Neither simple nor sequential arm movements are bradykinetic in parkinsonian patients with peak-dose dyskinesias

Objective To find out whether parkinsonian patients with levodopa-induced peak-dose dyskinesias are bradykinetic. Methods The performance of a sequential internally determined arm movement and a simple externally triggered arm movement was studied in a group of dyskinetic parkinsonian patients during their best clinical condition and when they were OFF treatment. Patients' performance was compared with that of an age-matched control group. Movements in the three-dimensional space were recorded by the ELITE motion analysis system. Kinematic variables analysed for the sequential motor task were total movement duration and total pause duration; for the simple motor task, movement duration and reaction time; and for both tasks, movement inaccuracy. Results When patients were OFF therapy they performed sequential and simple movement tasks slower than healthy subjects whereas when they were dyskinetic they did not. During the sequential task, when the patients were dyskinetic total pause duration shortened and movement inaccuracy increased. Conclusions Our kinematic finding indicates that parkinsonian patients' with peak-dose dyskinesias are not bradykinetic. Significance Parkinsonian patients with peak-dose dyskinesias are not bradykinetic, probably because dopamine at peak doses functionally normalizes the mechanisms controlling movement speed.