Here's a bit more background - from
http://www.sciam.com/0896issue/0896techbus01.html
...which I'll copy to the list so that it will go into the archives:
<<
MEDICAL TECHNOLOGY
MAGNET ON THE BRAIN
Safer neurosurgery
with magnetically steered implants
Children often learn about magnetism by dragging a paper
clip through a paper maze with the aid of a magnet held
below. Researchers now hope that before long they will
accomplish a similar feat in the maze of the human brain
with a refined version of a procedure called stereotaxis. The
technique, being tested by workers at Stereotaxis, a firm in
St. Louis, and at the Washington University School of
Medicine, would allow physicians to reach diseased areas
of the brain with the least possible damage to healthy tissue.
Stereotaxis is the procedure in which surgeons plunge, say,
needles or electrodes straight through the brain to treat a
trouble spot deep within. In the process, they tear healthy
and perhaps essential neural tissue-a risk complicated if
several needles or electrodes need to be inserted, as is
sometimes the case. (For instance, to treat Parkinson's
disease stereotaxically, six drug-delivering needles would be
inserted in different spots to saturate fully the deep-seated
striatum, which contains the defective tissue.) Physicians try
to minimize surgical damage by first reviewing a brain-scan
image and then avoiding the most crucial areas.
The magnetic version of stereotaxis is in principle less
destructive. Surgeons would insert a magnetic pellet the size
of a rice grain into a small hole drilled into the skull of a
patient. The patient's head would then be placed in a
housing the size of a small washing machine, which contains
six superconducting magnets. Using a magnetic resonance
image as a guide, surgeons would then direct the pellet
through the brain by adjusting the forces of the various
magnets. The pellet could tow a catheter, electrode or other
device to minister to the troublesome neural tissue.
With magnetic steering, surgeons can dodge especially
critical neurons. Moreover, they would also be able to
move the pellet around within the entire damaged area. A
patient being treated for Parkinson's would, therefore, have
only one path of neurons damaged, as opposed to six with
the conventional method.
The chief obstacle to applying this technique in the past,
notes Ralph G. Dacey, Jr., of Washington University, who
directs the stereotaxis research team, has been accurately
controlling the magnetic fields. A decade ago, however,
Matthew A. Howard III, then a physics student at the
University of Virginia, realized that the precise instruments
physicists use to measure gravity could be applied to the
control of magnetic fields. That recognition, coupled with
improved computers and brain-imaging devices, enabled
investigators to fashion the magnetic stereotaxis system,
explains Howard, now a neurosurgeon who assists the
researchers in St. Louis from his base at the University of
Iowa.
The team has demonstrated the technique on brains from
dead mammals and one from a live pig, as well as on a
block of gelatin, which has about the same consistency as
the human brain. For the moment, other neurosurgeons
remain cautious about the system's prospects, and
Stereotaxis, which holds the patent on the technique, is the
only company committed to this kind of magnetic
neurosurgery.
Howard says that although the hardware for magnetic
stereotaxis will probably cost more than the conventional
technology, it might nonetheless save money by reducing
operating time by one half to two thirds. The technology
could also be broadened to include use in other parts of the
body, such as the liver or blood vessels.
"The challenge," Dacey remarks, "is to find the best
complementary use of conventional stereotaxic surgery and
specific situations for magnetic stereotaxis." He plans to
apply to the Food and Drug Administration before
summer's end for approval to start tests with the new
method on humans. The first clinical trials, probably for
biopsies, could begin next year. -Philip Yam
>>
At 02:59 PM (?) 12/23/98 , Barb Mallut wrote:
>The following sounds like it'd be a "natural" to make a pallidotomy
>even safer then it already is...
>
>Barb Mallut
>[log in to unmask]
>
>NEW YORK, Dec 22 (Reuters Health) -- Magnets may soon help
>neurosurgeons perform delicate operations on the brain with less risk
>of complications.
>
>At a press conference on Tuesday, neurosurgeons at Washington
>University in St. Louis, Missouri, announced a medical first: on
>December 17th, they used a magnet-tipped flexible catheter to take a
>tissue biopsy from a brain tumor in a 31-year-old man.
>
>The new technique, the result of over a decade of research, allows
>the surgeon to follow a curved pathway to reach targeted areas of the
>brain. This helps in maneuvering around vital brain areas, such as
>those involved in speech or vision, instead of going through them, as
>is the case with rigid surgical instruments.
>
>Describing the magnet-guided technique, Dr. Ralph Dacey told Reuters
>Health that ``you can push a piece of cooked spaghetti, but it's
>better to pull it.''
>
>Before the procedure, surgeons mapped out a predetermined, nonlinear
>pathway for the flexible catheter through the brain. ''We chose sites
>that we wanted to avoid,'' he explained.
>
>The Magnetic Surgery System, a product of St. Louis-based Stereotaxis
>Inc., uses external magnetic fields to direct the magnet-tipped
>catheter the target area in the brain along the route planned by the
>surgeon.
>
>``The objective of the biopsy in this case was to specifically design
>chemotherapy and radiation therapy,'' Dacey said. ``The patient is
>now home and doing well,'' he added.
>
>``We've always used our muscle power'' in neurosurgery, Dacey said.
>``Now we're using magnetic power.''
>
>Dacey plans to perform a total of five surgeries using the Magnetic
>Surgery System in clinical trials before submitting the device for
>Food and Drug Administration approval.
>
I originally posted this URL to the list over two years ago. Note the date
(0896) on the Scientific American article.
Art
________________________________________________________________
Arthur Hirsch {} [log in to unmask] {} Lewisville, TX {} 972-434-2377
(nickname on instant mail, ICQ, and chat programs is cutterson)
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PAN Forum, other photos, and my approach to links:
http://www.fortunecity.com/meltingpot/farley/817/
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