Managing the late complications of Parkinson's disease.

Most patients with Parkinson's disease (PD) receiving chronic levodopa therapy eventually manifest one or more motor response complications, including "wearing-off" phenomena and "on-off" phenomena. Additionally, as the disease progresses, motor, neurologic, and neuropsychiatric complications increase and may include freezing spells, falls, dementia, depression, and psychosis. The management of patients with advanced PD presents a special clinical challenge because patients may experience an enhanced sensitivity to small changes in plasma levodopa levels and because they may suffer adverse reactions to antiparkinsonian drugs. Management of advanced PD is directed toward decreasing the dose of the offending drug while raising the dose of an alternative drug, with the goal of maintaining symptom control. In this article, the spectrum of late complications experienced by patients with advanced PD and their management are discussed.