Parkinson's disease: Seven questions physicians often ask

Parkinson's disease (PD) is a clinical diagnosis, based on the identification of parkinsonism, determination of its cause, and a positive clinical response to drug therapy. Six major groups of agents help control symptoms; levodopa, in combination with carbidopa, is the most effective, although each group of agents has a therapeutic niche. For example, dopamine agonists are somewhat less effective than levodopa, but are less likely to produce drug-induced dyskinesias; they also have a longer half-life than levodopa and provide steadier dopamine-receptor stimulation. Tokapone allows higher levels of levodopa to cross the blood-brain barrier without increasing the levodopa dose. Selegiline may help slow progression of early PD. The diagnosis of PD does not necessitate immediate drug therapy; start treatment when symptoms affect the patient's functional level. Surgery is reserved for patients who fail to benefit from medical therapy.