Deep Brain Stimulation for Parkinson’s Disease

Deep brain stimulation is a surgical intervention used to treat movement disorders such as Parkinson’s disease when the regimen of existing medications and the various rehabilitation strategies become less effective in managing symptoms. This surgical procedure received approval from the Food and Drug Administration to treat tremor in Parkinson’s disease in July 1997 and for advanced motor symptoms of Parkinson’s disease in January 2002.

For people with Parkinson’s disease, deep brain stimulation (DBS) surgery may be helpful if the individual is experiencing motor fluctuations including dyskinesias or "off" episodes.

The subthalamic nucleus and the globus pallidus are two locations in the brain that are targeted in the DBS procedure for Parkinson’s. Certain symptoms of Parkinson’s disease can be reduced when these two areas are turned "off" by the stimulator. These include tremor, rigidity, slowness of movement, difficulty walking, and "freezing," as well as extra movements or dyskinesia that are medication side effects. The amount of daily "on" time during which the Parkinson’s symptoms are better controlled can be increased as well.

The best marker of whether or not people with Parkinson’s disease will benefit from DBS is how well they respond to levodopa, an active ingredient in the drug SinemetTM or carbidopa/levodopa. Patients who benefit most from surgery have had a good response to levodopa. For many, this good response becomes less and less as the disease progresses.

The stimulator produces a more even, consistent effect than medications. This greatly decreases the "off" times and the dyskinesias. It is also effective for tremor even when the medications have never helped.

Unfortunately, the stimulator does not cure or halt the disease and residual symptoms can increase with disease progression. DBS does continue to provide the same percentage of symptom reduction.

When is it time to consider DBS surgery?

• DBS surgery may be helpful for people with Parkinson’s whose symptoms were once well controlled by anti-PD medication, but have become more challenging to treat and manage as the disease has progressed, requiring additional medications and increased doses.
• Once patients start to experience motor fluctuations including dyskinesias or "off" episodes, the options of DBS surgery should be considered, as this signals the onset of the decline in the ability of medications to control symptoms.
• Patients who have Parkinsonian tremor which is not responsive to medications may consider surgery even if they do not have the other symptoms of Parkinson’s disease. Typically the stimulator lead will be placed so that the other symptoms will also be treated when they arise in the future.

Who may be a candidate for DBS surgery?

People with Parkinson’s disease who have:

• Initially had a good response to medications to treat their movement disorder but later developed side effects that limit their effectiveness. Such side effects include:
  • Dyskinesias (extra movements)
  • Motor fluctuations including “wearing off” periods (medication wears off before the next dose is due)
  • Neuropsychiatric complications such as hallucinations
  • Other side effects such as nausea and hypotension
• Significant tremors even if the tremor has never been adequately managed by medications

Who may not be a candidate for DBS surgery?

For people who meet one of the following criteria, DBS surgery is not a good option:

• Are too unhealthy to undergo surgery
• Have significant dementia.
  • These individuals tend to recover more slowly, or not at all from surgery, and their dementia may worsen. Improved mobility from surgery, in the face of worsening dementia, often creates many new challenges.
• Are diagnosed with Parkinson’s plus or atypical Parkinsonism syndromes such as multiple system atrophy and progressive supranuclear palsy and/or who have never responded to PD medications.

For people who meet one of one of the following criteria, DBS surgery may not be advisable, and should be considered carefully:

• Cardiac pacemakers and defibrillators
  • By implanting the DBS generator more than 8 inches away from the cardiac device, most problems can be avoided. If the patient’s life is dependent on uninterrupted cardiac device function, DBS is generally contraindicated.
• Regular MRI imaging
  • Patients who have an implanted DBS system cannot have an MRI scan of any part of the body as it could lead to brain tissue damage.
  • Head MRIs can be performed using specific scanning equipment under the supervision of an experienced DBS team.
• Anti-coagulant therapy such as Coumadin or Aggrenox
  • A specific evaluation is needed to determine whether or not these medications can be safely withheld for approximately three weeks.

What outcomes can be expected from DBS for people with Parkinson’s?

• On average, DBS surgery results in a 40-60% improvement in motor features
• DBS can improve "off" times (times when medications are providing little or not benefit) to a pre-operative "best on" level of functioning. "On" time is when medications are acting optimally. With DBS, the "best on" periods are expected to improve only slightly.
  • This does not apply to those who cannot tolerate medications, or for those with dyskinesia or tremor.
• Dyskinesias worsened by the amount of medicine and tremor that is difficult to manage with medication are well treated with DBS.
• It is important to note that DBS does not stop the progression of Parkinson's disease.

What are the benefits and risks of deep brain stimulation surgery?

• Parkinsonian symptoms that significantly improve with DBS surgery:
  • festinating gait
  • freezing episodes
  • motor fluctuations
  • tremor
  • rigidity
  • dystonia
  • slow movements or bradykinesia
• Parkinsonian symptoms that may improve with DBS surgery:
  • masked face
  • pain related to tremor, stiffness, or dystonia
• Parkinsonian symptoms that will not improve or may worsen:
  • speech
  • dementia
  • mood - depression, anxiety, obsessive or compulsive

What are the potential risks of DBS surgery?

• 1-3% risk of intracranial hemorrhage which can lead to loss of speech, paralysis, coma, or death.
• 5% risk of infection which usually requires removal of the DBS system.
• DBS will offer little or no benefit. The chance of this is dependent on the patient's diagnosis or can be due to suboptimal lead placement, requiring revision.
• Risks of anesthesia which are dependent on the patient’s overall medical history.

What is the pre-operative DBS evaluation process?

Individuals interested in learning more about DBS surgery should call (804) 364-6519 to set up an informational appointment. At this appointment patients are given a packet of educational materials and if they have PD, are asked to complete a motor diary. Clinical notes are obtained from the referring neurologist and primary care provider. If a patient has not been seen by a neurologist, an appointment with a movement disorders specialist will be scheduled to confirm that the patient is a good candidate for surgery.

• Review steps of the evaluation process.

Deep Brain Stimulation Resources

• National Parkinson’s Foundation - information on deep brain stimulation
• NIH - National Institute of Neurological Disorders and Stroke
• Pallidal versus subthalamic deep-brain stimulation for Parkinson's disease. N Engl J Med. 362(22):2077-91. June 2010.

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