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Shining a (Blue) Light on Brain Tumors

brain_in_blue_by_silvergryphon8Glioblastomas are brain tumors that are difficult to remove completely. They grow tendrils that weave in and out of the structures around them. And those tendrils can be hard to tell apart from normal brain tissue.

For obvious reasons, a surgeon wants to leave a patient’s normal brain tissue intact. But the more tumor the surgeon can safely remove, the better the outcome is likely to be.

Current technology is very good at helping the doctor identify almost all of the tumor. But surgeons—and patients—are eager for even more effective and safer ways to distinguish tumor tissue from normal tissue.

That’s where a special yellow dye called sodium fluorescein comes in. Neurosurgeons at Columbia University Medical Center/New York Presbyterian Hospital and elsewhere have been using the dye during some glioblastoma surgeries. Under blue light, the dye glows the color of a fluorescent green highlighter.

Here’s how it helps: before surgery, a patient receives an intravenous (through the bloodstream) injection of the dye. The bloodstream carries the dye throughout the body…but normal brain tissue will not absorb it.  That’s because normal brain tissue is shielded from the bloodstream by a “filter” called the blood-brain barrier.

But glioblastomas disrupt the blood-brain barrier, so they do absorb the dye.

To make the dye in the glioblastoma cells show up, the surgeon fits a fluorescein- specific light filter onto the operating microscope before surgery. With this blue filter in place, all it takes is a simple flip-of-a-switch to turn it on or off. When the filter snaps into place, everything in the microscope’s viewfinder looks darkish blue. Everything but the tumor, that is. It glows highlighter-green.

Fluorescein dye glows green under blue light
Fluorescein dye, here dropped into water, glows green under blue light.

A surgeon removing a glioblastoma may perform much of the operation under regular white light. Then, when most of the tumor is gone, the surgeon may flip the switch for the blue filter. The remaining tumor will glow green and so will any other glioblastoma tissue “hiding” in the surrounding brain tissue. At any time, the surgeon can flip the switch back, illuminating the surgical field with regular white light once again.

Sodium fluorescein is traditionally used in eye procedures. Its use in glioblastoma surgery is a more recent innovation, but the Columbia neurosurgeons who use it have seen it benefit hundreds of patients already.

Recently, Dr. Jeffrey Bruce, Dr. Michael SistiDr. Guy McKhann, and Dr. Sameer Sheth shared the results of their research into the use of sodium fluorescein in glioblastoma surgery.

Their research has found that this use of the dye is both helpful and safe. Their methods and conclusions were presented in a poster at the meeting of the American Association of Neurological Surgeons. (See below for a full list of authors of that poster.) Read an overview of the study, or even take a look at the poster, on its AANS page here.

Learn more about Dr. Bruce on his bio page here.

Learn more about Dr. Sisti on his bio page here.

Learn more about Dr. McKhann on his bio page here.

Learn more about Dr. Sheth on his bio page here.

* Full list of authors: Justin Anthony Neira; Timothy Ung, BA; Randy D’Amico, MD; Jennifer Sims, PhD; Hani Malone, MD; Daniel Chow, MD; Jorge Samanamud;  Dr. Sameer Sheth, MD, PhD; Guy McKhann II, MD; Michael Sisti, MD; Peter Canoll, MD, PhD; Jeffrey Bruce, MD

Image credits

Brain in Blue: SilverGryphon8/[DeviantArt]

Fluorescein: Bricksnite/[Wikipedia]

patient journey

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