Three-dimensional measurement of essential tremor.
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.
Matsumoto
J Y
JY
Department of Neurology, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA.
Dodick
D W
DW
Stevens
L N
LN
Newman
R C
RC
Caskey
P E
PE
Fjerstad
W
W
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*