Date of Award

August 2016

Degree Type

Thesis

Degree Name

Master of Science

Department

Occupational Therapy

First Advisor

Ying-Chih (Inga) Wang

Committee Members

Bhagwandt Sindhu, Leigh Lehman

Keywords

Cerebrovascular Accident, Modified Ashworth Scale, Occupational Therapy, Rehabilitation, Spasticity, Stroke

Abstract

TRANSLATING MODIFIED ASHWORTH SCALE INTO FUNCTIONAL MEASURES AND QUANTITATIVE KINEMATIC VALUES: A PILOT STUDY

by

Patrick D. Frigge

The University of Wisconsin-Milwaukee, 2016

Under the Supervision of Professor Ying-Chih Wang, PhD

Introduction: Spasticity is a motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes. The gold standard for assessing spasticity in stroke patients is the Modified Ashworth Scale (MAS), but the scale is highly subjective to the clinician’s opinion and previous experience and lacks psychometric fidelity. Numerous studies have criticized the scale’s subjectivity and lack of rater reliability. Development of a quantitative spasticity device in routine clinical care is warranted. Before doing so, however, it is important to examine how MAS scores translate into functional measures and quantitative kinematic and/or kinetic values.

Methods: Data from 20 subjects (6 female, 14 male; mean age 57 ± 10) with chronic hemiparesis secondary to a cerebrovascular accident (stroke) were used to examine the relationships between the MAS and residual impairments (active range of motion of shoulder flexion, elbow, and wrist, and muscle strength of the elbow flexion and extension), the MAS and functional limitations as measured by the Fugl-Meyer upper extremity assessment, finger to nose movement, the MAS and overall health status following stroke as measured by the Stroke Impact Scale, and to inspect whether there are potential kinematic values or physiological responses that can be used to identify the characteristics of the passive stretch (passive stretch duration, catch angle, electromyography response). The data were collected at both the Rehabilitation Institute of Chicago and the University of Wisconsin-Milwaukee.

Results: Overall, results showed that stroke subjects who had more severe spasticity tended to have reduced range of motion at the shoulder (flexion) (Pearson correlation coefficient rp = -.601; Spearman correlation coefficient rs = -.607), elbow (rp = -.436; rs = -.495) and wrist (rp = -.206; rs = -.305) joints, as well as reduced muscle strength for elbow flexion (rp = -.547; rs = -.618). The relationship between the MAS scores and the muscle strength for elbow extension was weak (rp = -.160; rs = -.191). Analysis between the FM-UE subscale and MAS revealed a significant negative correlation. The strongest correlation occurred between the FM-UE total score (rp = -0.817; rs = -0.806), while the weakest correlation amongst all subscales occurred between coordination subscale (rp = -0.696; rs = -0.684). A one-way, between-subjects design ANOVA showed significant mean differences between MAS scores and all FM-UE subscales: the FM-Arm subscale (F4,15 = 17.4, p < .001), the FM-Wrist subscale (F4,15 = 4.3, p < 0.016), the FM-Hand subscale (F4,15 = 4.8, p < 0.011), the FM-Corr subscale (F4,15 = 4.4, p < 0.015) as well as FM-Total Score subscale (F4,15 = 12.6, p < 0.001). Overall, there was a tendency for increased levels of spasticity per scoring of the MAS to result in decreased motor performance as measured by the FM-UE subscale. There was a moderate negative correlation between MAS score and the Stroke Index Scale hand subscale (rp = -0.543; rs = -0.576), indicating that a higher MAS score may be indicative of the magnitude of impairment in the hand. No significant relationships were demonstrated between the remaining subscales of the Stroke Impact Scale, suggesting that there is little to no relationship between MAS scores and overall health status. In comparing EMG activity and motion capture analysis, there was a marked increase in the EMG response when the subjects affected limb is stretched into full elbow extension, such phenomenon was not observed when stretching the unaffected limb.

Conclusion: The strong correlation between MAS scores and the residual impairments as well as the FM-UE subscale suggests that a higher MAS score may be indicative of the general stage of motor recovery following incurrence of a stroke. Additionally, there was a marked increase in EMG activity through passive stretching of the affected limb into full elbow extension; conversely, such a phenomenon was not observed in the unaffected limb.

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