title: A novel quantitative method for 3D measurement of Parkinsonian tremor.
abstract: OBJECTIVE
  To demonstrate the usefulness of a three dimensional (3D) motion analysis system for the quantitative measurement of tremor in patients with Parkinson's disease (PD).
  
  
  METHODS
  Six PD patients with hand tremors were studied using a system that employed 3D electromagnetic position sensors to measure the actual, cumulative displacement of the tremoring finger. Patients were studied in different hand positions and activating conditions before and 30, 60, 90 and 120 min after intake of Pramipexole, a dopamine agonist known to reduce tremor. Tremor amplitude and frequency, before and after drug intake, were compared using Mann-Whitney U test and Wilcoxon rank test, respectively.
  
  
  RESULTS
  The motion analysis system allowed discrimination of tremor related events from movement artifact and allowed the calculation of real world movement of the finger tremor despite altered hand positions and orientation. Average 3D tremor frequency ranged from 3.71 to 4.34 Hz. Median tremor amplitude (total distance traveled per 5 s interval) decreased with drug from 4.9 to 1.6 cm for resting tremor, 4.5 to 3.7 cm for postural tremor, 3.4 to 3.3 cm for precision tremor, 10.2 to 3.3 cm for tapping activation and 108.6 to 5.7 cm for counting activation.
  
  
  CONCLUSIONS
  Our method of 3D analysis provides a robust, single quantitative measure of tremor amplitude that is intuitive and likely to reflect the functional impact of tremor. This methodology should be useful in comparing tremor across patients and in measuring the efficacy of therapeutic interventions.
authors.affiliation: Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark, NJ 07102, USA.
authors.forename: V
authors.initials: V
authors.lastname: Rajaraman
authors.forename: D
authors.initials: D
authors.lastname: Jack
authors.forename: S V
authors.initials: SV
authors.lastname: Adamovich
authors.forename: W
authors.initials: W
authors.lastname: Hening
authors.forename: J
authors.initials: J
authors.lastname: Sage
authors.forename: H
authors.initials: H
authors.lastname: Poizner
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000503:physiopathology*; D014202:Tremor / Q000503:physiopathology*