The source of this article is Science Daily: http://tinyurl.com/cwf8t

Deep Brain Stimulation In Parkinson Disease Reduces Uncontrolled Movements
CHICAGO – Deep brain stimulation of two different areas of the brain 
appears to improve problems with uncontrolled movements (dyskinesia) in 
patients with Parkinson disease (PD), according to an article in the April 
issue of Archives of Neurology, one of the JAMA/Archives journals.

Deep brain stimulation with electrical impulses delivered to structures 
deep within the brain is being intensively investigated for the management 
of advanced Parkinson disease, according to background information in the 
article. Although a number of studies have shown that stimulation of two 
different areas of the brain, the globus pallidus interna (GPi) and the 
subthalmic nucleus (STN), can be achieved safely and effectively, STN has 
been thought to be the preferred target. At the same time, the authors 
note, there does seem to be some evidence that the STN is more vulnerable 
during surgery and that STN patients may have more postoperative problems.

Valerie C. Anderson, Ph.D., of the Oregon Health and Science University, 
Portland, and colleagues compared 23 patients with Parkinson disease and 
problems with medication-induced uncontrolled movement who were randomly 
assigned to implantation of deep brain stimulators in either the GPi or the 
STN areas of the brain. Patients' Parkinson symptoms were evaluated with 
and without medication using a standard rating scale at three, six and 12 
months after surgery.

"Off-medication Unified Parkinson's Disease Rating Scale motor scores were 
improved after 12 months of both GPi and STN stimulation (39 vs 48 
percent)," the authors write. "Bradykinesia [extremely slow movement] 
tended to improve more with STN than GPi stimulation. No improvement in 
on-medication function was observed in either group. Levodopa [Parkinson 
medication] dose was reduced by 38 percent in STN stimulation patients 
compared with three percent in GPi stimulation patients. … Dyskinesia was 
reduced by stimulation at both GPi and STN ( 89 v 62 percent). Cognitive 
and behavioral complications were observed only in combination with STN 
stimulation."

"At this point, it appears that stimulation at either STN or GPi improves 
off-medication motor scores and levodopa-induced dyskinesia for at least 
one year, and there is no clear superiority of STN over GPi stimulation," 
the authors conclude. "Indeed, our comparison of GPi vs STN stimulation 
suggests that selection of a stimulation site should be influenced by 
symptom profile. Although GPi stimulation may be better for the patient 
with dose-limiting dyskinesia, STN stimulation may be better for the 
younger patient with prominent bradykinesia."


###
(Arch Neurol. 2005; 62:554-560. Available post-embargo at www.archneurol.com.)

Editor's Note: This study was supported in part by a grant from the Public 
Health Service.

Editorial: Will Pallidal Deep Brain Stimulation Make a Triumphant Return?

In an editorial accompanying this study, Michael S. Okun, M.D., and Kelly 
D. Foote, M.D., of the University of Florida, Gainesville, write, 
"Dyskinesia improves dramatically with both GPi and STN DBS [deep brain 
stimulation]. As suggested by the authors of this article and by others, 
the mechanism underlying this improvement may be different for each target. 
The majority of the anti-dyskinetic benefit of GPi DBS may be due to active 
stimulation, and the benefits in STN may be primarily a result of 
medication reduction. … the antidyskinetic effects of GPi DBS seem to be 
greater than those of STN DBS."

"One important and perhaps deciding factor in the rematch between GPi and 
STN DBS will be the incidence of surgical and postoperative complications," 
the authors suggest. "Assuming that the rates of the procedure-related and 
device complications are equal, then long-term cognitive, mood, and 
behavioral problems may lead to a victory of one target over the other."

"The unanswered questions regarding target selection will require several 
more head-to-head rematches between GPi and STN," the authors conclude. 
"Future improvements in implantation technique and in lead design may also 
enhance the benefit in each target. Studies may prove that STN is a better 
target than GPi or that there is no clear winner. Studies may also prove 
that STN is superior for certain features of the disease such as tremor, 
bradykinesia, and medication reduction. Alternatively, studies may show 
that GPi is equal to STN with regard to motor improvements, and is better 
antidyskinesia treatment, but has fewer cognitive, mood, and behavioral 
adverse effects. Whatever the outcome of these rematches, we should be open 
to changes in our current practices and recognize the possibility that we 
should match individual patient needs with the strengths and weaknesses of 
individual targets."

(Arch Neurol. 2005; 62:533-536. Available post-embargo at www.archneurol.com.)



Editor's Note: The original news release can be found here.

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