Parkinsons disease: When is deep brain stimulation an option
Elise Anderson, M.D.
Neurologist, Providence Neurological Specialties-East
March 3, 2014
Deep brain stimulation for Parkinson's disease was approved more than a decade ago, and since then the treatment has been found to be more effective than the best medical therapy for controlling symptoms and improving quality of life.
Although studies reported a higher incidence of serious adverse events in the treatment’s early applications, the past several years have seen advancements in surgical approaches, hardware and device software – all of which make deep brain stimulation surgery safer and more accessible for patients.
In treating Parkinson’s disease, deep brain stimulation targets one or two areas of the brain that affect motor function: the globus pallidus interna and subthalamic nucleus. A third area, the thalamus, is targeted for essential tremor. The target is chosen based on the individual patient's profile of symptoms and medication response.
It is believed that stimulating the target structures decreases excitability of affected cells, disrupting the aberrant signal flow. However, the exact mechanism of deep brain stimulation, or DBS, remains an area of research and debate.
When is it time to consider DBS?
Most patients enjoy a honeymoon period after starting medication for Parkinson’s disease, especially if they’re taking carbidopa-levodopa (Sinemet). But over time they start to develop complications, such as dyskinesia and “wearing off” phenomenon in which the medication loses its effectiveness or works unpredictably.
Initially, wearing off can be addressed with medication adjustments, but eventually patients find themselves with more “off” time and less “on” time. When we see this on the horizon, we start considering DBS, which can offer symptom relief with less dyskinesia and less “off” time.
Implantation of the DBS device involves bilateral surgery in a two-stage process – lead placement followed by connection to an implantable pulse generator, which looks like a pacemaker beneath the skin and includes the battery and programmable hardware.
With the advent of intraoperative MRIs, some medical centers now offer “asleep” DBS surgery in which patients are under anesthesia throughout the procedure. This technology avoids having to wake the patient during surgery for intraoperative testing to confirm lead placement. Patients typically spend several nights in the hospital, then return to the clinic four weeks later for device programming.
Red flags: When is DBS not a good option?
Patient selection is the key to a good result with deep brain stimulation. Just as with medication, DBS treats some Parkinson’s disease symptoms better than others. In particular, the therapy does not help as much with imbalance and dysphagia and actually can make these symptoms worse.
It also can increase cognitive dysfunction and affective issues, such as depression and anxiety. Each patient undergoes neuropsychological testing to screen for problems that DBS surgery might worsen.
Patients who are developing symptoms of dementia may not be good DBS candidates. Not only could the surgery increase cognitive impairment, but the treatment requires that the patient have enough cognitive engagement to participate in programming visits and manage the DBS system, which includes a patient-operated programmer.
Finally, patients who do not have a documented robust medication response are poor DBS candidates because they are likely to derive little benefit from the surgery. Often it turns out that these patients have a “Parkinson’s mimic,” such as multisystem atrophy or vascular Parkinsonism.
For patients who can benefit from this treatment, however, deep brain stimulation provides a durable improvement in the symptoms of Parkinson’s disease. To learn more, contact Providence Center for Parkinson’s Disease, a service of Providence Brain Institute.