| Summary: | 碩士 === 國立成功大學 === 醫學工程研究所 === 87 === Spasticity is a common sequela of an anatomic or physiologic anomaly of the central nervous system. It has been defined as a motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes with exaggerated tendon jerks. In clinical evaluation, spasticity is usually assessed by subjectively determining the resistance of a joint to an externally imposed passive movement, and lacks a good quantification tool.
In this study, an on-line spasticity measurement system was developed for quantifying the stretch reflex by stretching the elbow at ramp-and-hold mode of varied constant velocities. Subjects were tested at supine position with the upper limb stretched toward the ground, in contrast with the horizontally stretched movement used in other studies. So that the bias caused by the shoulder movement during horizontal stretch can be limited. The averaged speed-dependent reflex torque (ASRT), defined as the measured torque deviated from the baseline torque, is used for quantifying the spastic hypertonia.
From electrophysiologic aspect, reciprocal inhibition is a kind of conditioned H-reflex study. Stimuli on the nerves innervating on an antagonist muscle and on an agonist muscle are performed simultaneously under different intervals. Then the change on the H-reflex induced by stimulating the nerve innervating on an agonist muscle will be recorded. Former studies had shown that the third inhibitory phase in reciprocal inhibition is thought to be related to the polysynaptic long latency stretch reflex pathway. Therefore, it is also chosen to measure the spasticity. On the other hand, the Hmax/Mmax ratio in patients with spasticity is also evaluated in our study.
Patients with varying degrees of spasticity and control groups were recruited. The modified Ashworth scale (MAS), a clinical assessment of extremity tone, was evaluated first. Then the ASRT measurement, the reciprocal inhibition test and the Hmax/Mmax ratio test were performed in all subjects. The result shows good correlation between ASRT and MAS, and indicates that the ASRT is a good tool to quantify the spasticity. The result of reciprocal inhibition test discloses significant change between patients with spasticity and normal controls in the third inhibitory phase. That proves the relationship between the third inhibitory phase of reciprocal inhibition and the stretch reflex. However, the amount of change is unpredictable, so it is not suitable for quantifying the spasticity. As for the ratio of Hmax to Mmax, it shows disappointing results, and has no significant relationship with the severity of spasticity.
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