Author: So, Chung-wing
Title: Comparison of the effectiveness of agonist and antagonist stimulation on reducing spasticity of knee extensor for elderly hemiplegic stroke subjects
Degree: M.Sc.
Year: 1998
Subject: Hemiplegics -- Rehabilitation
Electric stimulation
Hong Kong Polytechnic University -- Dissertations
Department: Multi-disciplinary Studies
Jockey Club Rehabilitation Engineering Centre
Pages: xvi, 112 p. : ill. ; 30 cm
Language: English
Abstract: Stroke is a disease of ageing. The risk of stroke is more than doubled with each decade after the age of 55 years. One of the most common conditions following stroke is spasticity. Reduction of spasticity is one of the important goals in stroke rehabilitation. This research study consisted of two parts. Study 1 was a control study to compare the relaxation indices of the pendulum test about the knee between normal elderly and elderly spastic hemiplegic subjects, in an attempt to determine the validity of using this test as an outcome measure. Study 2 was to compare the immediate and short term post-stimulation effects by agonist and antagonist stimulation with placebo stimulation in reducing the spasticity of elderly hemiplegic stroke patients. For Study 1, ten normal elderly subjects with certain defined criteria were recruited from the patients' relatives in the Wong Tai Sin Hospital. They received 2 sets (i.e. 10 trials) of pendulum test. The relaxation indices of the normal elderly subjects were compared with baseline measures of 9 hemiplegic patients fulfilling certain inclusion criteria. For Study 2, a within-subjects design was used. Nine elderly spastic hemiplegic patients meeting all defined criteria were recruited from the Wong Tai Sin Hospital. They received three treatment protocols in a randomly assigned order: antagonist stimulation, agonist stimulation, and placebo stimulation on three different days within one week. The same stimulation parameters, which were 99 Hz in pulse frequency, 0.1 ms in pulse width delivered at twice the sensory threshold in current intensity, were used in both agonist and antagonist stimulation protocols. Both the pendulum test and a composite clinical spasticity score were used for the quantification of spasticity. The results of Study 1 indicated that there was a significant difference (p < 0.05) in the relaxation index between the normal elderly and the elderly spastic hemiplegic subjects. Therefore, it is a valid index for measuring treatment outcome in the hemiplegic subjects. The findings of Study 2 showed that, in contrast to placebo stimulation which produced negligible effects, both agonist and antagonist transcutaneous electrical stimulation produced significantly more reduction on spasticity as measured by relaxation index (p < 0.05) and clinical spasticity score (p < 0.05). However, no significant differences (p > 0.05) in the immediate and short term post-stimulation effects were found between the agonist and antagonist stimulation protocol. The time course of spasticity reduction after agonist stimulation was longer than that of antagonist stimulation, having at least 60 min. and about 50 min. as measured by relaxation index respectively (p < 0.05). The results also showed that the relaxation index was highly correlated (p < 0.05) with the composite clinical spasticity score. Our findings demonstrated that both agonist and antagonist stimulation was effective in reducing the spasticity of elderly hemiplegic subjects after a single treatment session. The time course of post-stimulation effect by agonist stimulation was longer than that by antagonist stimulation. Thus, agonist stimulation should be preferable to antagonist stimulation on reducing the spasticity of spastic hemiplegic patients. Further study of the effects of repeated applications of agonist and antagonist stimulation over a period of time is recommended.
Rights: All rights reserved
Access: restricted access

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