title: Quantitative magnetic detection of finger movements in patients with Parkinson's disease.
abstract: To develop a new measurement tool for quantitatively detecting the finger movement of a patient with Parkinson's disease (PD), we designed a magnetic sensing system consisting of a magnetic induction coil, a sensing coil, and a circuit unit. The sensing coil detects the inducted magnetic field that varies with the distance between the two coils, and the detected signals are demodulated in the circuit unit in order to obtain the variation voltage from the oscillation frequency. To obtain a coefficient for converting voltage to distance, we measured the output voltages for seven fixed finger positions of 12 normal volunteers. The voltage differences corresponding to the finger movement in 20 PD patients, six age-matched controls, and 12 normal volunteers were then recorded for 30s. To investigate the velocity and acceleration of the finger movement, we calculated their waveforms from the measured displacement waveform. We also detected the main frequency of the tapping rhythm by using a fast Fourier transform (FFT). The averaged amplitude of each waveform decreased with the disorder in the Hoehn-Yahr (HY) stage, while the averaged tapping frequency of PD patients did not have any correlation with this stage. It can be concluded that this magnetic sensing system can assess finger movement quantitatively.
authors.affiliation: Central Research Laboratory, Hitachi Ltd., Life Science Research Laboratory, 1-280 Higashi-Koigakubo, Kokubunji-shi, Tokyo 185-8601, Japan. kandori@crl.hitachi.co.jp
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kandori
authors.forename: Masaru
authors.initials: M
authors.lastname: Yokoe
authors.forename: Saburo
authors.initials: S
authors.lastname: Sakoda
authors.forename: Kazuo
authors.initials: K
authors.lastname: Abe
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Miyashita
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Oe
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Naritomi
authors.forename: Kuniomi
authors.initials: K
authors.lastname: Ogata
authors.forename: Keiji
authors.initials: K
authors.lastname: Tsukada
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D004560:Electricity; D005260:Female; D005385:Fingers / Q000503:physiopathology*; D005583:Fourier Analysis; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D010300:Parkinson Disease / Q000175:diagnosis / Q000503:physiopathology*; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time; D012737:Sex Factors; D014894:Weights and Measures