Motor response to levodopa and the evolution of motor fluctuations in the first decade of treatment of Parkinson's disease

Thirty-four patients with Parkinson's disease were followed for a mean period of 8 years from the time of initiation of levodopa medication. Levodopa response was charted from the starting point of pharmacological treatment to give a longitudinal point of view of the changes that evolve as the disease progresses. Objective measurements of the motor response to levodopa test-doses were made at approximately three yearly intervals. Motor fluctuations developed in 58% of the patient group after a mean treatment period of 35 months. Dyskinesia developed in parallel with fluctuations but appeared on average 7 months before symptomatic wearing-off effects of levodopa doses. The patients with motor fluctuations had significantly better responses to levodopa. By contrast, non-fluctuators were more prone to develop increasing midline motor disability affecting speech, gait and balance. Comparison of test-dose and pretreatment scores suggested that a substantial long-duration response to levodopa remains after many years of treatment, and that lateralized motor deficits show a stronger long duration response than midline ones. Motor fluctuations are a consequence of disease progression but their early development is, on balance, associated with better long-term functional ability because these patients have the greater capacity to respond to pharmacological treatment. (C) 2002 Movement Disorder Society.