New strategies for the treatment of Parkinson's disease hold considerable promise for the future management of neurodegenerative disorders

Neurodegenerative diseases are often considered incurable with no efficient therapies to modify or halt the progress of disease, and ultimately lead t o reduced quality of life and to death. Our knowledge of the nervous system in health and disease has, however, increased considerably during the last fifty years and today, neuroscience reveals promising new strategies to de al with disorders of the nervous system. Some of these results have been im plemented with success in the treatment of Parkinson's disease, a common ne urodegenerative illness affecting approximately 1% of the population aged s eventy or more. Parkinson's disease is characterized by a massive loss of d opaminergic neurons in the substantia nigra, leading to severe functional d isturbance of the neuronal circuitry in the basal ganglia. A thorough descr iption of basal ganglia circuitry in health and disease is presented. We de scribe how the functional disturbances seen in Parkinson's disease may be c orrected at specific sites in this circuitry by medical treatment or, in ad vanced stages of Parkinson's disease, by neurosurgical methods. The latter include lesional surgery, neural transplantation and deep brain stimulation , together with future treatment strategies using direct or indirect implan tation of genetically modified cell-lines capable of secreting neurotrophic factors or neurotransmitters. Advantages and disadvantages are briefly men tioned for each strategy and the implications for the future and the possib le use of these interventions in other neurodegenerative diseases are discu ssed, with special emphasis on deep brain stimulation.