Long-term evaluation of bilateral fetal nigral transplantation in Parkinson disease.

Background: Parkinson disease (PD) is associated with a progressive loss of nigrostriatal dopamine neurons. Medication therapy provides adequate control of symptoms for several years, but long-term treatment is complicated by progressive disability and the development of motor fluctuations and dyskinesias. In animal models of PD, fetal nigral transplants have been shown to survive grafting into the striatum, provide extensive striatal reinnervation, and improve motor function.