This month's issue has a number of very interesting articles covering topics from the prevention of head injury in a large population, a new syndrome found in a large series of patients with tethered cord and associated symptomatic descended cerebellar tonsils and a normal posterior fossa, the presentation of L3 radiculopathy in a series of patients, the genetic causes of aneurysm, virtual reality in preparing for surgery on AVMs, and many others.
Salvarani et al from Brazil report on the reduction in serious head injury after implementing a program in head injury prevention. The authors noted an increase in the use of helmets and seat belts after the education program they started. They also noted an associated reduction in serious head injury, hospital costs, and ICU stays for the head-injured patients. In the early 1990s, Carolyn Ausman introduced the “Think First” head and spinal cord injury program of the AANS/CNS to the Brazilian Society of Neurosurgery at one of its meetings. The Brazilian neurosurgeons then adapted this model to their culture with outstanding results. Prof Kao from Taiwan in his comments writes about a similar effect from an educational program and enforcement of seat belt and helmet use in Taiwan, resulting in a significant reduction in head injuries. Salvarani et al have provided an outstanding study, which indicates what can be done through public education to reduce head and spinal cord injuries in developing and developed countries. This is a must-read article.
In another article from Brazil, Gondim et al report on their experience in treating patients with acromegaly caused by miocroadenomas or intrasellar macroadenomas by the transsphenoidal route. One neurosurgeon specialized in pituitary surgery in a hospital that is a referral center for the surrounding area with 7 million people. The authors had no mortality; surgical remission occurred in 84% of their cases with 2 complications and no CSF leak in their 33 patients with acromegaly. They have presented data that the cost of surgical treatment is less than radiosurgery or medical therapy in a developing country—making surgery in experienced hands the best treatment option in every way for this defined group of tumors. (That conclusion is also true for developed countries.) The implication is that neurosurgeons who specialize will produce better results than those who are not specialized. I agree. This is a superb article with implications for health care everywhere. Also read the Letters to the Editor for further discussion of this topic.
Would you section the filum terminale in patients presenting with a Chiari I deformity (cerebellar tonsils more than 5 mm below the foramen magnum), a normal posterior fossa, and a normal position of the conus medullaris above L1, even with associated symptoms of Chiari I and tethered cord? Well, this controversial question was asked to the pediatric neurosurgical society in 2004, with results indicating “a high level of uncertainty.” For this reason, Milhorat et al from the United States had difficulty getting their extremely well-documented results—in a series of 288 adults and 74 children presenting with precisely these symptoms—published. This study is superbly done and is a model of excellence in clinical evaluation of a “syndrome” and the establishment of objective data and guidelines for treatment of this syndrome. The syndrome occurs in patients with a normal posterior cranial fossa, and in many cases a normal position of the conus at or above L1, presenting with symptoms of Chiari I and the tethered cord syndrome. The best way to read this article is to read the abstract first, then the “Conclusion” at the end, the “Introduction,” and then the “Material and Methods” section. The “Material and Methods” section is key, for it describes in detail how the authors selected the patients and made the quantitative imaging assessments. Next, look at the figures and the tables, which are excellent in providing the data. The “Discussion” summarizes the literature and the obvious criticisms that can be raised by this article and study. By any estimation, this is a superb study that will influence the treatment of this “syndrome” significantly. The authors' observations are extremely well-documented. The improvement by sectioning the filum terminale measured by shortening of an elongated brain stem, rising of the position of the brain stem and fourth ventricle, ascent of the conus, improvement in syrinx appearance, and disappearance of the tethered cord symptoms are overwhelming. This is a first-class piece of work.
Hirabayashi et al from Japan report on their retrospective study of 17 patients with an L3 radiculopathy. The patients presented with thigh, groin, and knee pain, which could confuse the neurosurgeon as indicating knee or hip pain. Fifty-three percent (53%) had a sensory disturbance over the L3 dermatome and 12% had quadriceps weakness. Of the 17 patients, 10 responded to lidocaine and dexamethasone injection around the L3 root, whereas 6 patients required surgery–all 17 having good results. The average age of the patients was 76 years, making this a disease of older adults. Read Pawl's comments at the end.
D'Agostino et al from the United States studied the results of using Matrix 360° coils for aneurysm obliteration. These coils were introduced to provide a higher rate of aneurysm obliteration. The authors found that the initial obliteration rate using these coils was 80%. However, the recanalization rate at 6 months was 22% and at 12 months, 37%. Thus, these co polymer-coated platinum coils had the same results as noncoated platinum coils after 12 months. The authors provide some evidence that the coating on the coils disappears after 6 weeks, leaving less densely packed platinum coils and recanalization. Matrix coils do not appear to have an advantage over bare platinum coils.
Joo et al from Korea studied a population of Koreans with intracranial aneurysms and controls without aneurysms to determine if a genetic abnormality in patients with aneurysms could be found in the Koreans as it had been discovered in the Japanese and German populations. On chromosome 7, there is a collagen gene that may have some mutations or substitutions that can lead to aneurysm formation. Those mutations can be in the molecular sequence in a single nucleotide in a DNA sequence. This “mutation” can alter the transcription of the message from the gene to the cytoplasm and protein produced to result in a collagen defect. As was found in Japanese and German subjects, there was a tendency for one type of genetic polymorphism to be associated with intracranial aneurysms in the Koreans. They did not find any relationship between a second polymorphism and aneurysmal formation. Relating genetic abnormalities to aneurysmal formation is not easy, as Nimelä et al from Finland describe in the comments at the end. But yet, there is a genetic basis for aneurysmal formation that may have different expression (penetrance) in different populations, or be part of an as-yet-undetermined genetic sequence leading to aneurysmal formation.
Majumdar et al from India developed a method to separate the anaplastic grade III oligodendrogliomas from the more stable, grade II, form of the tumor. The authors state that neuropathologists make the diagnosis of oligodendrogliomas more commonly because of the recognized criteria for the diagnosis. For this reason, oligos are becoming a more common form of glioma, representing 25% of all gliomas. Still, it is difficult to differentiate the anaplastic grade III oligos from the less active grade II oligos histologically. This information is important in diagnosis and treatment, as oligos are more sensitive to chemotherapy. Using the MIB-LI, or labeling index (LI), the authors identified the cells in the dividing phase and then correlated that information with the histology. The LI uses an antibody to identify the Ki-67 antigen produced by dividing cells. This antigen-antibody complex can be identified in histologic specimens histologically. The authors also used antibodies to identify the cells in which platelet-derived growth factor (PDGF) was present. Platelet-derived growth factor is believed to have important influence on the proliferation and growth of oligodendrogliomas. The authors found that the LI correlated with the tumor grade, and even identified tumor cells that were lower-grade oligos that had a high LI. So, the LI can be used to determine the proliferative activity of the oligo. Similarly, the PDGF expression was related to the LI, suggesting that the PDGF pathway would be used as a molecular marker for targeted therapy.
Sade et al from the United States have analyzed 58 patients with petrous meningiomas around the internal auditory canal. They divided the tumors anatomically into posterior (to the internal auditory canal), ventral, and superior groups. They found that the ventral tumors had a more fibrous histology than the others. To me, the critical part of this article was that the postoperative complications in removing the ventral tumors were much higher than with the other tumors. CSF leak was more common in this group. To reach these tumors, the surgeon must operate between cranial nerves 5, 7, 8, 9, and 10. This is dangerous territory, in my opinion. It is hard for me to see the justification in exposing patients to increased surgical risk in removing these tumors. Any of these cranial nerve deficits are significant—particularly 9 and 10. Subtotal removal and radiation would seem to be a better choice.
Horiuchi et al from Japan report a nice technical approach to distal anterior cerebral artery aneurysm. By turning the head 45° and flexing it to the side contralateral to the artery with the aneurysm, the authors can approach the aneurysm with minimal retraction of the contralateral hemisphere that falls away to allow an approach to the aneurysm. Read the article and look at the pictures for a good idea of what they are proposing. This is a nice technical article from Matsumoto, the center in Japan that Professor Sugita and his students Professors Kobyashi and Hongo made famous, and follows the tradition of excellent technical thought in neurosurgery from that group.
Wong et al from Singapore report on the use of a 3-dimensional virtual reality imaging simulation system for the preoperative understanding of the anatomy to be encountered during the removal of AVMs. Wu and Zhou from Shanghai comment on their experience with this technology in nearly 100 patients. Both find this technology helpful in performing virtual surgery before the actual procedure. This is the way of the future.
Iannotti et al from the United States report on the rapid identification of an organism using genetic technology in a patient with a brain abscess. This is a terrific medical advance in the rapid identification of microorganisms. Read Cone's comments at the end for a viewpoint from an infectious disease specialist.
Read Mel Cheatham's “Profiles in Volunteerism” for another inspiring story of a neurosurgeon “giving back” to help others.
Haase and Boisen from Denmark have written an excellent editorial challenging the classic concepts of resident education that began 100 years ago. They recommend cognitive and psychomotor testing, physical endurance, sensory, and perceptual assessment–all of which are critical to becoming a good neurosurgeon. They suggest that we have 2 methods of learning: one, the striatal system (left brain), and the other, the hippocampal, or right brain, memory systems. We test our residents' left brain function with written and verbal tests, but do little with the experiential, conceptual, and emotionally-based right brain learning. They state adding hours to resident training is meaningless unless we have a plan for those hours. They are right. They argue for virtual reality training (as the previous article by Wong reports) to perfect technical expertise. In his comments, Long supports competency-based learning, a position he took long ago that is now being accepted. Haase and Boisen have stimulated us to “think differently” (an Apple logo), something which is difficult for many to do. Change is not easy, but it is inevitable. I have heard many complaints about the reduction in resident hours, but few have creatively responded to the need to adapt our educational systems to the 21st century. It is way past time to change.
In keeping with the journal's policy of being open to all opinions, we are publishing some Letters to the Editor that present alternative opinions to some of those previously expressed.
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