Levodopa dose-related fluctuations in presumed olivopontocerebellar atrophy

The parkinsonism that occurs in some patients with olivopontocerebellar atrophy (OPCA) can cause diagnostic confusion with idiopathic Parkinson's disease (IPD). The response to levodopa is usually a distinguishing feature, the OPCAs either failing to benefit or losing efficacy relatively quickly. A fluctuating response to levodopa in those OPCA patients who do benefit has not been emphasized in the literature previously. Reported here are three patients with presumed OPCA, dominated by parkinsonian features, who eventually developed typical fluctuations with morning akinesia, wearing off, and periodic lack of response related to meals. These fluctuations were a major source of disability and an important reason for diagnostic confusion with IPD. The possible mechanisms of these fluctuations are discussed.