July/August 2008

A Messy Art

Continued from page 4

By Katrina S. Firlik

I complete the tumor resection (that is, removal), which is the quickest part of the operation; this particular tumor is easily "suckable," in the surgeon's vernacular. Also, with metastatic tumors such as this, the margins are relatively distinct; you can usually tell tumor apart from brain without too much difficulty. With primary brain tumors (gliomas, which arise from the brain itself), the tumor-brain interface can be very indistinct, and this is where navigation has yet an additional benefit. It can be used during the resection, to assess how deep you are within the tumor and how much work still remains to be done.

But though navigation can be a big help in tumor resection, it's not without its difficulties. Sometimes a new nurse or resident forgets that the camera needs an unbroken sight line to the wand and keeps sticking a head or an arm in the way, or a small spot of blood on one of the wand's shiny metal balls temporarily prevents the system from working. And those technological woes are nothing compared with the physio­logical problem of brain shift. Once the skull is opened, its contents can move a little: sometimes cerebrospinal fluid leaks out, causing the brain to sink downward; other times, the swollen brain bulges outward; and as more tumor tissue is removed, the surrounding brain can partially collapse into the cavity. Whatever the reason, the result is that after all the care we took in registration, the MRI images no longer match up with the patient's brain. This may not significantly affect the operation, but in some cases it's such a serious challenge that the surgeon must abandon the navigation technology altogether and rely on her own judgment.

Following the tumor resection, I spend the next several minutes making sure there's no ongoing bleeding. Then I close, which requires replacing the bone flap by affixing it to the skull with thin titanium plates and screws. Placing tiny screws into the skull presents its own set of problems--admittedly minor, but disproportionately annoying at the end of the operation. Sometimes a screw fails to gain adequate purchase in the bone and continues to spin freely with each twist of the wrist; or it falls off the diminutive screwdriver and gets lost in the folds of the sterile drapes; or it breaks through a very thin portion of the skull, threatening to irritate the tissue underneath. At this point, though, any expletives uttered by the surgeon are drowned out. With the more delicate parts of the operation behind us, "closing music" plays at high volume.

The two final steps of the operation--sewing the scalp closed and placing the surgical dressing--are refreshingly simple, low tech, and fiddle free. I remove my patient's head from the clamp, watch her wake up, and turn down the music.

New and Improved
Neurosurgery is an unusual specialty, in part because it encompasses such a broad range of operations. Cardiac surgery (in adults, at least) revolves largely around just two major procedures: bypass surgery and valve surgery. Neurosurgery, in contrast, covers operations on the brain, spine, peripheral nerves, and carotid arteries. And particularly within the categories of brain and spine operations, there are dozens of variations. Any one neurosurgeon, although he or she may have been trained to perform the entire spectrum of procedures, cannot actually do so in practice. So how do we neurosurgeons decide which cases to include or exclude? How do we decide which particular disorders to treat?

One big factor in the decision is the technology used to treat a given disorder. That may sound a bit backwards. Wouldn't a physician's decision about which cases to treat be based on more profound factors, like a passion to help those afflicted with a particular disease? In reality, though, technologic considerations may trump intellectual or emotional ones.