title: Three-dimensional measurement of essential tremor.
abstract: A mechanical linkage device was used to measure the three-dimensional position of the fingertip during a postural task. Thirty patients with essential tremor were tested simultaneously with the device, uniaxial accelerometry, and clinical tremor measures. Eighteen patients were tested again 16+/-4 days later. The device accurately recorded the three-dimensional behavior of essential tremor. Measures from the device included mean three-dimensional velocity, mean three-dimensional dispersion, and power of the three-dimensional acceleration. The logarithms of these measures were strongly correlated (r = .841-.984) with all clinical measures including self-reported tremor disability. The device measures were reliable within and between testing sessions (intraclass correlation coefficients = .971-.977). The performance of the device was superior to uniaxial accelerometry, most likely as a result of the three-dimensional nature of the measurements. We conclude that essential tremor can be validly and reliably quantified during a postural task providing the recording device records movement in three dimensions and the measurements are logarithmically transformed.
authors: Department of Neurology, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA.
authors: J Y
authors: JY
authors: Matsumoto
authors: D W
authors: DW
authors: Dodick
authors: L N
authors: LN
authors: Stevens
authors: R C
authors: RC
authors: Newman
authors: P E
authors: PE
authors: Caskey
authors: W
authors: W
authors: Fjerstad
mesh_terms: D000054:Acceleration; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D003936:Diagnosis, Computer-Assisted; D004185:Disability Evaluation; D005069:Evaluation Studies as Topic; D005260:Female; D005385:Fingers; D005583:Fourier Analysis; D006801:Humans; D008297:Male; D008328:Man-Machine Systems; D008875:Middle Aged; D009462:Neurology / Q000295:instrumentation / Q000592:standards; D015588:Observer Variation; D011187:Posture / Q000502:physiology*; D011594:Psychometrics / Q000295:instrumentation / Q000592:standards*; D011597:Psychomotor Performance / Q000502:physiology*; D015203:Reproducibility of Results; D012399:Rotation; D013996:Time and Motion Studies; D014159:Transducers; D014202:Tremor / Q000175:diagnosis*