Study objectives and hypothesis Aim of our study is to compare the efficacy and the safety of L-dopa monotherapy versus DAs monotherapy after STN DBS over a 3-month follow up period. The hypothesis is that DAs may be more efficacious than L-dopa in treating non-motor symptoms after surgery, thus further improving quality of life following surgery. On the other hand, in comparison with L-dopa, DAs might be associated with more side effects (in particular impulse control disorders) and less effective motor control.