title: Objective measurement of dyskinesia in Parkinson's disease using a force plate.
abstract: Clinical investigation of levodopa-induced dyskinesia (LID) in Parkinson's disease (PD) is limited because of lack of objective measurements and no consensus on use of a standard measuring tool. Currently, clinical trials use subject-completed diaries of dyskinesia throughout the day or investigator-administered clinical rating scales. An objective and valid method of measuring LID would reduce bias, variability, and decrease the time and number needed in trials of potential anti-dyskinetic agents. We have investigated using a force plate under standing subjects, which records movement of the center of pressure (CoP) to quantify LID over a levodopa (L-dopa) cycle. Twenty-two PD subjects (15 with LID, 7 without LID) admitted to an inpatient research facility had their PD meds withheld overnight, followed by a 2 hours intravenous L-dopa infusion the next day. The root mean squared of the velocity in the anterior-posterior direction (RMSV) derived from an analysis of the CoP, and, the modified Abnormal Involuntary Movement Scale (mAIMS) were performed repeatedly for 6 hours, initially as subjects were OFF before the infusion, through infusion until OFF again. There was a high correlation between the area under the curve (AUC) of the mAIMS and the RMSV within and between subjects. As a measure of LID, RMSV had excellent validity and reliability between subjects, and using a force plate was feasible. Sensitivity to changes in LID was initially demonstrated but should be repeated. Thus, CoP recordings on a force plate can objectively quantify LID in PD and may be very useful in clinical trials or other investigations of dyskinesia.
authors.affiliation: Department of Neurology, Oregon Health and Science University, Portland, Oregon, USA. chungka@ohsu.edu
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Chung
authors.forename: Brenna M
authors.initials: BM
authors.lastname: Lobb
authors.forename: John G
authors.initials: JG
authors.lastname: Nutt
authors.forename: James
authors.initials: J
authors.lastname: McNames
authors.forename: Fay
authors.initials: F
authors.lastname: Horak
mesh_terms: D000368:Aged; D000978:Antiparkinson Agents / Q000009:adverse effects*; D001696:Biomechanical Phenomena; D004409:Dyskinesia, Drug-Induced / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007980:Levodopa / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000188:drug therapy; D004856:Postural Balance / Q000502:physiology*; D011187:Posture; D011312:Pressure; D011597:Psychomotor Performance; D015203:Reproducibility of Results; D012720:Severity of Illness Index
chemical_list: D000978:Antiparkinson Agents; D007980:Levodopa