Deep Brain Stimulation (DBS) and its impact on Parkinson’s disease

Background on DBS

As PD progresses, patients must take increasingly large doses of medication to manage the escalating symptoms. These medications come with a heavy price, including the trademark tremors or muscle spasms most widely associated with the disease.

Beyond the standard pills and products, doctors have been working to enhance an existing surgical intervention known as Deep Brain Stimulation (DBS) to prevent the negative neurological impulses that cause some of the disease’s harmful effects.  This surgery works by impeding the neurological impulses in the brain that cause tremors and rigidity in the body.

Candidates and timing for DBS

DBS is not just a treatment for Parkinson’s disease.  It is used for a variety of illnesses, including depression, chronic headaches, and Alzheimer’s.  In terms of Parkinson’s, the procedure is most commonly prescribed for patients who no longer see positive results from their medications.  There is no uniform timeline for medication effectiveness; it varies by person and the progression of their disease.

How DBS works

The surgery involves the insertion of a stopwatch-sized, battery-powered “neurostimulator” in the brain, along with two insulated wires known as the “lead” and the “extension.”  The neurostimulator emits electrical impulses to targeted areas in the brain that are known to control movement; it also helps to prevent the abnormal signals that cause the tremors and other Parkinson’s symptoms. The extension wire, inserted under the skin, runs along the shoulder and neck and is used to connect the lead wire in the skull to the neurostimulator.

Typically, the surgery is completed over the course of a few appointments, during which the doctors first insert the wires and then connect them to the neurostimulator.  Once the wires and the neurostimulator are in place, the patient and the doctors begin a series of programming sessions to tune the neurological impulses to the appropriate level for the patient.

To determine the optimal placement of the wires, doctors have a few different options at their disposal, including magnetic resonance imaging (MRI), computed tomography (CT), or microelectrode recording.  MRI and CTs are visual tools, while microelectrode recording uses a small wire to track the movement of nerve cells in the target area in the brain.  These procedures help to ensure the precision of the neurostimulation.

Different types of DBS

There are two primary types of DBS: stimulation to the interior area of the brain, known as the subthalamic nucleus (STN), or to a larger, exterior part of the brain, known as the globus pallidus interna (GPi).  The surgery does not involve cutting or removing any part of the brain, so the process can be undone if necessary.

From 2007 to 2010, the Center for Management of Complex Chronic Care at the Hines VA Hospital in Illinois conducted a study comparing the effectiveness of STN and GPi DBS.  In the study, researchers randomly assigned patients with PD to receive DBS.  The patients were split into two groups, the first to receive interior brain or STN stimulation and the second to receive exterior brain or GPi stimulation.  According to Francis Weaver, director of the Center for Management of Complex Chronic Care, the study placed greater emphasis on STN stimulation “because stimulating that area could reduce the amount of medication” required for a Parkinson’s patient.

Ultimately, both groups of participants showed similar improvements after 36 months.  The data suggests “that [healthcare] providers should think about both targets and what else is going on and not just arbitrarily pick one [technique] over the other.”

However, it is important to note that GPi stimulation has been associated with fewer cognitive side effects.  As director Weaver explained, “the group that received the GPi stimulation saw positive results in terms of their mental abilities. Their verbal learning scores after three years went up…whereas the STN group saw their scores below their original baselines.  The difference could be because GPi stimulates a larger area of the brain than STN, or potentially has some ‘off-site’ side effects.”

Side effects of DBS

With time and increased research, DBS has gotten more efficient and will continue to improve.  Currently, DBS carries the risk of several side effects, some more serious than others, and all of which need to be considered by the patient and doctor before deciding on the procedure.  Side effects include, but are not limited to:

  • Body numbness or tingling
  • Discomfort from the placement of the neurostimulator
  • Risk of brain injuries such as stroke or internal bleeding
  • Changes in speech, personality, or motor functions

Please feel free to contact the Blechman Foundation for more information on DBS or refer to http://www.dbs-stn.org/, an affiliate of the Parkinson’s Alliance and an excellent resource for patients and their families.

References

1.    http://health.usnews.com/health-news/news/articles/2012/06/20/deep-brain-stimulation-may-offer-longer-term-relief-for-parkinsons

2.    http://www.ninds.nih.gov/disorders/deep_brain_stimulation/deep_brain_stimulation.htm

3.    http://www.news-medical.net/health/Deep-Brain-Stimulation-Side-Effects.aspx

 

 

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