6. Unless otherwise specified, enrolled patients must be on an optimally maximized oral therapy regimen. Optimized oral anti-PD medication included: levodopa/carbidopa in either immediate or delayed release forms, plus at least one other antiparkinson medication, which could include a direct acting oral dopamine agonist, a monoamine oxidase inhibitor (MAOB), or a catechol-O-methyltransferase inhibitor (COMT) for at least 30 days prior to enrollment into study.