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Benefit of Both Deep Brain Stimulation and Placebo Effect Are Confirmed With New Technology

A new type of deep brain stimulation (DBS) device, called constant-current DBS, has been proven safe and effective, opening the way to advances in DBS technology, according to a study published online in the January 11 edition of The Lancet Neurology.

DBS is a treatment that can help improve symptoms for people with Parkinson’s disease who experience motor fluctuations, dyskinesia or severe tremor that cannot be controlled by medication.  The technique involves the surgical insertion of tiny electrodes deep in the brain and the implantation of an impulse generator (similar to a pacemaker) under the collarbone to provide an electrical impulse to the brain.

Using the older constant-voltage system, the electrical current delivered to the brain may vary due to differences in the electrical resistance of brain tissues, but with the new “constant current” device, the electricity flow does not vary.

The new study led by Michael S. Okun, M.D., at the University of Florida College of Medicine in Gainesville, tested the safety and effectiveness of constant-current DBS devices.  The researchers also wanted to find out whether simply having the surgery, without turning on the DBS device, had an effect on Parkinson’s symptoms.

Between 2005 and 2010, researchers at several participating centers implanted the constant-current DBS devices in 136 people with Parkinson’s.  For 101 study participants in the active treatment group, the device was turned on immediately after surgery.  For the remaining 25 participants in the control group, their devices were activated after a three month delay.  The researchers evaluated changes in symptoms for all participants at regular intervals for a year, using both the Unified Parkinson’s Disease Rating Scale (UPDRS) and symptom diaries kept by participants.

Results

 

  • Three months after surgery, participants in the active stimulation group, whose DBS devices were turned on immediately after surgery, experienced on average, four hours more during the day than before the surgery when they were not bothered by dyskinesia or wearing off symptoms. 
  • Three months after surgery, those in the placebo group, with implanted electrodes that were not turned on, also experienced an improvement in good motor function, amounting to about two hours per day.
  • Study participants whose DBS devices were turned on were able to lower their levodopa dose much more than the surgery-only group at three months after surgery.
  • Symptoms of depression improved after three months, much more among those whose DBS device was turned on.
  • Participants in both groups experienced the most common cognitive side effect of the DBS surgery – a mild decline in verbal fluency.
  • A small percentage of participants experienced serious complications from surgery, including infections and hemorrhage.

What Does it Mean?

The study showed that new constant-current DBS devices can significantly improve movement symptoms much like the existing constant-voltage DBS treatments.  Although the two devices have never been compared to each other, the clinical effects, tolerability and adverse events appear similar, based on this study.

Additionally, the researchers were able to address some lingering questions about DBS surgery by delaying the start of stimulation in one group of participants.  Scientists have long wondered whether some people undergoing DBS experience a placebo effect—an improvement of symptoms perhaps due to their expectations.  This proved to be the case, although improvements were much smaller for participants whose devices were not activated than for those who received stimulation.  Another important finding was that a common cognitive side effect of DBS, a decline in verbal skills, is a consequence of the surgery itself and not the stimulation.

It is hoped that the presence of two different DBS devices will improve treatment options for people with Parkinson’s and spur therapeutic innovation in the field of deep brain stimulation.


Reference: Okun MS, Gallo BV, Mandybur G, Jagid J, Foote KD, Revilla FJ, Alterman R, Jankovic J, Simpson R, Junn F, Verhagen L, Arle JE, Ford B, Goodman RR, Stewart RM, Horn S, Baltuch GH, Kopell BH, Marshall F, Peichel D, Pahwa R, Lyons KE, Tröster AI, Vitek JL, Tagliati M, for the SJM DBS Study Group. Subthalamic deep brain stimulation with a constant-current device in Parkinson's disease: an open-label randomised controlled trial. Lancet Neurol 2012 Jan.; DOI: 10.1016/S1474-4422(11)70308-8; Published online, ahead of print.

Source Date: Feb 07 2012