Assessments of spasticity by Hoffmann reflex parameters in patients with spinal cord injury.
Resource
Taiwan Journal of Physical Medicine and Rehabilitation,37(3),195-200.
Journal
中華心理學刊
Pages
195-200
Date Issued
2009-11
Date
2009-11
Author(s)
Wang, JH
Wang, YH
Chang, CW
Pan, SL
Lin, CS
Abstract
Muscle spasticity is a common problem that affects patients who have suffered spinal cord injury (SCI). It can affect the motor skills, activities of daily living, and quality of life of these patients. The modified Ashworth scale (MAS) is a widely used clinical rating scale for spasticity, but its validity and reliability have been questioned. Much attention has been devoted to the evaluation of spasticity by using electrophysiological approaches. Increased excitation of motor neurons, exaggerated stretch reflex, decreased presynaptic inhibition, and reduced reciprocal inhibition have been found to be associated with spasticity. In several previous studies, the Hoffmann (H) reflex has been measured in order to evaluate the stretch reflex because these 2 reflexes share a common circuitry in the spinal cord. The objective of this study was to investigate whether the values of the H-reflex measured in persons with SCI differ from those measured in the control group; we also aimed to evaluate the relationship between various electrophysiological parameters and the clinical MAS score. We recruited 25 men with complete traumatic SCI (mean age = 36.5 years, standard deviation [SD] = 8.7 years, range = 21 to 53 years), and 24 healthy men as the control group (mean age = 37.7 years, SD = 12.1 years, range = 22 to 59 years). There was no significant difference between the 2 groups in terms of age. Among the participants with SCI, 68% had tetraplegia, and their MAS scores ranged from 0 to 2. The maximal amplitudes of the H-reflex and M-response (Hmax and Mmax), the thresholds of the H-reflex and M-response (Hth and Mth), the ratio of the maximal amplitude of the H-reflex to that of the M-response (Hmax/Mmax), and the ratio of the threshold of the H-reflex to that of the M-response (Hth/Mth) were measured. The results showed that the Mmax in the SCI group was smaller than that in the control group (mean, 14.39 mV vs. 19.97 mV, p = 0.03). No significant differences were found between the SCI and the control groups in terms of Hmax, Hth, and Mth. Besides, the log10 (Hmax/Mmax) value in the SCI group was greater than that in the control group (mean, -0.35 vs. -0.57, p = 0.03). However, no significant relationship was found between the log10 (Hmax/Mmax) and the MAS score. Although no significant difference in log10 (Hth/Mth) was observed between the SCI group and the control group, we found a
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