Unending pain meets electric brainstorm
News Desk
UNNATI GANDHI
>From Wednesday's Globe and Mail
Jen Dafoe pinpoints the moment she collapsed in the coffee aisle of a
grocery store a year ago as the lowest in her life -- as an
excruciating pain ran up the left side of her face.
"I was on the floor rocking my head in my hands and people were walking
by looking at me," recalls the 41-year-old who suffers from a rare
disorder that, for two years, felt like her jaw was "rotting" in her
face. The pain prevented her from venturing too far from her room in
Brights Grove, Ont.
"I couldn't even go to the store to buy a loaf of bread. My life
revolved around dealing with the pain, minute by minute."
After undergoing 21 different reconstructive and jaw surgeries, "taking
every medication under the sun," attending a pain clinic and even
trying physiotherapy, Ms. Dafoe was presented with the option of going
under the knife once more.
But this time, it would involve drilling a hole into her skull and
implanting a five-centimetre-wide electrode strip on the brain's
protective dura membrane. The idea is to send electrical signals
through the dura to the motor cortex -- the region of the brain that
controls movement in the face and other parts of the body and processes
sensory input from nerves in those areas. A wire connected to the
electrode strip would run under her skin and be attached to a
battery-powered, programmable device about the size of a pager that
would sit just below the collarbone. The device would send tiny,
imperceptible shocks to the motor cortex, stimulating it and
intercepting the pain signal coming from the nerves on the left side of
her face.
After the surgery and a two-week trial run last November, Ms. Dafoe
walked out of the London Health Sciences Centre pain free.
"The minute it was on, there was instant relief," she recalled.
The surgery is similar to a process called deep brain stimulation that
has been used to treat patients with Parkinson's disease and
depression, but instead of implanting electrodes deep inside the brain,
it sits on the outside. It is part of a growing trend to treat
neurological disorders with electricity that don't respond to
traditional treatments.
A handful of neurosurgeons across Canada are launching the country's
first clinical study on the procedure. Doctors have seen it reduce pain
in about half the patients, such as Ms. Dafoe, for whom nothing else
had worked.
"We're a relatively unique group of neurosurgeons here in Canada, we
meet on a regular basis, and we're more amenable to a large study of
this kind, the type you don't see carried out in the U.S.," said Andrew
Parrent, the neurosurgeon in London, Ont., who performed Ms. Dafoe's
latest operation, and who is leading the clinical study. (Smaller U.S.
studies tend to involve just the patients of one physician.)
The study is aimed at determining who is best suited for motor cortex
stimulation and how well it works. Doctors are in the process of
recruiting patients with post-stroke pain, neuropathic pain and neural
pain in the upper body.
"Because we have so few treatment options for these types of pain, this
study, if it shows that it's beneficial, will be able to increase
awareness among pain-treating physicians," Dr. Parrent said.
Fewer than two dozen patients in Canada have received this treatment in
the past two years.
As for Ms. Dafoe, she has started working again and is hoping to pursue
a master's degree.***
Zap goes the agony
Surgeons are now using implanted electrical devices to treat chronic
pain patients who don't respond to conventional treatments.
An electrode is surgically implanted on the dura, a protective membrane
covering the brain. A thin wire, running under the skin, connects the
electrode to a battery-powered "neurostimulator" implanted near the
collarbone.
The electrode emits an electrical signal which passes through the dura
to the motor cortex, the region of the brain governing movement and
sensations. The stimulation of the motor cortex also seems to have an
effect on deeper areas of the brain. For reasons which are not fully
understood, the electrical activity seems to dampen the sensation of
pain.
SOURCE: STANFORD UNIVERSITY MEDICAL CENTER