Much effort has been put into determining methods to make accurate thickness measurements, especially at elevated temperatures. An accuracy of +/- 0.001 inches is typically noted for commercial ultrasonic thickness gauges and ultrasonic thickness techniques. Codes and standards put limitations on many inspection factors including equipment, calibration tolerance and temperature variations. These factors are important and should be controlled, but unfortunately do not guarantee accurate and repeatable measurements in the field. Most technicians long for a single technique that is best for every situation, unfortunately, there are no 'silver bullets' when it comes to nondestructive testing. This paper will describe and discuss some of the major contributors to measurement error as well as some advantages and limitations of multiple echo techniques and why multiple echo techniques should be more widely utilized for ultrasonic thickness measurements.

Over the past 20 years, the management of intracranial meningiomas has changed. Surgical removal remains the gold standard to which alternative therapies are compared. However, advanced radiation oncology techniques, such as stereotactic radiosurgery and intensity-modulated radiotherapy, have increasingly been applied in the treatment of smalland medium-sized tumors as well as incompletely resected lesions.1,2 Furthermore, as Sughrue et al.4 mention, conservative management of asymptomatic meningiomas is an increasingly viable option for some patients. The overall result is that the population that undergoes microsurgical removal of meningiomas are, on average, older, more likely to have neurological symptoms, and more likely to harbor larger lesions, as compared with patients 20 years ago.3 These characteristics underscore the need for neurosurgeons to be able to accurately assess risks associated with microsurgical resection. The following study by Sughrue et al.4 features a large series of patients and evaluates the rate and types of medical complications in those who have undergone microsurgical removal of meningiomas. The authors included all craniotomies for meningiomas during a 15year period, numbering 834 cases. Overall, the findings are not unexpected, but they do provide valuable insights into the specific risk factors and variables that may lead to postoperative medical complications. The rate of serious medical complications in these patients was low (6.8%), which, in the authors’ estimation, reflects the indolent nature of the disease and the careful selection of surgical candidates. Given the low rate of medical complications in these patients, large studies such as this are necessary to accurately investigate rates of medical and neurological complications. Statistically significant predictors of postoperative medical complications in this study, such as an age > 65 years, hypertension, and 2 or more cardiac medications, are not unexpected. However, it is interesting to note that the strongest predictor of a serious medical complication was a new or worsened postoperative neurological deficit. The explanation offered by the authors that seems most plausible is that in many cases the new neurological deficit (for example, weakness in 1 or more extremities) predisposed a patient to a medical complication (for example, deep vein thrombosis and pulmonary embolus). Given the efficacy of radiosurgery for residual tumor, these data and observations perhaps underscore the notion of conservative resection with postoperative observation or radiation, especially for tumors in locations more difficult to access such as the foramen magnum and petroclival region. In other words, tailoring the goals of resection to minimize neurological complications may help to minimize the risk of serious medical complications. Patients expect and deserve their neurosurgeons to be fully aware of all risks associated with their surgery and to anticipate and intervene appropriately when complications arise. Much of the literature regarding complications from meningioma surgery is devoted to surgical and neurological complications. The authors of this study are to be commended not only for reinforcing the need to be mindful of serious medical complications, but also for observing the association between postoperative neurological and medical complications. Understanding the rates and risk factors for both types of complications can only help to reduce the incidence of potentially devastating outcomes.

The evaporator recycle streams of nuclear waste tanks may contain waste in a chemistry and temperature regime that exceeds the current corrosion control program, which imposes temperature limits to mitigate caustic stress corrosion cracking (CSCC). A review of the recent service history found that two of these A537 carbon steel tanks were operated in highly concentrated hydroxide solution at high temperature. Visual inspections, experimental testing, and a review of the tank service history have shown that CSCC has occurred in uncooled/un-stress relieved tanks of similar construction. Therefore, it appears that the efficacy of stress relief of welding residual stress is the primary corrosion-limiting mechanism. The objective of this experimental program is to test A537 carbon steel small scale welded U-bend specimens and large welded plates (30.48 × 30.38 × 2.54 cm) in a caustic solution with upper bound chemistry (12 M hydroxide and 1 M each of nitrate, nitrite, and aluminate) and temperature (125 °C). These conditions simulate worst-case situations in these nuclear waste tanks. Both as-welded and stress-relieved specimens have been tested. No evidence of stress corrosion cracking was found in the U-bend specimens after 21 days of testing. The large plate test was completed after 12 weeks of immersion in a similar solution at 125 °C except that the aluminate concentration was reduced to 0.3 M. Visual inspection of the plate revealed that stress corrosion cracking had not initiated from the machined crack tips in the weld or in the heat affected zone. NDE ultrasonic testing also confirmed subsurface cracking did not occur. Based on these results, it can be concluded that the environmental condition of these tests was unable to develop stress corrosion cracking within the test periods for the small welded U-bends and for the large plates, which were welded with an identical procedure as used in the construction of the actual nuclear waste tanks in the 1960s. The absence of evidence of stress corrosion cracking and general corrosion in the laboratory-scaled specimens indicate that this type of nuclear waste tank is not susceptible to highly caustic solutions up to 12 M hydroxide at 125 °C when sufficient nitrite inhibitor is present.

Radioactive wastes are confined in 49 underground storage tanks at the Savannah River Site. The tanks are examined by ultrasonic (UT) methods for thinning, pitting, and stress corrosion cracking in order to assess fitness-for-service. During an inspection in 2002, ten cracks were identified on one of the tanks. Given the location of the cracks (i.e., adjacent to welds, weld attachments, and weld repairs), fabrication details (e.g., this tank was not stress-relieved), and the service history the degradation mechanism was stress corrosion cracking. Crack instability calculations utilizing API-579 guidance were performed to show that the combination of expected future service condition hydrostatic and tensile weld residual stresses do not drive any of the identified cracks to instability.The cracks were re-inspected in 2007 to determine if crack growth had occurred. During this re-examination, one indication that was initially reported as a "possible perpendicular crack <25% through wall" in 2002, was clearly shown not to be a crack. Additionally, examination of a new area immediately adjacent to other cracks along a vertical weld revealed three new cracks. It is not known when these new cracks formed as they could very well have been present in 2002 as well. Therefore, a total of twelve cracks were evaluated during the re-examination.Comparison of the crack lengths measured in 2002 and 2007 revealed that crack growth had occurred in four of the nine previously measured cracks. The crack length extension ranged from 0.25 to 1.8 inches. However, in all cases the cracks still remained within the tensile weld residual stress zone (i.e., within two to three inches of the weld). The impact of the cracks that grew on the future service of Tank 15 was reassessed. API-579 crack instability calculations were again performed based on expected future service conditions and trended crack growth rates for the future tank service cycle. The analysis showed that the combined hydrostatic and tensile weld residual stresses do not drive the identified cracks to instability.This tank expected to be decommissioned in the near future. However, if these plans are delayed, it was recommended that a third examination of selected cracks in the tank be performed in 2014.

NEUROSURGERY IN THE future will witness an increasing influx of novel technologies, many of which will be based on developments in the emerging science of nanotechnology. Additionally, the continued trend in medicine toward minimally invasive diagnostic and surgical techniques will be aided by incorporation of applications of nanotechnology. Neurosurgeons of the future must facilitate the development of nanotechnology and nanomedicine in their clinical practice and research efforts to optimize patient benefit and facilitate scientific advancement. The fields of nanotechnology and nanomedicine remain in their infancy. Recently, however, the literature regarding nanoscience has rapidly expanded. This article is the second of two and provides a review of recent nanotechnology research relevant to clinical neurosurgery and neurology. The first article reviewed recent developments and issues in nanotechnology with a particular focus on applications to the neurosciences. This article also discusses current developments in nanotechnology and nanomedicine that may yield applications in neurosurgery in the future. Additional attention is given to other emerging technologies that are not truly nanotechnology, such as microelectromechanical systems, which will influence the future of medicine and neurosurgery. The goal is to provide the reader with a brief outline and description of some of the new developments in nanotechnology that may affect the clinical practice or operative experience of neurosurgeons. Continued innovation in nanotechnology presents novel opportunities for translation to the clinical arena. Neuroscience, neurology, and neurosurgery will be greatly affected by the influx of nanoscience and its applications. Through continued collaboration, physicians, scientists, and engineers will shape the futures of nanomedicine and nanoneurosurgery.

axons of a mouse oculomotor nerve genetically labeled with multiple fluorescent proteins (Fig. 1). It is one of a series of images from a recent article describing a novel method for labeling individual neurons. The original article appeared in Nature (4), and brief summations can also be found in popular science periodicals (5). These images demonstrate the use of a potentially powerful new tool for neuroscientists attempting to construct “connectivity maps,” which depict physical connections and spatial relationships between neural elements. The authors show that enhanced visualization of individual neurons and their processes can be achieved by genetically labeling them with varying combinations of multiple distinct fluorescent colors. These efforts will likely contribute to the larger goal of “connectomics ,” which aims to study neural circuitry by mapping each connection of all neurons in the central nervous system. Current investigations into the connectivity of individual neurons and other neural cells trace their origins to Camillo Golgi and Santiago Ramón y Cajal, who shared the Nobel Prize in Physiology or Medicine in 1906 (2). Tissue staining methods at that time were inadequate for studying neural tissue. This led Golgi to develop a method, which subsequently came to bear his name, for staining neural tissue using silver chromate particles. The “Golgi stain” provided random staining of a small number of cells in their entirety and offered the first method for identifying the paths and connections of individual n e u ro n s a n d t h e i r processes (Fig. 2). Cajal learned this staining technique from Golgi and further refined these methods throughout his career. His studies regarding the mammalian nervous system yielded numerous intricate drawings and sketches that documented his findings using his refined silver stain technique. Cajal’s work resulted in a very different conclusion regarding neural connectivity than his mentor’s. Whereas Golgi postulated that neural tissue was comprised of a continuous web of cells and processes, Cajal determined that the nervous system was comprised of billions of separate, polarized neurons that communicated with each other via unique junctions, later termed synapses. This theory became the basis for the “neuron doctr ine ,” which states that neurons are individual units within the nervous system and are discreet, metabolically distinct cells rather than part of a large meshwork of cells.

NANOTECHNOLOGY AS A science has evolved from notions and speculation to emerge as a prominent combination of science and engineering that stands to impact innumerable aspects of technology. Medicine in general and neurosurgery in particular will benefit greatly in terms of improved diagnostic and therapeutic capabilities. The recent explosion in nanotechnology products, including diverse applications such as beauty products and medical contrast agents, has been accompanied by an ever increasing volume of literature.Recent articles from our institution provided an historical and scientific background of nanotechnology, with a purposeful focus on nanomedicine. Future applications of nanotechnology to neuroscience and neurosurgery were briefly addressed. The present article is the first of two that will further this discussion by providing specific details of current nanotechnology applications and research related to neuroscience and clinical neurosurgery. This article also provides relevant perspective in scale, history, economics, and toxicology. Topics of specific importance to developments or advances of technologies used by neuroscientists and neurosurgeons are presented. In addition, advances in the field of microelectromechanical systems technology are discussed. Although larger than nanoscale, microelectromechanical systems technologies will play an important role in the future of medicine and neurosurgery.The second article will discuss current nanotechnologies that are being, or will be in the near future, incorporated into the armamentarium of the neurosurgeon. The goal of these articles is to keep the neuroscience community abreast of current developments in nanotechnology, nanomedicine, and, in particular, nanoneurosurgery, and to present possibilities for future applications of nanotechnology.As applications of nanotechnology permeate all forms of scientific and medical research, clinical applications will continue to emerge. Physicians of the present and future must take an active role in shaping the design and research of nanotechnologies to ensure maximal clinical relevance and patient benefit.

Intraoperative manipulation to correct scoliotic deformities relies upon spinal instrumentation for stabilization and fusion. However, novel strategies and innovative implant biotechnologies have emerged, applying natural growth and elongation of the immature spine for the treatment of scoliosis in young patients. In this work, we review the principles of growth modulation and the Hueter-Volkmann law as it applies to experimental models of scoliosis formation and correction. Current implant technologies, including shape memory alloy vertebral staples, growing rods, and vertical expandable titanium prosthetic ribs, are explored, with regards to implant design, surgical techniques, and clinical investigations. An exciting area of spinal implant technology is now becoming available to expand the surgical armamentarium for treating severe scoliotic deformity in young patients.

Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California Reprint requests: James B. Elder, M.D., Department of Neurological Surgery, Keck School of Medicine, University of Southern California, 1200 N. State Street, Suite 5046, Los Angeles, CA 90033. Email: [email protected] Received, April 10, 2008. Accepted, April 18, 2008.

STUDY DESIGN:A retrospective, case-control study was conducted to analyze postoperative outcomes in patients who received local anesthetic infusion pumps after lumbar spinal fusion procedures. Data were collected prospectively via nursing protocol and third party assessment, and analyzed retrospectively. OBJECTIVE:To review the safety and efficacy of continuous infusion of local anesthetic into the subfascial aspects of the wound after lumbar fusion surgery for treatment of postoperative pain, and to determine whether other outcome measures such as postoperative nausea and vomiting, ambulation and length of hospitalization were affected by the presence of the device. SUMMARY OF BACKGROUND DATA:Patients who undergo lumbar spine fusion procedures frequently experience significant, debilitating pain related to their surgery. This pain may delay postoperative mobilization, increase length of hospitalization, and require prolonged use of high doses of narcotics. Use of a local anesthetic continuous-infusion pump after surgery may lead to improvements in these outcome variables. METHODS:After posterior lumbar spine fusion procedures, 26 consecutive patients received the ON-Q PainBuster, which infused 0.5% marcaine via an elastomeric pump into the subfascial aspects of the wound. Retrospective analysis compared each of these patients with a case-matched control patient. Data included pain scores and opiate use during the first 5 postoperative days (PODs), length of hospital stay, and complications. Variables such as age, American Society of Anesthesiologists (ASA) physical status, and surgical procedure were similar between matched cases. One patient was excluded because of active heroine abuse. RESULTS:Patients with the ON-Q PainBuster used 41.2% less narcotics on POD 1, 50.1% less on day 2, and 47.1% less on day 3 compared with the control patients. Differences in opiate usage were not statistically significant on POD 4 (45.5% less) and 5 (50.3% less). A lower average pain score was observed among patients with the ON-Q PainBuster on each POD: 39.1% less pain on POD 1, 34.0% on day 2, 45.1% on day 3, 29.5% on day 4, and 43.6% on day 5. No differences were observed in length of hospital stay or complication rate. CONCLUSION:Patients who received the ON-Q PainBuster used less narcotic medications than case-matched patients during the first 3 PODs, and reported lower pain scores during the first 5 PODs. No complications attributable to the device were noted. These results suggest that continuous infusion of local anesthetic into the wound during the immediate postoperative period is a safe and effective technique that results in lower pain scores and narcotic use. Further data may reveal additional benefits such as lower incidence of nausea and vomiting and decreased times to mobility and functional independence.

OBJECTIVE:Several different methodologies for proximal occlusion and retrograde suction decompression of large paraclinoid aneurysms have been reported previously. In this article, we describe the novel use of an endovascular embolectomy device (F.A.S.T. funnel catheter; Genesis Medical Interventional, Inc., Redwood City, CA) for temporary internal carotid artery occlusion and suction decompression of an intracranial aneurysm to facilitate surgical clip ligation. The combination of atraumatic occlusion technology and large lumen size makes this technique safer and easier.CLINICAL PRESENTATION:A 53-year-old woman with progressive headaches underwent computed tomographic angiography, which revealed an unruptured large left paraclinoid aneurysm. Cerebral angiography confirmed the diagnosis. The patient did not tolerate a balloon test occlusion for therapeutic Hunterian internal carotid occlusion. The patient was subsequently taken to the operating room for a craniotomy and clip ligation of the aneurysm.INTERVENTION:A standard left pterional craniotomy was performed with opening of the sylvian fissure and exposure of the left paraclinoid aneurysm. Intraoperative angiography with introduction of a new endovascular embolectomy device was performed. The device was deployed to achieve temporary occlusion of the cervical internal carotid artery, and aspiration through the central lumen allowed for retrograde suction decompression of the aneurysm. Collapse of the aneurysm through this technique permitted visualization of the aneurysmal neck with successful clip ligation.CONCLUSION:A new endovascular embolectomy device can be used to safely perform suction decompression of large paraclinoid aneurysms to facilitate clip ligation.

THE EMERGING FUTURE of cerebral surgery will witness the refined evolution of current techniques, as well as the introduction of numerous novel concepts. Clinical practice and basic science research will benefit greatly from their application. The sum of these efforts will result in continued minimalism and improved accuracy and efficiency of neurosurgical diagnostic and therapeutic methodologies. Initially, the refinement of current technologies will further enhance various aspects of cerebral surgery. Advances in computing power and information technology will speed data acquisition, storage, and transfer. Miniaturization of current devices will impact diverse areas, such as modulation of endoscopy and endovascular techniques. The increased penetrance of surgical technologies such as stereotactic radiosurgery, neuronavigation, intraoperative imaging, and implantable electrodes for neurodegenerative disorders and epilepsy will enhance the knowledge and experience in these areas and facilitate refinements and advances in these technologies. Further into the future, technologies that are currently relatively remote to surgical events will fundamentally alter the complexity and scale at which a neurological disease may be treated or investigated. Seemingly futuristic concepts will become ubiquitous in the daily experience of the neurosurgeon. These include diverse fields such as nanotechnology, virtual reality, and robotics. Ultimately, combining advances in multiple fields will yield progress in diverse realms such as brain tumor therapy, neuromodulation for psychiatric diseases, and neuroprosthetics. Operating room equipment and design will benefit from each of the aforementioned advances. In this work, we discuss new developments in three parts. In Part I, concepts in minimalism important for future cerebral surgery are discussed. These include concrete and abstract ideas in miniaturization, as well as recent and future work in microelectromechanical systems and nanotechnology. Part II presents advances in computational sciences and technological fields dependent on these developments. Future breakthroughs in the components of the "computer," including data storage, electrical circuitry, and computing hardware and techniques, are discussed. Additionally, important concepts in the refinement of virtual environments and the brain-machine interface are presented, as their incorporation into cerebral surgery is closely linked to advances in computing and electronics. Finally, Part III offers insights into the future evolution of surgical and nonsurgical diagnostic and therapeutic modalities that are important for the future cerebral surgeon. A number of topics relevant to cerebral surgery are discussed, including the operative environment, imaging technologies, endoscopy, robotics, neuromodulation, stem cell therapy, radiosurgery, and technical methods of restoration of neural function. Cerebral surgery in the near and distant future will reflect the application of these emerging technologies. As this article indicates, the key to maximizing the impact of these advancements in the clinical arena is continued collaboration between scientists and neurosurgeons, as well as the emergence of a neurosurgeon whose scientific grounding and technical focus are far removed from those of his predecessors.

This article presents an assessment of the power of ideas and their role in initiating change and progress. The enormous potential cascade effect is illustrated by examining the movement of Modernism in the arts. Next, the immense scope and capabilities of the modern scientific endeavor-with robotic space exploration at the scale of 10 meters at one extreme and the wonders of nanoscience at the scale of 10 m at the other-are examined. The attitudes and philosophies of neurological surgery are related to those involved in the Modernist movement and placed on the defined scale of contemporary scientific activity.

Discovery of aging phenomena in the materials of a structure may arise after its design and construction that impact its structural integrity. This condition can be addressed through a demonstration of integrity with the material-specific degraded conditions. Two case studies of development of fracture and crack growth property data, and their application in development of in-service inspection programs for nuclear structures in the defense complex are presented. The first case study covers the development of fracture toughness properties in the form of J-R curves for rolled plate Type 304 stainless steel with Type 308 stainless steel filler in the application to demonstrate the integrity of the reactor tanks of the heavy water production reactors at the Savannah River Site. The fracture properties for the base, weld, and heat-affected zone of the weldments irradiated at low temperatures (110°–150°C) up to 6.4 dpaNRT and 275 appm helium were developed. An expert group provided consensus for application of the irradiated properties for material input to acceptance criteria for ultrasonic examination of the reactor tanks. Dr. Spencer H. Bush played a lead advisory role in this work. The second case study covers the development of fracture toughness for A285 carbon steel in high level radioactive waste tanks. The approach in this case study incorporated a statistical experimental design for material testing to address metallurgical factors important to fracture toughness. Tolerance intervals were constructed to identify the lower bound fracture toughness for material input to flaw disposition through acceptance by analysis.

Neurosurgery: September 2007 - Volume 61 - Issue 3 - p E662 doi: 10.1227/01.NEU.0000290923.01213.93