title: The relation between Ashworth scores and neuromechanical measurements of spasticity following stroke Validation of portable muscle tone measurement device for quantifying velocity-dependent properties in elbow spasticity. Reliability of elbow stretch reflex assessment in chronic post-stroke hemiparesis Differences in kinematic parameters and plantarflexor reflex responses between manual (Ashworth) and isokinetic mobilisations in spasticity assessment Regulation of stretch reflex threshold in elbow flexors in children with cerebral palsy: a new measure of spasticity. Objective motor response onset detection in surface myoelectric signals. Evaluation of reflex- and nonreflex-induced muscle resistance to stretch in adults with spinal cord injury using hand-held and isokinetic dynamometry. Are we underestimating the clinical efficacy of botulinum toxin (type A)? Quantifying changes in spasticity, strength and upper limb function after injections of Botox® to the elbow flexors in a unilateral stroke population Is an instrumented spasticity assessment an improvement over clinical spasticity scales in assessing and predicting the response to integrated botulinum toxin type a treatment in children with cerebral palsy? Comprehensive quantification of the spastic catch in children with cerebral palsy.
abstract: Background Spasticity is a common impairment that follows stroke , and it results typically in functional loss . For this reason , accurate quantification of spasticity has both diagnostic and therapeutic significance . The most widely used clinical assessment of spasticity is the modified Ashworth scale ( MAS ) , an ordinal scale , but its validity , reliability and sensitivity have often been challenged . The present study addresses this deficit by examining whether quantitative measures of neural and muscular components of spasticity are valid , and whether they are strongly correlated with the MAS . Methods We applied abrupt small amplitude joint stretches and Pseudor and om Binary Sequence ( PRBS ) perturbations to both paretic and non-paretic elbow and ankle joints of stroke survivors . Using advanced system identification techniques , we quantified the dynamic stiffness of these joints , and separated its muscular ( intrinsic ) and reflex components . The correlations between these quantitative measures and the MAS were investigated . Results We showed that our system identification technique is valid in characterizing the intrinsic and reflex stiffness and predicting the overall net torque . Conversely , our results reveal that there is no significant correlation between muscular and reflex torque/stiffness and the MAS magnitude . We also demonstrate that the slope and intercept of reflex and intrinsic stiffnesses plotted against the joint angle are not correlated with the MAS . Conclusion Lack of significant correlation between our quantitative measures of stroke effects on spastic joints and the clinical assessment of muscle tone , as reflected in the MAS suggests that the MAS does not provide reliable information about the origins of the torque change associated with spasticity , or about its contributing components The objective of this study is to develop a portable device for quantifying the velocity-dependent properties of spastic elbow muscles .  Based on a motor-driven system , validation tests of the portable system such as accuracy and response of sensors were first examined . Furthermore , simulated modules ( inertia , damper and spring ) as well as elbow joints ( 15 control and 15 hemiplegic subjects ) were manually stretched under four different frequencies ( 1/3 , 1/2 , 1 and 3/2 Hz ) through 60 degrees range of motion . Joint resistance and displacement during sinusoidal stretch were collected for further analysis . Two quantitative parameters ( i.e. , viscous components under each frequency and averaged viscosity across four frequencies ) were derived to estimate the velocity-dependent properties of elbow joint . Tests of simulated modules confirm the manual stretch protocol and data analysis are valid in estimating the velocity-dependent component during a sinusoidal stretch . Compared to normal control , viscous component in each stretch frequency and averaged viscosity were significantly higher in subjects with spasticity ( P < 0.001 ) . The viscous component and averaged viscosity were found highly correlated with the modified Ashworth scale . These findings suggest that measurements of viscous component and averaged viscosity during manual sinusoidal stretching using the portable device could be clinical ly useful in evaluating spasticity OBJECTIVE To establish reliability of quantitative measures of elbow joint spastic hypertonia in post-stroke hemiparesis . METHODS Nine subjects with post-stroke hemiparesis ( mn duration : 42 months ) were tested on three separate days . Biceps brachii and brachioradialis EMG were recorded during passive ramp- and -hold extensions applied at seven speeds between 30 and 210 degrees /s . EMG burst duration , onset position threshold , and burst intensity were used to evaluate reflex activity . Torque at 40 degrees of elbow flexion was used as a mechanical indicator of spastic hypertonia . RESULTS Across speeds ICCs were consistent , means ranged between 0.63 and 0.85 . Thus , relative reliability was fair to excellent for all parameters . Absolute reliability , determined using st and ard error of measurement expressed as a percentage of the mean score ( % SEM ) , improved at higher speeds ( > or = 120 degrees/s ) . CONCLUSIONS These results establish reliability of reflex and mechanical measures of elbow spastic hypertonia post-stroke . The data demonstrate greater reflex detection at high speeds , indicating greater potential to document meaningful changes in these distinct aspects of spastic hypertonia following intervention . SIGNIFICANCE Based on findings of this study , reliability was demonstrated using four parameters of reflex EMG and torque indicating measurement consistency across sessions . These observations motivate determination of requisite effect sizes for clinical trials that evaluate treatment outcome OBJECTIVE The purpose of this study was first to compare the kinematic parameters of imposed ankle mobilizations measured during Ashworth or isokinetic tests and , second , to better underst and why the stretch reflex was more or less easily elicited by one method or the other . METHODS Passive dorsiflexions were applied on eight adult patients with plantarflexor spasticity in two conditions : ( i ) manually , using the Ashworth test where passive dorsiflexions were performed freely by seven rehabilitation clinicians , and ( ii ) instrumentally , using an isokinetic device ( Cybex Norm ) and a dorsiflexion velocity at 300 degrees /s .  Mean values of initial ankle position , maximal angular velocity ( theta;'(max ) ) , maximal angular acceleration ( theta;''(max ) ) and plantarflexor reflex responses obtained with each method were compared . RESULTS During the Ashworth test , all the patients presented reflex activities in the triceps surae while , during the isokinetic mobilization , only three out of the eight patients tested shown reflex responses . theta;'(max ) values were significantly higher ( P<0.05 ) in the manual test ( 308+/-80 degrees /s vs 216+/-5.5 degrees /s for the isokinetic test ) . The most marked difference concerned the theta;''(max ) values ( 5046+/-2181 degrees /s(2 ) for the Ashworth test vs 819+/-18 degrees /s(2 ) for the isokinetic test , P<0.001 ) . This parameter was significantly correlated with the mean rms-EMG values of the gastrocnemius lateralis ( GL ) and the soleus ( SOL ) . CONCLUSIONS This study indicates that passive dorsiflexions imposed during Ashworth and isokinetic tests largely differ in velocity and acceleration , and the higher dynamic parameters evaluated during the Ashworth test could mainly explain that the stretch reflex was more easily elicited during this manual testing . SIGNIFICANCE If isokinetic devices offer numerous advantages in the assessment of passive resistance to spastic muscle stretch , they can not be used to simulate the manual test The tonic stretch reflex threshold in children with cerebral palsy ( CP ) was measured to determine its test-retest reliability and its concurrent validity as a potential measure of spasticity . Fourteen children with spastic CP aged 6 to 18 years were tested on three separate occasions for clinical spasticity and stretch reflex thresholds of affected elbow flexors .  Electromyographic ( EMG ) recordings were obtained by surface electrodes for elbow flexors and extensors during mechanical displacements of the passive joint towards extension . Displacements were produced by a torque motor at seven velocities which r and omly varied from trial to trial . EMG activity was measured in the stretched flexor muscles to determine threshold angles and velocities for each velocity of stretch . These were plotted on a velocity-angle-phase diagram and regression analysis was used to determine the static stretch reflex threshold for each participant . The measure showed good test-retest reliability for the group ( ICC 0.73 , p<0.001 ) whereas a significant correlation between the measure and the clinical spasticity scale was not found . This technique is a potential outcome variable for measuring the efficacy of treatments aim ed at decreasing spasticity in children with CP Precise detection of discrete motor events like the onsets of voluntary muscle contractions is a prerequisite for various psychophysiological approaches in sensorimotor system analysis . In biomedical research and clinical diagnosis , motor events frequently are determined from surface electromyographic ( SEMG ) signals by some computerized detection algorithm . However , little is known about the reliability and accuracy of these methods , which frequently rely on intuitive and heuristic criteria . Therefore , the systematic approach to computerized detection of discrete motor events from SEMG signals presented by this paper fills a basic gap in EMG signal processing . Based upon a dynamic process model for the SEMG signal , a formal detection scheme is established which incorporates the essential processing modules common to the majority of algorithms . In addition , using concepts of statistically optimal change detection in r and om processes , a new model-based algorithm is presented which serves as a reference for optimum performance . The validity of this concept is demonstrated for the specific example of accurate detection of muscle activation onsets in rapid voluntary contractions ; the estimation error ( i.e. , the deviation between estimated and " true " onset time ) was evaluated by statistical simulations for three representative methods . Results show a substantial decrease of performance of traditional methods in the case of highly variable dynamic muscle activation profiles and /or superimposed activation patterns ( e.g. , due to a secondary motor task simultaneously executed by the same muscle ) . The model-based approach provided significantly more accurate results , even when the exact model parameters were unknown but estimated from the SEMG signal actually measured . It is concluded that the detection algorithm has to be critically taken into consideration during interpretation of motor events resolved from SEMG signals . The process model together with the corresponding statistically optimal detector represents an efficient tool for selecting appropriate detection algorithms for a particular experimental condition , and it allows a quantitative assessment of their performance BACKGROUND AND PURPOSE In this study , we compared the intertrial reliability of resistive torque measurements obtained with h and -held and isokinetic dynamometers and examined the validity of the h and -held dynamometers for the assessment of spastic hypertonia , defined as reflex- and nonreflex-induced resistance to stretch . SUBJECTS Nine subjects ( mean age = 40.6 years ) with a chronic ( 1 - 5 years ) spinal cord injury participated . METHODS The plantar flexors were stretched at 5 degrees /s ( low velocity [ LV ] ) and 180 degrees /s ( high velocity [ HV ] ) with an isokinetic dynamometer while the evaluator attempted to match these velocities with a h and -held dynamometer .  Electromyographic activity of the soleus and tibialis anterior muscles as well as ankle displacements were recorded . Resistive torque and velocity , measured at -5 degrees of dorsiflexion , were averaged ( n = 4 ) . RESULTS High intraclass correlation coefficients ( ICCs ) were found at LV and HV for both the h and -held ( ICC = .93 and .84 ) and isokinetic ( ICC = .99 and .93 ) dynamometers . With the h and -held dynamometer , lower resistive torques were found at LV ( 0.8 N.m ) and HV ( 1.2 N.m ) , whereas higher velocities were attained at HV . CONCLUSION AND DISCUSSION The results indicate that the reproducibility of resistive torques obtained with h and -held dynamometry compares with that obtained with isokinetic dynamometry and allows testing of velocities that can be adjusted to the specific level of resistance to stretch . Electromyography confirmed the validity of h and -held dynamometry for assessing reflex and nonreflex components of SH . [ Lamontagne A , Malouin F , Richards CL , Dumas F. Evaluation of reflex- and nonreflex-induced muscle resistance to stretch in adults with spinal cord injury using h and -held and isokinetic dynamometry Objective : To quantify the clinical efficacy of botulinum toxin type A in treating elbow flexor spasticity in a unilateral stroke population . Location : A spasticity clinic at a regional neurological rehabilitation centre . Study design : A convenience sample longitudinal study . Fourteen subjects with elbow flexor spasticity secondary to a stroke were recruited . Two repeated measures , one before and another four weeks after treatment , were taken to quantify clinical efficacy . Outcome measures : Elbow flexor spasticity was simultaneously rated with the modified Ashworth scale ( MAS ) and quantified by measuring the surface EMG from the flexors using a custom-built device . Strength at the elbow ( isometric ) , grip strength and upper limb function ( Action Research Arm test ) were also assessed . Treatment : Injections of botulinum toxin type A ( Botox ® ) to the m.biceps brachii ( mean dose 70 U ) , m.brachioradialis ( mean dose 56.5 U ) and m.flexor digitorum longus ( mean dose 83.3 U ) . Results : Following treatment , spasticity ( as measured by flexor EMG activity ) reduced but the MAS was unable to detect this improvement . In some subjects , isometric flexor strength at the elbow as well as grip strength increased . This was contrary to the expected weakening following treatment with botulinum toxin type A and suggests an optimization of motor control . Conclusion : Treatment with Botox ® reduces spasticity but does not necessarily cause a reduction in the force generating capabilities at the joint . The improvement in strength may have contributed to the improvements in upper limb function . The MAS is an inappropriate measure of spasticity OBJECTIVE To compare responsiveness and predictive ability of clinical and instrumented spasticity assessment s after botulinum toxin type A ( BTX ) treatment combined with casting in the medial hamstrings ( MEHs ) in children with spastic cerebral palsy ( CP ) . DESIGN Prospect i ve cohort study . SETTING Hospital . PARTICIPANTS Consecutive sample of children ( N=31 ; 40 MEH muscles ) with CP requiring BTX injections . INTERVENTION Clinical and instrumented spasticity assessment s before and on average ± SD 53±14 days after BTX . MAIN OUTCOME MEASURES Clinical spasticity scales included the Modified Ashworth Scale and the Modified Tardieu Scale . The instrumented spasticity assessment integrated biomechanical ( position and torque ) and electrophysiological ( surface electromyography ) signals during manually performed low- and high-velocity passive stretches of the MEHs . Signals were compared between both stretch velocities and were examined pre- and post-BTX . Responsiveness of clinical and instrumented assessment s was compared by percentage exact agreement . Prediction ability was assessed with a logistic regression and the area under the receiver operating characteristic ( ROC ) curves of the baseline parameters of responders versus nonresponders . RESULTS Both clinical and instrumented parameters improved post-BTX ( P≤.005 ) ; however , they showed a low percentage exact agreement . The baseline Modified Tardieu Scale was the only clinical scale predictive for response ( area under the ROC curve=0.7 ) . For the instrumented assessment , baseline values of root mean square ( RMS ) electromyography and torque were better predictors for a positive response ( area under the ROC curve=.82 ) . Baseline RMS electromyography remained an important predictor in the logistic regression . CONCLUSIONS The instrumented spasticity assessment showed higher responsiveness than the clinical scales . The amount of RMS electromyography is considered a promising parameter to predict treatment response In clinical setting s , the spastic catch is judged subjectively . This study assessed the psychometric properties of objective parameters that define and quantify the severity of the spastic catch in children with cerebral palsy ( CP ) . A convenience sample of children with spastic CP ( N=46 ; age range : 4 - 16 years ) underwent objective spasticity assessment s. High velocity , passive stretches were applied to the gastrocnemius ( GAS ) and medial hamstrings ( MEH ) .  Muscle activity was measured with surface electromyography ( sEMG ) , joint angle characteristics using inertial sensors and reactive torque using a force sensor . To test reliability , a group of 12 children were retested after an average of 13 ± 9 days . The angle of spastic catch ( AOC ) was estimated by three biomechanical definitions : joint angle at ( 1 ) maximum angular deceleration ; ( 2 ) maximum change in torque ; and ( 3 ) minimum power . Each definition was checked for reliability and validity . Construct and clinical validity were evaluated by correlating each AOC definition to the averaged root mean square envelope of EMG ( RMS-EMG ) and the Modified Tardieu Scale ( MTS ) . Severity categories were created based on selected parameters to establish face validity . All definitions showed moderate to high reliability . Significant correlations were found between AOC3 and the MTS of both muscles and the RMS-EMG of the MEH , though coefficients were only weak . AOC3 further distinguished between mild , moderate and severe catches . Objective parameters can define and quantify the severity of the spastic catch in children with CP . However , a comprehensive underst and ing requires the integration of both biomechanical and RMS-EMG data
target: Parameters that integrated electrophysiological signals with joint movement characteristics were best able to quantify spasticity .
  There were conflicting results regarding biomechanical-based parameters that quantify the resistance to passive stretch .
background: AIM The first aim of this study was to systematic ally review and critically assess manually controlled instrumented spasticity assessment methods that combine multidimensional signals .
  The second aim was to extract a set of quantified parameters that are psychometrically sound to assess spasticity in a clinical setting .