Selecting patients for continuous dopaminergic stimulation therapy

In patients with advanced Parkinson's disease (PD), worsening motor symptoms, mainly owing to motor response complications and dyskinesia, may be treated optimally by switching to a continuous dopaminergic stimulation (CDS) treatment approach. There are three CDS options widely available for the treatment of PD: levodopa/carbidopa intraduodenal gel infusion (Duodopa ^®), subcutaneous apomorphine infusion (APO) and deep brain stimulation (DBS), which is not strictly a CDS treatment but has similar effects. Although large-scale direct comparisons of the CDS treatment options do not exist, there is a growing body of evidence that helps direct the choice of CDS therapy for individual patients. APO is the 'simplest' treatment, in terms of administration, but may be slightly less effective in treating motor complications than DBS or Duodopa. Furthermore, different CDS treatments appear to improve different non-motor symptoms. Several cases are presented in this article to illustrate some of the issues that lead to initiation of CDS therapy and that determine the choice between Duodopa, APO and DBS. In the absence of comparative trials, sharing clinical experience will help inform others of the best method of selecting patients for CDS therapy. Some simple algorithms have also been developed to direct this selection, but many unanswered questions remain, such as how early CDS therapies should be initiated. Future clinical studies and shared clinical experience should provide more definitive guidelines on the use of CDS therapy in the near future.