Electromyography characterization of stretch responses in hemiparetic stroke patients and their relationship with the Modified Ashworth Scale

Technology-assisted assessment of spasticity: a systematic review

BACKGROUND

Spasticity is defined as "a motor disorder characterised by a velocity dependent increase in tonic stretch reflexes (muscle tone) with exaggerated tendon jerks". It is a highly prevalent condition following stroke and other neurological conditions. Clinical assessment of spasticity relies predominantly on manual, non-instrumented, clinical scales. Technology based solutions have been developed in the last decades to offer more specific, sensitive and accurate alternatives but no consensus exists on these different approaches.

METHOD

A systematic review of literature of technology-based methods aiming at the assessment of spasticity was performed. The approaches taken in the studies were classified based on the method used as well as their outcome measures. The psychometric properties and usability of the methods and outcome measures reported were evaluated.

RESULTS

124 studies were included in the analysis. 78 different outcome measures were identified, among which seven were used in more than 10 different studies each. The different methods rely on a wide range of different equipment (from robotic systems to simple goniometers) affecting their cost and usability. Studies equivalently applied to the lower and upper limbs (48% and 52%, respectively). A majority of studies applied to a stroke population (N = 79). More than half the papers did not report thoroughly the psychometric properties of the measures. Analysis identified that only 54 studies used measures specific to spasticity. Repeatability and discriminant validity were found to be of good quality in respectively 25 and 42 studies but were most often not evaluated (N = 95 and N = 78). Clinical validity was commonly assessed only against clinical scales (N = 33). Sensitivity of the measure was assessed in only three studies.

CONCLUSION

The development of a large diversity of assessment approaches appears to be done at the expense of their careful evaluation. Still, among the well validated approaches, the ones based on manual stretching and measuring a muscle activity reaction and the ones leveraging controlled stretches while isolating the stretch-reflex torque component appear as the two promising practical alternatives to clinical scales. These methods should be further evaluated, including on their sensitivity, to fully inform on their potential.

Anterior or Posterior Ankle Foot Orthoses for Ankle Spasticity: Which One Is Better?

Background and Objectives: Ankle foot orthoses (AFOs) are commonly used by stroke patients to walk safely and efficiently. Both posterior AFOs (PAFOs) and anterior AFOs (AAFOs) are available. The objective of this study was to compare the efficacy of AAFOs and PAFOs in the treatment of ankle spasticity. Materials and Methods: A crossover design with randomization for the interventions and blinded assessors was used. Twenty patients with chronic stroke, a Modified Ashworth Scale (MAS) score of the ankle joint of 2, and a Tardieu angle ≥20 degrees were recruited. The patients were assigned to wear either an AAFO or PAFO at random and subsequently crossover to the other AFO. Results: Twenty stroke patients with ankle spasticity were recruited. The mean age was 46.60 (38−60) years. The mean time since stroke onset was 9.35 (6−15) months. It was discovered that the AAFO improved walking speed as well as the stretch reflex dynamic electromyography (dEMG) and walking dEMG amplitudes of the medial gastrocnemius muscles more significantly than the PAFO (p < 0.05). Conclusions: The AAFO had greater efficacy in reducing both static and dynamic ankle spasticity, and allowed for faster walking than the PAFO. The stretch reflex and walking dEMG amplitudes could be used for quantitative spasticity assessment.

Knee Muscle Stretch Reflex Responses After an Intrathecal Baclofen Bolus in Neurological Patients With Moderate-to-Severe Hypertonia

OBJECTIVES

To examine the prevalence, onset threshold, and response magnitude of stretch reflex response (SRR) in the knee extensors and flexors before and after an intrathecal baclofen (ITB) bolus injection in patients with moderate-to-severe hypertonia.

MATERIALS AND METHODS

SRRs were elicited by reciprocal passive knee extension/flexion movements at preset angular velocities of 5, 60, 120, 180, 240, and 300°/s using an isokinetic dynamometer and recorded with surface electromyographic (EMG) electrodes placed over the knee extensors and flexors in 53 neurologic patients before and at 2.5 and 5 hours after an ITB injection via lumbar puncture. Outcome measures included the number of patients with presence/absence of SRRs, the number of SRRs per session, SRR onset threshold angle and velocity, and response magnitudes (peak EMG and area under the EMG curve) for each muscle. Pre-post comparisons were completed using the Fisher's exact and Wilcoxon signed rank tests.

RESULTS

For both knee extensors and flexors, the proportion of patients with present SRRs (p < 0.0001) and the number of SRRs per session (p ≤ 0.027) decreased from pre- to post-ITB. The threshold velocity significantly increased post-injection in both muscles (p ≤ 0.001) without significant changes in the threshold angle. The response magnitudes significantly decreased in the knee extensors (p ≤ 0.016) but not the knee flexors after the injection.

CONCLUSIONS

The prevalence and threshold velocity of SRR emerged as the most robust and practical parameters for assessing hyperreflexia during ITB bolus trial that can complement clinical assessment of muscle hypertonia.

A Regression-Based Framework for Quantitative Assessment of Muscle Spasticity Using Combined EMG and Inertial Data From Wearable Sensors

There have always been practical demands for objective and accurate assessment of muscle spasticity beyond its clinical routine. A novel regression-based framework for quantitative assessment of muscle spasticity is proposed in this paper using wearable surface electromyogram (EMG) and inertial sensors combined with a simple examination procedure. Sixteen subjects with elbow flexor or extensor (i.e., biceps brachii muscle or triceps brachii muscle) spasticity and eight healthy subjects were recruited for the study. The EMG and inertial data were recorded from each subject when a series of passive elbow stretches with different stretch velocities were conducted. In the proposed framework, both lambda model and kinematic model were constructed from the recorded data, and biomarkers were extracted respectively from the two models to describe the neurogenic component and biomechanical component of the muscle spasticity, respectively. Subsequently, three evaluation methods using supervised machine learning algorithms including single-/multi-variable linear regression and support vector regression (SVR) were applied to calibrate biomarkers from each single model or combination of two models into evaluation scores. Each of these evaluation scores can be regarded as a prediction of the modified Ashworth scale (MAS) grade for spasticity assessment with the same meaning and clinical interpretation. In order to validate performance of three proposed methods within the framework, a 24-fold leave-one-out cross validation was conducted for all subjects. Both methods with each individual model achieved satisfactory performance, with low mean square error (MSE, 0.14 and 0.47) between the resultant evaluation score and the MAS. By contrast, the method using SVR to fuse biomarkers from both models outperformed other two methods with the lowest MSE at 0.059. The experimental results demonstrated the usability and feasibility of the proposed framework, and it provides an objective, quantitative and convenient solution to spasticity assessment, suitable for clinical, community, and home-based rehabilitation.

Position as Well as Velocity Dependence of Spasticity-Four-Dimensional Characterizations of Catch Angle

We investigated the muscle alterations related to spasticity in stroke quantitatively using a portable manual spasticity evaluator.

Methods: Quantitative neuro-mechanical evaluations under controlled passive elbow stretches in stroke survivors and healthy controls were performed in a research laboratory of a rehabilitation hospital. Twelve stroke survivors and nine healthy controls participated in the study. Spasticity and catch angle were evaluated at 90°/s and 270°/s with the velocities controlled through real-time audiovisual feedback. The elbow range of motion (ROM), stiffness, and energy loss were determined at a slow velocity of 30°/s. Four-dimensional measures including joint position, torque, velocity and torque change rate were analyzed jointly to determine the catch angle.

Results: The catch angle was dependent on the stretch velocity and occurred significantly later with increasing velocity (p < 0.001), indicating position dependence of spasticity. The higher resistance felt by the examiner at the higher velocity was also due to more extreme joint position (joint angle) since the spastic joint was moved significantly further to a stiffer elbow position with the higher velocity. Stroke survivors showed smaller ROM (p < 0.001), higher stiffness (p < 0.001), and larger energy loss (p = 0.005). Compared to the controls, stroke survivors showed increased reflex excitability with higher reflex-mediated torque (p < 0.001) and at higher velocities (p = 0.02).

Conclusion: Velocity dependence of spasticity is partially due to joint angle position dependence with the joint moved further (to a stiffer position where higher resistance was felt) at a higher velocity. The “4-dimensional characterization” including the joint angle, velocity, torque, and torque change rate provides a systematic tool to characterize catch angle and spasticity quantitatively.

Intra- and inter-rater reliabilities of measurement of ultrasound imaging for muscle thickness and pennation angle of tibialis anterior muscle in stroke patients

BACKGROUND

Dysfunction of skeletal muscle has been commonly reported in stroke patients.

OBJECTIVE

The purpose of this study was to investigate the intra- and inter-rater reliabilities of measurement of ultrasound imaging (USI) for pennation angle (PA) and muscle thickness (MT) of tibialis anterior muscle in stroke patients.

METHODS

Thirty-four stroke patients (19 men) participated in this study. USI was used for measurement of PA and MT of the tibialis anterior muscles at rest and during maximum voluntary contraction (MVC). Two examiners acquired images from all participants during two separate testing sessions, seven days apart. Intra-class correlation coefficients (ICCs), confidence interval (CI), standard error of measurement, minimal detectable change, and Bland-Altman plots were used for estimation of reliability.

RESULTS

In the intra-rater reliability between measures, for all variables (PA and MT of the paretic and non-paretic sides of tibialis anterior muscles at rest and during MVC), the ICCs ranged between 0.639 and 0.998 and the CI was within an acceptable range of 0.388-0.999. In inter-rater reliability between examiners for the two tests, for all variables, the ICCs ranged between 0.690 and 0.995 and the CI was within an acceptable range of 0.463-0.997. In addition, significant difference was observed between the paretic and non-paretic sides of the tibialis anterior muscle architecture (p < 0.05).

CONCLUSION

These finding demonstrate that measurements of the tibialis anterior muscle using USI can be useful for clinical assessment in stroke patients. In addition, objective and quantitative measurements of tibialis anterior muscle using USI may provide appropriate management for the walking recovery of stroke patients.

Primary and secondary gait deviations of stroke survivors and their association with gait performance

[Purpose] Stroke survivors exhibit abnormal pelvic motion and significantly deteriorated gait performance. Although the gait of stroke survivors has been evaluated at the primary level pertaining to ankle, knee, and hip motions, secondary deviations involving the pelvic motions are strongly related to the primary level. Therefore, the aim of this study was to identify the kinematic differences of the primary and secondary joints and to identify mechanism differences that alter the gait performance of stroke survivors. [Subjects and Methods] Five healthy subjects and five stroke survivors were recruited. All the subjects were instructed to walk at a self-selected speed. The joint kinematics and gait parameters were calculated. [Results] For the stroke survivors, the range of motion of the primary-joint motions were significantly reduced, and the secondary-joint motions were significantly increased. Additionally, for the healthy subjects, the primary joint kinematics were the main factors ensuring gait performance, whereas for the stoke survivors, the secondary-joint motions were the main factors. [Conclusion] The results indicate that while increasing the range of motion of primary-joint movements is the main target to achieve, there is a strong need to constrain and support pelvic motions in order to improve the outcome of gait rehabilitation.

The effects of mirror therapy on the gait of subacute stroke patients: a randomized controlled trial

Objective:

To investigate the effect of mirror therapy on the gait of patients with subacute stroke.

Design:

Randomized controlled experimental study.

Setting:

Outpatient rehabilitation hospital.

Subjects:

Thirty-four patients with stroke were randomly assigned to two groups: a mirror therapy group (experimental) and a control group.

Interventions:

The stroke patients in the experimental group underwent comprehensive rehabilitation therapy and mirror therapy for the lower limbs. The stroke patients in the control group underwent sham therapy and comprehensive rehabilitation therapy. Participants in both groups received therapy five days per week for four weeks.

Main measures:

Temporospatial gait characteristics, such as single stance, stance phase, step length, stride, swing phase, velocity, and cadence, were assessed before and after the four weeks therapy period.

Results:

A significant difference was observed in post-training gains for the single stance (10.32 SD 4.14 vs. 6.54 SD 3.23), step length (8.47 SD 4.12 vs. 4.83 SD 2.14), and stride length (17.03 SD 6.57 vs 10.54 SD 4.34) between the experimental group and the control group ( p < 0.05). However, there were no significant differences between two groups on stance phase, swing phase, velocity, cadence, and step width ( P > 0.05).

Conclusion:

We conclude that mirror therapy may be beneficial in improving the effects of stroke on gait ability.

Effect of a local vibration stimulus training programme on postural sway and gait in chronic stroke patients: a randomized controlled trial

Objective:

To investigate the effect of a local vibration stimulus training programme on postural sway and gait in stroke patients.

Design:

A randomized controlled trial with two groups: a local vibration stimulus training programme group and a sham group.

Setting:

Inpatient rehabilitation centre.

Subjects:

Thirty-one chronic stroke patients.

Interventions:

Both groups underwent a standard rehabilitation programme. The local vibration stimulus training programme group ( n = 16) participated in the local vibration stimulus training programme for 30 minutes a day, five times a week, for six weeks. The sham group ( n = 15) participated in a sham local vibration stimulus training programme for 30 minutes a day, five times a week, for six weeks.

Main measures:

A forceplate was used to measure postural sway under two conditions: standing with eyes open and eyes closed. Gait ability was measured using the GAITRite system.

Results:

In postural sway, greater improvements in the postural sway distance with eyes-open (–11.91 vs. 0.80) and eyes-closed (–20.67 vs. –0.34) conditions and postural sway velocity with eyes-open (–0.40 vs. 0.03) and eyes-closed (–0.69 vs. –0.01) conditions were observed in the local vibration stimulus training programme group, compared with the sham group ( P < 0.05). In gait ability, greater improvement in gait speed (15.06 vs. 2.85), cadence (8.46 vs. 1.55), step length (7.90 vs. 3.64), and single limb support time (0.12 vs. 0.01) were observed in the local vibration stimulus training programme group, compared with the sham group ( P < 0.05).

Conclusions:

These findings suggest that local vibration stimulus training programme is an effective method for improvement of the postural sway and gait ability of chronic stroke patients.

Elbow spasticity during passive stretch-reflex: clinical evaluation using a wearable sensor system

BACKGROUND

Spasticity is a prevalent chronic condition among persons with upper motor neuron syndrome that significantly impacts function and can be costly to treat. Clinical assessment is most often performed with passive stretch-reflex tests and graded on a scale, such as the Modified Ashworth Scale (MAS). However, these scales are limited in sensitivity and are highly subjective. This paper shows that a simple wearable sensor system (angle sensor and 2-channel EMG) worn during a stretch-reflex assessment can be used to more objectively quantify spasticity in a clinical setting.

METHODS

A wearable sensor system consisting of a fibre-optic goniometer and 2-channel electromyography (EMG) was used to capture data during administration of the passive stretch-reflex test for elbow flexor and extensor spasticity. A kinematic model of unrestricted passive joint motion was used to extract metrics from the kinematic and EMG data to represent the intensity of the involuntary reflex. Relationships between the biometric results and clinical measures (MAS, isometric muscle strength and passive range of motion) were explored.

RESULTS

Preliminary results based on nine patients with varying degrees of flexor and extensor spasticity showed that kinematic and EMG derived metrics were strongly correlated with one another, were correlated positively (and significantly) with clinical MAS, and negatively correlated (though mostly non-significant) with isometric muscle strength.

CONCLUSIONS

We conclude that a wearable sensor system used in conjunction with a simple kinematic model can capture clinically relevant features of elbow spasticity during stretch-reflex testing in a clinical environment.

Clinical assessment of ankle plantarflexor spasticity in adult patients after stroke: inter-and intra-rater reliability of the Modified Tardieu Scale

PRIMARY OBJECTIVE

To evaluate the reliability of the Modified Tardieu Scale (MTS) in the measurement of ankle plantarflexor spasticity in patients after stroke.

RESEARCH DESIGN

Inter- and intra-rater reliability study.

INTERVENTIONS

Not applicable.

METHODS AND PROCEDURES

Adult patients after stroke participated. Patients were tested by two raters for inter-rater reliability. Patients were re-tested by one rater at least 1 week later for intra-rater reliability. The plantarflexors on the hemiparetic side were tested.

MAIN OUTCOMES AND RESULTS

The ICCs of inter and intra-rater reliability across all components of MTS were moderate and moderately high (range 0.40-0.71). Inter- and intra-rater reliability for the dynamic component of spasticity (R2-R1) were moderate (ICC = 0.57 and 0.40, respectively). The difference between the two raters for R2 was statistically significant (p = 0.001).

CONCLUSIONS

The reliability of the Modified Tardieu Scale in the measurement of ankle plantarflexor spasticity in adult patients after stroke was insufficient for routine use in clinical settings and research.

Clinical measurement of limb spasticity in adults: state of the science

Spasticity is a neuromuscular dysfunction characterized by tight or stiff muscles. Spasticity occurs across the spectrum of upper motor neuron disease and complicates the course and quality of life of those affected. Accurate and precise assessment of spasticity is the first step in providing safe and effective treatments to patients for management of spasticity. Examiner evaluations (Ashworth Scale, Modified Ashworth, and Visual Analog Scale) and patient self-reports (Visual Analog Scale and Numeric Rating Scale) are used to assess spasticity in clinical practice. We reviewed the biology of spasticity and summarized research that assessed properties of scores obtained from clinical scales when used in a variety of upper motor neuron diseases. The definition of spasticity was inconsistent. Rater reliability or agreement on clinical scales varied widely. Correspondence with electromyogram results was mixed. There was dissimilarity in patient reports and examiner assessments. Scores from clinical scales are responsive (decrease after initiation of treatment with known effectiveness), but the utility of scores for indexing individual change associated with the natural history of upper motor neuron disease is unknown. Future research incorporating patient reports and examiner findings over time will help to clarify the definition and capture the essence of spasticity.

Characterization of spasticity in cerebral palsy: dependence of catch angle on velocity

AIM

To evaluate spasticity under controlled velocities and torques in children with cerebral palsy (CP) using a manual spasticity evaluator.

METHOD

The study involved 10 children with spastic CP (six males, four females; mean age 10 y 1 mo, SD 2 y 9 mo, range 7-16 y; one with quadriplegia, six with right hemiplegia, three with left hemiplegia; Gross Motor Function Classification System levels I [n=2], II [n=3], III [n=2], IV [n=2], and V [n=1]; Manual Ability Classification System levels II [n=5], III [n=4], and V [n=1]) and 10 typically developing participants (four males, six females; mean age 10 y 3 mo, SD 2 y 7 mo, range 7-15 y). Spasticity and catch angle were evaluated using joint position, resistance torque, and torque rate at velocities of 90 degrees, 180 degrees, and 270 degrees per second, controlled using real-time audio-visual feedback. Biomechanically, elbow range of motion (ROM), stiffness, and energy loss were determined during slow movement (30 degrees/s) and under controlled terminal torque.

RESULTS

Compared with typically developing children, children with CP showed higher reflex-mediated torque (p<0.001) and the torque increased more rapidly with increasing velocity (p<0.001). Catch angle was dependent on velocity and occurred later with increasing velocity (p=0.005). Children with CP showed smaller ROM (p<0.05), greater stiffness (p<0.001), and more energy loss (p=0.003).

INTERPRETATION

Spasticity with velocity dependence may also be position-dependent. The delayed catch angle at higher velocities indicates that the greater resistance felt by the examiner at higher velocities was also due to position change, because the joint was moved further to a stiffer position at higher velocities.

Inter-rater reliability of the Modified Modified Ashworth Scale in assessing lower limb muscle spasticity

PRIMARY OBJECTIVE

To assess the inter-rater reliability of the Modified Modified Ashworth Scale (MMAS) in lower limb muscle spasticity.

RESEARCH DESIGN

Cross-sectional observational study.

INTERVENTIONS

Not applicable.

METHODS AND PROCEDURES

Twenty-two adults with neurological conditions (17 women, five men, age range 21-82 years; mean +/- SD, 44 +/- 18 years) participated. Hip adductor, knee extensor and ankle plantarflexor were assessed in a random order.

MAIN OUTCOMES AND RESULTS

Inter-rater agreement for two raters was very good for the hip adductor and the knee extensor (weighted kappa = 0.82, p < 0.0001) and good for the ankle plantarflexor (weighted kappa = 0.74, p < 0.0001).

CONCLUSIONS

The Modified Modified Ashworth Scale produced reliable measurements between raters in the assessment of lower limb muscle spasticity.

Electromyographic Response to Manual Passive Stretch of the Hemiplegic Wrist: Accuracy, Reliability, and Correlation With Clinical Spasticity Assessment and Function

Background. The management of spasticity is important in neurorehabilitation and needs to be assessed accurately. The commonly used clinical tools have been criticized for lack of validity and sensitivity. Objective. To investigate the reliability of electromyographic (EMG) response to manual stretches of the hemiplegic wrist and its correlation with clinical assessments of spasticity and physical function. Methods. EMG activity was measured in 10 stroke patients and control participants (53.7 ± 10 and 32 ± 9.1 years respectively, mean ± SEM) during 3 cycles of 10 seconds passive manual movements of the wrist at 60 to 360° • s-1. Isometric maximal voluntary contractions (MVC) strength, range of movement (ROM) of the wrist flexors and extensors, spasticity (Modified Ashworth Scale [MAS]) and hand function (Block and Box Test [BBT]) were also assessed. Results. EMG activity of the stroke patients increased with velocity from 4% to 40% MVC ( P < .001) but there was none in the controls. It was unaffected by repetition and good to moderate reliability occurred at all speeds (ICC, 0.71-0.81). EMG correlated negatively with MVC strength ( r = -.9), active wrist flexion ROM ( r = -.8), and hand function scores ( r = —.7), but not with clinical measures of spasticity except at the lowest velocity ( r = .72). Conclusions. Consistent and accurate stretch velocities and EMG responses can be achieved with manual wrist stretches for the assessment of the neural component of spasticity. These objective tests did not correlate well with the standard clinical assessment of spasticity. They showed significant negative relationships with function, indicating that increased reflex excitability contributes to hand disability after stroke.

Inter- and intrarater reliability of the Modified Modified Ashworth Scale in patients with knee extensor poststroke spasticity

Muscle spasticity is a common motor disorder following upper motor neuron syndrome. A reliable and valid clinical tool is essential to document the effect of therapeutic interventions aimed to improve function by reducing spasticity. The Modified Ashworth Scale (MAS) is the most widely used and accepted clinical scale of spasticity. The MAS has been recently modified. The aim of this investigation was to determine the interrater and intrarater reliability of clinical test of knee extensor post-stroke spasticity graded on a Modified Modified Ashworth Scale (MMAS). Two raters scored the muscle spasticity of 15 patients with ischaemic stroke. For the inter- and intrarater reliability, two raters agreed on 80.1% and 86.6%, respectively. The Kappa values were good (kappa=0.72, SE=0.14, p<0.001) between raters and very good (kappa=0.82, SE=0.12, p<0.001) within one rater. The values of Kendall tau-b correlation were acceptable for clinical use with 0.87 (SE=0.06, p<0.001) between raters and 0.92 (SE=0.05, p<0.001) within one rater. The MMAS demonstrated reliable measurements for a single rater and between raters for measuring knee extensor post-stroke spasticity. The results encourage further study on the reliability and the validity of the scale.

Clinometric properties of a clinical spasticity measurement tool

PURPOSE

To investigate clinometric properties of an Anglo-Dutch spasticity measurement tool (ADSMT), an objective tool providing information about both neurophysiological and biomechanical aspects of spasticity about the wrist joint in the clinical setting.

METHOD

ADSMT measurements were performed with 12 healthy and 11 participants with post-stroke spasticity, and consisted of assessing the maximum range of passive wrist movement (pROM) and passive wrist extension at different cycle rates. Outcome measures were wrist angle, flexor and extensor activation, and resistance to movement. Intra-class Correlation Coefficients (ICCs) were calculated for inter-rater and test-retest reliability. Validity was investigated by calculating Spearman's rho between ADSMT outcome measures and the Modified Ashworth Scale (n=12), the Action Research Arm Test (n=6), and a validated wrist rig (n=6).

RESULTS

Impaired participants had higher flexor activity and higher resistance to movement during passive wrist extension compared to unimpaired participants. For all outcome measures inter-rater and test-retest reliability were satisfactory to good and concurrent validity was sufficient.

CONCLUSIONS

Outcome measures related to wrist flexor activity and resistance to movement during extension are promising for spasticity assessment using the ADSMT. Further knowledge on reference values and practicality is necessary for this tool to become incorporated in the clinical setting.