Deep brain stimulation improves movement skills and quality of life in patients with advanced Parkinson's disease better than other medical treatments, but it also carries with it a higher risk for complications, a new study says.
Deep brain stimulation is a surgical procedure that involves the implantation of electrodes that send electrical currents to specific regions in the brain. This electrical stimulation can reduce involuntary movements and tremors, which are common Parkinson's symptoms.
Deep brain stimulation is often performed on Parkinson's patients when medication fails to adequately control symptoms, according to the researchers.
For their study, researchers included 255 Parkinson's patients who either received deep brain stimulation or so-called "best medical therapy," which included being monitored by a neurologist, taking medication and undergoing physical and speech therapy.
After six months of follow-up, they found that patients who received deep brain stimulation obtained an average of 4.6 hours per day of so-called "on" time, defined as the amount of time symptoms are under control and a patient's motor function is not compromised.
The subjects who received best medical therapy gained little or no "on" time.
The study also found that:
- Seventy-one per cent of patients who received deep brain stimulation experienced significantly improved motor function, compared to only 32 per cent of patients who received best medical therapy.
- Three per cent of deep brain stimulation patients had their symptoms worsen, compared to 21 per cent of best medical therapy patients.
We expected that patients with deep brain stimulation would improve in motor function - what we did not expect was the magnitude of the improvement," said study author Frances M. Weaver, of Hines VA Hospital in Hines, Illinois.
The study is also significant because, in contrast to similar research, subjects included patients over the age of 70, who are usually excluded from studies.
"The take home message from this study is that each patient should weigh the benefits and risks of undergoing deep brain stimulation," Weaver said. "But that being older and having Parkinson's does not exclude a person from being appropriate for receiving this treatment."
The study is published in the Jan. 7 edition of the Journal of the American Medical Association.
While the patients who underwent deep brain stimulation had significant improvement in their quality of life, they also were at greater risk for complications.
The overall risk of experiencing a serious adverse side effect was nearly four times greater for those patients compared to those who received other medical treatment.
Forty-nine of the surgery patients experienced a total of 82 serious adverse effects, compared to 15 medical treatment patients who experienced a total of 19 serious adverse effects.
The most common of these was an infection at the surgical site. Other side effects included nervous system, cardiac or psychiatric disorders.
According to the authors, the risks and benefits of deep brain stimulation must still be fully explored.
"Caution should be exercised, however, against overstating or understating the risks of deep brain stimulation for patients with Parkinson's disease," the authors concluded.
"Physicians must continue to weigh the potential short-term and long-term risks with the benefits of deep brain stimulation in each patient."
According to Weaver, the next phase of her research will focus on whether placement of the electrodes leads to better symptom control.
In an editorial accompanying the study, Dr. Gunther Deuschl, of the Universitatsklinikum Schleswig-Holstein, in Kiel, Germany, said there are many unanswered questions about deep brain stimulation therapy.
"For instance, the optimal timing for the implantation is unknown," Deuschl wrote. "The majority of patients undergo deep brain stimulation surgery more than 10 years after disease onset when the patients are already incapable of working and when the disease-related psychosocial decline has already begun."
Therefore, studies must be done to determine if the treatment could be helpful for younger patients, Deuschl wrote.
