04/19/13

A Game of Shadows 3

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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.

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 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.

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…

End of A GAME OF SHADOWS postings.

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04/17/13

A Game of Shadows 2

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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.

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 is 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.

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.

Next time: MRI & CT take over.

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04/15/13

A Game of Shadows 1

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Shadows

A GAME OF SHADOWS, 1/3
by Edison McDaniels, MD

A truism: the evolution of neurosurgery has largely paralleled the evolution of imaging of the nervous system. Great strides have been made since the 1970′s, when the first CT scans became available and it thus became possible to localize an anatomic lesion within the central nervous system with great accuracy.

There was imaging available before the 1970′s, of course. The period before about 1974 or ’75 might be called the era of shadows—for that is what the imaging amounted to. In fact, even today, plain x-ray imaging is really a game of shadows. Different tissues of the human body are composed of different densities, with the most dense being the teeth, followed by the bones, and the least dense being the air-filled structures, especially the lungs. The denser the tissue, the more prominent the shadow on x-ray.

With the exception of the teeth, bones cast the most prominent shadow on x-ray. Indeed, the shadow of a bone may be so dense as to obscure everything both in front and behind it (remember, plain x-ray is a 2D affair—it’s as if the body has been flattened to a single plane, like a photo, which is exactly what an x-ray is; as an example, if you take a picture of a person, the person obscures everything behind them—in the case of an x-ray, the bone obscures everything behind and in front of it). Reading a plain x-ray is thus, largely, about learning pattern recognition—what sorts of shadows various tissues cast. Sometimes, the shadows overlap, the densities summing to appear to show something when in fact there is nothing there. This is known as a superfluous confluence of shadows.

The situation is made all the more complicated by the idea that the shadows are often not representative of the structures themselves, but only of their relative presence or absence. What?

One example will do nicely to illustrate the situation. Consider the state of the art in neuroimaging prior to the mid-1970′s, pneumoencephalography (the title image is a pneumoencephalogram). This test, invented in 1919 by one of the founding fathers of modern neurosurgery, Walter Dandy, involved replacing the CSF with air injected into the ventricular system within the brain. The ventricles are normally fluid filled and thus, on plain x-ray at least, have a density similar to that of the surrounding brain (for the purposes of plain x-ray, brain and water have nearly the same density). As such, a normal or even abnormal ventricle is not visible on a plain x-ray and certainly is not discernable from the surrounding brain.

Dandy, for various reasons, had the idea to replace the CSF of the ventricles with something either more or less dense than the surrounding brain and thus make them visible on x-ray. Why? Because of the whole shadow idea. If the ventricles could be made visible, their shape would be discernable. If their shape was discernable, the prying eyes of the physician would be able to see if they were enlarged, say by hydrocephalus. Or, more to the point, if they were distorted—that is the ventricles were shifted out of their normal position or shape—by the presence of a tumor. In visualizing this, the location of the tumor would thus be suggested and the tumor localized not directly by the shadow of the tumor but indirectly by the abnormal shadow of the ventricle.

And localizing the tumor was of course, the holy grail of neurosurgery since one could not safely or even comfortably operate upon a tumor in the human brain if one did not have a fairly good idea of where it was to be found in the first place.

Part 2: More on pneumoencephalography, and the development cerebral angiography—one of the great advances in medicine.

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04/13/13

Saving King

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Killing King

The time is the 4th of April 1968, a cool Spring evening close on six pm. The place is a predominantly black neighborhood on the south edge of downtown Memphis, Tennessee. An area of run-down homes and low incomes. At 450 Mulberry Street there sits a small, modestly upscale boarding establishment, the Lorraine Motel. It is two stories and there is a pool, installed by the motel’s long time owner, Mr. Walter Bailey. The motel is popular among black musicians who frequent the nearby Stax Records. Over the years these have included Ray Charles, Lionel Hampton, Aretha Franklin, Ethel Waters, and Otis Redding before his death the year before.

Across the street and beyond a small brushy knoll is a two-story brick rooming house. 422 Main Street. On the second floor of this shoddy establishment, at the window of a small bathroom, a man named James Earl Ray waits with a 30.06 rifle. Ray has a clear view of the Lorraine Motel, of room 306 on the second floor.

It is one minute after six in the evening and, in the time it takes a bullet to fly the length of the knoll, everything changes.

Martin Luther King, 39 years old, has already survived one assassination attempt. Ten years earlier, on September 20th, 1958, a deranged black woman with the bewitched name of Izola Curr plunged a steel letter opener into his chest—his sternum actually—while he was holding a book signing at a Harlem bookstore. Three hours of emergency surgery at Harlem Hospital saved his life. The blade missed his aorta by a hair’s breath.

He will not be nearly so lucky this time…

 

In all of American history, surely one of the most atrocious acts of gun violence took place on the evening of April 4, 1968. No less a personage than George Wallace, the avowed segregationist, called the shot that rang out at 6:01 pm in Memphis, Tennessee “a senseless, regrettable act.” President Lyndon Johnson canceled an important trip to Hawaii—he had been scheduled to meet with his military commanders about strategy in Vietnam—upon learning of King’s death.

Over 100 American cities erupted into rioting on the news of what this single gunshot wrought: the stilling of the greatest single voice in the American civil rights movement, the Rev. Dr. Martin Luther King, Jr.

These facts are well known and not in dispute: King was shot at 6:01 pm and was pronounced dead at 7:05 pm at St. Joseph’s Hospital after a failed attempt at open cardiac massage. He was 39 years old.

According to King biographer Taylor Branch (At Canaan’s Edge: America in the King Years, 1965-68), King was standing on the balcony outside room 306 on the second floor of the Lorraine Motel when Jesse Jackson hollered up to him: “Doc, you remember Ben Branch?” King replied “Oh yes, he’s my man.” King then said, “Ben, make sure you play ‘Precious Lord, Take My Hand,’ in the meeting tonight. Play it real pretty.”

Ben Branch replied “Okay, Doc, I will.”

There was no reply.

King had spoken his last words, and in the words of biographer Taylor Branch, time on the balcony had turned lethal and King’s sojourn on earth went blank.

But did it? Did it do so immediately? Was King doomed the moment that bullet crashed through him? Is there any action that might have saved his life as he lay supine on that balcony. Bleeding profusely from a wound to his right jaw and neck? He wasn’t pronounced dead for 64 minutes. Was he, in fact, alive during that time? Was there ever a chance he could have been saved by the relatively crude trauma care of 1968? And how about today? If King was shot in 2013, might he survive?

The answers to these questions and more are interesting and worth pursueing. They illustrate, if nothing more, how far trauma care has come in the forty-five years since that fateful night. Based on a close reading of eyewitness reports, the autopsy filing, the 1978 House Select Committee on Assassinations’ investigation into the assassination of Martin Luther King, and other sources, I have put together a creative but nonfictitious account of the efforts to save Dr. King’s life in the 64 minutes that followed his shooting.

This is an intense, no holds barred look at what transpired in 1968, and an equally intense account of what might occur under similar circumstances today. If you have any interest in medicine, surgery, the drama of the emergency room, or trauma in general, you won’t want to miss this.

SAVING KING is about one of life’s harder moments. It’s coming shortly as an eBook to the Kindle store. Just 99¢ & you can touch a piece of history.

Now that’s damn interesting!

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04/8/13

The Chiari Malformations, 6/6

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Chiari, Part 6 of 6: The Tethered Cord

Chiari1Tethered Cord is a nearly universal finding after myelomeningocele (MMC) repair. It is the result of normal scarring after surgery, which can bind the spinal cord at the level of the MMC repair and prevent the cord from sliding the way it needs to with normal everyday movement.

It turns out that the tip of spinal cord is at about the level of the L3/4 disk in a newborn. However, because the spinal canal grows (lengthens) rapidly and the spinal cord does not, the normal spinal cord appears to ascend in the canal as the spine lengthens. By the first year, the cord has attained its normal position, with the tip at the level of the L1/2 disk space.

In a MMC patient, the post-op scarring from the initial repair surgery causes the spinal cord to form adhesions to the surrounding tissue, thus tethering it and preventing it from ascending. The spinal cord tolerates such stretching poorly, and the result is generally a reversal or loss of milestones. Patients become incontinent when they had previously been continent, gait changes and deteriorates, child may demonstrate shortening of their heel cords and appear to be walking on tip toes, back pain, headaches (especially when trying to flex neck to look down). In advanced cases, young kids will arch their backs and extend their necks (as if looking up all the time) and refuse to do otherwise. They become fussy and irritable.

Tethered cord tends to make its appearance during growth spurts, such as around puberty. Also commonly seen at four or five years of age.

Surgery involves general anesthetic and re-exploration of the previous repair site. Usually takes about 2 hours. Unfortunately, there is a risk of recurrent tethering. Most kids only need a single detethering, a few will need two surgeries (generally separated by many years). Occasionally an adult will present with a tethered cord.

Results are generally good, though it is better to prevent loss of function than to try to recover it once lost. For this reason, detethering is often undertaken at the first sign of trouble.

The greatest risk of surgery is that of making a patient worse. This is unusual, but not rare. It is more frequent during a revision.

Note that Chiari I is not associated with tethered cord. Also note that if a patient has a vp shunt, its proper function should be verified before operating on the tethered cord. If hydrocephalus is present or the vp shunt is not working, these things should be attended to prior to operating on the tethered cord.

Tethered cord surgery is generally elective and can be scheduled during school vacations.

 

HydroCover0

Hydrocephalus

Please see my monograph, Hydrocephalus: An Owner’s Manual, for a thorough discussion of this condition. This monograph is available on Amazon by clicking HERE.

 

 

 

End of Chiari Postings

 

fiction by Edison McDaniels…
The trade paperback edition of the most amazing Civil War novel since Cold Mountain & The Killer Angels is now available!

NOATW Print CoverNOT ONE AMONG THEM WHOLE: A Novel of Gettysburg by Edison McDaniels tells the story of the surgeons working under the most horrendous conditions imaginable: the chaos, carnage, & blood soaked tables of a battlefield hospital in the midst of the Battle of Gettysburg. It’s all here: the brutal and unrelenting chaos of battle; the terrible humanity of the operating rooms; the failures and triumphs of primitive medicine and surgery.

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“Heart breaking, engaging, and absolutely fantastic. I would give this book 6 stars if I could.”

Download an excerpt today by clicking here.

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04/6/13

Download: A Rare Kind of Faith

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This story was the grand prize winner in the 2002 Obadiah Press Writing Contest.

A Rare Kind of Faith
By Edison McDaniels

I knew there was nothing I could do as soon as I saw those films. One o’clock in the damn morning and raining, but the cold that came over me as I studied those images had nothing to do with either the night or the rain. It was the dread of knowing she was beyond any help modern medicine could offer.

She was going to die…

RareKindFaith

Thus begins this award winning tale of one physician’s lesson in life at the hands of a three year-old girl. From the mind of Edison McDaniels & based upon a true story.

CLICK THE IMAGE TO DOWNLOAD THE ENTIRE STORY AS A PDF.

Thanks for reading A RARE KIND OF FAITH.

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04/5/13

The Chiari Malformations, 5/6

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Chiari, Part 5 of 6: Syringomyelia

Chiari1Syringomyelia is an enlargement of the central spinal canal, sometimes to hugh dimensions. This central canal is almost imperceptible on a normal MRI. A very small syrinx is of no consequence generally. However, when very large or showing enlargement over time on several MRIs, chronic spinal cord injury is occurring and loss of function (weakness, decreased feeling, decreased dexterity, even paralysis) can result.

Syringomyelia, when associated with Chiari, generally resolves or stabilizes with adequate treatment of the Chiari. Very rarley it will not, and then another source for the syringomyelia must be sought, such as a tethered cord or the very rare tumor of the spine.

There are many causes of syringomyelia. In Chiari I, the Chiari is generally assumed to be the culprit. In Chiari II, the problem can be the Chiari itself, hydrocephalus, a tethered cord, or some combination of all of these.

In Chiari I, the syrinx, if present, is generally in the mid-cervical range C4-C6, and this should be checked for on a pre-op MRI. In Chiari II, the syrinx can involve the entire spinal cord and imaging of the entire spine is necessary. This will generally show a radiographic tethered cord, which may or may not be clinically significant. In either Chiari I or II, the syrinx can extend into the brainstem itself, called syringobulbia. This is usually associated with lower cranial nerve problems (swallowing issues, facial pain, etc). Syringobulbia is rare and indicates a very advanced condition.

Unless tumor is present, it is rare to operate on a syrinx directly. Such surgery is generally disappointing and can be dangerous.

Here is a picture of a large focal syrinx behind (dorsal to) the C6-T1 vertebral bodies. The cause of this particular syrinx is not immediately apparent from this image, as there is no significant chiari. A syrinx this size almost certainly warrants treatment of some sort. I will discuss syrinx further in future post, as it is an important subject in itself, with many discussion points.

SyrinxFocal

Next time: The Tethered Cord

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