Randomised controlled study of deep brain stimulation confirms benefit of constant current system for patients with Parkinson’s


Results from the first St Jude Medical controlled study on deep brain stimulation for Parkinson’s disease were published online in the January issue of Lancet Neurology. The aim of the study was to evaluate the Libra and Libra XPDBS constant current systems to determine the devices’ safety and effectiveness in managing the symptoms of the disease.

Conducted at 15 medical centres in the USA, the study enrolled 136 patients and was designed to compare patients implanted with deep brain stimulation systems with and without stimulation. The primary endpoint was defined as an increase in the duration of “on time” without bothersome dyskinaesia when measured after three months. “On time” refers to the amount of hours each day that a patient has good control of his or her symptoms and motor functions with non-bothersome dyskinaesia.


The results of the study were statistically significant, demonstrating that participants in the stimulation group averaged an increase of 4.27 hours of “on time,” compared with an increase of 1.77 hours in the group without stimulation. Additionally, patients reported an overall improvement in their quality of life.


“These results are important as they represent the first large, randomised, controlled study of a constant current device for managing the symptoms of Parkinson’s disease,” said Michael S Okun, administrative director of the University Of Florida College Of Medicine’s Center for Movement Disorders and Neurorestoration, National Medical Director for the National Parkinson Foundation and the primary author of the article. “The data from this study represents the evolution of the approach to deep brain stimulation treatment and provides new evidence supporting the positive benefits this therapy can provide patients.”


Additional key findings at three months were as follows:


  • Patients receiving stimulation had a 73% response rate compared to a 38% response rate in the group without stimulation (response was defined as at least a two hour increase from baseline in good quality “on time”).
  • Motor scores for those in the stimulation group improved 39% compared to the baseline as measured by the Unified Parkinson’s Disease Rating Scale (UPDRS).
  • There was a statistically significant decrease in the amount of medications needed to control Parkinson’s disease symptoms in the stimulation group compared to the group without stimulation.


The study enrolled patients who on average had suffered from Parkinson’s disease for at least five years and who had six or more hours each day with diminished motor symptom control and with moderate to severe dyskinesia. All patients were treated with bilateral stimulation in the subthalamic nucleus area of the brain. The adverse event and safety profile were similar to those in other recent randomised studies of deep brain stimulation. Participants in the stimulation group saw an increase in the occurrence of slurred speech and fatigue. The most common serious adverse event following deep brain stimulation implantation was infection, which occurred in five patients.


The Libra and LibraXP neurostimulators evaluated in the study are constant current devices that are currently approved for use in Europe, Latin America and Australia for managing the symptoms of Parkinson’s disease.