Parkinson's disease (PD) is neurodegenerative disease which often afflicts the elderly. Among the symptoms are motor impairments (tremor, muscle rigidity, posture disorders, and akinesia). Especially, the tremor poses a serious problem in daily life, leading to considerable anxiety. The primary therapy for PD is medication. But it causes direct and indirect side effects including a decrease in medicinal effect. In this study we focused on biofeedback (BF) as a method of controlling the tremor in PD without using medicine. As a BF index, root mean square (RMS) was calculated using a three-axial acceleration sensor of the piezoelectric type fixed on the thumb base of the subjects. And the sound pressure level converted into the pure tone of 1kHz corresponding to the RMS was used as BF information. Subjects were PD patients who did not have auditory abnormalities, and were randomly assigned to a BF group (10 patients, 74.9±5.1 of age, Yahr's Grade I〜IV) and control group (7 patients, 67.5±10.5 of age, Yahr's Grade I〜III). Experimental procedure was as follows: 1. RMS was measured a minute before BF training. 2. Subjects experienced a combination of training and rest period 3 times. 3. RMS was measured a minute after BF training. In the experiment, subjects were instructed to sit in a chair and put their hands on a desk in front of them. In RMS after training, we found a significant difference between the BF and control groups. The RMS value of the BF group was significantly decreased compared with the control group (t=2.43, p<.05). For this reason, it was concluded that subjects could learn to inhibit their tremor by changing the sound pressure level. Therefore, the training method in this study was shown to be effective in the inhibition of PD tremor.
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