MEDICAL DEVICE INNOVATION - Medical Device Daily

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New neurostimulation helps with
treatment-resistant depression
By LYNN YOFFEE
Medical Device Daily Staff Writer
A neurosurgeon at the Medical University of South
Carolina (Charleston) has reported positive results with a
new neurosurgical procedure for treatment-resistant
depression. A small study – just five patients – found that
bilateral epidural prefrontal cortical stimulation (EpCS) was
generally safe and provided significant improvement of
depressive symptoms.
Seven months after implantation, patients experienced
an average 54.9% improvement based on the Hamilton
Rating Scare for Depression and 60.1% on the Inventory of
Depressive Symptoms Self Report. Three patients reached
remission and one had a minor complication that required
removal of the implants.
“I came up with the idea because I’ve been researching
brain stimulation for over a decade,” Ziad Nahas, MD, director
of the Mood Disorders Program at MUSC and medical
director of the Brain Stimulation Laboratory, told Medical
Device Daily. “We focused on these two regions because
they are part of a larger brain network critical in regulating
mood. Both play complementary roles integrating emotional
and cognitive experiences and offer a distinct opportunity
for targeted antidepressant treatments.”
In a study published in Biological Psychology, Nahas
and his team reported that five patients were implanted
with EpCS over the anterior frontal poles and the lateral
prefrontal cortex bilaterally. Four separate paddle leads
were then connected to two small generators surgically
implanted in the upper chest area of the patient. They then
individualized the treatment parameters for each patient to
maximize the long-term antidepressant effects. They relied
in part on input from the patients who signaled positive
mood changes when first stimulated in the operating room.
“In the OR, we tested for the first time the stimulation
and showed that in the small group of patients, we had significant
immediate changes in terms of reducing anxiety
and sadness,” Nahas said. “A couple of patients voiced an
immediate feeling of increased attention and clarity. One
patient had no reaction in the OR at all. But it was exciting
as well as surprising that we could change emotions right
there in the OR.”
Only the sickest patients were included in this study,
those who failed to respond to several antidepressant
treatments, including medications, psychotherapy, transcranial
magnetic stimulation, vagus nerve stimulation or
electroconvulsive therapy.
Medtronic (Minneapolis) donated its SynergyPlus+ neurostimulation
system for the experiments, although the
company is taking no part in this study or Nahas’ research.
The devices were set to periodically deliver electrical
MEDICAL DEVICE INNOVATION 2010
charges at intensities below the seizure threshold and they
were never active at night.
One of the unique aspects of this application of cortical
stimulation is that Nahas and team are using the stimulation
intermittently and repeatedly, rather than continuously.
“The idea with this is that we would implant electrodes
over areas involved in mood regulation and stimulate
intermittently so we could, over time, improve depressive
symptoms,” he said. “By using repeated and intermittent
stimulation, we could try to push the brain to adapt and
change its function to have a better role at sustaining
response. So one of the most critical elements in what we
did, aside form the site targets, was that we also chose to
go in not in a continuous mode of stimulation, but to got
with intermittent cycles to not only bank on the immediate
effect, but to help the brain choose to adapt to . . . a new
homeostasis.”
Nahas said this therapy is probably safer than deep
brain stimulation because electrodes aren’t inserted deep
into brain tissue, which avoids any potential for brain damage.
Although the current study reports on seven-month
data, Nahas has been following the patients for 1.5 years. He
said that three out of the five patients had a recurrence of
symptoms, but “It was fairly different from previous
episodes. Their recurrence was short lived, whereas prior
to having the implanted device, their average depressive
episode lasted two-plus years.”
He will continue to follow the patients indefinitely as
he now seeks grant money to scale up for a larger trial.
The average battery life for the SynergyPlus+ runs
between one and four years, depending on usage. Nahas
said he’ll advocate for replacement batteries down the road
as needed, assuming these participants continue to reap
benefits and remain depression free.
(This story originally appeared in the Oct. 16, 2009 edition
of Medical Device Daily.)
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