Proprioception in Parkinson's disease is acutely depressed by dopaminergicmedications

Objectives-Impaired proprioception has been previously reported in patients with Parkinson's disease. It was hypothesised that dopaminergic medication s transiently depress proprioception, with amplification of adventitious mo vements as a result. This study tested for effects on proprioception of dop aminergic drugs, and for associations between such effects and drug induced dyskinesias. Methods-In 17 patients with Parkinson's disease, arm proprioception was tes ted in the practically defined "off" state, and retested I hour after takin g levodopa or dopamine agonist. Testing consisted of side to side compariso n of elbow angle, matching the contralateral elbow angle, and spatial recal l of an unrestrained arm. Results-Proprioception deteriorated as hypothesised, reaching significance by one tailed t test for each of the three tasks. The relative deterioratio n (and the 95% lower confidence bound for estimated deterioration) was 31% (4%) for side to side elbow comparison, was 27% (11%) for accuracy in match ing the contralateral elbow angle, and was 11% (0%) for spatial recall. Dys kinetic (n=6) and non-dyskinetic (n=11) patients did not differ significant ly in these effects on proprioception. Control subjects (n=6) and untreated parkinsonian subjects (n=5) did not significantly differ from the parkinso nian patients in the off state. Conclusions-Administration of levodopa and dopamine agonists were associate d with a modest acute suppression in central responsiveness to joint positi on. It is speculated that compensatory exaggerated movement could account i n part for the phenomenon of drug induced dyskinesias.