Another Day in the Frontal Lobe (8 page)

Eventually, he woke up in a confused and somewhat stuporous state. We tried to convey to his family that we were actually pleased with his outcome so far. Recovery takes time. We reminded them how close to death he had been when he first hit the ER. We reminded them that survival was the first goal, and that that was achieved. He should continue to improve. He went off to rehabilitation.

I saw him in the clinic a few months later and he was back to being a walking and talking eighteen-year-old (a “walkie-talkie” as we like to call patients with this level of functioning). Young brains bounce back well. He wasn’t normal, though, and still had significant memory deficits. His mother shook my hand and turned to her son: “Remember this nice doctor? She operated on you.” He didn’t remember, of course. He had no idea who I was. His memory deficit didn’t seem to faze him, though. His main concern was whether or not we would allow him to go on roller coasters. He delivered the question in an apathetic monotone drone. (Was that the teenager in him or the head injury? Hard to tell.) Still, I was encouraged. He should look great in another six months or so.

I examined him with my attending, the trauma guru. He pointed out that the incision had healed nicely but that next time, I shouldn’t take it quite so low along the front of the ear. I made a mental note and acknowledged to myself that I was still a peon in this lengthy training process. Then, glancing into the patient’s equal pupils, I told him to always wear his seat belt.

As an aside, trauma patients like this are great examples of the enigma of consciousness. After a severe head injury, severe enough to cause coma (a prolonged absence of awareness), the recovery process eventually reaches a fork in the road. A patient will emerge from the coma—which is a temporary state—to either regain consciousness or enter a persistent vegetative state. In other words, he may wake up or he may not.
¹

The term “wake up” may be confusing, though, as a person in a persistent vegetative state actually has sleep/wake cycles, with eyes open during the wake cycle (this is part of what distinguishes it from coma). The patient is not truly “awake,” as in aware. The opened eyes, sometimes wandering, can be misleading and mistaken for conscious interaction, as they were in the famous Terry Schiavo case, where the parents battled the husband over the feeding tube, claiming it should remain in place. It was pulled, and on autopsy of the brain, she was found to have no anatomical capacity for vision.

In the case of a head injury victim, we may round in the ICU at six a.m. and find that the patient responds, at best, in only a reflexive manner to various stimuli. Then, upon rounding again at six p.m., we may be delighted to find that he has crossed over the threshold into a conscious state, opening his eyes and showing us two fingers when we ask. What happened to his brain over those intervening twelve hours? The short answer is: no one really knows.

The serious scientific study of consciousness has been in vogue only relatively recently. It was previously considered too messy a topic, better suited to philosophers and theologians than to scientists. Now, the search for the “neural correlates of consciousness” is on. How does the physical substrate of the brain—individual neurons, chemical interactions, large-scale neural networks, the brain as a whole—produce awareness, self-reflexive thought, the appreciation of existence? There is no shortage of debate. Some scientists believe that consciousness is a sort of “emergent” property of the entire brain’s functioning, not specifically a physical phenomenon, but more an elusive property that cannot be pinpointed or studied directly.

Dr. Francis Crick, of the famous Watson and Crick who discovered DNA in the early 1950s, strongly disagreed. He spent the last several years of his life in a quest to answer just that question, before his death in 2004. In his work with Dr. Christof Koch of the California Institute of Technology, he came to the conclusion that consciousness is most likely mediated by relatively few specific neurons (maybe thousands, rather than millions or billions) at any given time.
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  He even speculated that a thin ribbon of brain tissue, known as the claustrum, located on both sides of the brain near the inner aspect of the temporal lobes, may play a major role.
³
 

On a related note, Koch wonders whether a newborn baby is truly conscious from day one.
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  Although this question may remain permanently in the philosophical realm, it’s ripe for quirky dinner conversation with open-minded friends, if not for scientific study. I could see how consciousness might arise over time as the brain develops during the ensuing days, weeks, or months and forms critical connections not yet present at birth, similar—in a tangential way—to how the brain of a comatose patient flips on, mysteriously, after an incubation period.

Although neurosurgeons witness this mysterious flip of the switch in their own patients, only a rare few have been directly involved in consciousness research per se, and articles about consciousness are rare in the neurosurgery journals. One exception is an article written by the aforementioned Dr. Crick, published in the journal
Neurosurgery
after he was invited to give a lecture at one of our national meetings. The last paragraph reads:

“Consciousness remains one of the major unsolved scientific problems of this new century. The solution of it may well change our whole view of ourselves. We hope very much that neurosurgeons, with their privileged access to the human brain, will join in the search for the (neural correlates of consciousness) in one way or another.”
⁵

I can speculate as to why so few neurosurgeons have broached the subject in depth. Although the mystery of consciousness is a fascinating one, maybe even
the
most fascinating, the more practical concerns tend to be most pressing, like the patient who is rolling through the ER doors, or having a seizure in the ICU, or bleeding on the OR table.

Another punctuation in my evolution as a junior neurosurgery resident involved being stuck in the OR, by myself, in the face of profuse and ongoing bleeding. This one requires a brief anatomy lesson. Some of the most high-volume bleeding that can be encountered in brain surgery arises from what are called the dural sinuses. For that reason, we try to stay out of them whenever possible. These sinuses are distinct from the better-known sinuses underneath the face that can cause headaches or sinusitis. Those sinuses are totally different. They are filled with air. (We try to stay out of those during surgery, too, but for a different reason: infection.) The sinuses that I’m talking about are filled with blood. This blood is of the darker venous variety as opposed to the brighter, more highly oxygenated arterial variety, because the dural sinuses are charged with the task of draining used blood from the brain.

There is a complex network of sinuses, and they all come together at the base of the skull, ultimately draining into the jugular vein. Most people have heard of the “jugular,” and the word usually conjures up images of cheetahs stalking gazelles and “going for the jugular.” (In an effort to stamp out multisyllabic words, or maybe just to be cute, surgeons sometimes refer to the vein simply as the “jug.”)

I was at a dinner party recently and introduced myself to another guest. When he learned that I was a neurosurgeon, his curiosity perked up, not because he had any particular interest in neurosurgery, but because he knew I would be qualified to settle a bet he had made with a friend. He had seen the movie
Hannibal,
in which Anthony Hopkins plays the highly disturbed and cunning lead character. Near the end of the movie, Hannibal stages an elaborate and grotesque dinner party in which he plans to feed a guest pieces of his own brain (the guest’s brain, that is). In order to do so, he drugs the guy, uses a large electrical autopsy saw to remove the top of his skull (presumably in one large piece), covers his exposed brain with a baseball cap, and sits him down at the head of the table, still groggy from the sedatives. I was a bit embarrassed to say that I had seen the movie, too, so I was able to recall the entire scene, in detail.

The bet centered around the technicalities of skull removal. Was it really possible to remove such a large area of skull without having the guy bleed to death? After all, the procedure was performed in a kitchen, without proper equipment, and with no assistant. I thought the debate was fairly sophisticated as it seemed to presume an understanding of the dural sinuses and the pitfalls of working around them.

My answer was that it would have been nearly impossible to remove the top of the skull in a living being using only such a crude saw. The largest sinus, called the superior sagittal sinus, runs like a racing stripe along the middle of the head, from the forehead all the way to the back. It lies just underneath the skull, encased by the dura and embedded between the two halves of the brain. It is usually partially stuck to the inner skull surface. During surgery, if we have to cross over the sinus in removing a portion of skull, we are very careful about freeing it up from the underside, or else it is easily torn open upon lifting off the bone.

If the sinus is torn, the bleeding can be difficult to stop. The sinus cannot simply be tied off as might be done with a vein of lesser importance. (Disrupting normal flow through this sinus can cause a large stroke known as a venous infarct.) Holding firm pressure, another common surgical technique used elsewhere in the body, is also problematic. First of all, you can’t really hold firm pressure against the soft brain. Second, you wouldn’t want to hold pressure too firmly because the sinus could clot off, which, as I just mentioned, could cause a stroke. Suffice it to say that the Hannibal maneuver would have been neurologically devastating, or fatal, for the dinner guest.

I smiled at my new acquaintance and concluded that Hollywood used artistic license in that scene. Smiling and self-satisfied, he presumably looked forward to a payout and an “I told you so.”

Although we try our best to stay out of the dural sinuses, we are not always perfect. A particular procedure that I performed countless times during my training requires creating an opening in the skull just behind the ear. The residents, especially the junior residents, were sometimes referred to as “can openers” because we had to open and close the cases by ourselves, over and over again in almost an assembly-line fashion. After completing the opening, we would call the attending neurosurgeon in for the critical (and most enjoyable) part of the procedure. Often, three cases would be going on simultaneously in three different ORs, with the attending flitting from one room to the next as cans were opened and closed.

The tricky part of the bone work is this: The landmark for the opening is at the junction of two sinuses that come together just behind the ear, the transverse and the sigmoid sinuses. If you don’t come right up to this corner, the exposure is inadequate and you will feel like a fool when the attending walks in and realizes that he can’t see what he needs to see. Often, a sinus can be recognized by the bluish appearance of the overlying dura or the presence of a small vein entering into it. These rules of thumb, though, are not always consistent or reliable. So, if you’re working away at the bone, little by little, and don’t recognize that the sinus is just underneath, you could be in for a surprise if you create a nick in the dura with a bone spicule or an instrument. This is quite easy to do, especially in a patient with “old lady dura,” which tends to be flimsier than most, and also more adherent to the bone.

I had seen minor holes in a sinus before and was surprised at the volume of blood that could escape. With two pairs of hands working at it, though, the bleeding can be stopped with gentle pressure, a special foam material, and patience. If the bleeding is profuse, we may have the anesthesiologist elevate the head of the bed to decrease the overall pressure on the system (this deceptively simple maneuver can actually help).

So there I was as a junior “can opener” alone in the room. After making the small scalp incision behind the ear, I chose the best area to touch down on the skull with the perforator drill. The drill stopped, as it should, upon completing its full thickness excursion. As I pulled the drill out, though, I was met with a torrent of blood that filled the operative field, started to spill over onto the sterile drapes, and just kept coming. Without a doubt, the drill had torn open the sinus, and the hole wasn’t small.