title: Differential response of speed, amplitude, and rhythm to dopaminergic medications in Parkinson's disease.
abstract: Although movement impairment in Parkinson's disease includes slowness (bradykinesia), decreased amplitude (hypokinesia), and dysrhythmia, clinicians are instructed to rate them in a combined 0-4 severity scale using the Unified Parkinson's Disease Rating Scale motor subscale. The objective was to evaluate whether bradykinesia, hypokinesia, and dysrhythmia are associated with differential motor impairment and response to dopaminergic medications in patients with Parkinson's disease. Eighty five Parkinson's disease patients performed finger-tapping (item 23), hand-grasping (item 24), and pronation-supination (item 25) tasks OFF and ON medication while wearing motion sensors on the most affected hand. Speed, amplitude, and rhythm were rated using the Modified Bradykinesia Rating Scale. Quantitative variables representing speed (root mean square angular velocity), amplitude (excursion angle), and rhythm (coefficient of variation) were extracted from kinematic data. Fatigue was measured as decrements in speed and amplitude during the last 5 seconds compared with the first 5 seconds of movement. Amplitude impairments were worse and more prevalent than speed or rhythm impairments across all tasks (P < .001); however, in the ON state, speed scores improved exclusively by clinical (P < 10(-6) ) and predominantly by quantitative (P < .05) measures. Motor scores from OFF to ON improved in subjects who were strictly bradykinetic (P < .01) and both bradykinetic and hypokinetic (P < 10(-6) ), but not in those strictly hypokinetic. Fatigue in speed and amplitude was not improved by medication. Hypokinesia is more prevalent than bradykinesia, but dopaminergic medications predominantly improve the latter. Parkinson's disease patients may show different degrees of impairment in these movement components, which deserve separate measurement in research studies. © 2011 Movement Disorder Society.
authors.affiliation: UC Neuroscience Institute, Department of Neurology, Gardner Center for Parkinson's disease and Movement Disorders, University of Cincinnati, Cincinnati, Ohio 45267-0525, USA. alberto.espay@uc.edu
authors.forename: Alberto J
authors.initials: AJ
authors.lastname: Espay
authors.forename: Joe P
authors.initials: JP
authors.lastname: Giuffrida
authors.forename: Robert
authors.initials: R
authors.lastname: Chen
authors.forename: Megan
authors.initials: M
authors.lastname: Payne
authors.forename: Filomena
authors.initials: F
authors.lastname: Mazzella
authors.forename: Emily
authors.initials: E
authors.lastname: Dunn
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Vaughan
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Duker
authors.forename: Alok
authors.initials: A
authors.lastname: Sahay
authors.forename: Sang Jin
authors.initials: SJ
authors.lastname: Kim
authors.forename: Fredy J
authors.initials: FJ
authors.lastname: Revilla
authors.forename: Dustin A
authors.initials: DA
authors.lastname: Heldman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015259:Dopamine Agents / Q000008:administration & dosage*; D016903:Drug Monitoring / Q000706:statistics & numerical data; D006801:Humans; D018476:Hypokinesia / Q000188:drug therapy / Q000503:physiopathology; D007980:Levodopa / Q000008:administration & dosage*; D008875:Middle Aged; D009068:Movement / Q000187:drug effects*; D009460:Neurologic Examination / Q000706:statistics & numerical data*; D009462:Neurology / Q000706:statistics & numerical data; D015588:Observer Variation; D010300:Parkinson Disease / Q000188:drug therapy* / Q000503:physiopathology; D014743:Videotape Recording
chemical_list: D015259:Dopamine Agents; D007980:Levodopa