05/20/14

The Exposed Brain

 

BrainExposedLogo

The Exposed Brain
by Edison McDaniels, MD

This is a picture of a craniotomy, one of the most ancient of all surgical procedures.

Man has been trephining the skull, that is opening a hole through the skull, for thousands of years. The purpose of those early operations is not readily apparent, though there are numerous examples of those skulls which show the patient (victim?) survived. Many more most have died during the attempt or in its aftermath.

Modern day brain surgery dates only from the early 1900s, with a few surgeries having been accomplished ten or so years before that. Many of those early patients, if not most, died as well. The road to the modern craniotomy is paved with broken skulls and enough spilled blood and spinal fluid to fill more than one olympic sized swimming pool. Perhaps many more.

Modern brain surgery, although still risky, is a remarkable undertaking. Advances in neuroimaging (see my article “A Game of Shadows” at www.surgeonwriter.com) and anesthesia have made brain surgery very safe today. Death in surgery is a very rare thing, and most patients survive with little or no deficits. There are virtually no parts of the extra-axial space, the complicated 3-D anatomic space surrounding the brain, into which a neurosurgeon’s knife cannot venture. There are areas of the brain itself which still elude our reach, but only in the most extreme circumstances, such as intrinsic tumors of the brainstem. Today, neurosurgeons routinely remove blood clots, clip aneurysms which would have killed even 20-30 years ago, excise once inoperable tumors, and selectively obliterate brain tissue to cure such ills as Parkinson’s disease and obsessive-compulsive disorder. Other neuro specialists, including therapuetic radiologists and interventional neuroradiologists, treat with radiation and endovascular therapies what were once dreaded operative diseases, such as vascular malformations, many aneurysms, and certain tumors.

What does a modern day brain surgery look like? Through the magic of photography, let us glimpse one moment in the exposure of the living, pulsating human brain.

 

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The picture is of an exposed living brain. It’s a still photo, so one needs to imagine the brain actually pulsating with the rhythms of life, both the beating heart at perhaps eighty beats per minute, and the breathing, which in the operating room is controlled at a rate sixteen to twenty breaths per minute. These rhythms are very noticeable to the surgeon, and the surgeon learns to time his activity to them in a more or less subconsious fashion.

Blood tends to pool constantly during brain surgery, along the dependent areas of the exposure. You can see this in the lower left portion of the image. Note also the bloody sponges, which have slowly taken up the oozing blood. Along the border of the sponges are skin clips. These clips attach to the edge of the skin along the line of the incision and have only one purpose: to stop the otherwise copious bleeding from the scalp blood vessels. The scalp is quite vascular and it is very possible to bleed to death from an otherwise simple scalp laceration (as did the actor William Holden, who bled to death in his hotel room after stumbling and striking his head on the corner of his nightstand).

Accumulating blood is removed with a sucker. The sucker is a hollow tube, a straw actually, attached to a suction device. It provides a constant low level of suction that can be used to remove accumulating debris from the operative field. This debris includes not only accumulating blood, but also spinal fluid, bone dust (from drilling the skull), brain itself (sometimes, one will have to remove good brain in making a path to a tumor or other target; surgeons refer to this as ‘taking brain’), and tumor. The sucker is finely controlled by the surgeon using his nondominant hand, and comes in various shapes and configurations. One becomes very adept at its use, as a wrong swipe here or there can be quite costly.

The surgeon’s dominant hand might hold any number of devices. In this picture, it holds the yellow bipolar forceps. This is a cauterizing device. By pressing a foot pedal, the surgeon can send a gentle pulse of electricity between the tips of the bipolar. This brief pulse cauterizes whatever is between the tips of the bipolar. In the picture, the bipolar is cauterizing the edge of the dura mater. The dura mater, latin for tough mother, is a leathery membrane that encases the entire central nervous system (brain and spinal cord) in a protective envelope. Anatomically, it rests just under the bone of the skull, tending to adhere to the inner aspect of the skull in the aged. Sometimes, especially after a blow to the head which fractures the skull, bleeding can occur in the potential space between the skull and the dura (a potential space is one that normally does not exist and only arises under duress—not good). This accumulating blood is called an epidural hematoma and can be life-threatening. It’s what killed the actress Natahsa Richardson after she fell and suffered a ‘minor’ head injury on a ski slope. A craniotomy almost certainly would have saved her, though apparently the severity of the injury was not recognized. When it is, the only reasonable course in many cases is a craniotomy. Fortunately, the prognosis is excellent in most cases—if the surgery is timely.

The dura mater is perhaps a few millimeters thick and can be quite vascular. Here, the bipolar is cauterizing a bleeding point on the edge of the dura. The sucker is clearing the field of the blood so the surgeon can see what he is doing and so the bipolar can work properly. Note also that the dura mater is thick enough to hold stitches. It is often tacked up to the bone during the surgery (B in the images). The tack-ups help prevent oozing of blood from the epidural space. At the conclusion of the surgery, the dura mater will be closed with a row of closely approxiamated stitches. It will also be tacked up to the over lying bone flap, so as to prevent any accumulation of blood under the bone and above the dura. Such bleeding, an iatrogenic epidural hematoma, would necessitate a return to the operating room and reopening of the craniotomy to evacuate the accumulated blood. This is one of many potential complications of a craniotomy. It is one of the chief things neurosurgeons watch for in the first hours after a cranitomy.

Note the cut edge of the skull in our image. A large circular piece of skull has been removed to gain the exposure shown. The removal of the bone is the actual craniotomy. Drilling the skull is one of the more dramatic moments in any craniotomy, especially to the uninitiated. How is it done?

A Civil War era trephine for opening the skull.

A Civil War era trephine for opening the skull.

Drilling the skull is surprisingly easy. In the old days a trephine was used. This is a T-shaped handheld instrument with a circular base of sharp teeth. When pressed to the skull, the user presses his weight down on the T-shaped handle and simultaneously turns it, like a cookie cutter. Nowadays, at least in the United States, such a trephine is rarely used.

Another way to open the skull is with a pneumatic drill. These drills have a failsafe that causes them to stop when the bone is drilled through. The surgeon drills several holes spaced at intervals around the desired exposure area, then simply connects the dots with a saw. Today the saw is often pneumatic itself. However, another very good option is to pass a thin wire under the bone between the holes and saw through the bone with a to and fro action. This is called a gigly saw and has been used for decades. It carries the advantage of removing very little bone along its path, which makes for a better fit when the bone is replaced.

Replacing the bone is easy today. It is usually screwed in place with several tiny plates and screws. In the past it was wired or sutured.  

Craniotomy implies the bone will be returned to its proper anatomic position at the end of the operation. A craniectomy implies the bone will not, or has not been, returned to its normal position (it has been left out). Most elective operations are craniotomies. Many emergent procedures involve a craniectomy, since brain swelling or the threat of brain swelling sometimes prevents replacement of the bone flap. A decompressive craniectomy is a procedure done for uncontrolled brain swelling wherein a large portion of the overlying skull is purposely removed in an effort to control increased pressure in the head. This is often a last ditch effort to control such swelling.

Patients who have had a craniectomy will require further surgery to replace the missing bone flap if they survive. Sometimes, if the defect is especially large, they will need to wear a helmet in the interval between recovery and replacement surgery (called cranioplasty). What do we use to replace a missing bone flap? Usually, in the United States, it is a custom designed acrylic prosthesis that fits the defect more or less exactly. Such a procedure has a significant risk of infection however, and patients need to be watched for signs or symptoms of infection around the prosthesis for many months.

The patient in our image does not appear to have any brain swelling. The architecture of the surface of the brain is well preserved. Notice the large blue veins coursing over the surface of the brain, as well as the fine, spidery, red branching vessels, the arteries. The surface of the brain is composed of peaks (gyrus, or gyri for plural) and valleys (sulcus, or sulci for plural). Some surgeons prefer to operate through the depth of a sulcus in order to minimize brain tissue injury, others are more adept at going through the gyrus. When such a decision is crucial, as when working around the motor strip (which controls movement on the opposite side of the body) the brain can be mapped intra-operatively. This requires special equipment however—and an awake patient!

An awake craniotomy is possible because the brain itself does not feel any pain, despite the presence of billions of nerve cells. With awake surgery, the patient is gently sedated and the scalp is numbed with local anesthetics. Once the incision and the bone work are done, the dura mater is opened. There are many pain fibers in the dura mater, and so the patient is kept sedated until the dura mater has been incised and tacked up. Only then is the patient awakened to respond to the surgeon’s questions. The exposed brain in the image could well belong to an awake patient.

Note the glare in the image. This is caused by a thin and wispy web of issue over the brain, the arachnoid mater. The arachnoid is a flimsy membrane, generally not tough enough to hold stitches. Coursing under it, in the subarachnoid space (a true space, not a potential space) is the elusive cerebrospinal fluid, CSF. The CSF bathes the entire brain and spinal cord. It may provide nutrients and acts as a shock absorber. Infection in the CSF is called meningitis and can be life threatening.

The vessels over the brain also couse through the subarachnoid space. A subarachnoid hemorrhage is caused by the rupture of one of these vessels, often as a result of an aneurysm (a weak spot in a blood vessel). A ruptured aneurysm is a dire circumsance, fatal half the time. However, if the patient survives the initial hemorrhage, clipping the aneurysm via a craniotomy is one option. Coiling the aneurysm through an endovascular approach is another.

A simple craniotomy, as for an epidural hematoma, can be done in 60-90 minutes. Clipping an aneurysm might take three hours. Complicated tumor surgery can take 12-24 hours. These types of operations are usually done at university medical centers, with residents to assist the surgeon with the opening and closing portions of the craniotomy.

As a neurosurgeon, and a fiction writer, I’ve incorporated craniotomies into my stories several times. By way of bringing the reader into the operating room and closer to the action, I have included a scene from one of my novels below. For a graphic and dramatic depiction of a neurosurgeon in action, I refer the reader to my short story, THE CRUCIBLE, available for free at the Summerset Review website. Click the image at the end of this posting to go to the story directly.

 

What follows is an excerpt from NOT ONE AMONG THEM WHOLE, an audacious novel I wrote about surgeons amid the chaos and carnage of a battlefield hospital during the Battle of Gettysburg. While the scene is fictitious, it effectively portrays a trephination during the Civil War era. A trephination is not quite a craniotomy, but before one can master the rudiments of a craniotomy, one most know the trephine. Such an operation was uncommon during the Civil War, but not unheard of. At least twenty are known to have been done. 

Josiah Boyd is a tobacco chewing surgeon, Tobias Ellis his assistant surgeon, and Tiny is their hospital aide. This is a graphic scene, as is the novel itself. The trephination:

The wind howled around them, but the rain stopped abruptly. Boyd looked up from the soldier on the table, toward the cloudy sky. He didn’t pray though, knowing beyond any doubt that God had long ago abandoned him. He was not a prayerful man.

He could have been the last physician in a land besieged by plague.

He spat tobacco gruel and tried to concentrate on the problem at hand. From the corner of his eye, he saw Tobias Ellis watching him. The assistant surgeon stood directly opposite, waiting to take his cues. To Ellis’s left was a skeletally thin negro stretcher bearer named Abel. Abel’s job was to hold a lantern, to fan Boyd, to hold an umbrella, whatever might be needed. Tiny, Boyd’s long-time assistant, stood at the head prepared to administer the chloroform whenever the word was given.

The right side of Spencer’s head was discolored the blue of days-old bruised skin. Boyd smoothed the blond hair back and saw the small hole where the bullet had pierced him. Another hole just behind and above the ear where it had exited. “I guess that’s as good a place as any to cut,” he said with a lack of enthusiasm. “Sleep ‘im.”

Tiny let go a few drops of chloroform into the mask and Spencer’s heel stopped moving. The lack of movement was eerie, like he was dead. But he was only playing at dead, for every now and again he swallowed or suffered a slight cough. Boyd waited what he thought was a full minute, probably longer as he was in no hurry to get the thing started. Once started however, he was most certainly in a hurry to get it ended.

“Give me a knife.”

Tiny wiped the blade on his apron and slapped it hard into the surgeon’s outstretched palm.

Boyd sucked hard at the wad in his cheek, putting the cold edge of the steel against Spencer’s temple. He ignored the hair and pressed the blade into the skin, cutting not quite to the bone, and dragged it upward over a distance of two inches. He made a second incision at right angles to the first, the effect of which was to fashion an ‘X.’ The incisions were half in, half out of the hairline so that if Spencer survived, the marks would be forever obvious to all.

The skin parted and a brisk stream of bright blood jetted out, as if proof of life. The stream pulsed twice more in quick succession, each striking Assistant Surgeon Ellis in the belly. Ellis was quick to act though, knew the import of blood after more than a year of watching it spill. He put a stubby finger over the artery and halted the flow.

“Ligature,” Ellis said, and tied off the exposed ends of the temporal artery and vein with lengths of silk thread Tiny handed him.

Done smartly, Boyd was impressed with the assistant surgeon’s hands.

Boyd deepened the cut through the muscle over the side of Spencer’s head, running the knife over the same path as before, this time sinking the knife all the way to the skull. The wound filled to overflowing with the dark red of venous blood.

“Retractors.”

Ellis continuously swabbed the wound with a lint sponge, but the effort did little good until Boyd inserted a couple of curved metal tongs under the skin on each side of the X-shaped incision. “Here,” Boyd said, indicating Ellis should take control of them.

The assistant surgeon tugged the retractors apart from each other, opening the wound as wide as the split skin allowed. Boyd wiped again at the blood, then leaned back to spit and wiped his hand across his forehead.

“Hold that lantern up now.”

“Yassah,” Abel said and came around the table to a spot behind Boyd.

The long shadows of morning leaned lazily against the exterior of the church. The spot was the same a priest had given last rites the day before, though not a man among them had been present for that solemn observance.

Once or twice the white skull chanced into a fleeting view, but for the most part Boyd worked blindly and by feel.

“Elevator.”

The instrument was six inches long and resembled the gnawed clean bone of a chicken leg the way it flared at one end. The other tip was flat and blunt and he scraped this back and forth against the hard skull, detaching whatever muscle was there and confirming the need for the trephine. Dark blood and gray matter slowly percolated up through the bullet hole in the skull. All the while a steady stream of blood oozed from the skin edges, enough to be a nuisance but not so much the man would bleed out. Ellis pulled the skin edges taut with the retractors and the bleeding slowed to a trickle.

Boyd pushed a naked finger against the skull and felt around, rolling the digit under the skin and making a small pocket. He tried not to think too much about what he was doing, hoping only that he was making a difference.

“Trephine.”

Three minutes had passed since the incision. Boyd was exhausted.

Tiny passed the T shaped trephine to the surgeon. It had an ebony cross bar handle and a metal shaft that ended in a hollow conical drill with a flange of teeth. The whole thing was built compactly, no more than five inches long, and was solidly built, so that one could put his weight behind the turning of it; a human skull is hard, not meant to be penetrated.

He gripped the handle in his palm, the shaft between the middle and ring fingers.

Boyd knew the drilling would require muscle and backbone, though he was hesitant having never done this before—at least not in a living person where the drill could potentially plunge brainward. He thought for a moment about that word. Brainward. Like rightward or leftward, though it didn’t seem a direction one wanted to test all that often. But he was committed now, and so he leaned over the open head and pressed the teeth of the drill against the bone. He tested the unyielding nature of it, gaining confidence. Boyd simultaneously pushed down and turned the handle the way one might work a stuck door latch. The teeth bit the bone and stopped. He tried a second time using more force. The teeth moved slightly, then popped out of the skull and skittered across Spencer’s forehead, leaving a pattern of tiny bleeding nicks.

Hardy’s words haunted him: You ever trephined a man still this side of the grave?

He hadn’t pressed hard enough, that’s all. He replaced the thing and turned the drill, learning the art and work of it. It sank deeper into the bone and Hardy was at him again: I’m telling you it can’t be done without killing him.

He ignored the thought and pressed forward. The work was tedious and the minutes passed like days. At one point Spencer stirred and Tiny poured a few more drops of chloroform into the mask. Ellis too strained, holding the retractors and the head both. The assistant surgeon swallowed at the sight of the drill poking out of the head but didn’t falter when the thing skittered. 

Boyd turned the drill in small jerks, a quarter arc at a time. Simple brute force, with no way to build momentum. Despite the cool morning, sweat dripped from the tip of his nose. After every few turns, he leaned over and spat, sometimes on the floor and sometimes on the trouser leg of the man beside him.

From the post-mortem trephination he’d done and the several skull fractures he’d seen, Boyd recollected the skull to be about a quarter-inch thick. But a quarter-inch came and went and the drill was still anchored in firm bone. Several times he took the trephine out and tapped the cut skull with a mallet and chisel. Finally, on the fourth such occasion, he felt it give. He tapped again and the bone popped free and floated up, a clot of blood welling up with it.

Ellis grinned at Boyd, still holding the retractors in place. “Hot damn.”

The blood was thick and almost black. Several large chunks pushed out and slid down the side of Spencer’s head. Boyd pushed his little finger into the hole and twirled it, feeling the inside of the smooth skull and dislodging several additional pieces of clot. There didn’t look to be any fresh bleeding though, and after a few minutes he considered how he would end the operation. He decided not to put the bone back in place, there being no good way to secure it. In the case of a fracture the bone would simply be discarded and he saw no reason to deviate from that. Ellis removed the retractors, and Boyd proceeded to stitch the skin with a needle and silk thread. The entire operation had taken just under thirty minutes. When done, the right side of Spencer’s head was dimpled where the bone was missing. They wrapped his head with a length of muslin and waited for the chloroform to wear off.

Boyd spat in the dirt again and stepped back from the table. He picked up the trephine, stared at it a moment or two, then set it back down. Leaning against a wall, he closed his eyes and slept standing up for several minutes.

Another half hour passed before Spencer Hardy began to come out of his stupor. As he did so, he crossed his legs and reached up to grab his head. This was more movement than he’d done in a day and those present cheered.

Boyd at least was satisfied. He slumped to the bloody grass and slept.

Edison McDaniels, MD is a board certified neurosurgeon and practices in the American South. Follow him on twitter @surgeonwriter and read his fiction at Amazon in paperback and on kindle.

05/18/14

Hydrocephalus Owner’s Manual

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Click image to download the entire Hydrocephalus Owner’s Manual as a free pdf.

Hydrocephalus: An Owner’s Manual

by Edison McDaniels II, MD

WHY I WROTE THIS MONOGRAPH

I am a brain surgeon.

Several years ago, I was confronted with a young man in the emergency room who had earlier that morning been found unconscious by his college roommates. In fact, when I met him he was essentially comatose, that is, unresponsive in any meaningful way. Fortunately, one of his roommates recalled something about him having a shunt. With this piece of information, the emergency physician quickly called for a stat head CT and a diagnosis of shunt malfunction was made. I was called, took the patient to surgery for an emergent shunt revision, and he recovered and lived happily ever after.

Well almost. It turned out he was a college student and the ordeal left him rather exhausted, though neurologically normal, and he would spend several months recovering from his near death experience. His mother, who lived in a city 160 miles away, drove over immediately and was waiting for me when I came out of the operating room. I have seldom seen a mother so grateful as that woman—unless it be virtually every other mother I have ever dealt with as a neurosurgeon.

Largely because of their children, parents are special people.

The bond between parent and child is like no other. I have seen octogenarians break down while recalling the death of a forty-year-old son or daughter—never mind that the death occurred fifteen years before. Perhaps the only bond in all of nature that can never be fully broken, it continues beyond divorce, separation, abandonment, illness, and even death. At its best, the parent-child bond drives us to be our best, to meet our full potential. Even when it is missing, entire lives are predicated, even formulated, on the basis of such a loss.

Almost without exception, the parents I meet would gladly exchange places with their child in these moments of extreme stress. These parents feel helpless and at the mercy of the situation. I am often asked What could I have done? Or Is there anything I can do to prevent this from happening again? 

I know the feeling.

I am a brain surgeon. I am also a parent. Several years ago, my oldest son died suddenly. In my years on this earth I have lost people close to me—a brother, a half-brother, both parents, several close friends—but all of their deaths paled in comparison to losing a child of my own. It was and remains the single most difficult event of my life, the defining moment if you will.

A bond which cannot be broken.

Which brings me to this monograph.

Hydrocephalus—loosely defined as a build-up of fluid in the brain—is a life-threatening, fairly common, and relatively easily treated condition. Unfortunately, with existing medical technology, the treatment requires a lifelong diligence on the part of loved ones as well as the patient himself/herself. But that being said, the treatment is not onerous on a daily basis and the benefits are dramatic. Most patients with hydrocephalus live normal lives in virtually every respect. They play sports (even extreme ones), marry, have regular jobs, carry babies through labor and delivery, and die as an old man or woman (or at least we expect they will—the technology is only fifty or so years old and thus people shunted as young children are only now reaching late middle age). With the possible exception of the more remote parts of Alaska, if you live in the United States you almost certainly have at least one friend, acquaintance, student, or co-worker with a vp shunt—though you may not know it.

So why this monograph?

Because, to put it in the simplest terms possible, failure to recognize a shunt malfunction can be fatal. The boy I took care of above had failed to get out of bed for class one morning. When his roommates returned home for lunch, they found him unresponsive and still in bed. They called an ambulance and he was taken to my hospital, where a CT of the brain showed the problem. He received prompt medical attention—but only belatedly and it nearly cost him his life.

Had his roommates known the gravity of his failure to arise that morning, his brush with death would likely have been avoided. His mother recognized this fact. She knew how close to the edge he had come. She was one of those who asked What could I have done? Is there anything I can do to prevent this from happening again?

The advice I gave her became this monograph.

Author’s note: This is not an exhaustive treatment of hydrocephalus. It’s a brief, informative, interesting, and I hope useful summation of some of the more common questions I have been asked repeatedly over the years. There are many longer, much more exhaustive books on hydrocephalus. This, however, will answer most of your questions. And it is written with the lay person in mind.

 

 

About The Author

Edison McDaniels is a writer, wordsmith, novelist, and physician living in the American midwest. His writing tends to involve ordinary people in extraordinary circumstances and is often informed by medicine. His stories showcase historical fiction and the supernatural, especially ghosts. He received honorable mention in The Seventeenth Edition of the Year’s Best Fantasy and Horror (2003), and has been published in Paradox Magazine, The Summerset Review (available online), The Armchair Aesthete, On The Premises Magazine, and others. Several of his short stories can be found online.

He is also a graduate of Stanford University and is a neurosurgeon. He is board certified in the practice of adult and pediatric neurosurgery, with over 6,000 operations to his credit.

He and his wife collect historical etchings and attend at least 1-2 baseball games a week between April and October, more if the Minnesota Twins are in town.

His novels include NOT ONE AMONG THEM WHOLE, THE BURDEN, and the forth coming THE MATRIARCH OF RUINS. His latest novella, BLADE MAN, is available as an eBook.

 

04/19/13

A Game of Shadows 3

Shadows

A GAME OF SHADOWS, 3/3
by Edison McDaniels, MD

Beginning in the mid 1970’s, when the first CT scans became available, the ease and ability with which neurosurgeons could localize anatomic lesions within the skull skyrocketed. The initial CT era, which spanned about 15 years, saw the development of higher resolution imaging as well as faster machines. An entire head CT in 1990 took about 10-12 minutes or even longer. Today, about 20 seconds. This means very few patients have a serious enough injury to bypass CT and go straight to surgery. If they can be stabilized at all, a stop in CT will generally increase their chance of survival by allowing detailed imaging of not just the brain, but the chest, abdomen, pelvis, and other injuries as well. In fact, such imaging in trauma not only allows the recognition of injuries requiring surgery, it also allows the recognition of injuries suitable for nonoperative observation—injuries that would have been operated in the past but, under close observation and supervision, are not operated today.

That 15 years also saw the development of contrast agents of various sorts. These contrast solutions, you might think of them as dyes, make tumors which would otherwise be invisible on CT or MRI visible. Many tumors have the same density as the surrounding brain and are only rendered truly visible by this contrast solution. A large tumor will give itself away by the distortion it causes to the surrounding structures whether or not it is itself visible, but such distortion may not be apparent post-op. In such a case, regrowth of the tumor can be checked for with contrast solutions. This has had a tremendous effect on modern day neuroimaging and neurosurgery.

E MCD 004

MRI of a large brain tumor sitting between the frontal lobes. It is only visible because the patient has been given a contrast agent, otherwise it would appear quite similar to normal brain—though distortions in that normal brain would still announce its presence to the informed eye. This tumor is almost certainly benign (not cancer).

By the way, the difference between CT and plain x-ray is that CT does have a 3D aspect to it, which allows very fine discernment of tissue density. What looks like a solid structure on plain x-ray, the heart for instance, actually can be seen as a multichambered muscular organ on CT. In a practical sense, this means a radiologist can tell the difference between normal gas inside the small intestine, and abnormal gas within the wall of the small intestine, as might be present if the small intestine has been damaged by tumor, infection, or trauma. This means the surgeon can operate early rather than waiting for the patient to develop signs of peritonitis—life threatening infection—first.

In fact, the ability to discern the fine details of anatomy is so good on CT and MRI, that some medical schools are now foregoing real human cadavers and teaching anatomy virtually, using programs composed of thousands of pictures (CT and/or MRI slices) of the human body.

MRI has come into its own since about 1995. MRI is extraordinarily sensitive in terms of anatomic detail. One can see very fine vessels, perhaps just 2-3 mm in diameter, on MRI. Very small tumors, too small even to be operated upon, are also visible. In fact, sometimes we find things which aren’t tumors at all but incidental curiosities. These are things we would only have found at autopsy in the past. As a neurosurgeon, I see several patients a month with such findings. We generally don’t operate on these incidental findings.

ICHVeryLarge

CT of a large, life-threatening hemorrhage (the white stuff). It’s on the right side of the brain. This patient is almost certainly comatose. Without an emergent craniotomy, he or she will not survive. With surgery, his or her long term outcome might be surprisingly good if operated in time. In neurosurgery, Time is Brain. Time is life. This is one of the first lessons a neurosurgeon in training learns.

Sometimes the incidental findings seen on MRI are important. A small lesion shows up in the frontal lobe, perhaps too small to cause symptoms just yet. Is it a tumor? Or just a curiosity? Sometimes we can’t know. Such cases have to be individualized. Occasionally surgery is recommended to biopsy the lesion or remove it entirely. More often a wait and see approach is taken, wherein the imaging is repeated in a few months looking for growth or some other change.

Up until recently, most all imaging has been anatomic. Today that is changing. More and more, functional MRI is coming to the forefront. fMRI actually observes and measures physiology—neuronal activity and connectivity. This is useful to avoid damage to elegant areas of the brain during tumor surgery, or to identify the focus of seizure activity. Or, in the case of post-surgical recovery or after a stroke, to assess neural plasticity. Much of this is still experimental and only available at tertiary centers, but stay tuned. It has been called Neurosurgery 2.0.

By the way, functional imaging of the human brain has another promising use. It is now possible to see nonorganic disease—psychiatric disorders—in action. This technology is in its infancy, but imagine being able to visualize how a human thinks in an objective fashion. Schizophrenia may show activity is one particular area, mania in another. One can imagine scanning a patient to check on the efficacy of a particular treatment or medication. Taking it still further, might it be possible to ferret out a murderer in this fashion, or maybe even a future murderer?

In other words, be careful what you think—big brother just might be watching…

Edison McDaniels, MD, is a board certified neurosurgeon practicing in the American South. Follow him on twitter @surgeonwriter and read his fiction on Amazon in both paperback and kindle. 

04/17/13

A Game of Shadows 2

 

Shadows

A GAME OF SHADOWS, 2/3
by Edison McDaniels, MD

Dandy ultimately discovered that replacing the CSF with air, called pneumoencephalography, did a tolerable job of visualizing the ventricles and any tumor either in the ventricles or large enough to distort the ventricles (hence, most of the tumors discovered this way were quite large). Unfortunately for the patient, pneumoencephalography was a difficult and dangerous test to perform. The brain normally floats in the CSF. Removing most of the CSF for this procedure was no easy feat, and was extremely painful with severe headaches lasting days to weeks afterwards. Not to mention the nausea that accompanied the test. As if these things were not enough, once the air was injected every attempt was made to get it to flow into just about every nook and cranny within the skull. To accomplish this, the patient was placed on sort of tilt-a-whirl chair that spun them every which way—including upside-down. Imagine having the worst headache of your life, being utterly nauseous, probably vomiting, and then being flipped upside-down—repeatedly. Think about that next time you’re having a bad day.

For about 50 years or so, this, cerebral angiography, and plain xray were the only games in town. Today, pneumoencephalography is relegated to the pages of history. There is no real indication for it in this modern era of CT and MRI.

ICA-Angiogram

A cerebral angiogram. The black squiggles are the arteries of the brain, viewed as if looking at the side of the head. The carotid artery is the largest squiggle, coming up from the bottom of the image and branching like a tree.

Cerebral angiography was invented a few years after Dandy’s development of pneumoencephalography, in 1927, by a physician named Egas Moniz. Moniz was looking for a way to visualize the vessels inside the head. He finally settled on a solution containing heavy metals which are dense and easily visible on x-ray (though toxic to the kidneys in large doses). When injected into the arteries of the head and x-rayed, the arteries (and the veins as well) of the brain—the cerebral vasculature—are completely visualized.

This turns out to be useful both directly and indirectly. Directly because one can visualize aneurysms and other vascular malformations of great importance. Indirectly, and here we go back to the shadows again, because of what we can’t see. One of the most important past uses of cerebral angiography, as it is called, was to identify the presence or absence of epidural and subdural hematomas following trauma. This was done by reading the shadows, that is, the shift in the normal position of the blood vessels. If an acute epidural or subdural hematoma was present, it would push the normal vessels away from the side with the hemorrhage. That is, the presence of the hemorrhage would be implied by the lack of any vessels where they should normally exist.

The scenario went something like this: Little Joey gets hit by a car and is rushed to the ER. Finding him to be unconscious, but lacking any other clinical localizing signs to discern whether or not a blood clot was pushing on the brain (after all, he could just have a concussion, or worse, diffuse brain injury which does not respond to or require brain surgery), Little Joey would be rushed over to the radiology room where a neurosurgeon (not a radiologist in those days) would inject the solution of heavy metals directly into Little Joey’s carotid artery in the neck. A few quick x-rays of Little Joey’s head would be taken, and voila, the shadows would show the presence or absence of hematoma.

Or something like that.

SDHacuteShift

An acute subdural hematoma. The hemorrhage is the irregular white pattern on the right side of the image (which, do to the arbitrarily agreed upon conventions of imaging is the LEFT side of the patient’s head). A hemorrhage such as this pushes everything out of its normal place, including the vessels seen on an angiogram.

If Little Joey also had other injuries, he might just as well be whisked off to surgery for an operation on his belly or chest or whatever. Then the neurosurgeon would be left to his own devices in the operating room without any imaging to guide him. This often meant drilling a series of holes at strategic points around the head, sort of like drilling for oil. Problem was, you always got oil. The trick was to determine when you had a normal amount of oil or too much. And of course this was on top of the confusion of whatever other surgery was being conducted on Little Joey as well…

Thank God those days are largely behind us.

Oh, and that Moniz fella? In 1949 he won the Nobel Prize in Medicine for the development of his other great (uh, not so great?) contribution to medicine, the prefrontal lobotomy. Today, of course, lobotomies are rarely—if ever—indicated. But for a brief period in the late 1940s and 1950s, in the era before psychoactive medications, they were all the rage for treating psychiatric disorders. Of course, lobotomy does not treat psychiatric disease, it simply disconnects the emotional, thinking part of the brain—the part that contains little things like personality & makes you you—from everything else. Jack Nicholson’s character Randle Patrick McMurphy in Ken Kesey’s One Flew Over The Cuckoo’s Nest was lobotomized at the end of that great movie, and for once Hollywood got it right. The horrifically vacant, the lights are on but nobody’s home expression on Nicholson’s face when McMurphy returns from surgery was not an exaggeration. Not one of the Nobel committee’s more stellar moments.

As big a bust as lobotomy has proven to be however, cerebral angiography—which lead to the use of angiography throughout the body—has proven to be one of the greatest developments of modern medicine. None of the endovascular interventions for brain aneurysms, aortic aneurysms, heart disease, etc., would be possible without Moniz’s invention. In fact, it is no exaggeration to say much of modern medicine would not be possible without angiography. It saves hundreds of thousands of lives every year. That probably was Nobel worthy.

Edison McDaniels, MD, is a board certified neurosurgeon practicing in the American South. Follow him on twitter @surgeonwriter and read his fiction on Amazon in both paperback and kindle. 

Click here for the final installment. Next time: MRI & CT take over.