Short-term levodopa test assessed by movement time accurately predicts dopaminergic responsiveness in Parkinson's disease

Short-term challenges with dopaminergic agents are used in patients with idiopathic Parkinson's disease (IPD) to predict the therapeutic effect of sustained levodopa treatment, but false-negative results often occur. We prospectively evaluated 74 patients with clinically diagnosed IPD and compared the predictive value of a short-term levodopa test assessed by movement time (MT) with the predictive value obtained by the evaluation with the motor examination part of the Unified Parkinson's Disease Rating Scale (UPDRS-ME). The response to long-term levodopa was accurately predicted in 96% of patients by assessing the response to the short-term test with MT and in 80% of cases with UPDRS-ME. Similar predictive values were obtained by separately analyzing 21 de novo patients. The short-term test also accurately predicted the magnitude of improvement with long-term treatment. We conclude that the predictive value for long-term dopaminergic responsiveness may be further enhanced by evaluating the shortterm pharmacologic challenges with MT analysis. This is particularly useful to select de novo patients for drug trials with dopaminergic agents