Deep Brain Stimulation
Provides Treatment Options for Parkinson's Disease
May / June 2002
Deep Brain Stimulation (DBS) of the subthalamic nucleus (STN),
a neurological procedure approved by the FDA in January 2002
for treating Parkinson's disease (PD), is available at just
a few centers in the United States, including the Penn
Neurological Institute.
DBS is based on the principle that electronic stimulation
of particular regions of the brain can ameliorate the major
symptoms of PD, including tremor, slowness, rigidity and
walking problems. The procedure involves guiding electrodes
deep inside the brain to the tiny STN, a structure only
about six mm to eight mm in size.
Electrophysiologic mapping,
done in the operating room under stereotactic guidance,
provides more precise localization. When the electrode is
in place, the STN is stimulated and the surgical team observes
the effect on the patient, who is awake during the operation.
A second electrode is placed on the right side of the brain
and a battery-powered pacemaker-like device is implanted
under each collarbone.
"This is the biggest advancement in the treatment of
Parkinson's disease in 40 years," says Gordon
Baltuch, MD, PhD, a Penn neurosurgeon who has performed
DBS on more than 60 patients.
DBS has many advantages. Stimulators can be turned on and
off and individually programmed and adjusted depending on
the patient's requirements. In addition, DBS is reversible
and does not damage the brain. If a cure for PD is developed,
the electrodes can simply be removed. And although it is still
brain surgery, the complication and morbidity rate is very
low-about two percent.
For patients, DBS can bring about monumental life changes
such as living independently, going back to work, driving,
playing tennis or even eating at a restaurant. "The clinical
effects are spectacular. Besides taking about half of the
medication that was necessary before the DBS, most have a
remarkable decrease in tremors and rigidity, improvement in
walking, and less dyskinesia, a common side effect of the
medications," says Dr. Baltuch. Some patients have discontinued
the need for medications entirely.
Although not a cure for PD, the positive results of the surgery
seem to be lasting for many patients. "We now have patients
who had the surgery three-and-a-half years ago and they still
have relief from or a considerable decrease in the symptoms
of Parkinson's disease," adds Dr. Baltuch. "If not
for the DBS, many of these patients would now be in nursing
homes."
PD affects one percent of the American population over age
60 including approximately 2,000 to 3,000 people in the Delaware
Valley. Over time, patients tend to have a fluctuating response
to the medications, which may leave patients with severe tremors
and walking difficulties. In most cases, the surgery eliminates
these down periods.
"DBS is a great addition to our menu of treatment options,
but one big question remains: does DBS fundamentally change
or even halt the course of the illness or is it simply just
another symptomatic therapy that will eventually lose its
potency?" says neurologist Howard
I. Hurtig, MD, who along with Matthew
B. Stern, MD, directs the Parkinson's Disease and Movement
Disorders Center at Pennsylvania Hospital. "If it does
slow the progression of this disease, then it is likely that
we will be recommending DBS much earlier, even before patients
encounter problems."
Relatively young patients who experience fluctuations are
the best candidates for DBS, and in most cases, the surgery
eliminates or greatly reduces the frequency of the "off"
periods and dyskinesia. "It is important to select the
right patients for DBS. Only 10 to 20 percent of people with
PD are candidates for the operation. Unfortunately, the disease
affects many others who are old, in poor health and no longer
respond to medications," says Dr. Hurtig.
Penn Neurological Institute is a training center for neurosurgeons
throughout the world. "There is a real shortage of
neurosurgeons who know how to perform this procedure and
there are many
people with PD who could benefit greatly," adds Dr.
Baltuch.
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