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.

Be quick about it. Endogenous estradiol level, menstrual cycle phase and trait impulsiveness predict impulsive choice in the context of reward acquisition

“…It is therefore possible that the present observation basically reflected an accelerating effect of rising E2 on general motor performance in the late FP. In fact, the typical slowness (bradykinesia) of Parkinson patients improves following dopaminergic intervention (Espay et al, 2011). For this reason, a natural DA-agonist like E2 could have a similar effect on motor performance.…”

Characterisation of movement disorder in parkinson's disease using evolutionary algorithms

“…This is a concern, as amplitude has been shown to be one of the variables of movement least affected by Parkinsonian medication [2]. As such, an objective analysis of the finger tapping exam would allow for a more accurate understanding of exactly what constitutes bradykinesia and how it manifests itself in simple repetitive motor tasks.…”

Regression models for the quantification of Parkinsonian bradykinesia

“…To acquire the trend of movement from the oscillating velocity and displacement, first, RMS values were repeatedly calculated for 1-second window sliding throughout the entire data (10 s). Then, the mean and standard deviation of the RMS values were calculated and the CV was defined as the ratio of the standard deviation and the mean [13].…”