lateralis, and vastus medialis is observed, which demonstrates feasibility of operation and potential future usage of the soft inflatable exosuit by impaired users.

Aerobic With Resistance Training or Aerobic Training Alone Poststroke: A Secondary Analysis From a Randomized Clinical Trial

BACKGROUND

Stroke is associated with muscle atrophy and weakness, mobility deficits, and cardiorespiratory deconditioning. Aerobic and resistance training (AT and RT) each have the potential to improve deficits, yet there is limited evidence on the utility of combined training.

OBJECTIVE

To examine the effects of AT+RT versus AT on physiological outcomes in chronic stroke with motor impairments.

METHODS

Participants (n = 73) were randomized to 6 months of AT (5 d/wk) or AT+RT (3 and 2 d/wk, respectively). Outcomes included those related to body composition by dual-energy X-ray absorptiometry, mobility (6-minute walk distance [6MWD], sit-to-stand, and stair climb performance), cardiorespiratory fitness (VO_2peak, oxygen uptake at the ventilatory threshold [VO_2VT]), and muscular strength.

RESULTS

A total of 68 (93.2%) participants (age, mean ± SD = 63.7 ± 11.9) completed the study. AT+RT and AT yielded similar and significant improvements in 6MWD (39.9 ± 55.6 vs 36.5 ± 63.7 m, P = .8), VO_2peak (16.4% ± 43.8% vs 15.2% ± 24.7%, P = .9), sit-to-stand time (-2.3 ± 5.1 vs 1.02 ± 9.5 s, P = .05), and stair climb performance (8.2% ± 19.6% vs 7.5% ± 23%, P = .97), respectively. AT+RT produced greater improvements than AT alone for total body lean mass (1.23 ± 2.3 vs 0.27 ± 1.6 kg, P = .039), predominantly trunk ( P = .02) and affected-side limbs ( P = .04), VO_2VT (19.1% ± 26.8% vs 10.5% ± 28.9%, P = .046), and upper- and lower-limb muscular strength ( P < .03, all except affected-side leg).

CONCLUSION

Despite being prescribed 40% less AT, AT+RT resulted in similar and significant improvement in mobility and VO_2peak, superior improvements in VO_2VT and muscular strength, and an almost 5-fold greater increase in lean mass compared with AT. RT is the most neglected exercise component following stroke but should be prescribed with AT for metabolic, cardiorespiratory, and strength recovery.

Surface Electromyographic Examination of Poststroke Neuromuscular Changes in Proximal and Distal Muscles Using Clustering Index Analysis

Whether stroke-induced paretic muscle changes vary across different distal and proximal muscles remains unclear. The objective of this study was to compare paretic muscle changes between a relatively proximal muscle (the biceps brachii muscle) and two distal muscles (the first dorsal interosseous muscle and the abductor pollicis brevis muscle) following hemisphere stroke using clustering index (CI) analysis of surface electromyograms (EMGs). For each muscle, surface EMG signals were recorded from the paretic and contralateral sides of 12 stroke subjects versus the dominant side of eight control subjects during isometric muscle contractions to measure the consequence of graded levels of contraction (from a mild level to the maximal voluntary contraction). Across all examined muscles, it was found that partial paretic muscles had abnormally higher or lower CI values than those of the healthy control muscles, which exhibited a significantly larger variance in the CI via a series of homogeneity of variance tests (p < 0.05). This finding indicated that both neurogenic and myopathic changes were likely to take place in paretic muscles. When examining two distal muscles of individual stroke subjects, relatively consistent CI abnormalities (toward neuropathy or myopathy) were observed. By contrast, consistency in CI abnormalities were not found when comparing proximal and distal muscles, indicating differences in motor unit alternation between the proximal and distal muscles on the paretic sides of stroke survivors. Furthermore, CI abnormalities were also observed for all three muscles on the contralateral side. Our findings help elucidate the pathological mechanisms underlying stroke sequels, which might prove useful in developing improved stroke rehabilitation protocols.

New device for nonvolitional evaluation of quadriceps force in ventilated patients

INTRODUCTION

In mechanically ventilated patients, nonvolitional assessment of quadriceps weakness using femoral-nerve stimulation (twitch force) while the leg rests on a right-angle trapezoid or dangles from the bed edge is impractical. Accordingly, we developed a knee-support apparatus for use in ventilated patients.

METHODS

Ninety subjects (12 ventilated patients, 28 ambulatory patients, and 50 healthy subjects) were enrolled. Twitches with leg-dangling, trapezoid, and knee-support setups were compared.

RESULTS

Knee-support twitches were similar to trapezoid twitches but smaller than leg-dangling twitches (P < 0.0001). Inter- and intraoperator agreement was high for knee-support twitches at 1 week and 1 month. In ventilated patients, knee-support twitches were smaller than in healthy subjects and ambulatory patients (P < 0.004).

DISCUSSION

The new knee-support apparatus allows accurate recording of quadriceps twitches. The ease of use in ventilated patients and excellent inter- and intraoperator agreement suggest that this technique is suitable for cross-sectional and longitudinal studies in critically ill patients. Muscle Nerve 57: 784-791, 2018.

Prevalence and Clinical Correlates of Sarcopenia, Identified According to the EWGSOP Definition and Diagnostic Algorithm, in Hospitalized Older People: The GLISTEN Study

Background

Prevalence of sarcopenia is substantial in most geriatrics settings, but estimates vary greatly across studies because of difference in population characteristics, diagnostic criteria, and methods used to assess muscle mass, muscle strength, and physical performance. We investigated the feasibility of the European Working Group on Sarcopenia in Older People (EWGSOP) algorithm assessment in hospitalized older adults and analyzed prevalence and clinical correlates of sarcopenia.

Methods

Cross-sectional analysis of 655 participants enrolled in a multicenter observational study of older adults admitted to 12 acute hospital wards in Italy. Sarcopenia was assessed as low skeletal mass index (kg/m2) plus either low handgrip strength or low walking speed (EWGSOP criteria). Skeletal muscle mass was estimated using bioimpedance analysis.

Results

Of the 655 patients (age 81.0 ± 6.8 years; women 51.9%) enrolled in the study, 275 (40.2%) were not able to perform the 4-m walking test because of medical problems. The overall prevalence of sarcopenia on hospital admission was 34.7% (95% confidence interval 28-37) and it steeply increased with aging (p < .001). In multivariable analysis, patients with sarcopenia on hospital admission were older and were more likely to be male and to have congestive heart failure, cerebrovascular disease, and severe basic activities of daily living disability. The prevalence of sarcopenia was inversely correlated with body mass index.

Conclusion

Based on EWGSOP criteria, prevalence of sarcopenia is extremely high among older adults on admission to acute hospital wards. Older age, male gender, congestive heart failure, cerebrovascular disease, severe activities of daily living disability, and body mass index were the clinical variables significantly associated with the presence of sarcopenia.

Review of devices used in neuromuscular electrical stimulation for stroke rehabilitation

Neuromuscular electrical stimulation (NMES), specifically functional electrical stimulation (FES) that compensates for voluntary motion, and therapeutic electrical stimulation (TES) aimed at muscle strengthening and recovery from paralysis are widely used in stroke rehabilitation. The electrical stimulation of muscle contraction should be synchronized with intended motion to restore paralysis. Therefore, NMES devices, which monitor electromyogram (EMG) or electroencephalogram (EEG) changes with motor intention and use them as a trigger, have been developed. Devices that modify the current intensity of NMES, based on EMG or EEG, have also been proposed. Given the diversity in devices and stimulation methods of NMES, the aim of the current review was to introduce some commercial FES and TES devices and application methods, which depend on the condition of the patient with stroke, including the degree of paralysis.

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.

Evaluation of C-terminal Agrin Fragment as a marker of muscle wasting in patients after acute stroke during early rehabilitation

BACKGROUND

C-terminal Agrin Fragment (CAF) has been proposed as a novel biomarker for sarcopenia originating from the degeneration of the neuromuscular junctions. In patients with stroke muscle wasting is a common observation that predicts functional outcome. We aimed to evaluate agrin sub-fragment CAF22 as a marker of decreased muscle mass and physical performance in the early phase after acute stroke.

METHODS

Patients with acute ischaemic or haemorrhagic stroke (n = 123, mean age 70 ± 11 y, body mass index BMI 27.0 ± 4.9 kg/m(2)) admitted to inpatient rehabilitation were studied in comparison to 26 healthy controls of similar age and BMI. Functional assessments were performed at begin (23 ± 17 days post stroke) and at the end of the structured rehabilitation programme (49 ± 18 days post stroke) that included physical assessment, maximum hand grip strength, Rivermead motor assessment, and Barthel index. Body composition was assessed by bioelectrical impedance analysis (BIA). Serum levels of CAF22 were measured by ELISA.

RESULTS

CAF22 levels were elevated in stroke patients at admission (134.3 ± 52.3 pM) and showed incomplete recovery until discharge (118.2 ± 42.7 pM) compared to healthy controls (95.7 ± 31.8 pM, p < 0.001). Simple regression analyses revealed an association between CAF22 levels and parameters of physical performance, hand grip strength, and phase angle, a BIA derived measure of the muscle cellular integrity. Improvement of the handgrip strength of the paretic arm during rehabilitation was independently related to the recovery of CAF22 serum levels only in those patients who showed increased lean mass during the rehabilitation.

CONCLUSIONS

CAF22 serum profiles showed a dynamic elevation and recovery in the subacute phase after acute stroke. Further studies are needed to explore the potential of CAF22 as a serum marker to monitor the muscle status in patients after stroke.

The relationship between bilateral knee muscle strength and gait performance after stroke: the predictive value for gait performance

[Purpose] The purpose of this study was to assess the relationships between bilateral knee extension strengths and gait performance in subjects with poststroke hemiparesis and to predict gait performance by the paretic and nonparetic knee extension strength. [Subjects and Methods] This was a correlational study in which 238 consecutive inpatients with poststroke hemiparesis were enrolled. Knee extensor muscle strengths in paretic and nonparetic lower limbs were measured with a handheld dynamometer, and the presence or absence of impaired gait was also determined. [Results] The mean strength in the paretic lower limb was 0.90 Nm/kg, and that in the nonparetic lower limb was 1.24 Nm/kg. Discriminant analysis classified the difference between the possibility and impossibility of gait by knee extensor muscle strength (standardized discriminant coefficient: paretic, 1.32; nonparetic, 0.55). Thus, paretic and nonparetic knee extension strengths were integrated in the strength index. A threshold level of 2.0 provided the best balance between positive and negative predictive values for the strength index. [Conclusion] The results indicated that both paretic and nonparetic knee extension strengths were related to gait performance. The strength index deduced from bilateral knee extension strengths may serve as a clinically meaningful index for rehabilitation assessment and training.

Unaffected arm muscle hypercatabolism in dysphagic subacute stroke patients: the effects of essential amino acid supplementation

Alterations in muscle protein turnover of the unaffected side of stroke patients could contribute to physical disability. We investigated whether hypercatabolic activity occurred in unaffected arm muscle and whether supplemented essential amino acids (EAAs) could limit muscle hypercatabolism (MH). Thirty-eight dysphagic subacute stroke subjects (<3 months after acute event) (29 males+9 females; 69.7±11.4 yrs) were enrolled and randomized to receive 8 g/day EAAs (n=19; EAA group) or isocaloric placebo (maltodextrin; n=19, Plac group). Before randomization, all patients had their arterial (A) and venous (V) amino acids measured and muscle (A-V) differences calculated in the unaffected arm. Eight matched and healthy subjects served as controls. When compared to healthy controls, the entire stroke population showed significant muscle release (=negative value A-V) of the amino acid phenylalanine (phenyl-) indicating a prevalence of MH. Moreover, randomized EAA and Plac groups had similar rates of MH. After 38 days from the start of the protocol, the EAA group but not the Plac group had MH converted to balanced protein turnover or anabolic activity. We concluded that muscle protein metabolism of the unaffected arm of dysphagic subacute stroke individuals could be characterized by MH which can be corrected by supplemented EAAs.

Impaired foot-force direction regulation during postural loaded locomotion in individuals poststroke

Following stroke, hemiparesis results in impaired motor control. Specifically, inappropriate direction of foot-forces during locomotion has been reported. In our previous study (Liang and Brown 2011) that examined poststroke foot-force direction during a seated, supported locomotor task, we observed that foot-force control capabilities were preserved poststroke. In this current study, we sought to better understand the mechanisms underlying the interaction of locomotor and postural control as an interactive mechanism that might interfere, poststroke, with appropriate foot-force generation. We designed an experiment in which participants performed biomechanically controlled locomotor tasks, under posturally challenged pedaling conditions while they generated mechanical output that was comparable to pedaling conditions without postural challenge, thus allowing us to monitor the strategies that the nervous system adopts when postural conditions were manipulated. We hypothesized that, with postural influence, individuals poststroke would generate inappropriate shear forces accompanied by inappropriate changes to muscle activity patterns when performing a mechanically controlled locomotor task, and would be exaggerated with increased postural loading. Sixteen individuals with chronic poststroke hemiparesis and 14 age-similar nonimpaired controls pedaled on a cycle ergometer under 1) seated supported and 2) nonseated postural loaded pedaling conditions, generating matched pedal force outputs of two effort levels. When we compared postural influence with seated pedaling, we observed increased magnitudes of forward-directed shear forces in the paretic legs associated with increased magnitude of leg extensor muscle activity, but not in controls. These findings provide evidence to support a model that describes independent controllers for posture and locomotion, but that the interaction between the two controllers is impaired poststroke.

Motor impairment of the ipsilesional body side in poststroke subjects

BACKGROUND

In poststroke hemiparetic patients, motor weakness usually occurs on the contralesional body side to the brain. Impairment on the ipsilateral body side also occurs, but less than the contralateral side. The level and type of deficits on the less-affected side is still unclear. Clinicians usually do not consider the less-affected side for assessment and management.

OBJECTIVE

The main purpose is to explore the motor weakness (coordination, gross and fine motor dexterity, and muscle strength) of the less-affected side. The secondary aim is to determine the relationship between the impairments of both body sides (affected and less-affected).

METHOD

A prospective, cross-sectional, and nonexperimental study was conducted at an outpatient occupational therapy unit of a rehabilitation institute. A convenient sample of 27 poststroke (19.0 ± 14.28 months) subjects (21 males and 6 females, 22 right-sided and 5 left-sided hemiparesis) was recruited. Outcome measures for the less-affected side were Minnesota Manual Dexterity Test (MMDT), Purdue PegBoard Test (PPBT) and Manual Muscle Testing (MMT). Brunnstrom Recovery Stage (BRS) and Fugl-Meyer Assessment (FMA) were applied for the affected side. The less-affected side of the poststroke subjects was compared with the side-, age-, and gender-matched controls.

RESULT

The results showed highly significant (p < 0.001) difference between the scores of the ipsilesional body side of the poststroke subjects (MMDT = 105.21 ± 22.70 s, PPBT = 9.30 ± 2.47, and median MMT grade range from 3 to 4) and the matched side of the controls (MMDT = 72.41 ± 11.69 s, PPBT = 13.78 ± 1.76, and median MMT grade 5). The findings also suggested no significant relation between the motor deficits of the less-affected and affected sides.

CONCLUSION

The ipsilesional body side of poststroke subjects had impaired coordination, gross and fine motor dexterity, and the upper and lower limb muscle strength. The side must be assessed and managed accordingly. Management would promote motor and functional recovery on both the sides.

Walking performance and muscle strength in the later stage poststroke: a nonlinear relationship

OBJECTIVES

To evaluate the relation between muscle strength in the lower extremities and walking performance (speed and distance) in subjects in the later stage poststroke and to compare this with normative data.

DESIGN

A cross-sectional observational study.

SETTING

University hospital department.

PARTICIPANTS

Subjects poststroke (n=41; 31 men, 10 women) with a mean age of 59±5.8 years and a time from stroke onset of 52±36 months were evaluated. An urban sample (n=144) of 40- to 79-year-olds (69 men, 75 women) formed the healthy reference group.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Muscle strength in the lower extremities was measured with an isokinetic dynamometer and combined into a strength index. Values for the 30-meter walk test for self-selected and maximum speed and the 6-minute walk test were measured. A nonlinear regression model was used.

RESULTS

The average strength index was 730±309 in the subjects after stroke compared with 1112±362 in the healthy group. A nonlinear relation between walking performance and muscle strength was evident. The model explained 37% of the variance in self-selected speed in the stroke group and 20% in the healthy group, and 63% and 38%, respectively, in the maximum walking speed. For the 6-minute walk test, the model explained 44% of the variance in the stroke group.

CONCLUSIONS

Subjects in the later stage poststroke were weaker than the healthy reference group, and their weakness was associated with walking performance. At the same strength index, subjects walked at lower speeds and shorter distances after stroke, indicating that there are multiple impairments that affect walking ability. Treatments focused on increasing muscle strength thus continue to hold promise.

Optimizing muscle power after stroke: a cross-sectional study

Background

Stroke remains a leading cause of disability worldwide and results in muscle performance deficits and limitations in activity performance. Rehabilitation aims to address muscle dysfunction in an effort to improve activity and participation. While muscle strength has an impact on activity performance, muscle power has recently been acknowledged as contributing significantly to activity performance in this population. Therefore, rehabilitation efforts should include training of muscle power. However, little is known about what training parameters, or load, optimize muscle power performance in people with stroke. The purpose of this study was to investigate lower limb muscle power performance at differing loads in people with and without stroke.

Methods

A cross-sectional study design investigated muscle power performance in 58 hemiplegic and age matched control participants. Lower limb muscle power was measured using a modified leg press machine at 30, 50 and 70% of one repetition maximum (1-RM) strength.

Results

There were significant differences in peak power between involved and uninvolved limbs of stroke participants and between uninvolved and control limbs. Peak power was greatest when pushing against a load of 30% of 1RM for involved, uninvolved and control limbs. Involved limb peak power irrespective of load (Mean:220 ± SD:134 W) was significantly lower (p < 0.05) than the uninvolved limb (Mean:466 ± SD:220 W). Both the involved and uninvolved limbs generated significantly lower peak power (p < 0.05) than the control limb (Mean:708 ± SD:289 W).

Conclusions

Significant power deficits were seen in both the involved and uninvolved limbs after stroke. Maximal muscle power was produced when pushing against lighter loads. Further intervention studies are needed to determine whether training of both limbs at lighter loads (and higher velocities) are preferable to improve both power and activity performance after stroke.