Researchers at Texas Health Dallas Publish Major Paper on Deep Brain Stimulation for Parkinson’s Disease

DALLAS — Researchers at Texas Health Presbyterian Hospital Dallas are part of a major new study that shows deep brain stimulation (DBS) can control many of the symptoms of advanced Parkinson’s disease.

Dr. Malcolm Stewart
Dr. Malcolm Stewart, a neurologist on the medical staff at Texas Health Dallas, helped author the paper.
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The study, published this month in Lancet Neurology, is the first randomized, controlled trial to test the effects of the surgery alone — versus surgery and stimulation. The procedure, which can treat a variety of disabling neurological conditions, is a highly technical surgery in which neurosurgeons place a battery-operated neurostimulator, similar to a heart pacemaker, into the brain.

In Parkinson’s patients, the DBS probes are placed in areas of the brain (the subthalamic nucleus or globus pallidus) where “electrical storms” rage, causing motor-function problems. The device delivers pulses of electricity to block abnormal electrical signals between cells that can cause tremors, stiffness and slow movements.

“The results of our research offer hope to people with Parkinson’s who are no longer responsive to medication,” said Dr. Malcolm Stewart, a neurologist on the medical staff at Texas Health Dallas and an author of the paper. “In many cases, deep brain stimulation can help them get their lives back.” More than a million people in the United States suffer from Parkinson’s disease, according to the National Institute of Neurological Disorders and Stroke. About 50,000 new cases are reported annually, the Institute says.

The FDA approved DBS for Parkinson’s disease in 2002 — but exactly how it helps Parkinson’s patients is not known.

Stewart and Texas Health Dallas were selected to participate in the study because of the high number of DBS cases that have been performed at the hospital. When the study began in 2006, neurosurgeons on the medical staff at Texas Health Dallas had implanted more than 300 devices. Today, more than 400 of the devices have been implanted.

Texas Health Dallas was one of 15 sites for the trial. Other institutions involved in the research include the University of Florida, Cedars-Sinai in Los Angeles, Columbia University Medical Center and the University of North Carolina.

The study analyzed the effectiveness of a newer type of DBS device, which uses constant current stimulation. Existing DBS devices on the market use voltage-controlled systems. Stewart said the difference in type of DBS device is not as significant as the findings about improved symptoms.

Study subjects treated at Texas Health Dallas were seen by Stewart and selected for surgery based on symptoms, effectiveness of previous medical treatments and other criteria.

Of the 136 study subjects implanted with DBS devices, 101 were randomly assigned to have immediate stimulation from the implant, while 35 patients received delayed stimulation. Motor function scores in the immediate-stimulation group went up 39 percent.

But researchers also found that the non-stimulation group also had improved motor-function. They theorize that simply placing the DBS probes in the area of the brain where the electrical signals were miscommunicating helped disrupt the misfiring brain cells.

“This study demonstrated clearly for the first time that there is both a lesion effect and a stimulation effect,” said Stewart, who is a nationally-renowned movement disorders specialist. “The electrical stimulation of the DBS device provides the greatest affect on Parkinson’s symptoms overall, but most of the cognitive and speech improvements seem to be primarily from the lesion effect rather than the DBS stimulation alone. This information may help in research in targeting.”

Patients were eligible if they had suffered from Parkinson’s disease for at least five years. The study enrolled 136 patients who were received DBS implants and were randomly assigned to receive immediate (101 patients) or delayed (35 patients) stimulation.

About Texas Health Presbyterian Hospital Dallas
Texas Health Presbyterian Hospital Dallas is an 898-bed acute care hospital and recognized clinical program leader, having provided compassionate care to the residents of Dallas and surrounding communities since 1966. U.S. News and World Report has ranked Texas Health Dallas among the nation’s best hospitals in digestive disorders, orthopedics, and neurology and neurosurgery. An affiliate of the faith-based, nonprofit Texas Health Resources system, Texas Health Dallas has approximately 4,000 employees and an active medical staff of more than 1,000 physicians. For more information, call 1-877-THR-WELL, or visit