July/August 2008

A Messy Art

Continued from page 1

By Katrina S. Firlik

All systems go: Firlik and the tools of her trade in Operating Room 2, Greenwich Hospital, Greenwich, CT Credit: Steve Moors

Most brain trauma cases don't require the navigation technology, for three reasons. First of all, if the case is urgent, we don't have time to set up the equipment and do the necessary scanning. Second, what we're after is usually large and can't be missed, like a big blood clot. Third, in trauma cases we're less concerned about the niceties that navigation helps us provide, such as a minimal hair shave and a minimal incision.

A small tumor, on the other hand, is a perfect situation for navigation. I'll walk you through a sample case, altering (in the interest of patient privacy) a few unimportant details.

The patient is a 62-year-old woman who has had a seizure, the first of her life. Upon visiting the hospital, she undergoes a brain MRI, which picks up a round, two-centimeter tumor in her left frontal lobe. She has been a smoker since age 20. She has no previous history of cancer.

In a long-term smoker, a small, round tumor in the brain certainly doesn't look good, but we always hedge our bets: "We won't know what it is for sure until we actually get a piece of it." In our line of work, it's not unusual to see a diagnosis of lung cancer made only after the disease has metastasized to the brain. The parent tumor may have lurked silently within the lung for years.

The decision for surgery is made by the patient, her oncologist, and me. Such decisions take many variables into account, but suffice it to say that medicine is often equal parts science and art. As is often the case in neurosurgery, the best treatment is not entirely obvious. Something has to be done, but that something doesn't necessarily need to be surgery: the patient could choose the noninvasive option of stereotactic radiosurgery, a focused form of radiation that can control or shrink (but not necessarily get rid of) a tumor in the brain. This woman's oncologist, however, strongly favors surgery. So now the patient is about to go under the knife. I spend plenty of time with her and her family, preparing them for the experience.

Just before surgery, my patient is required to undergo a second MRI ("You want me to get another one of those?" she asks me), this time with several fiducial markers (small, round foam stickers with holes in their centers) applied to her head to serve as reference points. This particular MRI is sliced even finer than her original one, and the images will be downloaded into our navigation equipment. We're aiming for millimeter-scale accuracy.

Next, in the operating room, while waiting for the patient to be put under general anesthesia and "lined up" (fitted with various catheters, or lines), I speak with the circulating OR nurse and my physician assistant about the navigation setup. (Given that we'll use a lot of bulky equipment, we give thanks if we're in one of the larger operating rooms.) Where will the head of the bed be? Did the disc with the patient's MRI actually make it up from radiology? Where do we position the monitor? What about the camera that tracks the location of the pointer probe? We don't want to move any major navigation equipment to the other side of the room once everything is already plugged in; that, we worry, could trigger a full-scale meltdown. In reality, though, I believe the occasional meltdown occurs randomly, just because the system is so complex.