The construct validity of a spasticity measurement device for clinical practice: An alternative to the Ashworth scales

Institute of Life Course Studies & School of Health and Rehabilitation, Keele University, Keele, UK.
Disability and Rehabilitation (Impact Factor: 1.99). 06/2006; 28(9):579-85. DOI: 10.1080/09638280500242390
Source: PubMed


Introduction. Spasticity is a significant cause of disability in people with an upper motor neurone lesion, but there is a paucity of appropriate outcome measures to evaluate this phenomenon. The aim was to test the construct validity of a clinically relevant, non-invasive measure of spasticity. Methods. A cross-section study design in which participants with elbow flexor spasticity and capable of providing written informed consent were recruited. Results. Fourteen stroke patients participated (six female and eight male). Median age was 61 years and the median time post stroke was 48 months. Six patients had a MAS grading of '1+' three a grade of '2'and five a grade of '3'. The velocity of the brisk stretch was significantly higher than that of the slow stretch (p < 0.05: median difference, 2.0μV; IQR, 0.04-8.4). In contast the RPE was not significantly different between the slow and the fast strecthes (p > 0.1: median difference, 0107 N/deg; IQR, -0.09-0.16). There were no patterns of association between the MAS, elbow flexor muscle activity and RPE. Other important observations, in some patients, were: Continuous background muscle activation consistent with descriptions of spastic dystonia; muscle activity at the slow velocity stretch; muscle activation patterns consistent with the clasp-knife phenomenon. Conclusions. The measurement system was capable of measuring spasticity as defined by Lance (1980; In: Lance et al., editors. Spasticity: Disordered motor control. Chicago, IL: Year Book. p 185 - 204). In addition, it enabled various other clinical phenomena associated with spasticity to be measured. Assessing spasticity by measuring changes in resistance to passive movement only may not be sufficient, as the latter is influenced by many factors of which spasticity may only be one. Further work is now required to investigate repeatability and sensitivity.

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    • "The cost of rehabilitation and management of problematic spasticity and related complications (pain, contracture, etc.) can be extraordinarily high [27] and “cost-benefit” research of pharmacological treatments often use standard clinical assessment tools such as the MAS [28,29] as outcomes measurements. Furthermore, according to Pandyan et al. [8] all randomized clinical trials on stroke therapy published between October 1989 and October 2004 used the MAS as a primary outcome measure. Therefore, it is not only critical to determine what the MAS is actually measuring, but there is a clear need to explore better ways to incorporate more objective assessment of spasticity into clinical research and practice. "
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    ABSTRACT: 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.
    Full-text · Article · Jun 2013 · Journal of NeuroEngineering and Rehabilitation
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    • "Active and passive tasks were found in 10 articles [17,19,20,26,27,29,33,34,38,46]. Different measuring velocities were found in 19 articles [18-22,24,27,30-35,37-39,43,44,47]. In 6 articles, all of the aforementioned properties were present (see Figure  2) [19,20,27,33,34,38]. "
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    ABSTRACT: Background Movement disorders after stroke are still captured by clinical gaze and translated to ordinal scores of low resolution. There is a clear need for objective quantification, with outcome measures related to pathophysiological background. Neural and non-neural contributors to joint behavior should be separated using different measurement conditions (tasks) and standardized input signals (force, position and velocity). Methods We reviewed recent literature for the application of biomechanical and/or elektromyographical (EMG) outcome measures under various measurement conditions in clinical research. Results Since 2005, 36 articles described the use of biomechanical and/or EMG outcome measures to quantify post-stroke movement disorder. Nineteen of the articles strived to separate neural and non-neural components. Only 6 of the articles measured biomechanical and EMG outcome measures simultaneously, while applying active and passive tasks and multiple velocities. Conclusion The distinction between neural and non-neural components to separately assess paresis, stiffness and muscle overactivity is not commonplace yet, while a large gap is to be bridged to attain reproducible and comparable results. Pathophysiologically clear concepts, substantiated with a comprehensive and concise measuring protocol will help professionals to identify and treat limiting factors in movement capabilities of post-stroke patients.
    Full-text · Article · Aug 2012 · Journal of NeuroEngineering and Rehabilitation
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    • "This lack of a significant association is consistent with previous research [1]. Although the MAS is widely used as a measure of spasticity in research and clinical practice, the measure has several limitations (e.g., reliance upon subjective judgment of clinician and lack of specificity for spasticity) and has questionable validity and reliability [14]. Such problems question the meaningfulness of the observed reduction in the MAS after exercise in the current study and the use of the MAS in future studies of exercise and spasticity in individuals with MS. "
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    ABSTRACT: This study examined the effect of a single bout of unloaded leg cycling on the soleus H-reflex and modified Ashworth scale (MAS) in 27 individuals with multiple sclerosis (MS) who had spasticity of the leg muscles, but were not currently taking anti-spastic medications. The soleus H-reflex and MAS data were collected before and 10, 30, and 60 min after 20 min of unloaded leg cycling and a control condition. The acute bout of unloaded leg cycling resulted in concomitant and prolonged reductions in the soleus H-reflex and MAS scores compared with the control condition. This provides converging evidence for the anti-spastic potential of acute unloaded leg cycling in individuals with MS.
    Full-text · Article · Nov 2006 · Neuroscience Letters
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