Awake Crani I

This is why I love anesthesia and the impetus for the post yesterday.

A 50 year old woman who has been healthy her entire life develops nausea and vomiting, then has a seizure. She is brought to the emergency department where an MRI scan shows a brain tumor involving her right hemisphere. A detailed neurologic exam finds that she is weaker on the left arm with poor coordination. A biopsy of the mass shows glioblastoma multiforme. A dreaded diagnosis, glioblastoma has a prognosis measured in months to years. She is evaluated by the neurosurgeons because debulking the tumor, especially if they can get nearly all of it, can improve her quality and length of life.

But the problem is this: the brain cancer infiltrates the motor strip of her cortex; it's starting to affect her movement, sensation, and coordination. The surgeons want to get as much of the tumor as possible without damaging that precious real estate. If they go a centimeter too far, the patient may be paralyzed as a result of the surgery, and since this is a virtually incurable disease, that's not a risk worth taking.

In many of our complex spine and brain surgeries, we do neuromonitoring; while the patient is asleep under anesthesia, our neurologists can stimulate various nerves and parts of the brain to test the crude function of basic pathways. But this technique is hardly perfect and may only catch gross damage to brain and spinal structures. Instead, the best and perhaps only way to guarantee that a patient does not wake up worse off from brain surgery than she started is to have her awake when they're working on the brain. This way, if the surgeons are near a crucial area, the patient can give immediate feedback about any loss of sensation, function, coordination, or other abilities.

Here's the rub. How do you provide anesthesia for a patient whose skull will be pinned (skull pinning is essential in brain surgery because micromovements while the surgeon is operating can be catastrophic) for hours, whose scalp will be dissected and turned back, whose skull will be drilled, and whose brain will be open to a surgeon with a scalpel? All through this, the patient has to be calm, collected, relaxed, awake, and aware enough to remain still, follow instructions, and communicate; this greatly limits how much pain medication and sedation the patient can receive.