The findings expand on previous work done

The findings expand on previous work done
at the University of Michigan, Harvard
University and the City University of New
York where researchers delivered electricity
through sensors on the skulls of chronic
migraine patients, and found a decrease in
the intensity and pain of their headache
attacks. However, the researchers then
couldn't completely explain how or why.
The current findings help ex...plain what
happens in the brain that decreases pain
during the brief sessions of electricity, says
Alexandre DaSilva, assistant professor of
biologic and materials sciences at the U-M
School of Dentistry and director of the
school's Headache & Orofacial Pain Effort
Lab.
In their current study, DaSilva and colleagues
intravenously administered a radiotracer that
reached important brain areas in a patient
with trigeminal neuropathic pain (TNP), a
type of chronic, severe facial pain. They
applied the electrodes and electrically
stimulated the skull right above the motor
cortex of the patient for 20 minutes during a
PET scan (positron emission tomography).
The stimulation is called transcranial direct
current stimulation (tDCS).
The radiotracer was specifically designed to
measure, indirectly, the local brain release of
mu-opioid, a natural substance that alters
pain perception. In order for opiate to
function, it needs to bind to the mu-opioid
receptor (the study assessed levels of this
receptor).
"This is arguably the main resource in the
brain to reduce pain," DaSilva said. "We're
stimulating the release of our (body's) own
resources to provide analgesia. Instead of
giving more pharmaceutical opiates, we are
directly targeting and activating the same
areas in the brain on which they work.
(Therefore), we can increase the power of
this pain-killing effect and even decrease the
use of opiates in general, and consequently
avoid their side effects, including addiction."
Most pharmaceutical opiates, especially
morphine, target the mu-opioid receptors in
the brain, DaSilva says.
The dose of electricity is very small, he says.
Consider that electroconvulsive therapy
(ECT), which is used to treat depression and
other psychiatric conditions, uses amperage
in the brain ranging from 200 to 1600
milliamperes (mA). The tDCS protocol used
in DaSilva's study delivered 2 mA,
considerably lower than ECT.
Just one session immediately improved the
patient's threshold for cold pain by 36
percent, but not the patient's clinical, TNP/
facial pain. This suggests that repetitive
electrical stimulation over several sessions
are required to have a lasting effect on
clinical pain as shown in their previous
migraine study, DaSilva says.
The manuscript appears in the journal
Frontiers in Psychiatry . The group just
completed another study with more subjects,
and the initial results seem to confirm the
findings above, but further analysis is
necessary.
Next, researchers will investigate long-term
effects of electric stimulation on the brain
and find specific targets in the brain that may
be more effective depending on the pain
condition and patients' status. For example,
the frontal areas may be more helpful for
chronic pain patients with depression
symptoms.