Parkinson’s disease (PD) is characterized by trembling, stiffness, and poor balance. These symptoms result from the death of brain cells that make dopamine, a chemical necessary for smooth, coordinated muscle movements. Drug therapy designed to mimic the effects of dopamine can minimize symptoms. However, after several years, medications may work only sporadically and may cause troublesome involuntary movements called dyskinesias .

Another option for PD patients is deep brain stimulation in which a stopwatch-sized neurostimulator is surgically implanted in the brain. Here, it sends electrical impulses to the areas that control movement and blocks abnormal signals that provoke unwanted symptoms. This treatment can improve motor function while reducing dyskinesias. In a trial that compared the efficacy of neurostimulation plus drug therapy to drug therapy alone, the German Parkinson Study Group found that six months of neurostimulation improved both quality of life and reduced motor symptoms. These findings are detailed in the August 31, 2006 New England Journal of Medicine .

About the Study

German researchers enrolled 156 adults who had PD for at least five years with symptoms that limited their daily activities. All of the patients were treated with drug therapy, based on widely accepted guidelines. Half of the patients also underwent brain surgery for the placement of a neurostimulator. After six months of treatment, researchers compared quality of life scores and the severity of motor symptoms between patients receiving neurostimulation plus drug therapy and those receiving only drug therapy.

Significant improvements—25% in the quality of life score and 41% in the symptom severity score—were seen in the neurostimulation group; neither measure changed in the medication-only group. But these benefits came with a greater risk for severe adverse events: 12.8% in the medication-surgery group vs. 3.8% in the medication-only group. However, the incidence of all adverse events (mild to severe) was greater in the medication-only group (64.1%) than the surgery group (50%).

The lack of a so-called blinded placebo group—that is, a set of patients who had brain surgery, but did not receive a neurostimulator and did not know whether they received the stimulator or not—is a major limitation to this study.

How Does This Affect You?

Is deep brain stimulation the treatment of choice for all PD patients? It’s too soon to say. While this and previous trials have shown improvements in symptoms and quality of life with reductions in dyskinesias, the lack of a placebo group is grounds for caution. Without such a group, it is impossible to know for sure whether it was the neuostimulation itself or the patients’ expectation of recovery with neurostimulation that led to the observed improvement.

If you are living with PD, talk with your doctor about the benefits and risks of this treatment for you. The Parkinson’s Disease Foundation has identified two groups of patients who are good candidates for neurostimulation:

  1. Patients with severe, disabling tremors that are not eased by medications.
  2. Patients with serious fluctuations in motor function and dyskinesias, as well as complicated drug regimens.

Also, have realistic expectations—neurostimulation does not slow or stop the progression of PD, but it may, for some people, significantly reduce symptoms and improve quality of life.