Compared with patients in the best medical therapy group, patients in the deep brain stimulation group said they experienced significant improvements in quality of life, as measured by seven of eight PD quality-of-life scores.

However, the overall risk of experiencing a serious adverse event was 3.8 times higher in deep brain stimulation patients than in best medical therapy patients. Forty-nine deep brain stimulation patients (40 percent) experienced 82 serious adverse events. Fifteen best medical therapy patients (11 percent) experienced 19 serious adverse events.


The most common serious adverse event was surgical site infection, with other serious adverse events including nervous system disorders, psychiatric disorders, device-related complications and cardiac disorders.

"The clinical significance of the adverse events and minor neurocognitive changes observed in patients in the deep brain stimulation group and, more importantly, whether patients who undergo deep brain stimulation view improvement in motor function and quality of life as outweighing adverse events, remain to be explored. More detailed analyses of adverse events and neurocognitive functioning following the conclusion of phase 2 of this study will shed light on these issues. Caution should be exercised, however, against overstating or understating the risks of deep brain stimulation for patients with PD. Physicians must continue to weigh the potential short-term and long-term risks with the benefits of deep brain stimulation in each patient," the authors conclude.

Drugs and Devices Studied

Deep brain stimulation technology involves implanting a pacemaker-like device in the chest and then running wires deep into the patient's brain where energy is used to stimulate areas linked to movement. This study is one of the first to measure this technology against the best-available medical (drug) treatment.

Study participants received deep-brain stimulation systems made by Medtronic Inc. (MDT), which gained Food and Drug Administration approval to sell the technology for Parkinson's in 2002. Medtronic's system is approved for essential tremor, Parkinson's and dystonia. The company hopes to gain approval for epilepsy, depression and obsessive-compulsive disorder in the near future. Note that doctors can choose to use devices for so-called off-label purposes.

Total cost for implantation of the system is approximately $60,000.

Medtronic is the only company with an approved deep-brain stimulation system, although St. Jude Medical Inc. (STJ) has a device and plans to seek approval to treat multiple disorders as well.

Joan Trombetti contributed to this coverage.

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