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Michael Morgan, a neurosurgeon from Sydney, Australia and specialist in arteriovenous malformations (AVM) spoke today. He has seen approximately 600 patients with AVMs and operated on 529 of them. In his hands, the risks of a surgical resection of a SM grade 1 AVM is less than the risks of gamma knife. It is also more commonly definitive therapy. It is far less risky than Onyx embolization. However, Dr. Morgan is a unique surgeon and not every surgeon is going to be able to achieve similar results.
Other interesting points from his lecture:
- The risk of hemorrhage from AVMs with no prior history of hemorrhage is approximately 1% per year.
- The risk of hemorrhage from AVMs with a prior history of hemorrhage is approximately 6% per year. Continue reading ‘Michael Morgan, AVMs, and the Spetzler Grading System’
Non-operative reduction of a cervical dislocation can be extremely difficult. Even with modern techniques and technology, it is occasionally not possible to reduce a cervical subluxation non-operatively. However, with modern anesthesia, muscle relaxants, and traction systems, it has to be much easier than what it was in 1936.
Here’s another video produced by the British Medical Association; this time demonstrating an attempted cervical reduction of bilateral jumped facets at C5-6. The x-ray is striking. Cases of such severe subluxation without spinal cord injury are rare. The attempted reduction is brutal and ineffective. Modern reduction techniques are much more controlled and safe.
Also shown is a case of unilateral subluxation in an infant after a tonsilectomy. Although there are no x-rays, no images of the reduction procedure, and no follow-up, the pre-reduction examination is striking and informative.
I don’t want to turn this into a nutrition blog, but I find some of the recent studies coming out on the science very interesting. The evidence that there is an epidemic of obesity in our country is overwhelming. And, more and more evidence is accumulating that dieting is not the answer. It’s going to take more than just telling people to eat better and exercise more.
One aspect of nutrition that has probably been under-appreciated is the interaction of nutrition and neuroscience. Well, thanks to a new study published in Nature Neuroscience, that may not be the case much longer.
Addiction to certain drugs, like cocaine and heroin, are accompanied by changes in the level of specific neurotransmitter receptors in the brain. In a process called negative feedback, as the neurotransmitter level increases, the number and sensitivity of its receptors decrease.
The neurotransmitter most closely associated with addictions is dopamine. Dopamine is active in the “reward” or “pleasure” centers in the brain. One of these reward centers is called the striatum. The authors showed that in rats exposed to chronic high fat foods, the level of the dopamine receptor D2 in the striatum is decreased. That means that it would take even more fatty food to get the same pleasure response. In other words, this is the first clear evidence that fatty foods are addictive.
From a neurosurgical perspective, this is very interesting. Neurosurgeons are able to modulate brain activity in specific regions of the brain by implanting electrical stimulators. Current surgical techniques for the treatment of obesity (called bariatric surgery) are principally performed by general surgeons. Procedures including gastric bypass, banding, stomach stapling, and others are accompanied by severe side effects. They also carry risks of vitamin deficiencies. Furthermore, although there are many successful outcomes from the surgery, there are failures as well. A deep brain stimulator could be a very attractive alternative.
Video of a Craniotomy in 1932
Someone posted on Youtube footage from a craniotomy in 1932. From the British Medical Association Library, the video shows a “Prefrontal Tuberculoma: Removal with complete recovery by Prof. R. E. Kelly and Dr. Henry Cohen.”
The film is full of historical gems:
- A diagnositic pneumoencephalogram which demonstrates compression of the right lateral ventricle with midline shift.
- A hand-powered Souter’s craniotome. Even after watching it several times, I cannot completely understand how it worked.
- Manual dissection and excision of the tumor.
- Tumor histology with silver stains
- Post-operative follow-up evaluation of the patient. Although the patient had a significant hemiparesis, he looked remarkably good.
It really is incredible. Advance upon advance has dramatically changed the way modern neurosurgery is performed. Yet, there is an eerie similarity in the video as well. Maybe it’s because, like what Sir Isaac Newton said, if we see a little further, it is by standing on the shoulders of these giants.
(H/T Mindhacks)
Errata
1. Thiago Alves, one of the stars of mixed martial arts and the Ultimate Fighting Championship has withdrawn from UFC 111 due to an irregularity found on a CT scan. He is scheduled to undergo an angiogram on Wednesday.
The CT scan was a routine part of his preoperative medical clearance for the fight. An “irregularity” was found in the left side of his brain. It likely represents some kind of vascular anomaly, given the choice of an angiogram to further characterize the lesion. It has been reported that it is not an aneurysm. Some of the more common vascular anomalies include arteriovenous malformations, cavernomas, and dural arteriovenous fistulas. An old stroke would also be visible on a CT scan. The presence of a stroke could be suggestive of a traumatic vascular dissection, which could also be detected via angiogram.
Lateral cerebral angiogram after contrast injection into the common carotid artery
An angiogram defines the vascular anatomy providing blood supply to the head. It is a relatively minor procedure. A small catheter is inserted into an artery, usually in the groin or arm, and then directed to the cerebral blood vessels. At that point, a small amount of contrast is injected into the blood vessels. Fluorscopy pictures detect the contrast showing the anatomy and general flow characteristics of the blood vessels. Abnormalities of the blood vessels can be readily observed.
The good news is that Alves is expected to be able to return to the octagon soon.
2. Mexican americans, women, and persons who live alone are the least likely to pursue emergency medical assistance following a stroke reports Businessweek.
3. Neurosurgery better than ‘Avatar’? An operation in Liege, Belgium was recorded in 3-D and transmitted to a local movie theater. The audience was apparently able to interact with the surgeon in real-time. I guess I don’t have to give up on my Hollywood aspirations quite yet after all.
The Perils of HFCS
I was wrong. I was always of the philosophy that a calorie was a calorie was a calorie. That obesity was based upon a simple formula:
weight change = [calories in] – [calories out]
In other words, if you spent more calories than you consumed, you lost weight. If you consumed more calories than you spent, you gained weight.
However, a recent study published in the Journal of Pharmacology, Biochemistry, and Behavior suggests that all calories are not created equal.
All calories may not be created equal
The authors fed three groups of rats: one group was given regular chow ad lib. The second group was given regular chow ad lib and supplemented with sucrose. The third group was given regular chow ad lib and supplemented with high fructose corn syrup (HFCS). Although the overall number of calories consumed by the sucrose group and the HFCS groups were the same, the HFCS group gained significantly more weight.
It gets even more interesting. Fructose, on a per calorie basis, is much sweeter than sucrose. That is why it has replaced sugar in many food items, particularly soft drinks. The manufacturer can maintain the sweetness of the product while including fewer calories – tastes great and less filling, or at least fewer calories.
In the current study, however, the sucrose and the HFCS group consumed a similar number of calories overall. But the HFCS group actually obtained a smaller percentage of their calories from the corn syrup. The study suggests that the HCFS was able to drive more calories towards becoming fat than sucrose, even when HCFS made up a lower percentage of the total caloric intake.
Actually, this does make sense from a biochemical standpoint. Fructose is not like the other sugars common in our diet. Nicholas J Krilanovich described it nicely in a letter to the American Journal of Clinical Nutrition:
Basic biochemistry indicates that glucose and fructose have different chemical properties. Of the 3 major sugars that digest into the human bloodstream, the 2 that are vital to humans, galactose and glucose, are both aldoses, whereas fructose is a ketose—this sugar is the one that the human liver tries hard to keep at essentially a zero concentration in the blood. Murray et al (10) wrote that, “Biomedically, glucose is the most important monosaccharide and ingestion of large quantities of fructose has profound metabolic consequences …because it bypasses the regulatory step catalyzed by phosphofructokinase. This allows fructose to flood the pathways in the liver, leading to enhanced fatty acid synthesis, increased esterification of fatty acids, and increased VLDL secretion, which may raise serum triacylglycerols and ultimately raise LDL cholesterol concentrations.”
I am definitely going to pay more attention to the amount of HFCS I consume. Perhaps, my math has been wrong all along. I all likelyhood:
weight change does not equal [calories in] – [calories out]
Errata
1. I met Chris Shaffrey from the UVA Department of Neurosurgery. He’s a specialist in spinal disorders with an emphasis on spinal deformity. I came away very impressed, particularly with his evidence-based approach to spine surgery.
2. X-rays can miss many fractures. It has long been debated about the relative cost-benefit ratio of x-rays versus computed tomography (CT) for spinal fractures after trauma. X-rays are much cheaper. CT scans are much more thorough and sensitive. This paper suggests that more fractures may be missed by traditional x-rays than had previously been thought. Perhaps a CT scan is worth the additional cost.
3. Vycor medical products has developed a novel brain retractor called the Viewsite. Traditionally, malleable blade retractors have been used to retract the brain during a neurosurgical procedure. These retractors have many limitations: they concentrate the retractive force on a small segment of brain; they have sharp edges that can cut into the brain; they are opaque blocking visualization of tissues behind the retractor. The Viewsite uses a novel circumferential retraction system to distribute the retractive force on a wider surface. Here’s how the company describes it:
The ViewSite™ Brain Access System is a revolutionary approach in brain retraction. Each ViewSite system consists of an introducer and a working channel port that allows the surgeon a seamless entry to the targeted site while distributing brain tissue evenly in a 360° dispersion pattern. Other ViewSite benefits include superior binocular vision to see in and around the surgical site; multiple sizes in different widths and lengths to meet all surgical needs and compatibility with most surgical arms to avoid accidental displacement or movement during surgery.
Penetrating Trauma
An x-ray of the skull demonstrates a knife entering the right temple and transiting the brain until it protrudes from the left temple.
If you get stabbed in the brain with a knife, you are going to die, right? Maybe not. Brain trauma comes in a variety of forms, but can generally be divided into two categories: blunt and penetrating.
Blunt trauma, the kind that typically results from car accidents or falls from height, is far more common. The head strikes a hard surface, resulting in a rapid acceleration or deceleration. This results in differential forces passing through the brain parenchyma. The differential forces cause microscopic tears in the brain (sheer injuries) as it shakes around inside the skull. Microscopic injury throughout the brain is called diffuse axonal injury.
Penetrating trauma, on the other hand, occurs when a bullet, knife, or other object passes through the skull into the brain. Like blunt trauma, gunshot wounds can send shockwaves through the brain as the kinetic energy from the bullet get transferred to the brain. This results in diffuse injury and is commonly fatal. Knife injuries, however, are unique. They don’t send shockwaves, therefore the injury to the brain is localizes to site of the wound. That means that if a knife penetrates the brain but does not damage a major blood vessel (which would cause a stroke), only a relatively small amount of the brain gets damaged. That is not to say that a knife wound to the head is not dangerous; it is. However, the majority of the risk comes from potential injury to important blood vessels. There is no diffuse injury.
The patient seen above, was unlucky because he was stabbed in the head with a knife. However, he was also extremely lucky. The blade missed all of the important blood vessels. In fact, the patient actually walked into the emergency department with the knife buried deep in his skull. He had to be taken to surgery for removal of the knife and is currently convalescing.
During his recovery, he needs to be watched carefully for signs of infection or seizures – common consequences of penetrating trauma. Usually, patients are given prophylactic therapy for both.
For more details, see the Telegraph article.
Errata
Today was match day. Congratulations to all of those who matched in neurosurgery and welcome to the profession. I know that we are very happy with the students who matched at our program. The quality of the applicants this year was outstanding, as always. There are so many qualified individuals that it really is hard to go wrong. The residency is a long but rewarding seven years.
If you are looking for a book that will change the way you look at the world, you might want to check out Moneyball by Michael Lewis. It tells the story of how Billy Beane and Paul DePodesta, management of the Oakland A’s baseball team, revolutionized the sport in the last decade. The most interesting part is the way they did it: they took 100 years of baseball history and tradition and threw it out the window. Instead they reduced baseball to a series of probabilities and mathematical equations. They used hard data to identify not only what the most successful plays are, but also to find the characteristics of the most successful players. Then, they looked for players that fit that model. And, to put it bluntly, they found that the entire major league had been looking for the wrong players. For a few brief years, they were able to produce a highly successful baseball team disproportionate to their payroll.
It really makes you wonder, “How could I improve my life, achievements, etc., if I had better data?”
