Predicting muscle forces of individuals with hemiparesis following stroke

Background  

Functional electrical stimulation (FES) has been used to improve function in individuals with hemiparesis following stroke. An ideal functional electrical stimulation (FES) system needs an accurate mathematical model capable of designing subject and task-specific stimulation patterns. Such a model was previously developed in our laboratory and shown to predict the isometric forces produced by the quadriceps femoris muscles of able-bodied individuals and individuals with spinal cord injury in response to a wide range of clinically relevant stimulation frequencies and patterns. The aim of this study was to test our isometric muscle force model on the quadriceps femoris, ankle dorsiflexor, and ankle plantar-flexor muscles of individuals with post-stroke hemiparesis.     

Relationship between static muscle strength deficits and spasticity in stroke patients with hemiparesis

The purpose of this retrospective investigation was to determine whether a relationship exists between static strength deficits in the shoulder medial (internal) rotator and elbow flexor muscles and spasticity in these muscles or their antagonists. We reviewed the records of the first 50 stroke patients with hemiparesis who met the entry criteria for the study and who were admitted over a four-month period of time. Static muscle strength was measured by hand-held dynamometry. Spasticity was graded on the Ashworth scale. Kendall's tau correlations were calculated between static muscle strength deficits and spasticity. Static strength deficits of the shoulder medial rotator and elbow flexor muscles were correlated (p less than .01) with the agonist muscles' spasticity, but not with the antagonist muscles' spasticity. Muscle group spasticity and strength deficits, therefore, appear to be covarying manifestations of cerebrovascular accidents. Clinicians, thus, may interpret an agonist muscle's capacity for force production in light of its own tone rather than that of its antagonist.     

The relative and absolute reliability of two balance performance measures in chronic stroke patients

PURPOSE: To examine the relative reliability and absolute reliability of the Berg Balance Scale (BBS) and the Postural Assessment Scale for Stroke Patients (PASS) in chronic stroke patients. METHOD: A total of 52 mild to moderate stroke patients, who had a stroke more than 6 months previously, participated in the study. Both balance measures were administered twice, seven days apart, to the patients. A relative reliability index (intra-class correlation coefficient, ICC2,1) was used to examine the level of agreement between test and retest. Absolute reliability indices, including the Bland and Altman method, the standard error of measurement (SEM), and the smallest real differences (SRD), were used to define the extent to which a balance score varies on test-retest measurements. RESULTS: Test-retest agreements were high (ICC2,1: BBS = 0.98; PASS = 0.97), indicating excellent agreement from a relative perspective. The SEM of the BBS and PASS, representing the smallest change threshold that indicates a real improvement for a group of individuals, were 2.4 and 1.1, respectively. The SRD of the BBS and PASS were 6.7 and 3.2, respectively, exhibiting the smallest change threshold that indicates a real improvement for a single individual. CONCLUSIONS: The test-retest agreements of the BBS and PASS were high in mild to moderate chronic stroke patients. The thresholds of both measures to detect real change are acceptable in research and clinical settings.     

The relative and absolute reliability of two balance performance measures in chronic stroke patients

Purpose. To examine the relative reliability and absolute reliability of the Berg Balance Scale (BBS) and the Postural Assessment Scale for Stroke Patients (PASS) in chronic stroke patients.

Method. A total of 52 mild to moderate stroke patients, who had a stroke more than 6 months previously, participated in the study. Both balance measures were administered twice, seven days apart, to the patients. A relative reliability index (intra-class correlation coefficient, ICC_2,1) was used to examine the level of agreement between test and retest. Absolute reliability indices, including the Bland and Altman method, the standard error of measurement (SEM), and the smallest real differences (SRD), were used to define the extent to which a balance score varies on test-retest measurements.

Results. Test-retest agreements were high (ICC_2,1: BBS = 0.98; PASS = 0.97), indicating excellent agreement from a relative perspective. The SEM of the BBS and PASS, representing the smallest change threshold that indicates a real improvement for a group of individuals, were 2.4 and 1.1, respectively. The SRD of the BBS and PASS were 6.7 and 3.2, respectively, exhibiting the smallest change threshold that indicates a real improvement for a single individual.

Conclusions. The test-retest agreements of the BBS and PASS were high in mild to moderate chronic stroke patients. The thresholds of both measures to detect real change are acceptable in research and clinical settings.     

Incremental predictive value of carotid arterial strain in patients with stroke

Although increased carotid intima-media thickness (IMT) is a well-known risk factor for stroke, carotid IMT alone is not sufficient for risk stratification. The assessment of arterial properties using velocity vector imaging (VVI) represents a new method for quantifying structural changes. We sought to investigate the characteristics and the clinical value of carotid arterial mechanics using VVI in patients with stroke. Fifty male patients (55?±?5 years) with stroke, 30 healthy age-matched volunteers (54?±?8 years), and 30 healthy young male volunteers (29?±?5 years) were evaluated. The peak circumferential strain, strain rate, and the standard deviation of the time to peak strain and strain rate, representing the synchronicity of the arterial expansion, were analyzed using VVI of the left common carotid artery. The circumferential strain and strain rate significantly decreased with age, and patients with stroke showed the lowest degree of strain and strain rate compared with healthy age-matched volunteers. In addition, patients with stroke showed decreased strain and strain rate even in participants with a normal carotid IMT (<?0.8 mm). Although carotid IMT did not improve the incremental predictive value of stroke over that of multiple clinical risk factors (diabetes mellitus, hypertension, coronary artery disease, smoking), adding carotid arterial strain and strain rate provided an incremental predictive value over both multiple risk factors and carotid IMT for stroke. Along with assessment of conventional risk factors, VVI analysis could provide improved risk stratification for stroke.     

Reliability of gait performance tests in men and women with hemiparesis after stroke.

OBJECTIVE: To assess the reliability of 6 gait performance tests in individuals with chronic mild to moderate post-stroke hemiparesis. Design: An intra-rater (between occasions) test-retest reliability study. Subjects: Fifty men and women (mean age 58+/-6.4 years) 6-46 months post-stroke. METHODS: The Timed "Up & Go" test, the Comfortable and the Fast Gait Speed tests, the Stair Climbing ascend and descend tests and the 6-Minute Walk test were assessed 7 days apart. Reliability was evaluated with the intraclass correlation coefficient (ICC(2,1)), the Bland & Altman analysis, the standard error of measurement (SEM and SEM%) and the smallest real difference (SRD and SRD%). RESULTS: Test-retest agreements were high (ICC(2,1) 0.94-0.99) with no discernible systematic differences between the tests. The standard error of measurement (SEM%), representing the smallest change that indicates a real (clinical) improvement for a group of individuals, was small (< 9%). The smallest real difference (SRD%), representing the smallest change that indicates a real (clinical) improvement for a single individual, was also small (13-23%). CONCLUSION: These commonly used gait performance tests are highly reliable and can be recommended to evaluate improvements in various aspects of gait performance in individuals with chronic mild to moderate hemiparesis after stroke.     

Performance and capacity-based measures of locomotion,compared to impairment-based measures,best predicted participation in individuals with hemiparesis due to stroke

Purpose: To determine the potential predictors of participation of individuals with post-stroke hemiparesis, taking into account modifiable variables of impairments, activity limitations, and environmental factors.

Methods: One hundred and nine individuals (58?±?12 years; 64 men) participated in this study. Outcomes included measures of impairments (depressive symptoms: Geriatric Depression Scale and motor-based impairments: finger-to-nose test, lower extremity (LE) motor coordination test, and handgrip strength, isometric strength of the LE muscles), activity (capacity: 10-meter walking speed test and Test d'Évaluation des Membres Supérieurs de Personnes Agées; performance: locomotion and manual abilities; environmental factors (Measure of the Quality of the Environment); and participation: Assessment of Life Habits (LIFE-H 3.1 Brazil)).

Results: Regression analyses revealed that the explanatory variables accounted for 59% and 49% of the variance in the LIFE-H 3.1 Brazil daily activity and social role sub-scales, respectively. Locomotion performance (R²?=?39%; p?R²?=?32%; p?Conclusions: Performance and capacity-based measures of locomotion showed to be the best predictors of participation. Additionally, depressive symptoms should not be underlooked.

• Implications for Rehabilitation

• Activity-related measures of locomotion showed to be the main predictors of participation in individuals with post-stroke hemiparesis, as assessed by the daily activity and social role sub-scales of the LIFE-H 3.1.

• The daily activity model was best predicted by measures of performance, whereas the social role sub-scale, by measures of capacity.

• Although small, the impact of depressive symptoms on participation should not be underlooked.

• Locomotion appeared to be essential for participation and increases in walking speed and locomotion ability should be the main goals for both professionals and individuals, when the aim is to increase participation.

     

Testing a motor performance series and a kinematic motion analysis as measures of performance in high-functioning stroke patients: reliability, validity, and responsiveness to therapeutic intervention

OBJECTIVE: To assess measurement properties of motor performance tests when used with high-functioning stroke patients. DESIGN: Test-retest reliability study with an interval of 2 days; responsiveness study with assessment before and after training; validity study assessing the tests' ability to discriminate between the high-functioning stroke patients and healthy subjects. SETTING: Referral center for neurorehabilitation. PARTICIPANTS: Twenty-nine high motor-functioning stroke patients and 20 healthy control subjects. INTERVENTION: Two special training sessions per day on 5 consecutive days, plus regular therapy. OUTCOME MEASURES: Scores on the motor performance series, a two-dimensional tracking test, and a kinematic task analysis. RESULTS: All tests (except the bimanual test) were able to document performance deficits with these patients and showed a moderately high to high test-retest reliability without systematic trend from test to retest (intraclass correlation coefficients for main variables, .61 to .89). The kinematic task especially demonstrated changes after training (standardized response means for timing variables, .53 to .66). A subset of variables indicated a modifying effect of limb side, age, and gender. CONCLUSION: All tests (except the bimanual test) can be used for both cross-sectional and follow-up group studies with high-functioning stroke patients. Measurement properties and the lack of comprehensive normative data limit their use with individual patients.     

Test-retest reliability of isokinetic muscle strength of the lower extremities in patients with stroke

OBJECTIVE: To i the test-retest reliability of isokinetic strength measurements of 3 muscle groups of the lower extremities in stroke patients. DESIGN: Isokineth tests of bilateral hip flexors, knee extensors, and ankle plantarflexors at 2 angular velocities, performed during 2 sessions scheduled 1 week apart for each subject. SETTING: Outpatilitation clinic of a local hospital in Taiwan. PARTICIPANTS: Nts with mild spastic hemiparesis secondary to stroke and with poststroke onset time of at least 6 months. All subjects could communicate and voluntarily move the affected lower extremity. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: The maximal peak torque, total work, and average power of the 3 muscle groups on the affected side examined during each test were quantified by using the normalization and the deficit methods. The normalization method divides the measured strength value by the patient's body weight, whereas the deficit method divides the difference between the strengths of the unaffected and affected extremities by the strength of the unaffected extremity. RESULTS: The normalized strength measures for muscles on the affected side showed good to excellent test-retest reliability (intraclass correlation coefficient [ICC] range,.62-.94; P<.05), whereas the deficit strength measures did not always show good reliability (ICC range,.13-.91). The knee extensors and ankle plantarflexors, but not the hip flexors, on the affected side showed better test-retest reliability of isokinetic strength generated at faster velocity (ICC range,.73-.94) than that generated at slower velocity (ICC range,.62-.88). The normalized peak torque (ICC range,.76-.94) and total work (ICC range,.83-.91) were more reliable than the normalized average power (ICC range,.62-.90) for all 3 muscle groups on the affected side. CONCLUSIONS: Quantitative assessment of muscle strength of the affected lower extremity in patients with mild spastic hemiparesis secondary to stroke is feasible using isokinetic testing. However, the test-retest reliability of isokinetic strength measures is affected by the quantifying method, testing velocity, and strength measures.     

Ultrasound is a reliable measure of muscle thickness in acute stroke patients, for some, but not all anatomical sites: a study of the intra-rater reliability of muscle thickness measures in acute stroke patients

This prospective, blinded study investigates the test retest reliability of measures of muscle thickness made by one sonographer across two cohort groups (n = 29) of people hospitalised with acute stroke. Reliability was assessed in cohort one (n = 14) for measurements made bilaterally at the anterior and posterior upper arms, the anterior and posterior thighs (total of eight measurements) and in cohort two (n = 15), for measurements made bilaterally at the lateral forearms, the anterior abdominal wall and the anterior and lower legs (total of eight measurements). Reliability estimates varied between measurement sites; intraclass correlation coefficients (ICCs) ranged from -0.26 (lateral forearm, paretic side) to 0.95 (anterior thigh, nonparetic side), percent mean differences ranged from 0.42% (posterior upper arm, nonparetic side) to 14.68% (anterior lower limb, nonparetic side) and method error ranged from 1.08 (abdomen, nonparetic side) to 9.69 mm (posterior lower limb, nonparetic side). Only four measurement sites (anterior upper arm, posterior upper arm, abdomen and anterior thigh) were within the acceptable ranges (ICC 0.60 to 1.00, mean percent difference range 0%-5% and method error range 0-5 mm) and considered reliable to use for measures of muscle thickness in people hospitalised with acute 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.Key words: Stroke, Handheld dynamometer, Gait     

Discriminative, predictive and evaluative properties of the simplified stroke rehabilitation assessment of movement instrument in patients with stroke.

OBJECTIVE: To justify the utility of the Simplified Stroke Rehabilitation Assessment of Movement Instrument (S-STREAM), we examined the discriminative, predictive and evaluative properties of the 3 subscales of the S-STREAM (i.e. upper-limb movements, lower-limb movements and mobility) in patients after stroke. SUBJECTS: A total of 388 patients after stroke participated in this study. To examine the discriminative property, the patients were divided into 3 groups according to their Barthel Index scores. A comprehensive measure of activities of daily living was administered at 6 months after hospital discharge as an external criterion to examine the predictive property. Changes in the S-STREAM scores from the time of admission for rehabilitation, to hospital discharge, were used to examine the evaluative property. RESULTS: All pair-wise comparisons of mean scores among the 3 groups on the 3 subscales of the S-STREAM were significant. The scores of the S-STREAM showed moderate to good correlations with the comprehensive activities of daily living scores. There were large changes in the 3 subscales of the S-STREAM. CONCLUSION: All 3 subscales of the S-STREAM demonstrate good discriminative, predictive and evaluative properties in patients after stroke. These findings provide strong evidence that the S-STREAM is useful in measuring motor and mobility function in patients after stroke.     

Acquiring and maintaining self-care skills after stroke. The predictive value of apraxia

The degree of self-care in 120 patients who had suffered unilateral cerebrovascular accident (CVA) was assessed at different stages of recovery. The level of ADL (activities of daily living) function was determined on admission and discharge. Patients with right-sided hemiplegia (r. hem.) were given a set of apraxia tests on admission to the hospital. The results of ADL evaluation showed improved ADL function between admission and discharge, but a worsening after returning home. There were some significant relationships between ADL function in hospital and apraxia. All the apraxia variables are significant as predictors of subsequent dependency. The results show the seriousness of problems related to apraxia in rehabilitation of stroke patients with a lesion in the left hemisphere. One conclusion is that the treatment procedure ought to be directed to the various symptoms of apraxia. The effect of apraxia on ADL in the domestic situation has to be given more attention. More treatment should be given in the home, as patients seem to have difficulty in transferring the skills learned in hospital to the home situation and in maintaining them.     

Discriminative, predictive, and evaluative properties of a trunk control measure in patients with stroke

BACKGROUND AND PURPOSE: The trunk control items of the Postural Assessment Scale for Stroke Patients (PASS-TC) have been proposed for use in examining patients with stroke. The purpose of this study was to examine the discriminative and predictive validities and the evaluative properties of the PASS-TC at 14, 30, 90, and 180 days after stroke onset. SUBJECTS AND METHODS: A total of 269 patients with stroke participated in this prospective study. The PASS-TC was administered at the 4 time points after stroke onset. The distributions of the PASS-TC scores were used to determine the discriminative ability to distinguish between individuals at the 4 time points. A comprehensive activities of daily living (CADL) measure was administered 1 year after stroke onset as an external criterion for examining the predictive ability of the PASS-TC. Changes in PASS-TC scores between the intervals of 14 to 30, 30 to 90, and 90 to 180 days after stroke onset were used to examine the evaluative properties of the measure. RESULTS: The PASS-TC scores exhibited differences between the patients with disability and the patients without disability at the 4 time points. The scale, however, showed a notable ceiling effect at the 4 time points (>30% of the subjects), indicating a limited discriminative ability between individuals. The scores of the PASS-TC at the 4 time points were moderately correlated with the CADL scores at 1 year after stroke onset (Spearman rhof.5), evidence of its predictive validity. The responsiveness of the PASS-TC was moderate at 14 to 30 days after stroke (standardized response mean [SRM]=.65) and limited at 30 to 90 and 90 to 180 days after stroke (SRM=.42 and .02, respectively). DISCUSSION AND CONCLUSION: The results provide evidence that the PASS-TC can predict CADL function at 1 year after a stroke, but the discriminative and evaluative abilities are limited over the first 6 months after a stroke. To promote the utility of the PASS-TC in stroke research, it will be necessary to reduce its ceiling effect and improve its evaluative ability.     

偏瘫患者强化上肢训练的价值及简易手功能评定箱的可信性研究

本研究目的是验证脑血管意外（ＣＶＡ）患者发病３个月后手功能是否继续恢复及一种简易手功能评定箱（ＳＨＥＦ）的可信性。４６例ＣＶＡ患者，平均病程１１６．７±２３．５天，同时用Ｆｕｇｌ－Ｍｅｙｅｒ法和ＳＨＥＦ法评定，采用强化上肢训练法治疗２５．４±１８．９次后，观察组（３２例）有非常显著的改善（Ｐ＜０．００１），而对照组不明显，两组比较差异也非常显著（Ｐ＜０．００１）。两种评定方法呈显著相关（ｒ＝０．９６２，Ｐ＜０．００１），得出回归方程为Ｙ＝０．６６６Ｘ－０．０５。作者认为病程在３个月以上的患者们有康复价值。ＳＨＥＦ法是一种可信度高、定量化好的评定方法。     

The Orpington Prognostic Scale for patients with stroke: reliability and pilot predictive data for discharge destination and therapeutic services

PURPOSE: To determine the inter-rater and test-retest reliability of the Orpington Prognostic Scale (OPS) in patients with stroke. Pilot data were gathered to evaluate its predictive validity for discharge destination and therapeutic services required on discharge.METHOD: Ninety-four consecutive patients, admitted to hospital due to stroke participated. Pairs of physiotherapists (PT) and occupational therapists (OT) assessed patients using the OPS on days 7 and 14 post stroke. For inter-rater reliability, one rater performed the OPS while the other observed, each scoring the scale independently. For test-retest reliability, two different raters tested the subjects separately within the same day. Data were gathered on the discharge destination and the number of follow-up services prescribed.RESULTS: The inter-rater reliability as measured by the intraclass correlation coefficient (ICC) was 0.99 (95% CI 0.97 - 0.99). For test-retest reliability, the ICC was 0.95 (95% CI 0.90 - 0.98). The accuracy for predicting discharge to home using OPS 5.0 was 65% (95% CI 0.52 - 0.76). OPS scores were not related to number of follow-up services prescribed.CONCLUSIONS: Despite high inter-rater and test-retest reliability, the OPS has limited predictive accuracy for discharge destination and is a poor predictor of follow-up services.     

Relative decreases in knee extension torque with increased knee extension velocities in stroke patients with hemiparesis

I examined the isokinetic knee extension torque (KET) produced by the paretic and nonparetic lower limbs of 27 stroke patients, with hemiparesis, at knee extension velocities (KEVs) of 30 degrees, 60 degrees, 120 degrees, and 180 degrees/sec. The purpose of this study was to determine whether the relative decreases in KET at velocities greater than 30 degrees/sec were different on the two sides. To further investigate this relative decrease, the relationship between the torque at 30 degrees/sec and those at higher speeds also was examined on each side. Relative decreases in KET differed between speeds, but not between sides. Torques at speeds greater than 30 degrees/sec were correlated significantly with the torque at 30 degrees/sec. These findings suggest that patients with hemiparesis and minimal muscle spasticity may have difficulty moving forcefully at higher speeds because they are weak. Therapeutic interventions, therefore, might be most beneficial when they are directed toward helping patients with hemiparesis activate their weak muscles.