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Michael P Barnes

Publications and source records attributed to Michael P Barnes.

6 recordsLinked to original sources
PubMed2006

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

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, 34 degrees /s: IQR, 20 - 46). Flexor muscle activity during the brisk stretch was significantly higher than that of the slow stretch (p < 0.05: median difference, 2.0 microV; IQR, 0.4 - 8.4). In contrast the RPE was not significantly different between the slow and the fast stretches (p > 0.1: median difference, 0.07 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.

Biomechanical Phenomena↗
PubMed2003

A biomechanical investigation into the validity of the modified Ashworth Scale as a measure of elbow spasticity.

OBJECTIVE: To investigate the criterion validity of the modified Ashworth Scale. POPULATION: Volunteers from a stroke population admitted to a district general hospital stroke unit diagnosed with a first ever stroke less than 26 weeks previously. OUTCOME MEASURES: Resistance to passive movement about the elbow was simultaneously quantified (biomechanically) and graded (modified Ashworth Scale). Passive range of movement and peak instantaneous velocity during passive movement were also measured. ANALYSIS: Criterion validity was investigated as convergent construct validity (using the Spearman's correlation coefficient) and concurrent validity (using analysis of variance). RESULTS: One hundred measurements were taken on 63 subjects. Correlation between the modified Ashworth Scale and resistance to passive movement was 0.511. Resistance to passive movement and velocity showed significant differences between the modified Ashworth score of '0' and a modified Ashworth score greater than '0' (p < 0.01). There were no significant differences between MAS '1', '1+' and '2'. Resistance to passive movement in the impaired arm was significantly higher than in the nonimpaired arm (p < 0.01). CONCLUSION: The modified Ashworth Scale does not provide a valid measure of spasticity at lower grades but it may provide a measure of resistance to passive movement.

Biomechanical Phenomena↗
PubMed2002

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.

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.

Adult↗