Neurology Today:
17 November 2016 - Volume 16 - Issue 22 - p
48–49
ARTICLE
IN BRIEF
Patients
with early-stage Parkinson's disease who received deep brain stimulation
continued to have better motor scores five years later than those who only
received medical treatment.
 |
| Dr. Mallory Hacker |
BALTIMORE
— Patients with early-stage Parkinson's disease (PD) who received deep brain
stimulation (DBS) continued to have better motor scores five years later than
those who only received medical treatment, according to new pilot-study data
reported by Vanderbilt University investigators here in October at the annual
meeting of the American Neurological Association.
The
researchers said the evidence supports the need for a larger phase 3 trial of
DBS in patients with very early disease. The FDA has approved such a trial,
planned for 280 patients enrolled across 18 US centers, for which researchers
are now pursuing funding.
Subthalamic
nucleus DBS is already approved for patients with mid- and advanced stage PD,
but its efficacy in early PD is still being investigated. Medical therapy is
better at controlling symptoms in early PD than in later stages. Other
researchers have tried to demonstrate a disease-modifying effect, but no
therapy has been definitively shown to halt or slow the progression of disease.
In
this study, patients were eligible if they had a stable response to
dopaminergic therapy and had been on levodopa or dopamine-agonist therapy for
six months to four years. The average duration for medication use before
enrollment was just over two years
What's
distinct about this population is that these are very early stage Parkinson's
disease patients,” said Mallory Hacker, PhD, assistant professor of neurology
at Vanderbilt. “Patients couldn't have any signs or history of dyskinesias or
motor fluctuations when they enrolled.”
STUDY METHODOLOGY
Thirty
patients were randomized to receive either optimal drug therapy alone or
deep-brain stimulation plus optimal drug therapy. In this study, DBS therapy
was applied to the bilateral subthalamaic nucleus to deliver electrical
stimulation to modify the brain circuits responsible for Parkinson's disease
symptoms.
After
the initial study period of two years, four out of 14 total patients in the
optimal drug therapy group elected to receive DBS. Feedback received during
peer review also led investigators to narrow the inclusion criteria for
medication duration for the future pivotal trial to one to four years.
Patients
who had DBS and optimal drug therapy — who had been on medical therapy for one
to four years — experienced improvements in motor scores on the United
Parkinson's Disease Rating Scale Part III that were an average of 8.9 points
better than the group that only received medical therapy five years after
baseline (p<.03). That represented more than three times the minimal
clinically meaningful change for this measure, researchers noted.
“In
this study, the medication group progressively worsens over five years as you
would expect in early stage Parkinson's,” Dr. Hacker said. “And these results
show that average scores were improved over years for the DBS and optimal drug
therapy group.”
Patients
on medical therapy for six months to four years at the beginning of the study
also showed a trend of greater improvement in motor scores; the DBS and optimal
drug therapy group improved by an average of 4.6 points more than the group on
medical therapy alone — but the difference wasn't statistically significant.
Dr.
Hacker acknowledged the small study size of the pilot trial, but said the
results reinforce the rationale for studying DBS further to determine whether
the DBS should be offered for patients with very early stage PD.
“This
is further evidence to support why a multicenter, pivotal study should be
done,” she said.
David
Charles, MD, FAAN, professor and vice chairman of neurology, chief medical
officer of the Vanderbilt Neuroscience Institute and principal investigator of
the study, said: “Our team's overarching goal is to determine if very early DBS
will dramatically slow the progression of Parkinson's disease. If that were
proven true, it would be a landmark achievement in the battle against this
devastating disease.”
EXPERTS
COMMENT
 |
| Dr. Charles Adler |
Charles
H. Adler, MD, PhD, FAAN, professor of neurology at the Mayo Clinic in Phoenix,
AZ, who conducts research on Parkinson's, said: “This is a very small study so
the results need to be interpreted with great caution. But the fact that there
were statistically significant differences between these groups is promising.”
Commenting
on the abstract, he said he would like to know what medications the patients
were taking, and how many of the patients in each group developed motor
fluctuations or dyskinesias. As this therapy moves to phase 3, there will be
more questions that need to be answered, he said.
“I
would like to know more than just the effect on motor score,” he said. “It will
be important to know how early DBS might affect activities of daily living,
non-motor symptoms, development of motor fluctuations or dyskinesias, overall
medication needs, quality of life, etc.”
http://journals.lww.com/neurotodayonline/Fulltext/2016/11170/News_from_the_American_Neurological_Association.14.aspx
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