For some people with Parkinson's disease, deep brain stimulation can have immediate and dramatic effects on tremors, rigidity, balance, and other motor symptoms.

Now new research shows that these benefits may last at least three years. The findings appear online in Neurology.

Deep brain stimulation uses a battery-operated device to deliver electrical impulses -- similar to a pacemaker for the heart -- to areas of the brain that control movement. The impulses are thought to block abnormal signals that cause many of the movement problems (motor symptoms) of Parkinson's. This procedure is typically reserved for individuals who no longer respond to their Parkinson's medications or who experience unacceptable side effects from them.

According to the new findings, this treatment helped with motor symptoms such as tremor, but individuals did show gradual declines over time in their quality of life, ability to perform tasks of daily living, and thinking skills.
After the 'Wow Effect'

"This study looked past the immediate 'wow effect,'" says Michele Tagliati, MD. He wrote an editorial accompanying the new study.

"Now we want to know what we can expect over the next 10 years, and this starts to make it clearer," says Tagliati, the director of the Movement Disorders Program at Cedars-Sinai Medical Center in Los Angeles.

"The effect on motor function is sustained," says researcher Frances M. Weaver, PhD. She is the director of the Center for Management of Complex Chronic Care at Edward Hines Jr. VA Hospital in Hines, Ill. But "deep brain stimulation does not have an impact on the other symptoms of the disease, so there will be progression."

Weaver's study included 89 people whose device was implanted in a part of the brain called the globus pallidus interna (GP) and 70 who were stimulated in a part of the brain known as the subthalamic nucleus (STN).

While there were early improvements in quality of life and the abilities to perform activities of daily living, these gradually diminished, and there was a decline in mental abilities. This likely reflects the progression of the disease and the emergence of symptoms that are resistant to treatment, Weaver says.

The research still helps doctors in more ways than one, though. "People got a fairly even motor benefit from both implantation sites," says Stuart Isaacson, MD. He is the director of the Parkinson's Disease and Movement Disorders Center of Boca Raton, Fla., and an associate professor of neurology at Florida International University's Herbert Wertheim College of Medicine in Miami.

"This is hopeful because it allows different places for us to implant the device," he says. "We would expect the procedure to have a good benefit over years and years, but we just didn't have great evidence until now."

Isaacson reiterates that deep brain stimulation is not a cure for Parkinson's disease. "We are still looking for a cure, and this is a way of trying to manage the symptoms for a longer period of time while we await the cure."

Weaver agrees: "Deep brain stimulation is not a cure for Parkinson's disease, but it is a treatment option for many people who are no longer benefiting from their medication," she says.