'Black Tar' Liquid Gold When It Comes To Brain Surgeries

'Black Tar' Liquid Gold When It Comes To Brain Surgeries

The following is a transcript of a report by medical editor Marilyn Brooks that first aired March 31, 2008, on WTAE Channel 4 Action News at 5 p.m.

A substance that looks like black tar is proving to be liquid gold when it comes to certain brain surgeries.


Neurosurgeons are using Onyx to prevent ruptures and strokes in abnormal vessels in the brain.

Onyx yields some pretty remarkable results when doctors inject it into the brain to treat arteriovenous malformations or AVMs.

Arteriovenous malformations are a tangled coil of arteries and veins that disrupt blood flow through tiny capillaries. High pressure then develops in veins, so they widen and rupture.

"You're actually born with them as opposed to aneurysms, which may, in part, have a congenital predisposition, but they're formed over time," said Allegheny General Hospital radiologist Dr. Robert Williams.

And because people are born with them, patients don't know they have them until the AVM bleeds or hemorrhages and causes a stroke.

There's different ways to treat AVMs, including radio surgery, open surgery or brain surgery, and there's something else called embolization or Onyx.

If surgeons can get a small catheter into the AVM, they can fill the abnormal vessels with Onyx.

Patients can be injected with Onyx one day and scheduled for follow-up surgery two days later, but that's not always necessary.

"We are more effectively able to reduce the size of the nidus, so the surgeons can remove the AVM or treat with gamma knife," said Williams.

Onyx has chemical properties that clog and shrink the tiny clusters enough to reduce blood loss before or after surgery. In fact, a recent study in the January issue of the American Journal of Neuro-Radiology shows Onyx reduced the size of AVMs an average of 75 percent and cured some all together, making surgery unnecessary.

Onyx is used for other conditions including trauma and certain cancers where bleeding needs to be controlled.

The American Stroke Association estimates 3 million Americans have AVMs and don't know it. For every year an AVM goes untreated, it brings a 4 percent risk of bleeding. So, a patient living 10 years with an AVM has a 40 percent chance it will rupture.

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