The purpose of this study is to study different kinds of dyskinesias in advanced Parkinson's disease appearing at different levels of levodopa infusion dose. The hypothesis is that different dyskinesias (dystonia, chorea) correlate to different levels of levodopa concentrations, as detected in plasma.

By using duodenal infusion of levodopa/carbidopa, the plasma concentration of levodopa can be kept fairly constant. Different doses, 10-20% higher or lower than the individually optimized dose will be used. Motor performance is captured by video recordings to be compared to/correlated with plasma levodopa concentrations.

Inclusion Criteria:

• Clinical diagnosis of idiopathic Parkinson's disease
• Ongoing treatment with Duodopa
• Occurrence of dyskinesias, difficult to manage
• Age 30-90 years
• Hoehn & Yahr stage 3-5 at worst

Exclusion Criteria:

• Treatment with dopamine agonist or glutamate antagonist
• Dementia
• Psychosis
• Treatment with typical neuroleptics