A Study Comparing Efficacy of Levodopa-Carbidopa Intestinal Gel/Carbidopa-Levodopa Enteral Suspension and Optimized Medical Treatment on Dyskinesia in Subjects With Advanced Parkinson's Disease (DYSCOVER)

* Participants must have a diagnosis of idiopathic Parkinson's disease (PD) according to the United Kingdom Parkinson's Disease Society (UKPDS) Brain Bank Criteria * Participants with advanced levodopa-responsive PD and persistent motor fluctuations who have not been controlled with optimized medical treatment (OMT: the maximum therapeutic effect obtained with pharmacological antiparkinsonian therapies when no further improvement is expected with regard to any additional manipulations of levodopa and/or other antiparkinsonian medication based on the Investigator's clinical judgment) * Unified Dyskinesia Rating Scale (UDysRs) Total score ≥ 30 at Visit 3

* Participant(s) treated with levodopa-carbidopa intestinal gel (LCIG) previously * Participant's PD diagnosis is unclear or there is a suspicion that the subject has a parkinsonian syndrome such as secondary parkinsonism (e.g. caused by drugs, toxins, infectious agents, vascular disease, trauma, brain neoplasm), parkinson-plus syndrome (e.g. Multiple System Atrophy, Progressive supranuclear Palsy, Diffuse Lewy Body disease) or other neurodegenerative disease that might mimic the symptoms of PD * Participant(s) has undergone neurosurgery for the treatment of Parkinson's disease. * Participant(s) has contraindications to levodopa (e.g. narrow angle glaucoma, malignant melanoma) * Participant(s) experiencing clinically significant sleep attacks or clinically significant impulsive behavior (e.g. pathological gambling, hypersexuality) at any point during the three months prior to the Screening evaluation as judged by the Principal Investigator