Effects of stroke injury on the shear modulus of the lower leg muscle during passive dorsiflexion

Quantifying Plantar Flexor Muscles Stiffness During Passive and Active Force Generation Using Shear Wave Elastography in Individuals With Chronic Stroke

OBJECTIVES

This study aims to investigate the mechanical properties of paretic and healthy plantar flexor muscles and assesses the spatial distribution of stiffness between the gastrocnemius medialis (GM) and lateralis (GL) during active force generation.

METHODS

Shear wave elastography measurements were conducted on a control group (CNT, n=14; age=59.9±10.6 years; BMI=24.5±2.5 kg/m2) and a stroke survivor group (SSG, n=14; age=63.2±9.6 years; BMI=23.2±2.8 kg/m2). Shear modulus within the GM and GL was obtained during passive ankle mobilization at various angles of dorsiflexion (P0 =0°; P1=10°; P2=20°; P3=-20° and P4=-30°) and during different levels (30%, 50%, 70%, 100%) of maximal voluntary contraction (MVC). Muscle activations of GM, GL, soleus and tibialis anterior were also evaluated.

RESULTS

The results revealed a significant increase in passive stiffness within the paretic plantar flexor muscles under high tension during passive mobilization (p<0.05). Yet, during submaximal and maximal MVC, the paretic plantar flexors exhibited decreased active stiffness levels (p<0.05). A notable discrepancy was found between the stiffness of the GM and GL, with the GM demonstrating greater stiffness from 0° of dorsiflexion in the SSG (p<0.05), and from 10° of dorsiflexion in the CNT (p<0.05). No significant difference in stiffness was observed between the GM and GL muscles during active condition.

CONCLUSION

Stroke affects the mechanical properties differently depending on the state of muscle activation. Notably, the distribution of stiffness among synergistic plantar flexor muscles varied in passive condition, while remaining consistent in active condition.

Changes in Lower Extremity Muscle Quantity and Quality in Patients with Subacute Stroke

OBJECTIVE

To analyze the changes in muscle mass and quality with time on the paretic and non-paretic sides in subacute stroke patients and identify correlations between the variation of muscle mass and quality and lower limb functions.

METHODS

Thirty hemiplegia patients diagnosed with stroke participated in this study. To evaluate poststroke muscle changes, longitudinal measurement of muscle mass and quality was conducted with bilateral lower limbs. The elastic shear modulus was measured using shear wave elastography and muscle thickness (MT) of rectus femoris, vastus intermedius, vastus lateralis (VL), vastus medialis, tibialis anterior, and gastrocnemius (GCM) muscles. Functional evaluation was performed using Berg Balance Scale (BBS), Five Times Sit to Stand Test (FTSST). Follow-up was performed at discharge. The muscle mass and quality were compared according to time. We analyzed whether muscle quantity and quality were related to function.

RESULTS

MT demonstrated no significant change with time. The elastic shear modulus increased significantly in the paretic VL and GCM muscles and did not change significantly in the muscles on the non-paretic side. Correlation analysis detected that elastic shear modulus in the VL has a cross-sectional negative relationship between BBS and positive relationship between FTSST. There were significant correlation between variation of FTSST and the variation of the elastic shear modulus in VL.

CONCLUSION

Only paretic VL and GCM muscle quality changed in subacute stroke patients and muscle's property related to lower limb functions. Therefore, the lower extremity requires an approach to muscle quality rather than quantity for subacute stroke patients.

Spatial distribution of stiffness between and within muscles in paretic and healthy individuals during prone and standing positions

This study investigated the inter- and intramuscular variability of plantar flexors stiffness during prone and standing positions at different muscle lengths in healthy and paretic individuals. To access tissue stiffness, shear wave elastography (SWE) measurements were carried out on two groups: control group (CG; n=14; age 43.9±9.6 years; body mass index [BMI]=24.5±2.5 kg/m2) and stroke survivor group (SSG; n=14; age 43.9±9.6 years; BMI=24.5±2.5 kg/m2). Shear Modulus (μ, kPa) within three plantar flexors (the gastrocnemius medialis [GM], gastrocnemius lateralis [GL], and soleus [SOL]) was obtained during two conditions: prone and standing position, at different angles of dorsiflexion (0°, 10°, and 20°). Measurements were also performed in different proximo-distal regions of each muscle. Muscle activation of the GM, GL, SOL, and tibialis anterior were evaluated during the two conditions. Results showed a high spatial stiffness variability between and within plantar flexors during dorsiflexion. The highest stiffness was observed in the GM, especially in the distal region at 20° in healthy and paretic muscles. In the prone position, the paretic muscle exhibits greater stiffness compared to the healthy muscle (p < 0.05). In contrast, in the standing position, an increase of stiffness in the healthy muscle compared to the paretic muscle was observed (p < 0.05). Thus, mechanical properties are differently affected by stroke depending on active and passive states of ankle muscles during dorsiflexion. In addition, the modification of ankle muscle state change stiffness distribution between and within plantar flexors.

Characteristics of the static muscle stiffness of ankle plantar flexors in individuals with chronic ankle instability

PURPOSE

Individuals with chronic ankle instability (CAI) have deficits in closed kinetic chain dorsiflexion that may perpetuate injury. Determining the characteristics of muscle stiffness in the plantar flexors of individuals with CAI may help in developing appropriate treatments. We aimed to highlight the characteristics of static muscle stiffness in ankle plantar flexor muscles during the passive dorsiflexion of the ankle joint in individuals with CAI.

METHODS

A total of 30 patients were included in the study based on the International Ankle Consortium criteria. The patients were categorized evenly into healthy, coper, and CAI groups (i.e., 10 patients in each group). After measuring the dorsiflexion range of motion (non-weight-bearing/weight-bearing) of the ankle joint, the static muscle stiffness measurements of the medial gastrocnemius, lateral gastrocnemius, soleus, and peroneus longus were obtained. The measurements were performed during the knee joint's extension and 50° flexion and passive dorsiflexion between the range of 40° plantar flexion and 20° dorsiflexion.

RESULTS

The dorsiflexion range of motion of the CAI group was significantly smaller than that of the healthy and coper groups in the weight-bearing position. No interaction was observed for muscle stiffness in both the knee flexion and extension positions, and no significant differences were identified among the three groups. The shear modulus of the soleus at 20° ankle dorsiflexion with knee flexion had a significant negative correlation with the weight-bearing range of motion of the ankle.

CONCLUSION

The limitation in the weight-bearing dorsiflexion range of motion in CAI was largely due to factors other than the increased elasticity of the ankle plantar flexor muscles.

Acute passive stretching has no effect on gastrocnemius medialis stiffness in children with unilateral cerebral palsy

PURPOSE

The aim of this study was to investigate the effects of an acute high-intensity, long-duration passive stretching session of the plantar flexor muscles, on maximal dorsiflexion (DF) angle and passive stiffness at both ankle joint and gastrocnemius medialis (GM) muscle levels in children with unilateral cerebral palsy (CP).

METHODS

13 children [mean age: 10 years 6 months, gross motor function classification system (GMFCS): I] with unilateral CP underwent a 5 min passive stretching session at 80% of maximal DF angle. Changes in maximal DF angle, slack angle, passive ankle joint and GM muscle stiffness from PRE- to POST-intervention were determined during passive ankle mobilization performed on a dynamometer coupled with shear wave elastography measurements (i.e., ultrasound) of the GM muscle.

RESULTS

Maximal DF angle and maximal passive torque were increased by 6.3° (P < 0.001; + 50.4%; 95% CI 59.9, 49.9) and 4.2 Nm (P < 0.01; + 38.9%; 95% CI 47.7, 30.1), respectively. Passive ankle joint stiffness remained unchanged (P = 0.9; 0%; 95% CI 10.6, - 10.6). GM muscle shear modulus was unchanged at maximal DF angle (P = 0.1; + 34.5%; 95% CI 44.7, 24.7) and at maximal common torque (P = 0.5; - 4%; 95% CI - 3.7, - 4.3), while it was decreased at maximal common angle (P = 0.021; - 35%; 95% CI - 11.4, - 58.5). GM slack angle was shifted in a more dorsiflexed position (P = 0.02; + 20.3%; 95% CI 22.6, 18).

CONCLUSION

Increased maximal DF angle can be obtained in the paretic leg in children with unilateral CP after an acute bout of stretching using controlled parameters without changes in passive stiffness at joint and GM muscle levels.

CLINICAL TRIAL NUMBER

NCT03714269.

Motor performance, motor impairments, and quality of life after eccentric resistance training in neurological populations: A systematic review and meta-analyses

BACKGROUND

Many overlapping factors impair motor performance and quality of life in neurological patients. Eccentric resistance training (ET) has potential benefits for improving motor performance and treating motor impairments better than some traditional rehabilitation approaches.

OBJECTIVE

To estimate the effect of ET in neurological settings.

METHODS

Seven databases were reviewed up to May 2022 according to PRSIMA guidelines to find randomized clinical trials involving adults with a neurological condition, who underwent ET as set by the American College of Sports Medicine. Motor performance (main outcome) was assessed as strength, power and capacities during activity. Secondary outcomes (impairments) were muscle structure, flexibility, muscle activity, tone, tremor, balance and fatigue. Tertiary outcomes were risk of fall, and self-reports of quality of life.

RESULTS

Ten trials were included, assessed using Risk of Bias 2.0 tool, and used to compute meta-analyses. Effective effects in favour of ET were found for strength and power, but not for capacities during activity. Mixed results were found for secondary and tertiary outcomes.

CONCLUSION

ET may be a promising intervention to better improve strength/power in neurological patients. More studies are needed to improve the quality of evidence underlying changes responsible for these results.

Shear wave elastography combined with electromyography to assess the effect of botulinum toxin on spastic dystonia following stroke: A pilot study

Background

Shear wave elastography (SWE) is a method for carrying out a quantitative assessment of the mechanical properties of soft tissues in terms of stiffness. In stroke survivors, the paretic muscles may develop hypertonia due to both neural-mediated mechanisms and structural alterations with consequent muscular fibrous-fatty remodeling.

Methods

Fourteen adult patients with spastic dystonia following stroke were recruited. Muscle hypertonia was assessed using the modified Ashworth scale (MAS). Muscle activation was measured by surface electromyography (sEMG) with the selected muscle in shortened (spastic dystonia) and stretched (dynamic stretch reflex) positions. SWE was performed on a selected paretic muscle and on the contralateral non-paretic one to calculate shear wave velocities (SWV) along and across muscular fibers. The modified Heckmatt scale (MHS) pattern was also determined. All evaluations were performed shortly before BoNT-A injections (T0) and one month later (T1).

Results

All SWV on paretic muscles were higher than contralateral non-paretic ones (p < 0.01). After BoNT-A injection, a significant reduction in MAS (p = 0.0018), spastic dystonia (p = 0.0043), and longitudinal SWE measurements, both in shortened (p = 0.001) and in stretched muscular conditions (p = 0.0029), was observed. No significant changes in SWV on non-paretic muscles were observed. Higher SWV resulted along the direction of muscular fibers vs. across them (p = 0.001). No changes resulted from the MHS evaluations after BoNT-A. There was a positive correlation between MHS scores and SWV values while the muscle was in the shortened position, but not with spastic dystonia recorded by sEMG.

Conclusions

This is the first study evaluating the effect of BoNT-A on muscle hypertonia following stroke, assessed by both SWE and sEMG. These findings support SWE as a useful method to disclose intrinsic muscular remodeling, independently of the effect of spastic dystonia, in particular, while muscles were assessed in a neutral position. SWE measurements of muscle stiffness cannot tell apart neural-mediated and intrinsic muscle hypertonia. Interestingly, when sEMG activity is very limited, as in spastic muscles kept in a shortened position, SWE can provide a measurement of stiffness due almost completely to intrinsic muscle changes. Alongside sEMG, SWE could aid clinicians in the assessment of responses to treatments.

Effects of Extensor Digitorum Longus and Tibialis Anterior Taping on Balance and Gait Performance in Patients Post Stroke

The purpose of this study was to investigate the effects of extensor digitorum longus taping (EDLT) and tibialis anterior taping (TAT) on balance and gait performance in patients post-stroke. The study included 40 stroke patients randomly assigned to two intervention groups: the EDLT group and the TAT group. Therapeutic taping was applied to the extensor digitorum in the EDLT group and applied to the tibialis anterior in the TAT group. Balance variables were measured using BioRescue equipment, and gait variables were measured using G-walk equipment. Balance and gait variables were significantly increased in both the EDLT and TAT groups after the intervention, but there were no significant differences between the two groups. Therefore, we concluded that eversion (EDLT) or inversion (TAT) through taping did not affect the outcome. Only dorsiflexion affects gait speed increase post-stroke. As a result of this study, extensor digitorum longus taping and tibialis anterior taping were taping methods with no difference in the improvement of balance ability and gait performance.

Shear wave elastography of the brachioradialis spastic muscle and its correlations with biceps brachialis and clinical scales

BACKGROUND

Shear wave elastography technique estimates biological tissue shear elastic modulus (μ[kPa]), which can be used as an objective, muscle-specific indicator of stiffness increase caused by spasticity. We measured both the brachioradialis and biceps brachialis μ in hemiparetic post-stroke patients (n = 11). The spastic arm was compared with the supposedly non-affected contralateral limb and correlated with Fugl-Meyer Assessment and Modified Ashworth Scales.

METHODS

Shear elastic modulus was estimated using an Aixplorer V.9 ultrasound device with the elbow at full extension. Average shear elastic modulus t-test, effect sizes, correlation matrix, spider plots and factor analysis were used to check for differences between spastic and nonspastic sides and explore relationships among the variables.

FINDINGS

Spastic brachioradialis μ (22.54 ± 11.59 kPa) and biceps brachialis (26.86 ± 12.07 kPa) were significantly greater than the non-spastic counterparts (13.13 ± 2.81 kPa, p = 0.031, η_p² = 0.3846 for brachioradialis and 15.25 ± 5.00 kPa, p = 0.007, η_p² = 0.5345 for biceps brachialis). Significant correlations were observed between the spastic brachioradialis and biceps μ and Modified Ashworth Scales, but no correlation with Fugl-Meyer Assessment.

INTERPRETATION

Elastography can provide muscle-specific shear elastic modulus estimations of spastic brachioradialis and biceps brachialis, which are distinct from the nonspastic side. In some patients, there was no clear correspondence of the Fugl-Meyer Assessment functional scale with Modified Ashworth Scales and μ, suggesting that spasticity is not the only determinant of arm function. Additionally, shear wave elastography of brachioradialis and biceps brachialis muscles may guide the spasticity treatment, for instance, selecting the preferable candidate for botulinum toxin therapy.

Structural and passive mechanical properties of the medial gastrocnemius muscle in ambulatory individuals with chronic stroke

BACKGROUND

This study aimed to investigate the structural, morphological and passive mechanical properties of the medial gastrocnemius muscle among ambulating chronic stroke survivors using a computational model previously established in healthy individuals without stroke.

METHODS

Individuals with chronic stroke (n = 14, age = 63.4 ± 6.0 years) and healthy controls (n = 15, age = 59.6 ± 8.4 years) participated in the study. The mechanical properties of the medial gastrocnemius were measured during continuous passive ankle motion using ultrasound elastography and a corresponding muscle mechanical property-angle curve was estimated where slack angle and elasticity were determined. Muscle thickness, fascicle length, pennation angle, and echo intensity were also assessed using B-mode ultrasound.

FINDINGS

No significant differences in slack angle (paretic: -16.2° ± 6.13°, non-paretic: -16.93° ± 6.80°, p = 0.82), or slack elasticity (paretic: 4.36 ± 1.94 kPa, non-paretic: 4.54 ± 1.24 kPa, p = 0.64) were found between sides or groups. Lower muscle pennation angle (paretic: 13.6 ± 2.9°, non-paretic: 15.9 ± 2.0°, p = 0.019) and higher echo intensity (paretic: 80.5 ± 13.6, non-paretic: 63.4 ± 17.1, p = 0.003) were observed for paretic muscles. No significant between-sides differences were found for muscle thickness (paretic: 1.5 ± 0.3 cm, non-paretic: 1.6 ± 0.2 cm, p = 0.255) or fascicle length (paretic: 6.6 ± 1.9 cm, non-paretic: 7.1 ± 2.2 cm, p = 0.216). Significant between-groups difference was also observed for fascicle length [non-dominant side (control): 6.2 ± 0.8 cm, paretic side (stroke): 6.6 ± 1.9 cm, p = 0.017].

INTERPRETATION

Although muscle mechanical properties increased exponentially over the slack ankle, measures between paretic and non-paretic sides were similar in ambulating participants with chronic stroke. Side-to-side differences in structural and morphological measures suggest the impact of stroke was relatively more pronounced for these muscle parameters than for passive mechanical properties.

Ultrasound elastography in the assessment of post-stroke muscle stiffness: a systematic review

Background

Post-stroke muscle stiffness is a major challenge in the rehabilitation of stroke survivors, with no gold standard in clinical assessment. Muscle stiffness is typically evaluated by the Modified Ashworth Scale or the Tardieu Scale; however, these can have low reliability and sensitivity. Ultrasound elastography is an advanced imaging technology that can quantitatively measure the stiffness of a tissue and has been shown to have good construct validity when compared to clinically assessed muscle stiffness and functional motor recovery.

Objective

The purpose of this article is to systematically review the literature regarding the change in muscle stiffness as measured by ultrasound elastography in stroke survivors.

Methods

Scopus, PubMed, Embase, CINAHL, MEDLINE and Cochrane Library were searched for relevant studies that assessed the change in stiffness of post-stroke muscle stiffness measured by ultrasound elastography following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines.

Results

In total, 29 articles were identified, using either strain elastography and shear wave elastography to measure the stiffness of muscles in stroke survivors, most frequently in the biceps and medial gastrocnemius muscles. The stiffness was typically higher in the paretic compared to the non-paretic or healthy control. Other variations that increased the stiffness include increasing the joint angle and introducing a passive stretch or muscle activation. The paretic muscle has also been assessed pre- and post-treatment demonstrating a decrease in stiffness.

Conclusion

Ultrasound elastography is a promising imaging technology for determining the muscle stiffness in stroke survivors with need for a standardized imaging protocol.

Reliability and diagnostic accuracy of corrected slack angle derived from 2D-SWE in quantitating muscle spasticity of stroke patients

Background

To explore the feasibility of corrected slack angle acquired from two-dimensional shear wave elastography (2D-SWE) for quantitating the spasticity of medial gastrocnemius (MG) in stroke patients.

Methods

Consecutive stroke patients with spastic MG and matched healthy controls were recruited. Intra- and interobserver reliability of 2D-SWE measurement were evaluated, and the correlation between corrected slack angle and modified Ashworth scale (MAS) score was examined. The corrected slack angle before and after botulinum toxin A (BoNT-A) injection was compared and its diagnostic performance in classifying the severity of spasticity were assessed with receiver operating characteristic (ROC) curve analysis.

Results

The intra- (0.791 95% CI 0.432–0.932) and interobserver (0.751 95% CI 0.382–0.916) reliability of slack angle acquired with 2D-SWE were good. Significant correlation was found between corrected slack angle and MAS score (R = − 0.849, p < 0.001). The corrected slack angle increased after BoNT-A injection. The cutoff value of MAS ≥ 3 had the highest sensitivity (100%) and specificity (93.33%). The positive predictive value (PPV) for classification of MAS ≥ 1+ and the negative predictive value (NPV) for classification of MAS ≥ 3 were greater than 90%.

Conclusion

2D-SWE was a reliable method to quantitate the post-stroke spasticity. The corrected slack angle had advantage in classifying the severity of spasticity, especially in early identification of mild spasticity and confirmation of severe spasticity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12984-022-00995-8.

Comparison Between Contract-Relax Stretching and Antagonist Contract-Relax Stretching on Gastrocnemius Medialis Passive Properties

Antagonist contract-relax stretching and contract-relax stretching is commonly used in sports practice and rehabilitation settings. To date, no study has compared these modalities regarding muscle stiffness and stretch tolerance. This study aimed to investigate the effects of contract-relax and antagonist contract-relax stretching on dorsiflexion range of motion (ROM), stretch tolerance, and shear elastic modulus. Forty healthy participants (24 men and 16 women) took part in the study. Participants were randomly assigned to perform either contract-relax stretching or antagonist contract-relax stretching for 2 min. Outcomes were assessed on ROM, stretch tolerance, and shear elastic modulus before and after stretching. The ROM and stretch tolerance significantly increased after both contract-relax stretching (+ 5.4 ± 5.8°, p < 0.05; + 3.5 ± 8.0 Nm, p < 0.05) and antagonist contract-relax stretching (+ 6.1 ± 4.9°, p < 0.05; + 4.2 ± 6.4 Nm, p < 0.05); however, no significant difference was found between the two groups. Alternatively, the shear elastic modulus significantly decreased after both contract-relax (-31.1 ± 22.6 kPa, p < 0.05) and antagonist contract-relax stretching (-11.1 ± 22.3 kPa, p < 0.05); however, contract-relax stretching (-41.9 ± 19.6%) was more effective than antagonist contract-relax stretching (-12.5 ± 61.6%). The results of this study suggest that contract-relax stretching instead of antagonist contract-relax stretching should be conducted to decrease muscle stiffness. However, either contract-relax or antagonist contract-relax stretching can increase ROM.

Quantitative Evaluation of Gastrocnemius Medialis Stiffness During Passive Stretching Using Shear Wave Elastography in Patients with Parkinson's Disease: A Prospective Preliminary Study

Objective

To prospectively investigate the feasibility of shear wave elastography (SWE) as a new quantitative and objective method for evaluating the stiffness of the gastrocnemius medialis (GM) muscle during passive stretching in patients with Parkinson's disease (PD).

Materials and Methods

SWE of the GM muscle was performed in 28 patients with PD [13 female and 15 male; mean age ± standard deviation (SD): 63.0 ± 8.5 years] and 12 healthy controls (5 female and 7 male; mean age ± SD: 59.3 ± 6.4 years) during passive ankle rotation. A Young's modulus-ankle angle curve was constructed. The GM slack angle and baseline Young's modulus (E₀) were compared between the markedly symptomatic and mildly symptomatic sides of patients with PD, and healthy controls. Additionally, the correlation between the GM slack angle and the severity of rigidity, and the observer reproducibility of SWE in determining the GM slack angle were evaluated.

Results

The GM slack angle was smaller on both the markedly and mildly symptomatic sides in patients with PD than in healthy controls (mean ± SD of −29.13° ± 3.79° and −25.65° ± 3.39°, respectively, vs. −21.22° ± 3.52°; p < 0.001 and p = 0.006, respectively). Additionally, in patients with PD, the GM slack angle on the markedly symptomatic side was smaller than that on the mildly symptomatic side (p = 0.003). The E₀ value was lower on both the markedly and mildly symptomatic sides in patients with PD than in healthy controls (mean ± SD of 10.11 ± 2.85 kPa and 10.08 ± 1.88 kPa, respectively, vs. 12.23 ± 1.02 kPa; p = 0.012 and p < 0.001, respectively). However, no significant difference was found between the markedly and mildly symptomatic sides in patients with PD (p = 0.634). A negative linear relationship was observed between the GM slack angle and lower limb rigidity score on the markedly symptomatic side in patients with PD (r = −0.719; p < 0.001). The intraclass correlation coefficients for observer reproducibility of SWE ranged from 0.880 to 0.951.

Conclusion

The slack angle determined by SWE may be a useful quantitative and reproducible method for evaluating muscle stiffness in patients with PD.

Quantifying upper limb motor impairment in chronic stroke: a physiological profiling approach

Upper limb motor impairments, such as muscle weakness, loss of dexterous movement, and reduced sensation, are common after a stroke. The extent and severity of these impairments differ among individuals, depending on the anatomical location and size of lesions. Identifying impairments specific to the individual is critical to optimize their functional recovery. The upper limb Physiological Profile Assessment (PPA) provides quantitative measures of key physiological domains required for adequate function in the upper limbs. The present study investigates the use of the upper limb PPA in a chronic stroke population. Fifty participants with chronic stroke completed all tests of the upper limb PPA with both their affected and less affected upper limbs. Performance in each test was compared to that of 50 age- and sex-matched control subjects with no history of a stroke. Correlations between test performance and validated measures of stroke, sensorimotor function, and disability were examined. Compared with control subjects, people with stroke demonstrated substantially impaired upper limb PPA performance for both their affected and less affected limbs. Performance in the upper limb PPA was associated with validated measures of sensorimotor function specific to the stroke population (Fugl-Meyer Assessment) and stroke-related disability (Stroke Impact Scale). The upper limb PPA shows good concurrent validity as a means to quantify upper limb function in a chronic stroke population. These tests identify domain-specific deficits and could be further tailored to an individual patient by the clinician to inform rehabilitation and track recovery.NEW & NOTEWORTHY Upper limb motor impairment is a common manifestation after stroke, compromising independence in fundamental daily activities involving the ability to reach, grasp, and manipulate objects. The upper limb Physiological Profile Assessment (PPA) offers a means of quantifying performance of the individual sensorimotor domains that are essential for upper limb function. Establishing individual performance profiles based on age- and sex-based normative scores may facilitate individualized treatment decisions by identifying the stroke patient's specific strengths and limitations.

Mechanical properties of ankle joint and gastrocnemius muscle in spastic children with unilateral cerebral palsy measured with shear wave elastography

The aim of this study was to describe passive mechanical and morphological properties of the ankle joint and gastrocnemius medialis (GM) muscle in paretic and contralateral legs in highly functional children with unilateral cerebral palsy (UCP) using shear wave elastography (SWE). SWE measurements on the GM muscle were performed in both paretic and contralateral legs during passive ankle dorsiflexion using a dynamometer in 11 children (mean age: 10 years 6 months) with UCP. Torque-angle and shear modulus-angle relationships were fitted using an exponential model to determine passive ankle joint and GM muscle stiffness respectively. Based on shear-modulus-angle relationship, slack angle and shear modulus of GM muscle were compared between legs. GM and Achilles tendon length were determined at rest using ultrasonography. No significant difference was found between legs for passive ankle joint (p = 0.26; 11.2%; 95 %CI: 31.9, -9.4) and GM muscle passive stiffness (p = 0.62; -4.4%; 95 %CI: 14.7, -23.4). GM shear modulus at a common angle was significantly higher on the paretic leg (p = 0.02; +56.5%; 95 %CI: 100.5, 12.6). GM slack angle on the paretic leg was significantly shifted to a more plantarflexed position (p = 0.04; +25.5%; 95 %CI: 49.7, 1.3) and this was associated with a non-significant lower muscle length compared to the contralateral leg (p = 0.05; -4.5%; 95 %CI: -0.4, -8.7). Increased passive tension on the paretic leg when compared to the contralateral one may be explained in large part by muscle shortening. The role of altered mechanical properties remains unknown.

Effect of prolonged sitting immobility on shear wave velocity of the lower leg muscles in healthy adults: A proof-of-concept study

Objective

The purpose of this study is to investigate the physical changes of the lower leg muscles in the compartment by observing the changes in the shear wave velocity of the gastrocnemius, soleus and tibialis anterior muscles with time in the sitting position for 2 hours and after elevation of the lower leg.

Materials and methods

The subjects were 24 healthy adult males (average age 26.6 years). Shear wave velocity was measured by Aplio 500 in immobilized leg immediately after the start of sitting, 60 minutes and 120 minutes after the start of sitting. After 120 minutes the subjects raised the lower leg for 3 minutes, then measured again.

Results

In the lateral and medial gastrocnemius, there was a significant increase in the velocity at 60 (1.58 ± 0.06, 1.70 ± 0.09 m/s) and 120 minutes (1.70 ± 0.10, 1.83 ± 0.11 m/s) after the start of the test (1.52 ± 0.06, 1.66 ± 0.10 m/s), respectively (p<0.01). In the soleus and the tibialis anterior, there was a significant increase in the velocity at 120 minutes (1.89 ± 0.17, 2.30 ± 0.24 m/s) compared to after the start (1.60 ± 0.15, 2.15 ± 0.26 m/s), respectively (p<0.01). In all muscles, there was a significant decrease in the velocity after the raising compared to that of 120 minutes (p<0.01).

Conclusions

It has been reported that the change of shear wave velocity with time is proportional to the intramuscular pressure in the leg compartment, and it is assumed that the increase of shear wave velocity in the 2-hour seated leg is due to fluid retention in extra-cellular space of the compartment.

Comparison Between Contract-Relax Stretching and Antagonist Contract-Relax Stretching on Gastrocnemius Medialis Passive Properties

Antagonist contract-relax stretching and contract-relax stretching is commonly used in sports practice and rehabilitation settings. To date, no study has compared these modalities regarding muscle stiffness and stretch tolerance. This study aimed to investigate the effects of contract-relax and antagonist contract-relax stretching on dorsiflexion range of motion (ROM), stretch tolerance, and shear elastic modulus. Forty healthy participants (24 men and 16 women) took part in the study. Participants were randomly assigned to perform either contract-relax stretching or antagonist contract-relax stretching for 2 min. Outcomes were assessed on ROM, stretch tolerance, and shear elastic modulus before and after stretching. The ROM and stretch tolerance significantly increased after both contract-relax stretching (+ 5.4 ± 5.8°, p < 0.05; + 3.5 ± 8.0 Nm, p < 0.05) and antagonist contract-relax stretching (+ 6.1 ± 4.9°, p < 0.05; + 4.2 ± 6.4 Nm, p < 0.05); however, no significant difference was found between the two groups. Alternatively, the shear elastic modulus significantly decreased after both contract-relax (-31.1 ± 22.6 kPa, p < 0.05) and antagonist contract-relax stretching (-11.1 ± 22.3 kPa, p < 0.05); however, contract-relax stretching (-41.9 ± 19.6%) was more effective than antagonist contract-relax stretching (-12.5 ± 61.6%). The results of this study suggest that contract-relax stretching instead of antagonist contract-relax stretching should be conducted to decrease muscle stiffness. However, either contract-relax or antagonist contract-relax stretching can increase ROM.

Human plantar fascial dimensions and shear wave velocity change in vivo as a function of ankle and metatarsophalangeal joint positions

The plantar fascia (PF), a primary contributor of the foot arch elasticity, may experience slack, taut, and stretched states depending on the ankle and metatarsophalangeal (MTP) joint positions. Since PF has proximodistal site difference in its dimensions and stiffness, the response to applied tension can also be site specific. Furthermore, PF can contribute to supporting the foot arch while being stretched beyond the slack length, but it has never been quantitatively evaluated in vivo. This study investigated the effects of the ankle and MTP joint positions on PF length and localized thickness and shear wave velocity (SWV) at three different sites from its proximal to distal end using magnetic resonance and supersonic shear imaging techniques. During passive ankle dorsiflexion, rise of SWV, an indication of slack length, was observed at the proximal site when the ankle was positioned by 10°-0° ankle plantar flexion with up to 3 mm (+1.5%) increase in PF length. On the other hand, SWV increased at the distal site when MTP joint dorsiflexed 40° with the ankle 30°-20° plantar flexion, and in this position, PF was lengthened up to 4 mm (+2.3%). Beyond the slack length, SWV curvilinearly increased at all measurement sites toward the maximal dorsiflexion angle whereas PF lengthened up to 9 mm (+7.6%) without measurable changes in its thickness. This study provides evidence that the dimensions and SWV of PF change in a site-specific manner depending on the ankle and MTP joint positions, which can diversify foot arch elasticity during human locomotion.NEW & NOTEWORTHY Joint angle dependence and site specificity of the plantar fascial dimensions and SWV were examined by combining sagittal magnetic resonance and supersonic shear imaging techniques. We revealed that the site-specific changes in PF SWV were related to joint angle positions, i.e., PF slackness and elasticity changed in varying combinations of ankle and MTP angle. Our findings suggest that PF can elastically support the foot arch throughout the stance phase of human bipedal locomotion.

Shear wave elastography potential to characterize spastic muscles in stroke survivors: Literature review

BACKGROUND

Post-stroke spasticity contributes to impairments, disabilities and decline in quality of life. Quantitative measurements of spasticity are needed in order to assess the impact of specific treatments and to choose the more accurate technique for each patient. The aim of this review is to examine the use of shear wave ultrasound elastography as a quantitative tool for monitoring biomechanical muscle properties such as stiffness and to determine whether it is a reliable method to assess spastic muscle in stroke survivors.

METHODS

Studies were sought from Academic Search Complete, CINAHL, PubMed/Medline, Scopus and SportDiscus with the following keywords: shear wave elastography, spasticity, stiffness, elasticity, hardness, stroke, cerebrovascular accident, cerebral vascular event and transient ischaemic attack. Titles and abstracts were screened, and relevant full-text articles were retrieved for further review.

FINDINGS

Of the 76 screened studies, nine captured elastography data of the spastic biceps brachii (n = 6) or the plantar flexors (n = 3) with stroke victims. All consulted studies had a different way of utilizing this technology which was expected considering no guidelines had been developed. Shear wave speed values obtained are compared and discussed with clinical measures. Reliability of the devices is also discussed.

INTERPRETATION

Shear wave ultrasound elastography can provide useful quantitative information on the mechanical properties of the spastic muscles in post-stroke patients. Nevertheless, new studies using common terminology and parameters are needed to develop reliable methods that could help in assessing treatment efficiency.

Influence of low muscle activation levels on the ankle torque and muscle shear modulus during plantar flexor stretching

During stretching studies, surface electromyography (sEMG) is used to ensure the passive state of the muscle, for the characterization of passive muscle mechanical properties. Different thresholds (1%, 2% or 5% of maximal) are indifferently used to set "passive state". This study aimed to investigate the effects of a slight activity on the joint and muscle mechanical properties during stretching. The joint torque and muscle shear modulus of the triceps surae muscles were measured in fifteen healthy volunteers during ankle dorsiflexions: (i) in a "fully relaxed" state, (ii) during active conditions where participants were asked to produce an sEMG amplitude of 1%, 2% or 5% of their maximal sEMG amplitude of the triceps surae. The 1% condition was the only that did not result in significant differences in joint torque or shear modulus compared to the relaxed condition. In the 2% condition, increases in joint torque were found at 80% of the maximal angle in dorsiflexion, and in the shear modulus of gastrocnemius medialis and gastrocnemius lateralis at the maximal angle in dorsiflexion. During the 5% condition, joint torque and the shear modulus of gastrocnemius medialis were higher than during relaxed condition at angles larger than 40% of maximal angle in dorsiflexion. The results provide new insights on the thresholds that should be considered for the design of stretching studies. A threshold of 1% seems much more appropriate than a 2% or 5% threshold in healthy participants. Further studies are required to define similar thresholds for patients.