The three major symptoms of Parkinson's disease are tremor, rigidity and akinesia. Tremor most disturbs the daily life of the patient. For the treatment of tremor, L-DOPA as a precursor of dopamine has been used. However it has serious side effects, such as wearing-off phenomena or delusion. In previous studies, we have investigated the relationship of the tremor and patients' physiological parameters for the control of tremor. The two major parameters were dopamine level in the blood and Hoehn & Yahr's grade of Parkinsonian. We found a correlation between the dopamine level and the peak tremor frequency between 6Hz and 10Hz. A correlation was also found between the Hoehn & Yahr's grade and the peak frequency, In this study, we adopted peak frequency for the patient's biofeedback training. Subjects were 16 healthy volunteers, 10 male and 6 female. The mean age was 23.3±2.1. The upper limb tremor accelerations were measured using a modified biofeedback system to calculate the peak frequency between 6Hz and 10Hz. The subjects trained to increase the peak of tremor frequency during the biofeedback training. Before and after the biofeedback training, the upper limb tremor was measured. It was found that subjects who were able to increase tremor frequency tended to also be able to depress the power of peak tremor frequency. This result suggests that tremor control by a biofeedback system may be possible.
For spasmodic torticollis patients we have heretofore selected from the bilateral trapezius muscles and sternocleidomastoid muscles two sites which strongly reflect the symptoms and employed them as indices of feedback. However, as the sites and EMGs which reflect the symptoms commonly change with changes in status of spasmodic torticollis, there have been phases in which 2-channel feedback does not provide sufficient information. We have therefore attempted 4-channel EMG biofeedback for two cases of spasmodic torticollis. 4-channel indices employed as indices were EMGs of bilateral trapezius muscles and sternocleidomastoid muscles. In 4-channel display of EMGs, feedback indices were shown as pattern on the computer display. As result, in both case-1 (60-year-old, female, office worker) and case-2 (27-year-old, male, store worker), control of EMGs was possible and torticollis almost completely disappeared. By the present 4-channel EMG pattern feedback, both direct control of EMG and control of balance became possible. In EMG biofeedback for spasmodic torticollis, it is considered that not only feedback of myogenic potential but also feedback of pattern of the entire neck image are important. However, the treatment period did not show any change when compared to that of the heretofore employed 2-channel feedback and 4-channel feedback did not immediately lead to shortening of treatment period. Furthermore, in observing the changes in fingertip skin temperature during trial of EMG biofeedback, it was ascertained that there was decrease in EMG together with elevation of skin temperature in both cases. These suggest that fingertip skin temperature can be employed as an index of feedback of spasmodic torticollis.
With the wide-spread use of the information display devices, the dry-eye symptom is increased through intensive observation of CRT screen. Since the dry-eyes may be developed through the absence of eye-blinking for a long time, except for certain pathological cases, it is intended to induce the eye-blinking by the biofeedback training. The eye-blinking interval increases with a visual task accompanying mental concentration is noted as a typical case. It is tried to recover the regular eye-blinking interval by feeding back the time elapsed from the last eye-blinking through a sound signal. Two kind of trainings were tried, i. e., the procedure where a sound is presented unless an eye-blinking does not occur within a specified time, as well as the procedure where the regular eye-blinking is learned through specified. The absence of eye-blinkings for longer than a preset time is used as the evaluation measure, and it is observed as the elongation of the eye-blinking interval can be prevented by either method, with a better result in the training by a musical rhythm. Thus, the proposed biofeedback training seems useful in preventing dry-eyes.