Platinum coils make brain aneurysm surgery safer
By Jennifer Lauren Lee
Nov. 3, 2002 9:00 p.m.
Platinum slinkies implanted in your brain may save your
life.
A new study conducted by Oxford University suggests that a less
invasive procedure for treating brain aneurysms may be much safer
than standard surgery.
The procedure, which was invented and first implemented at UCLA,
uses special coils of platinum wire injected into the aneurysm via
the blood vessels to stop blood flow to the aneurysm.
Doctors have been using the coil procedure to treat brain
aneurysms (balloon-like bulges in the wall of a blood vessel) since
it was approved by the Food and Drug Administration in 1995,
according to Dr. Gary Duckwiler, a UCLA professor of radiological
sciences and principal investigator of UCLA’s beginning
clinical trials.
The bulges are dangerous because they can easily rupture,
causing internal bleeding in the brain. However, uncertain about
whether the coil was a safe substitute for surgery, doctors were
using the coils only in the extreme cases where surgery would be
too difficult (such as for the sick or elderly).
Surgery requires that the patient’s skull be opened, so
that the aneurysm may be found and “clipped” shut. But
because of the high risks involved in having this invasive surgery,
many doctors were anxious to use a safer method for treating
aneurysms.
The purpose of the new study was to determine which of these
alternatives was safer and more effective: coiling or clipping?
“Overall, the coiling group did better,” Duckwiler
said.
Of the 2,143 patients involved in the most recent trial, roughly
half were treated with surgery and half with the coil
procedure.
One year later, doctors had the results: Over 30 percent of
those treated with surgery had serious side effects including
death, brain stroke and paralysis, while less than 24 percent of
those who had had the less invasive coil procedure experienced
those consequences.
“(The study) showed that coiling was better than surgery
at reducing the incidence of death and (at increasing the chances
of) better neurological outcome at one year,” said Dr. Reza
Jahan, UCLA assistant professor of radiological sciences and one of
three doctors who participated in the first clinical trials with
Duckwiler.
The other two were Dr. Yuichi Murayama, UCLA adjunct professor
of radiological sciences, and Dr. Fernando Vinuela, UCLA professor
of radiological sciences and co-inventor of the coiling
procedure.
Using X-ray images to guide them, doctors feed a catheter, a
tube less than one millimeter in diameter, through an artery in the
groin, up the aorta, and into the targeted blood vessel in the
brain. Carefully, they guide the tube into the aneurysm itself.
They then manually feed the thin platinum wire into the tube and
watch it reassume its natural coil shape as it emerges from the
other end. When doctors are satisfied with its position, they apply
a weak electric current that causes the coil to detach from the end
of the wire.
“This detachment mechanism gives you tremendous control
over the placement (of the coils) in the aneurysm,” Jahan
said.
“The coils are very soft, so the chance of rupturing an
aneurysm is very low,” Jahan said.
Doctors pack the aneurysm with enough coils (typically four to
seven) to keep blood from flowing back into it. The soft platinum
coils stay there permanently, keeping blood from reopening the
aneurysm until the membrane heals over it.
The coiling procedure not only reduces the chances of brain
damage, but it also reduces the amount of recovery time.
“My recovery was extremely quick and uneventful,”
said Dr. Brenda Sowter, who had the coiling procedure to treat a
brain aneurysm in late August. Just four days after being
discharged from the hospital at UCLA, Sowter could walk the long
distance to the airport gate for her flight back home to
Tennessee.
Despite the success, doctors at UCLA are still working to
improve the coils.
“One of the problems with the old coils that we’re
trying to solve is the fact that old coils allow the reopening of
the aneurysm,” Jahan said.
“The new coils reduce the chances of the aneurysm opening
again,” Jahan said.
The polymer coating of the new coils speeds up the process of
converting jelly-like blood clots into tougher scar tissue,
reducing the risk that blood pumping through the vessel will push
its way back into the aneurysm and begin to feed it anew.
Even though they have been shown to be safer than surgery, the
coils are not for everyone.
“(Sometimes) the anatomy of the aneurysm is not suitable
for coils,” Duckwiler said. “(An aneurysm shaped like)
a lollipop retains the coils well, but (an aneurysm shaped like) a
bowler hat doesn’t retain them well,” he said.
