This month we have 2 major sections of original articles. One relates to work on neoplasms, and the second is concerned with spine and spinal cord issues. The lead articles in each section are devoted to molecular topics, both of which are very interesting. These articles are followed by practical articles. There are the usual case reports that follow.
The article by Zhou et al from China is a superb scientific study and thoughtfully performed. The authors state that a specific gene, EphA2, is found more commonly in low- and high-grade gliomas than in normal brain cells. This gene makes a protein, which is located on the cell membrane. Messenger RNA is an RNA sequence that carries the gene code from the nucleus to the cytoplasm and forms a template on which proteins are made. These proteins then come from a specific gene sequence in the nucleus. Scientists can make a nucleotide sequence, called small interfering RNA (siRNA), which can be the mirror or the messenger gene RNA sequence. The siRNA then blocks the regular messenger RNA and prevents it from being a template to make the specific proteins. Thus, the expression of the gene is blocked because its specific protein cannot be made. The authors used a specific siRNA that blocks the expression of the gene, EphA2. When the EphA2 is blocked in cultured tumor glioblastoma cells, the authors found that the cell produced more caspases—a protein that leads the cell to commit suicide or cell death. When they checked the tumor cells after blocking the EphA2, they found evidence of nuclear fragmentation and chromatin condensation that are found when a cell dies. So, the specific siRNA was able to kill the tumor cells. When they added some chemotherapeutic agents, they found that the combined effect—of both the siRNA and the drug—produced more cell deaths. This work was done “in vitro.” It is a very interesting piece of science as it may show the way to developing more effective therapy to treat glioblastomas. More work “in vivo” needs to be done. Another important part of this work is the understanding that there is a genetic abnormality in glioma cells that can be attacked with success to kill the tumor cell.
Hu et al from China report a very innovative approach, using radiofrequency coagulation to help remove large vascular cerebral tumors. The radiofrequency current, passed to electrodes in the center of the tumor, coagulates the blood and blood vessels to reduce the vascularity of the tumor. I have seen videos of this procedure in China, and it works! The authors have performed an additional 20 or more cases with similar success. This is a very promising idea to me.
Hernesniemi et al from Finland report on their experience with the removal of pineal region masses in 119 patients from 1980 to 2007. The authors used 1 of the 2 operative approaches to the pineal region: the infratentorial supracerebellar route. The surgical anatomy of the region is described well in the article. Almost all patients were operated in the sitting position. The complications were minimal. In Surgical Neurology 1988;29:298-304, my colleagues and I reported the “…3/4 prone operated side down occipital transtentorial approach…” to the pineal region. With that approach, the patient is in the lateral position rotated forward to the 3/4 prone position. The operated side is down, allowing the occipital lobe to fall away from the tentorium and falx. A ventricular drain is placed in the atrium of the lateral ventricle to allow the hemisphere to fall away further and a spinal drain is used to remove more cerebrospinal fluid to allow even more relaxation of the brain. One of the major complications of the occipital transtentorial approach in the past was homonomous hemianopsia from occipital lobe retraction. These steps and position eliminate that complication. With the patient in the horizontal position, 2 surgeons can sit comfortably to do the surgery. For the supracerebellar approach, arm fatigue occurs in the sitting position with the arms extended forward and up to reach the pineal region. Also, the horizontal position avoids the chance of air embolism that is present in the sitting position. Using the 3/4 prone approach, the surgeon sections the tentorium to approach the pineal. With this position, one can visualize the pineal region from the posterior third ventricle to the top of the fourth ventricle, which is covered by cerebellar vermis. If the tumor extends underneath the corpus callosum, then a small section of the corpus can be made to reach that tumor. So, these are the 2 approaches to the pineal region. You should try both and decide which you prefer.
Schiefer et al from the United States report on the Mayo Clinic experience with the surgical removal of epidermoids located in the cerebellopontine angle. The study covers 20 years and 24 patients. What they found was that there was no difference between those who had total or subtotal removal in recurrence. This is a fundamentally important fact for neurosurgeons to know. There is no value in pursuing total removal “to prevent recurrence” while giving the patient any cranial nerve deficit. That approach makes no sense to me. The authors have done a fine job of clarifying this point for our readers.
Lorenzoni et al from Chile report on a series of 103 patients with high-grade gliomas, whom they followed after surgical removal of the lesions. They do not have access to positron emission tomography scanners, neuronavigation systems, functional magnetic resonance, intraoperative magnetic resonance, or other advanced technologies to perform their surgery. What they found is important. The survival of their patients is the same as that reported by others who use sophisticated technology. There are multiple messages here. First, to our own colleagues in the developing world, the conventional surgical approaches for these tumors will produce results as good, if not better, than the results using advanced technology. Second, this tumor will not be cured by surgery or radiation therapy. Chemotherapy and radiation will add only a few months of survival; glioma is a molecular disease. Read comments of Jens Haase after the article on this subject.
In the group of articles on the spine and spinal cord, Ron Pawl provides editorial comments on an article that appeared in the journal, Pain. This article described some newly published work using molecular agents to destroy cells in the dorsal gray matter of the spinal cord resulting in a chemical cordotomy. Is this another example of what the future is for neurosurgery?
The next article by Parr et al from Canada reports on an animal experiment (rats) in which stem cell therapy was used after spinal cord injury to promote spinal cord recovery. The stem cells came from the bone marrow or from neural stem cells (NSC) located around the central canal of the spinal cord. No functional recovery was seen in the animals, and no neurons were found to grow from these stem cells. Some oligodendroglial cells grew from the NSC, suggesting that myelin sheaths were going to be produced in those animals with the NSC treatment. We will see much more of this kind of work in the next decades. Spinal cord injury will be much better understood and treated. Read the comments of Christopher Shields at the end; he leads one of the laboratories working in the area of spinal cord injury research.
Gökhan et al from Turkey tested 3 agents to prevent the inflammatory response and scar formation that occurs after a laminectomy. The authors wanted to see if scarring in the epidural area could be prevented. The agents were more effective than no agent in preventing scar formation. Now the critical issue is will these agents alter the pain response of patients who have less scar formation?
Nancy Epstein, one of the members of our editorial board, has written an article on “Bloodless spinal surgery.” Initially, I thought the article was about techniques to stop blood loss, but it is really about methods to avoid transfusion-associated complications in spinal surgery. The important issue she discusses is removal of the patient's blood either before or at the beginning of surgery and retransfusing it—diluted with colloid or crystalloid—at surgery. The need for transfusions declines significantly using these methods. Still to me, as I see all kinds of spinal and cranial surgery, I am appalled at the disregard surgeons have for bleeding during surgery and for their lack of skill in producing hemostasis. I see bags underneath the head of the patient to catch the blood draining from the operative site. What happened to hemostasis? Careful technique, the use of an irrigating bipolar, (yes, an irrigating bipolar), packing with cotton to allow hemostasis, and a meticulous surgical technique to maintain hemostasis, are all important. Where have such techniques gone? The article of Epstein is important because there are some situations in which there is bleeding and oozing, and her suggestions are excellent in these situations. Yet, first principles are to use meticulous hemostasis.
Palma et al from Italy prospectively studied the outcomes of repeat lumbar disk herniation surgery. The authors find that their outcomes for repeat surgery are 89% good or excellent compared with 95% for the initial surgery. The percentage of poor results for second-time surgery was 2%. The authors did not define the clinical picture for recurrence. Their results for repeat surgery are very good compared to “the retrospectroscope,” or recalled experience. Still, these results seem better than I would have expected.
Hellbusch et al from the United States evaluated the use of one dose of preoperative antibiotics vs preoperative and extended antibiotic use for 7 days after surgery in patients undergoing instrumented lumbar fusions. Surprisingly to the authors, their infection rate was 3% with no significant differences in either protocol. A larger number of patients, more than the 233 (calculated to be about 1400), would be necessary to prove a difference at this low rate of infection. All infections were superficial. So, practically, what should the surgeon do? In the end, the surgeon must balance the use of antibiotics and the incidence of complications from antibiotic use vs the risk of infection. Read the article and decide for yourself.
Cho et al from Taiwan have done a very nice retrospective study on the surgical treatment of their patients with putaminal or thalamic hematomas. Their conclusions make sense to me. Read the Abstract for a quick summary of their work. Their approach is one that many neurosurgeons have adopted over time.
Kawahara et al from Japan have an interesting case report on the evolution of carotid atherosclerotic plaques with a discussion of the known factors leading to their rupture. The cardiology scientific literature has already reported much of this work for the coronary arteries. Molecular and anatomical imaging has allowed us to follow the changes in the plaque morphology and biochemistry. From this information, physicians may be able to tell when it is time to treat a plaque. This is an important article to read. It shows how the evaluation of atherosclerotic plaques will change.
Bassem Yousef Sheikh et al from Saudi Arabia describe the use of a branch of the superficial temporal artery to perform a cerebral angiogram at surgery. Horiuchi et al from Japan apply a similar approach in using the occipital artery to visualize the vertebral basilar circulation.
This month I have an editorial commenting on the financial crisis and its meaning for all of us in and out of medicine.
All of us at Elsevier and Surgical Neurology wish our readers throughout the world a very happy and healthy holiday season and New Year for 2009.
FULL TEXT