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Now that we’ve completed the navigation prep work, we can start the operation. Just before heading out to the scrub sink in the hallway, I shave a narrow path of hair along my patient’s scalp, apply the brown Betadine soap, and nod to the anesthesiologist: “Got any good music?”

Before the arrival of user-friendly navigation technology in the 1990s, neurosurgeons often had to shave a large amount of hair, create a generous incision, and remove a relatively large disc of skull, just to be certain that they got the whole tumor. Now that we can pinpoint exactly where a tumor is ahead of time, that’s no longer necessary. My patient’s hair is long, so I anticipate that at the end of the case I will be able to flop it over to conceal the incision. Some patients get radical haircuts just before surgery (and some men decide to shave their heads), assuming that this will facilitate the operation or the healing in some way. But I find it’s actually better to keep the hair long: I believe that looking less like a patient can speed recovery.

When I remove the portion of skull overlying the woman’s small tumor, the brain appears perfectly normal. I expected this. Her tumor is not on the surface of the brain but about a centimeter below. This is where navigation makes a big difference: I know exactly where to enter the brain in order to reach the tumor. As a rule of thumb, we try to violate as little brain tissue as possible. There’s no way to avoid disturbing some of it, but you want to avoid excessive fishing around.

Before navigation came onto the scene, ultrasound was used more routinely for this purpose than it is today. Ultrasound, though, presents problems: a skilled technician (or an actual ultrasound radiologist) must often be in the room to help interpret the grainy images, and ultrasound has trouble pene­trating bone, so it can’t help the surgeon plan the incision or the bone opening. Besides, it’s clunky. Picture the setup used for prenatal ultrasounds, and now picture it being used on an exposed portion of someone’s brain. What’s more, you can’t actually squirt gel on the brain as you would on a woman’s belly, so a nonsterile person in the room applies the nonsterile gel to the ultrasound probe. Then the probe (plus the gel, plus the long cord) is carefully sheathed in a sterile plastic covering. This technophile finds the whole thing quite inelegant. I have actually resorted to using ultrasound a couple of times when the navigation system either broke down or was rendered inaccurate, and those operations felt very retro.

After opening the skull, I enter the cortex of my patient’s left frontal lobe. I dissect through the white matter to a depth of about one centimeter, and I hit tissue that is firmer and darker than white matter. This is clearly the tumor. I take a small piece of it and have it sent off to the pathologist, who looks at the tissue under a microscope and calls in to the OR to confirm my suspicion of a metastasis.

Considering the flashiness of our navigation systems (which have cool trade names like StealthStation and ­BrainLab), the reader might be eager to discover what technology we use to actually remove the tumor. I’m sorry to disappoint, but the answer is a lowly metal suction tube in one hand, paired with a simple cautery device in the other. But that’s modern surgery: part high tech, part seriously low tech.

These old-fashioned but reliable tools come with their own set of headaches, of course, as when the suction tubing gets clogged again and again or the cautery tips become caked with charred tissue and have to be wiped clean over and over, like a toddler’s runny nose. I do have access to an ultrasonic aspirator, if I want it, but it’s not worth bringing in another bulky item for such a small tumor.

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Credits: Steve Moors

Tagged: Biomedicine, imaging, neuroscience, image analysis, neurotechnology, brain surgery

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