A pacemaker-like device that stimulates the brain can help control some of the muscular problems brought on by Parkinson’s disease, the second most common neurodegenerative problem in America. A report in tomorrow’s New England Journal of Medicine may prompt doctors to recommend its use sooner rather than later.
Parkinson’s disease occurs when nerve cells in the brain that make the chemical messenger dopamine begin wasting away. Dopamine helps coordinate movements. Without dopamine, hands tremble, arms and legs become stiff, movement slows and sometimes stops, balance and coordination fail. People with Parkinson’s may have trouble walking, talking, swallowing, and doing simple everyday tasks.
Drugs such as levodopa can fill in for natural dopamine and ease symptoms. But symptoms can reappear as the body breaks down the drug. And levodopa can cause side effects such as hand tremor or uncontrolled movements.
For more than a decade, a non-drug approach known as deep-brain stimulation has been used to help control Parkinson’s symptoms. As shown in the image to the right, it involves placing a tiny wire called a lead (pronounced leed) in the part of the brain that controls movement and a matchbook-sized stimulator under the skin below the collarbone. The lead and stimulator are connected to each other by a second wire that runs under the skin of the shoulder, neck, and head. The device emits small pulses of electricity that help coordinate movement.
Deep-brain stimulation traditionally isn’t used until a person has lived with Parkinson’s for a decade or more. French and German researchers wanted to know whether it might be appropriate earlier in the course of the disease, soon after the onset of troubling muscle symptoms. It is, they report in the NEJM. In a randomized trial that included 251 men and women with Parkinson’s disease, deep-brain stimulation plus state-of-the-art drug therapy was better than drug therapy alone at improving quality of life, mobility, muscle symptoms, and the ability to carry out daily tasks.
“I’m not surprised to see these results, but I and others who work with Parkinson’s patients are certainly glad to see them,” said Dr. Alice Flaherty, a specialist in movement disorders and associate professor of psychiatry at Harvard-affiliated Massachusetts General Hospital. “This trial gives us more leeway to use deep-brain stimulation earlier in appropriate patients.”
Although deep-brain stimulation can be an excellent option for some people with Parkinson’s disease, it isn’t a miracle worker, isn’t for everyone, and comes with some risks, points out Dr. Daniel Tarsy, professor of neurology at Harvard Medical School and director of the Parkinson’s Disease and Movement Disorders Center at Beth Israel Deaconess Medical Center.
“Sometimes just adjusting a person’s medications can make a big improvement,” said Dr. Tarsy. Writing last year in JAMA, he described how changing a man’s levodopa schedule from every four hours to every three hours helped reduce his involuntary movements and episodes of “freezing,” where he couldn’t walk.
That said, when state-of-the-art medical therapy isn’t enough to control symptoms, “deep-brain stimulation can be a very effective addition,” said Dr. Tarsy.