Home' Technology Review : July August 2008 Contents ESSAY
TECHNOLOGY REVIEW JULY / AUGUST
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 o 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.
I complete the tumor resection (that is, removal), which is
the quickest part of the operation; this particular tumor is eas-
ily "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 di culty.
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 di culties. Sometimes a new nurse or resi-
dent 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 physio-
logical 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 a ect
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 a xing 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 o 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 sim-
ple, 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 encom-
passes such a broad range of operations. Cardiac surgery (in
adults, at least) revolves largely around just two major proce-
dures: bypass surgery and valve surgery. Neurosurgery, in con-
trast, 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, can-
not 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 a icted
with a particular disease? In reality, though, technologic con-
siderations may trump intellectual or emotional ones.
Take Parkinson's disease. Although this disorder is largely
treated with medication by our neurologist colleagues, a select
See the author show off the latest in neurosurgery
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