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Viewpoint: When Is It Time to Try Deep Brain Stimulation?
- Nov 04 2014
Recent studies suggest that deep brain stimulation (DBS) can benefit people with Parkinson’s disease (PD) who have only recently begun to experience side effects of levodopa therapy, such as dyskinesia and fluctuations in the medication’s effectiveness. A report in the early online edition of Movement Disorders, published September 16, 2014, looks closely at this research and concludes that the decision to undergo DBS is highly individual, and that there are physical costs to early DBS surgery that, for some, may outweigh the potential benefits.
Deep brain stimulation has become a standard therapy for people with PD who still respond well to levodopa but who experience fluctuations such as dyskinesias and sudden off-times. This surgical procedure involves placing electrodes in the brain. When switched on, the electrodes stimulate brain cells affected by PD and improve some aspects of movement. The benefits are clear for many people. Yet the risks associated with surgery — including the potential worsening of some PD symptoms (such as speech) and the lengthy process of fine-tuning the device — have led to DBS being considered only when other treatment options are failing.
A recent clinical trial looked at the effects of DBS surgery soon after participants began experiencing motor complications from levodopa – less than three years after the onset of mild symptoms – and compared it to a group that did not receive surgery. After two years, movement had improved in the DBS group, but not in the control group. In the new report, researchers led by Anthony E. Lang, M.D., at the University of Toronto, examined clinical, economic and other issues related to DBS, most of which have been studied to determine whether DBS should be offered earlier in the course of PD.
The study authors analyzed several considerations:
- A diagnosis of PD is difficult to make, especially early in the course of disease. There is a risk that individuals may have an atypical parkinsonism that does not respond to DBS, rather than true PD.
- People with the mild symptoms of early-stage PD receive a lesser benefit from DBS than those with more severe, later-stage symptoms, even though the risks of surgery are the same.
- Motor complications can remain stable for years — it is impossible to predict, but a person could undergo early DBS, and be subject to its risks, even though their symptoms may not have changed much without the treatment.
- DBS does not help all PD symptoms, such as cognitive issues, some of which take time to develop. By waiting until later in the course of PD to do DBS, doctors can better predict who will benefit from it.
- Not all treatment centers have the teams of experts needed to safely follow-up with younger people, who have a greater risk of suicide after DBS.
- Having DBS at a younger age means that people will live longer with the implants, increasing the chance of a malfunction, and making them subject to the risks of additional surgery.
- In economic terms, the benefits of early DBS vary by individual – for some, early DBS reduces later health care costs, for others it may not.
- The placebo effect may have exaggerated the benefits of early DBS. Participants knew they were getting the implants. A high expectation that DBS would help may have contributed to improvement in their symptoms.
What Does It Mean?
There is no question that DBS has revolutionized the treatment of PD, as a way of controlling disabling fluctuations, dyskinesia and movement symptoms induced by levodopa therapy. However, the authors of this article believe the question is not when is the best time to try DBS, but rather who would best benefit from its effects?
Although recent research suggests that early-stage DBS improves movement in people with PD, the authors of the current report argue that earlier is not always better. They emphasize that many factors need to be accounted for in making the decision to undergo DBS. The appropriate time for surgery, they conclude, is when the needs and expected benefits outweigh the risks in a person who has received objective and comprehensive information about his or her own individual situation. They further urge caution in considering early DBS until more is known about how the initial study participants fare over time, and until studies are done that control for the placebo effect. Also, in the meantime, new PD therapies are being developed that could have benefits similar to DBS, but with fewer risks.
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Reference: Mestre TA, Espay AJ, Marras C, Eckman MH, Pollak P, Lang AE (2014) Subthalamic nucleus-deep brain stimulation for early motor complications in Parkinson’s disease—the EARLYSTIM trial: Early is not always better. Movement Disorders. Ahead of Print. 16 SEP 2014 DOI: 10.1002/mds.26024 http://dx.doi.org/10.1002/mds.26024
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Source Date: Nov 04 2014