This study aims to develop a quantitative measure of bradykinesia which can be conveniently used during clinical finger taps test in patients with Parkinson's disease. A miniature, light-weight gyrosensor free from gravitational artifact was used for measurement of finger taps in order to impose minimal constraint on patients. Forty Parkinson's disease patients and 14 age-matched control subjects participated in the experiments. Subjects' finger taps in both right and left hands were scored by two independent neurologists according to the unified Parkinson's disease rating scale and were also measured by a gyrosensor. Four performance indices were derived from the gyrosensor signal of the index finger. All indices showed significant differences between control and patients (P < 0.001) and also significant correlations with the clinical finger taps score (r = -0.73 to -0.80, P < 0.001). ANOVA showed significant differences in all indices among different finger taps scores (P < 0.001), and post hoc tests showed significant differences in indices between most pairs of non-neighboring and part of neighboring pairs of finger taps scores (P < 0.01). The results suggest that indices from a gyrosensor can be used as quantitative measures of bradykinesia during the finger taps test.

The sex difference in balance performance (some of which are significant only in the elderly) and the sex difference in age-related change of balance performance were demonstrated in mediolateral direction. These sex differences may contribute to the sex difference in balance-related problems, such as falls.

Abstract. Essential tremor is an involuntary trembling of body limbs in people without tremor-related disease. In previous study, suppression of tremor by sensory electrical stimulation was confirmed on the index finger. This study investigates the effect of sensory stimulation on multiple segments and joints of the upper limb. It denotes the observation regarding the effect's continuity after halting the stimulation. 18 patients with essential tremor (8 men and 10 women) participated in this study. The task, "arms stretched forward", was performed and sensory electrical stimulation was applied on four muscles of the upper limb (Flexor Carpi Radialis, Extensor Carpi Radialis, Biceps Brachii, and Triceps Brachii) for 15 seconds. Three 3-D gyro sensors were used to measure the angular velocities of segments (finger, hand, and forearm) and joints (metacarpophalangeal and wrist joints) for three phases of pre-stimulation (Pre), during-stimulation (On), and 5 minute poststimulation (P5). Three characteristic variables of root-mean-squared angular velocity, peak power, and peak power frequency were derived from the vector sum of the sensor signals. At On phase, RMS velocity was reduced from Pre in all segments and joints while peak power was reduced from Pre in all segments and joints except for forearm segment. Sensory stimulation showed no effect on peak power frequency. All variables at P5 were similar to those at On at all segments and joints. The decrease of peak power of the index finger was noted by 90% during stimulation from that of On phase, which was maintained even after 5 min. The results indicate that sensory stimulation may be an effective clinical method to treat the essential tremor.

BACKGROUND: The sitting in an awkward posture for a prolonged time may lead to spinal or musculoskeletal disease. It is important to investigate the joint loads at spine while sitting.OBJECTIVE: The purpose of this study was to investigate the joint moment and antero-posterior (AP) reaction force at cervico-thoracic and lumbosacral joint for various sitting postures.METHODS: Twenty healthy males participated in this study. Six sitting postures were defined from three spinal curvatures (slump, flat, and lordosis) and two arm postures (arms-on-chest and arms-forward). Kinematic and kinetic data were measured in six sitting postures from which joint moment and AP reaction force were calculated by inverse dynamics.RESULTS: In the cervico-thoracic joint, joint moment and AP reaction force were greater in slump than the flat and lordosis postures (p< 0.001) and also in arms-forward posture compared to arms-on-chest posture. In the lumbosacral joint, joint moment and AP reaction force were greater in slump than flat and lordotic posture (p< 0.001) but there was no difference between different arm postures. The joint loads (moment and AP reaction force) at the cervico-thoriacic joint were closely related to the head flexion angle (r> 0.86) while those at the lumbosacral joint were correlated to the trunk flexion angle (r> 0.77). In slump posture, the joint moments were close to or over the extreme of the daily life such as sit-to-stand and walking. Consequently, if the slump is continued for a long time, it may cause pain and diseases at the cervico-thoracic and lumbosacral joints.CONCLUSIONS:The results of the study indicated that the lordosis or flat would be better spinal postures. Also, keeping arms close to body would be desirable to reduce joint loads.

The purpose of this study is to develop a more convenient system for measurement of hand rotation, and to validate the system by correlation of performance indices derived from the system with the bradykinesia score of hand rotation movement during on-medication state. Forty patients with Parkinson's disease and 14 age-matched control subjects participated in this study. The measurement system was developed using a ceramic gyroscope that is significantly smaller and lighter than those in the literature. The sensor signal was bandpass filtered and action tremor was eliminated by additional lowpass filtering (fc=5Hz) with automated tremor discrimination. Four performance indices (RMS velocity and RMS angle, peak power and total power) were derived from the angular velocity signal. Correlations of performance indices with clinical scores and difference of performance indices among subject groups were investigated. Correlations of all performance indices were far better with bradykinesia score of hand rotation (best r=-.78) than with the other categorized subscores of UPDRS (bradykinesia subscore, axial symptom subscore, and total motor score; best r=-.64). Elimination of action tremor resulted in improvement in correlations of RMS velocity and total power with bradykinesia score for hand rotation (r=-.84 from -.81). Differences between low scores were greater in total power and differences between high scores were greater in RMS velocity, suggesting that use of more than one PI would be beneficial for diagnosis of a wide range of patients. The convenient sensor system, action tremor elimination, and performance indices suggested in this study are expected to be useful in clinical situations.