BRADYKINESIA AND HYPOKINESIA IN PARKINSONS-DISEASE - WHATS IN A NAME

Because in the literature bradykinesia and hypokinesia are frequently confounded, we assessed I-he relation between these two fundamental as pects of altered movement and the influence of disease severity on the se measures in 41 patients with Parkinson's disease (PD) and 24 age-ma tched healthy controls. Bradykinesia was measured with a test microcom puter interfaced with a response-board. Hypokinesia was assessed by ac tivity monitoring at home over a period of 5 successive days. For each subject the choice reaction time and measures reflecting bradykinesia (tap rate, movement time) and hypokinesia (movement index, duration o f immobility periods) were calculated. Patients with PD had a normal c hoice reaction time and a significantly impaired execution of voluntar y movement and reduced amount of movement over time. Bradykinesia was clearly present in the less affected patients with PD, and worsened as the disease severity increased. Hypokinesia, however, emerged promine ntly only in the more affected patients. There was a striking lack of relation between the measures that reflect bradykinesia and hypokinesi a. The use of levodopa or dopamine agonists did not confound these fin dings. Our findings show the very different character and course of tw o tiers of altered movement in patients with PD and question the causa tive mechanisms of both motor features in PD. A more precise use of th e terms brady- and hypokinesia is a prerequisite for future studies th at attempt to provide insight in the causative mechanisms of both moto r features.