Showing papers in "Neurosurgery in 2010"

Transcranial magnetic resonance imaging- guided focused ultrasound surgery of brain tumors: initial findings in 3 patients.

Abstract: Objective This work evaluated the clinical feasibility of transcranial MRI-guided focused ultrasound surgery (TcMRgFUS).

A supplementary grading scale for selecting patients with brain arteriovenous malformations for surgery.

Abstract: Objective Patient age, hemorrhagic presentation, nidal diffuseness, and deep perforating artery supply are important factors when selecting patients with brain arteriovenous malformations for surgery. We hypothesized that these factors outside of the Spetzler-Martin grading system could be combined into a simple, supplementary grading system that would accurately predict neurological outcome and refine patient selection.

Is Preoperative Functional Magnetic Resonance Imaging Reliable for Language Areas Mapping in Brain Tumor Surgery? Review of Language Functional Magnetic Resonance Imaging and Direct Cortical Stimulation Correlation Studies

Abstract: Objective Language functional magnetic resonance imaging (fMRI) has been used extensively in the past decade for both clinical and research purposes. Its integration in the preoperative imaging assessment of brain lesions involving eloquent areas is progressively more diffused in neurosurgical practice. Nevertheless, the reliability of language fMRI is unclear. To understand the reliability of preoperative language fMRI in patients operated on for brain tumors, the surgical studies that compared language fMRI with direct cortical stimulation (DCS) were reviewed. Methods Articles comparing language fMRI with DCS of language areas were reviewed with attention to the lesion pathology, the magnetic field, the language tasks used pre- and intraoperatively, and the validation modalities adopted to establish the reliability of language fMRI. We tried to explore the effectiveness of language fMRI in gliomas. Results Nine language brain mapping studies compared the findings of fMRI with those of DCS. The studies are not homogeneous for tumor types, magnetic fields, pre- and intraoperative language tasks, intraoperative matching criteria, and results. Sensitivity and specificity were calculated in 5 studies (respectively ranging from 59% to 100% and from 0% to 97%). Conclusion The contradictory results of these studies do not allow consideration of language fMRI as an alternative tool to DCS in brain lesions located in language areas, especially in gliomas because of the pattern of growth of these tumors. However, language fMRI conducted with high magnet fields is a promising brain mapping tool that must be validated by DCS in methodological robust studies.

Burst spinal cord stimulation: toward paresthesia-free pain suppression.

Abstract: INTRODUCTION: Spinal cord stimulation is commonly used for neuropathic pain modulation. The major side effect is the onset of paresthesia. The authors describe a new stimulation design that suppresses pain as well as, or even better than, the currently used stimulation, but without creating paresthesia. METHODS: A spinal cord electrode (Lamitrode) for neuropathic pain was implanted in 12 2 patients via laminectomy: 4 at the C2 level and 7 at the T8-T9 level for cervicobrachialgia and lumboischialgia, respectively (1 at T11 at another center). During external stimulation, the patients received the classic tonic stimulation (40 or 50 Hz) and the new burst stimulation (40-Hz burst with 5 spikes at 500 Hz per burst). RESULTS: Pain scores were measured using a visual analog scale and the McGill Short Form preoperatively and during tonic and burst stimulation. Paresthesia was scored as present or not present. Burst stimulation was significantly better for pain suppression, by both the visual analog scale score and the McGill Short Form score. Paresthesia was present in 92% of patients during tonic stimulation, and in only 17% during burst stimulation. Average follow-up was 20.5 months. CONCLUSION:The authors present a new method of spinal cord stimulation using bursts that suppress neuropathic pain without the mandatory paresthesia. Pain suppression seems as good as or potentially better than that achieved with the currently used stimu - lation. Average follow-up after nearly 2 years (20.5 months) suggests that this stimulation design is stable.

A comprehensive review of the safety profile of bone morphogenetic protein in spine surgery.

Abstract: WE REVIEW OUR current understanding of the development and potential clinical applications of bone morphogenetic protein (BMP) in spine surgery. We also review the evidence for adverse events associated with the use of BMP and suggest potential reasons for these events and means of complication avoidance. Bone morphogenetic protein 2 (rhBMP-2) is approved by the Food and Drug Administration for anterior lumbar interbody fusion; rhBMP-7, on the other hand, is approved for long bone defects and has received a humanitarian device exemption for revision posterolateral lumbar operations and recalcitrant long bone unions. Nevertheless, "off-label" use in various spinal procedures has been reported and is increasing in frequency. Specific guidelines for rhBMP-2 and rhBMP-7 use are lacking because of the limited availability of randomized controlled clinical trials and its diverse use in many spinal applications. Mechanisms of delivery, carrier type, graft position, surgical location, and variations in BMP concentration may differ from one surgery to the next. Adverse events linked to either rhBMP-2 or rhBMP-7 use include ectopic bone formation, bone resorption or remodeling at the graft site, hematoma, neck swelling, and painful seroma. Other potential theoretical concerns include carcinogenicity and teratogenic effects. In this review, we provide the reader with a historical perspective on BMP, current and past research to support its use in spinal procedures, and a critical analysis of the complications reported thus far.

Awake mapping optimizes the extent of resection for low-grade gliomas in eloquent areas.

Abstract: Background Awake craniotomy with intraoperative electrical mapping is a reliable method to minimize the risk of permanent deficit during surgery for low-grade glioma located within eloquent areas classically considered inoperable. However, it could be argued that preservation of functional sites might lead to a lesser degree of tumor removal. To the best of our knowledge, the extent of resection has never been directly compared between traditional and awake procedures. Objective We report for the first time a series of patients who underwent 2 consecutive surgeries without and with awake mapping. Methods Nine patients underwent surgery for a low-grade glioma in functional sites under general anesthesia in other institutions. The resection was subtotal in 3 cases and partial in 6 cases. There was a postoperative worsening in 3 cases. We performed a second surgery in the awake condition with intraoperative electrostimulation. The resection was performed according to functional boundaries at both the cortical and subcortical levels. Results Postoperative magnetic resonance imaging showed that the resection was complete in 5 cases and subtotal in 4 cases (no partial removal) and that it was improved in all cases compared with the first surgery (P = .04). There was no permanent neurological worsening. Three patients improved compared with the presurgical status. All patients returned to normal professional and social lives. Conclusion Our results demonstrate that awake surgery, known to preserve the quality of life in patients with low-grade glioma, is also able to significantly improve the extent of resection for lesions located in functional regions.

Diagnostic intracranial pressure monitoring and surgical management in idiopathic normal pressure hydrocephalus: a 6-year review of 214 patients.

Abstract: Objective To review our experience of managing idiopathic normal pressure hydrocephalus (iNPH) during the 6-year period from 2002 to 2007, when intracranial pressure (ICP) monitoring was part of the diagnostic workup. Methods The review includes all iNPH patients undergoing diagnostic ICP monitoring during the years 2002 to 2007. Clinical grading was done prospectively using a normal pressure hydrocephalus (NPH) grading scale (scores from 3 to 15). The selection of patients for surgery was based on clinical symptoms, enlarged cerebral ventricles, and findings on ICP monitoring. The median follow-up time was 2 years (range, 0.3-6 years). Both static ICP and pulsatile ICP were analyzed. Results A total of 214 patients underwent the diagnostic workup, of whom 131 went on to surgery. Although 1 patient died shortly after treatment, 103 of the 130 patients (79%) improved clinically. This improvement lasted throughout the observation period. The static ICP observed during ICP monitoring was a poor predictor of the response to surgery. In contrast, among 109 of 130 patients with increased ICP pulsatility (ie, ICP wave amplitude >4 mm Hg on average and >5 mm Hg in >10% of recording time), 101 (93%) were responders (ie, increase in the NPH score of >2). Correspondingly, only 2 of 21 (10%) without increased ICP pulsatility were responders. Superficial wound infection was the only complication of ICP monitoring and occurred in 4 (2%) patients. Conclusion Surgical results in iNPH were good with almost 80% of patients improving after treatment. The data indicate that improvement after surgery can be anticipated in 9 of 10 iNPH patients with abnormal ICP pulsatility, but in only 1 of 10 with normal ICP pulsatility. Diagnostic ICP monitoring had a low complication rate.

True incidence of vestibular schwannoma

Abstract: Background The incidence of diagnosed sporadic unilateral vestibular schwannomas (VS) has increased, due primarily to more widespread access to magnetic resonance imaging. Objective To present updated epidemiological data on VS incidence, as well as patient age, hearing acuity, tumor size, and localization at diagnosis for the last 4 decades in an unselected population, with emphasis on developments in recent years. Methods From 1976 to 2008, 2283 new cases of VS were diagnosed and registered in a national database covering 5.0 to 5.5 million inhabitants. Incidence during the period, patient sex and age, data on hearing (pure tone average and speech discrimination), and tumor size at diagnosis were retrieved from the database. Results The incidence increased from 3.1 diagnosed VS per million per year in 1976 to a peak of 22.8 VS per million per year in 2004, which was followed by a decrease to 19.4 VS per million per year in 2008. Mean tumor size at diagnosis decreased from 30 mm in 1979 to 10 mm in 2008, whereas hearing acuity at diagnosis has improved over the years. Conclusion After a steady increase over the last 4 decades, the incidence of vestibular schwannomas appears to have peaked and decreased in recent years, stabilizing at about 19 tumors per million per year. Whereas the sex ratio and age at diagnosis have remained grossly unchanged over the years, hearing has improved, and tumor size has decreased considerably.

An assessment of current brain targets for deep brain stimulation surgery with susceptibility-weighted imaging at 7 tesla.

Abstract: Deep brain stimulation (DBS) surgery is used for the treatment of patients with movement disorders, including Parkinson disease, essential tremor, and dystonia. With the recent US Food and Drug Administration (FDA) approval of DBS for obsessive-compulsive disorder and the likelihood of FDA approval for the treatment of epilepsy, the indications for DBS are rapidly increasing. To date, > 75 000 patients worldwide have undergone DBS surgery, and this number is expected to increase significantly. The success of this surgical procedure is critically dependent on the precise placement of the DBS electrode into the brain target structure of interest. To date, most DBS surgeries have relied on a procedure that involves first an indirect targeting method in which normalized atlas-derived diagrams using set distances from the line connecting the anterior and posterior commissures1,2 are superimposed on a patient's brain magnetic resonance imaging (MRI) scan and approximate distances and coordinates are used for target localization. Indirect targeting can then be modified by anatomic information derived from the particular patient's MRI scan. However, no consensus exists about how best to normalize atlas-derived coordinates to a specific patient's brain3; significant variability exists in the location of thalamic and basal ganglia nuclei in humans4-7; and the target structures are small, measuring < 10 mm in most dimensions.7 All these factors lead to targeting errors in the operating room. Furthermore, current clinical imaging methods are not always sufficiently accurate for placing a DBS electrode and do not allow visualization of nuclei within the thalamus, the division between the lateral and medial segments of globus pallidus (GP) interna (GPi), or even a clear differentiation of the subthalamic nucleus (STN) from the adjacent substantia nigra (SN), distinctions that are critical to optimal electrode placement. As a result, multiple passes with microelectrodes through the brain are performed to refine and confirm the DBS electrode location within the target of interest. Although providing critical information about regional neurophysiology and thus the optimal location for the DBS electrode, these microelectrode recordings carry a risk of hemorrhage and require active patient participation during the procedure. An alternative approach might be surgery based on improving the visualization of the target structure.1,4,8,9 Currently, however, inadequate image resolution and contrast preclude the use of an anatomic imaging-based targeting method for structures as Vim (ventralis intermedius) or for optimally resolving STN from SN. If anatomic imaging-based targeting methods could be improved, the accuracy of target identification on MRI would increase, allowing more accurate selection of the anatomic target. Given recent advances in medical imaging, especially the advent of high-field-strength imaging techniques, our objective was to develop a new approach for the visualization of DBS targets that are FDA approved for the treatment of movement disorders. Using a state-of-the-art high-field (7-T) MRI scanner and capitalizing on the high resolution and enhanced image contrast afforded by high-field MRI, in conjunction with the use of susceptibility-weighted imaging (SWI)10,11 for enhancing MRI contrast, we set out to improve the in vivo detection of DBS target structures. Ultimately, the methods developed here, in addition to improving DBS surgery, will be advantageous for use in a wide range of neurosurgical procedures that could similarly benefit from direct visualization of small, low-contrast brain structures or abnormalities.

Smoking cessation and weight loss after chronic deep brain stimulation of the nucleus accumbens: therapeutic and research implications: case report.

Abstract: Objective Smoking and overeating are compulsory habits that are difficult to stop. Several studies have shown involvement of the nucleus accumbens in these and other addictive behaviors. In this case report, we describe a patient who quit smoking and lost weight without any effort, and we review the underlying mechanisms of action. Clinical presentation A 47-year-old woman presented with chronic treatment-refractory obsessive-compulsive disorder, nicotine dependence, and obesity. Intervention The patient was treated with deep brain stimulation of the nucleus accumbens for obsessive-compulsive disorder. Unintended, effortless, and simultaneous smoking cessation and weight loss were observed. Conclusion This study supports the idea of compulsivity with common circuitry in the processing of diverse rewards and suggests that deep brain stimulation of the nucleus accumbens could be a possible treatment of patients with a dependency not responding to currently available treatments.

Racial, ethnic, and socioeconomic disparities in patient outcomes after craniotomy for tumor in adult patients in the United States, 1988-2004

Abstract: OBJECTIVE: Racial disparities in American health care outcomes are well documented. We investigated racial disparities in hospital mortality and adverse discharge disposition after brain tumor craniotomies performed in the United States from 1988 to 2004. We explored potential explanations for the disparities. METHODS: The data source was the Nationwide Inpatient Sample. We used multivariate ordinal logistic regression corrected for clustering by hospital and adjusted for age, sex, primary payer for care, income in postal code of residence, geographic region, admission type and source, medical comorbidity, treatment year, hospital case volume, and disease-specific factors. Random-effects pooling was also used. RESULTS: A total of 99 665 craniotomies were studied. Hospital mortality and adverse discharge disposition (any discharge other than directly home) were more likely in black patients than others for all tumor types. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) for blacks were: hospital craniotomy mortality (OR, 1.64; 95% CI, 1.32-2.03; P < .001), and adverse discharge disposition (OR, 1.43; 95% CI, 1.31-1.56; P < .001). Medicaid patients had higher mortality, while private-pay patients had lower mortality. Hospital annual case volume was lower for black and Hispanic patients and for those with Medicaid as the primary payer in pooled analyses, whereas patients with private insurance received care at higher-volume hospitals. Black patients generally presented with higher disease severity, including more emergency or urgent admissions (OR,1.71; 95% CI, 1.54-1.89; P < .001); more hemiparesis and hemiplegia for primary tumors, meningiomas, and metastases (P < .04 for all); and more hydrocephalus for acoustic neuromas (P= .1). CONCLUSION: Black patients died more often or had an adverse discharge disposition after tumor craniotomies in the United States in the period studied (1988-2004). Blacks had more severe disease at presentation and were treated at lower-volume hospitals for surgery. Other socially defined patient groups also showed disparities in access and outcomes of care.

Extensions of the sphenoid sinus: a new classification.

Abstract: Objective The transsphenoidal approach has been extended in recent years from tumors of the sellar region to lesions involving other areas bordering the sphenoid sinus including the cavernous sinus, Meckel's cave, middle cranial fossa, planum sphenoidal, suprasellar region, and clivus. The goal of this study was to examine various pneumatized extensions of the sphenoid sinus that may facilitate extended approaches directed through the sinus. Methods The sphenoid sinus and its surrounding structures were examined in 18 cadaver heads, and the results were correlated with the findings from 100 computed tomography images of the sinus. The sellar type of the sphenoid sinus in which the pneumatization extended beyond the anterior sellar wall was further classified according to the various extensions of the sinus. Results The sellar type of the sphenoid sinus was classified into the following 6 basic types based on the direction of pneumatization: sphenoid body, lateral, clival, lesser wing, anterior, and combined. The recesses and prominences, formed by pneumatization of the sinus, act as "windows" opening from the sinus in different areas of the cranial base and may facilitate minimally invasive access to lesions in the corresponding areas. Conclusion The variations in the extensions of pneumatization of the sphenoid sinus may facilitate entry into areas bordering the sphenoid sinus and play a role in the selection of a surgical approach to lesions bordering the sinus.

Simulation in Neurosurgery: A Review of Computer-Based Simulation Environments and Their Surgical Applications

Abstract: BACKGROUND: Computer-based surgical simulators create a no-risk virtual environment where surgeons can develop and refine skills through harmless repetition. These applications may be of particular benefit to neurosurgeons, as the vulnerability of nervous tissue limits the margin for error. The rapid progression of computer-processing capabilities in recent years has led to the development of more sophisticated and realistic neurosurgery simulators. OBJECTIVE: To catalogue the most salient of these advances and characterize our current effort to create a spine surgery simulator. METHODS: An extensive search of the databases Ovid-MEDLINE, PubMed, and Google Scholar was conducted. Search terms included, but were not limited to: neurosurgery combined with simulation, virtual reality, haptics, and 3-dimensional imaging. RESULTS: A survey of the literature reveals that surgical simulators are evolving from platforms used for preoperative planning and anatomic education into programs that aim to simulate essential components of key neurosurgical procedures. This evolution is predicated upon the advancement of 3 main components of simulation: graphics/ volume rendering, model behavior/tissue deformation, and haptic feedback. CONCLUSION: The computational burden created by the integration of these complex components often limits the fluidity of real-time interactive simulators. Although haptic interfaces have become increasingly sophisticated, the production of realistic tactile sensory feedback remains a formidable and costly challenge. The rate of future progress may be contingent upon international collaboration between research groups and the establishment of common simulation platforms. Given current limitations, the most potential for growth lies in the innovative design of models that expand the procedural applications of neurosurgery simulation environments.

Transorbital neuroendoscopic surgery.

Abstract: Background Transorbital neuroendoscopic surgery (TONES) pathways attempt to address some of the technical challenges of accessing laterally placed anterior skull base lesions or paramedian lesions that cross neurovascular structures. TONES approaches allow simultaneous coplanar visualization and working space above and below the skull base. Objective To present an anatomic study, a description of the surgical techniques, and an analysis of the safety and efficacy of 20 consecutive procedures using TONES for a variety of pathological conditions. Methods Sixteen patients underwent 20 TONES procedures for anterior skull base pathology, including repair of cerebrospinal leak, optic nerve decompression, repair of cranial base fractures, and removal of 3 skull base tumors. Ten patients were male, and 6 were female. The mean age at presentation was 44 years. Follow-up was 6 to 18 months with a mean of 9 months. Results There were no significant complications or treatment failures in any of the 20 procedures. A variety of pathological conditions were treated, including cerebrospinal fluid leaks, fractures, mass lesions, and tumors. The TONES approach provided up to 4 separate access ports with ample exposure for manipulation and correction of the pathology. Conclusion This anatomic and prospective outcome study demonstrates that TONES provides safe and effective coplanar endoscopic access to the anterior and middle cranial base. These novel TONES approaches may be added to the wide range of published minimally invasive armamentarium when approaching challenging skull base pathology.

Very Late Thrombosis of a Pipeline Embolization Device Construct: Case Report

Abstract: Background The Pipeline embolization device (PED) is a new endoluminal construct designed to exclude aneurysms from the parent cerebrovasculature. We report the very late (>1 year) thrombosis of a PED construct placed for the treatment of a left vertebral aneurysm. Clinical presentation A patient with an occluded right vertebral artery and a large, fusiform intracranial left vertebral artery aneurysm was treated with PED and coil reconstruction. A durable, complete occlusion of the aneurysm was confirmed with control angiography at 1 year. The patient remained neurologically normal for 23 months until he experienced a transient visual disturbance followed weeks later by a minor brainstem stroke. Intervention Imaging evaluation showed thrombosis of the PED construct with complete occlusion of the left vertebral artery. After this stroke, he was initially treated with dual antiplatelet therapy and was then converted to warfarin. The patient remained neurologically stable for 5 months until he experienced progressive basilar thrombosis that ultimately resulted in a fatal stroke. Conclusion The PED represents a promising new endovascular technology for the treatment of cerebral aneurysms; however, as an investigational device, long-term follow-up data are sparse at this point. The etiology of the very late thrombosis of the PED construct in this case remains unknown; however, this report underscores the need for a continued, careful systematic evaluation and close long-term follow-up of treated patients.

Direct posterior reduction and fixation for the treatment of basilar invagination with atlantoaxial dislocation.

Abstract: Objective To report the surgical technique and clinical results for the treatment of basilar invagination (BI) with atlantoaxial dislocation (AAD) by direct posterior reduction and fixation using intraoperative distraction between the occiput and C2 pedicle screws. Methods From May 2004 to June 2008, 29 patients who had BI with AAD were surgically treated in our department. Pre- and postoperative dynamic cervical x-rays, computed tomographic scans, and 3-dimensional reconstruction views were performed to assess the degree of dislocation. Ventral compression of the cervicomedullary junction was evaluated by magnetic resonance imaging. For all patients, reduction of the AAD was conducted by intraoperative distraction between the occiput and C2 pedicle screws using a direct posterior approach. Results Follow-up ranged from 6 to 50 months in 28 patients. Clinical symptoms improved in 26 patients (92.9%) and were stable in 2 patients (7.1%) without postoperative deterioration. Radiologically, complete or more than 50% reduction was achieved in 27 of 28 patients (96.4%). In 1 patient, the reduction was less than 50% because the direction of the facets on 1 side of the C1-C2 joint was vertically oriented, instead of horizontal. Overall, good decompression and bone fusion were shown on postoperative magnetic resonance imaging, computed tomography, or x-ray scans for all patients. There was 1 death in the series because of basilar artery thrombosis 1 week after the operation. Conclusion The direct posterior distraction technique between occiput and C2 pedicle screws is an effective, simple, fast, and safe method for the treatment of BI with AAD. Transoral odontoidectomy and cervical traction for the treatment of BI with AAD should be reconsidered.

Clinical outcomes using modest intravascular hypothermia after acute cervical spinal cord injury.

Abstract: BACKGROUND: Although a number of neuroprotective strategies have been tested after spinal cord injury (SCI), no treatments have been established as a standard of care. OBJECTIVE: We report the clinical outcomes at 1-year median follow-up, using endovascular hypothermia after SCI and a detailed analysis of the complications. METHODS: We performed a retrospective analysis of American Spinal Injury Association and International Medical Society of Paraplegia Impairment Scale (AIS) scores and complications in 14 patients with SCI presenting with a complete cervical SCI (AIS A). All patients were treated with 48 hours of modest (33 degrees C) intravascular hypothermia. The comparison group was composed of 14 age- and injury-matched subjects treated at the same institution. RESULTS: Six of the 14 cooled patients (42.8%) were incomplete at final follow-up (50.2 [9.7] weeks). Three patients improved to AIS B, 2 patients improved to AIS C, and 1 patient improved to AIS D. Complications were predominantly respiratory and infectious in nature. However, in the control group, a similar number of complications was observed. Adverse events such as coagulopathy, deep venous thrombosis, and pulmonary embolism were not seen in the patients undergoing hypothermia. CONCLUSION: This study is the first phase 1 clinical trial on the safety and outcome with the use of endovascular hypothermia in the treatment of acute cervical SCI. In this small cohort of patients with SCI, complication rates were similar to those of normothermic patients with an associated AIS A conversion rate of 42.8%.

Novel bypass surgery for moyamoya disease using pericranial flap: its impacts on cerebral hemodynamics and long-term outcome.

Abstract: Objective We reviewed our 11-year experience with a novel bypass procedure, superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis and encephalo-duro-myo-arterio-pericranio-synangiosis (EDMAPS), for moyamoya disease regarding cerebral hemodynamics and long-term outcome. Methods This prospective study included 75 patients with moyamoya disease, including 28 children and 47 adults. We performed STA-MCA anastomosis and EDMAPS on 123 hemispheres of 75 patients. In addition to conventional STA-MCA anastomosis and indirect bypass for the MCA territory, the medial frontal lobe was revascularized using the frontal pericranial flap through medial frontal craniotomy. Surgical results were analyzed with magnetic resonance imaging, cerebral angiography, and single-photon emission computed tomography/positron emission tomography. Results Overall incidences of mortality and morbidity were 0% and 5.7%, respectively. The annual risk of cerebrovascular events during the follow-up periods was very low: 0% in pediatric patients and 0.4% in adults over approximately 67 months. Postoperative cerebral angiography showed that the pericranial flap functioned well as donor tissue for indirect bypass, especially in pediatric patients. Follow-up single-photon emission computed tomography/positron emission tomography studies revealed that cerebral blood flow and its reactivity to acetazolamide markedly improved in both the MCA and anterior cerebral artery territories. Conclusion These findings strongly suggest that STA-MCA anastomosis and EDMAPS using a frontal pericranial flap is a safe and effective surgical procedure to further improve the long-term prognosis in moyamoya disease by improving cerebral hemodynamics in both the MCA and anterior cerebral artery territories.

T1/T2 matching to differentiate tumor growth from radiation effects after stereotactic radiosurgery.

Abstract: OBJECTIVE: We define magnetic resonance imaging (MRI) and clinical criteria that differentiate radiation effect (RE) from tumor progression after stereotactic radiosurgery (SRS). METHODS: We correlated postoperative imaging and histopathological data in 68 patients who underwent delayed resection of a brain metastasis after SRS. Surgical resection was required in these patients because of clinical and imaging evidence of lesion progression 0.3 to 27.7 months after SRS. At the time of SRS, the median target volume was 7.1 mL (range, 0.5-26 mL), which increased to 14 mL (range, 1.3-81 mL) at the time of surgery. After initial SRS, routine contrast-enhanced MRI was used to assess tumor response and to detect potential adverse radiation effects. We retrospectively correlated these serial MRIs with the postoperative histopathology to determine if any routine MRI features might differentiate tumor progression from RE. RESULTS: The median time from SRS to surgical resection was 6.9 months (range, 0.3-27.7 months). A shorter interval from SRS to resection was associated with a higher rate of tumor recurrence (P = .014). A correspondence between the contrast-enhanced volume on T1-weighted images and the low signal-defined lesion margin on T2-weighted images ("T1/T2 match") was associated with tumor progression at histopathology (P < .0001). Lack of a clear and defined lesion margin on T2-weighted images compared to the margin of contrast uptake on T1-weighted images ("T1/T2 mismatch") was significantly associated with a higher rate of RE in pathological specimens (P < .0001). The sensitivity of the T1/T2 mismatch in identifying RE was 83.3%, and the specificity was 91.1 %. CONCLUSIONS: We found that time to progression and T1 /T2 mismatch were able to differentiate tumor progression from RE in most patients. When REs are suspected, surgery may not be necessary if patients respond to conservative measures. When tumor progression is suspected, resection or repeat radiosurgery can be effective, depending on the degree of mass effect.

Developing an Articular Cartilage Decellularization Process Toward Facet Joint Cartilage Replacement

Abstract: OBJECTIVE: The facet joint has been identified as a significant source of morbidity in lower back pain. In general, treatments have focused on reducing the pain associated with facet joint osteoarthritis, and no treatments have targeted the development of a replacement tissue for arthritic facet articular cartilage. Therefore, the objective of this study was to develop a nonimmunogenic decellularized articular cartilage replacement tissue while maintaining functional properties similar to native facet cartilage tissue. METHODS: In vitro testing was performed on bovine articular cartilage explants. The effects of 2% sodium dodecyl sulfate (SDS), a detergent used for cell and nuclear membrane solubilization, on cartilage cellularity, biochemical, and biomechanical properties, were examined. Compressive biomechanical properties were determined using creep indentation, and the tensile biomechanical properties were obtained with uniaxial tensile testing. Biochemical assessment involved determination of the DNA content, glycosaminoglycan (GAG) content, and collagen content. Histological examination included hematoxylin and eosin staining for tissue cellularity, as well as staining for collagen and GAG. RESULTS: Treatment with 2% SDS for 2 hours maintained the compressive and tensile biomechanical properties, as well as the GAG and collagen content while resulting in a decrease in cell nuclei and a 4% decrease in DNA content. Additionally, treatment for 8 hours resulted in complete histological decellularization and a 40% decrease in DNA content while maintaining collagen content and tensile properties. However, a significant decrease in compressive properties and GAG content was observed. Similar results were observed with 4 hours of treatment, although the decrease in DNA content was not as great as with 8 hours of treatment. CONCLUSION: Treatment with 2% SDS for 8 hours resulted in complete histological decellularization with decreased mechanical properties, whereas treatment for 2 hours maintained mechanical properties, but had a minimal effect on DNA content. Therefore, future studies must be performed to optimize a treatment for decellularization while maintaining mechanical properties close to those of facet joint cartilage. This study served as a step in creating a decellularized articular cartilage replacement tissue that could be used as a treatment for facet cartilage osteoarthritis.

Deep Brain Stimulation Results in Local Glutamate and Adenosine Release: Investigation into the Role of Astrocytes

Abstract: BACKGROUND: Several neurological disorders are treated with deep brain stimulation; however, the mechanism underlying its ability to abolish oscillatory phenomena associated with diseases as diverse as Parkinson's disease and epilepsy remain largely unknown. OBJECTIVE: To investigate the role of specific neurotransmitters in deep brain stimulation and determine the role of non-neuronal cells in its mechanism of action. METHODS: We used the ferret thalamic slice preparation in vitro, which exhibits spontaneous spindle oscillations, to determine the effect of high-frequency stimulation on neurotransmitter release. We then performed experiments using an in vitro astrocyte culture to investigate the role of glial transmitter release in high-frequency stimulation-mediated abolishment of spindle oscillations. RESULTS: In this series of experiments, we demonstrated that glutamate and adenosine release in ferret slices was able to abolish spontaneous spindle oscillations. The glutamate release was still evoked in the presence of the Na + channel blocker tetrodotoxin, but was eliminated with the vesicular H + -ATPase inhibitor bafilomycin and the calcium chelator 2-bis(2-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid tetrakis acetoxymethyl ester. Furthermore, electrical stimulation of purified primary astrocytic cultures was able to evoke intracellular calcium transients and glutamate release, and bath application of 2-bis (2-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid tetrakis acetoxymethyl ester inhibited glutamate release in this setting. CONCLUSION: Vesicular astrocytic neurotransmitter release may be an important mechanism by which deep brain stimulation is able to achieve clinical benefits.

New insights into the anatomic dissection of the temporal stem with special emphasis on the inferior fronto-occipital fasciculus: implications in surgical approach to left mesiotemporal and temporoinsular structures.

Abstract: OBJECTIVE: To analyze the 3-dimensional relationships of the inferior frontooccipital fasciculus (IFOF) within the temporal stem using anatomic dissection and to study the surgical application. METHODS: Ten postmortem human hemispheres (5 right, 5 left) were dissected using the Klingler fiber dissection technique. The 3-dimensional relationships of the IFOF with different landmarks of the temporal stem, insula, and temporal lobe were analyzed and measured. RESULTS: An average distance of 10.9 mm (range, 8–15 mm) was observed between the limen insulae and the anterior edge of the IFOF under the inferior limiting sulcus of the insula. This anterior one-third of the temporal stem is crossed by the uncinate fasciculus. The IFOF crosses the posterior two-thirds of the temporal stem, in the space between the posterior limit of the uncinate fasciculus and the lateral geniculate body. The average superoinferior distance between the IFOF and the inferior limiting sulcus was 3.8 mm. The auditory radiations and the claustro-opercular and insulo-opercular fibers of the external and extreme capsules pass through the temporal stem above the IFOF, whereas the optic radiations pass below. CONCLUSION: Regarding surgical application, in the transsylvian approach to the mesiotemporal structures in the left dominant hemisphere, an incision within the posterior 8 mm from the limen insulae is less likely to damage the IFOF than more posterior incisions along the inferior limiting sulcus. In the temporal transopercular approach to left temporo-insular gliomas, the IFOF constitutes the deep functional limit of the resection within the temporal stem.

Bone Morphogenetic Proteins and Cancer: Review of the Literature

Abstract: Objective In addition to their well-known osteogenic properties, bone morphogenetic proteins (BMPs) have developmental and regenerative roles that may impact tumorigenesis and promote tumor spread. Given that the most common site of tumor metastases to bone is the spine, determining whether BMPs can be linked to cancer is of particular relevance to surgeons treating primary or metastatic spinal disease. This article reviews the basic scientific and clinical background of BMPs and their potential role in promoting cancer. Methods A literature review to identify studies relating to BMP and tumorigenesis was conducted. Databases evaluated included MEDLINE and EMBASE as well as the Cochrane Controlled Trials Register through 2008. Results Bone morphogenetic proteins are a diverse class of molecules belonging to the transforming growth factor-beta superfamily that serve a variety of biologic functions. Bone morphogenetic proteins have critical roles in stem and progenitor cell biology as regulators of cellular expansion and differentiation. Transforming growth factor-beta and related cell signaling pathways as well as stem and progenitor cell signaling have been linked to cancer. Multiple in vitro and in vivo studies suggest a significant role of BMPs in promoting tumorigenesis and metastasis. However, there are also comparable studies that imply that BMPs may have a negative effect on cancer. Conclusion There is no definitive association between BMPs and the promotion of tumorigenesis or metastasis. However, given the relatively large number of studies reporting a positive effect of BMPs on tumorigenesis or metastasis, the use of BMPs in patients with primary or metastatic spinal tumors should be carefully considered.

"Far-medial" expanded endonasal approach to the inferior third of the clivus: the transcondylar and transjugular tubercle approaches.

Abstract: OBJECTIVE The endoscopic endonasal transclival approach is a valid alternative for treatment of lesions in the clivus. The major limitation of this approach is a significant lateral extension of the tumor. We aim to identify a safe corridor through the occipital condyle to provide more lateral exposure of the foramen magnum. METHODS Sixteen parameters were measured in 25 adult skulls to analyze the exact extension of a safe corridor through the condyle. Endonasal endoscopic anatomic dissections were carried out in nine colored latex-injected heads. RESULTS Drilling at the lateral inferior clival area exposed two compartments divided by the hypoglossal canal: the jugular tubercle (superior) and the condylar (inferior). Completion of a unilateral ventromedial condyle resection opens a 3.5 mm (transverse length) * 10 mm (vertical length) lateral surgical corridor, facilitating direct access to the vertebral artery at its dural entry point into the posterior fossa. The supracondylar groove is a reliable landmark for locating the hypoglossal canal in relation to the condyle. The hypoglossal canal is used as the posterior limit of the condyle removal to preserve more than half of the condylar mass. The transjugular tubercle approach is accomplished by drilling above the hypoglossal canal, and increases the vertical length of the lateral surgical corridor by 8 mm, allowing for visualization of the distal cisternal segment of the lower cranial nerves. CONCLUSION The transcondylar and transjugular tubercle "far medial" expansions of the endoscopic endonasal approach to the inferior third of the clivus provide a unique surgical corridor to the ventrolateral surface of the ponto- and cervicomedullary junctions.

Optic canal involvement in tuberculum sellae meningiomas: influence on approach, recurrence, and visual recovery.

Abstract: Background Tuberculum sellae meningiomas frequently extend into the optic canals. Objective To emphasize the high frequency of optic canal (OC) involvement in tuberculum sellae meningiomas; the importance of opening the OC and of removing tumor within the canal; and the effect of this maneuver on visual outcome, recurrence rates, and surgical approach selection. Methods A retrospective review of 58 patients with tuberculum sellae meningiomas treated surgically by the senior author (O.A.M) between 1993 and 2009 was performed. The frequency of involvement of the OC was documented, as well as the impact of removal of this part of the tumor on visual outcome and recurrence. Results Total resection (Simpson grade 1) was achieved in 51 of 58 patients (87.9%). The tumor invaded the optic canal in 67%. Tumor resection from the optic nerve was achieved in all cases, and most (92%) underwent deroofing of the OC for this purpose. The dura over the tuberculum sella and/or planum sphenoidale was removed in all patients. Eighty-three percent required removal of affected hyperostotic bone. Vision was improved and/or spared in 88%. The average follow-up period was 23 months with 1 recurrence detected. Conclusion In the majority of cases, tuberculum sellae meningiomas extend into 1 or both OCs. Opening the OC for resection of the intracanalicular portion of the tumor enabled us to achieve excellent visual outcome. The supraorbital craniotomy remains the favored approach for removal of such tumors because it allows unroofing of both OCs, wide excision of the dura, and drilling of the affected bone.

Surgical treatment of spinal dural arteriovenous fistulae: a consecutive series of 154 patients.

Abstract: BACKGROUND: Embolization of spinal dural arteriovenous fistulae (SDVAFs) has emerged as an alternative to surgery. However, surgical disconnection is a simple and effective procedure. OBJECTIVE: To review results and complications of surgical treatment of 154 consecutive SDAVFs. METHODS: The records of 154 consecutive patients with SDAVFs were retrospectively reviewed. RESULTS: There were 120 males and 34 females (male/female ratio 3.5:1, mean age 63.6 years). The SDAVFs were located at the thoracic level in 92 patients and at the lumbar and sacral spine levels in 45 and 15 patients, respectively. The most common presenting symptoms were motor dysfunction (65 patients), sensory loss (31 patients), and paresthesias without sensory loss (13 patients). The mean interval from symptom onset to definitive diagnosis was 24.7 months (median 12 months). Surgery resulted in complete exclusion of the fistula at first attempt in 146 patients (95%). There were no deaths or major neurological complications related to the surgery. Six percent of patients experienced subjective or objective worsening of preoperative symptoms and signs by the time of discharge that persisted at follow-up. Other surgical complications consisted of wound infection in 2 patients and deep venous thrombosis in 3. Eight patients were lost to follow-up; 141 patients (96.6%) experienced improvement (120 patients, 82.2%) or stability (21 patients, 14.4%) of motor function at last follow-up compared with their preoperative status. Other symptoms such as numbness, sphincter dysfunction, and dysesthesias/neuropathic pain improved in 51.5%, 45%, and 32.6%, respectively. CONCLUSION: Surgical obliteration of SDAVFs is safe and very effective. Prognosis of motor function is favorable after surgical treatment.

Gamma knife surgery of meningiomas involving the cavernous sinus: long-term follow-up of 100 patients.

Abstract: OBJECTIVE: Resection of meningiomas involving the cavernous sinus often is incomplete and associated with considerable morbidity. As a result, an increasing number of patients with such tumors have been treated with gamma knife surgery (GKS). However, few studies have investigated the long-term outcome for this group of patients. METHODS: 100 patients (23 male/77 female) with meningiomas involving the cavernous sinus received GKS at the Department of Neurosurgery at Haukeland University Hospital, Bergen, Norway, between November 1988 and July 2006. They were followed for a mean of 82.0 (range, 0-243) months. Only 2 patients were lost to long-term follow-up. Sixty patients underwent craniotomy before radiosurgery, whereas radiosurgery was the primary treatment for 40 patients. RESULTS: Tumor growth control was achieved in 84.0% of patients. Twelve patients required re-treatment: craniotomy (7), radiosurgery (1), or both (4). Three out of 5 patients with repeated radiosurgery demonstrated secondary tumor growth control. Excluding atypical meningiomas, the growth control rate was 90.4%. The 1-, 5-, and 10-year actuarial tumor growth control rates are 98.9%, 94.2%, and 91.6%, respectively. Treatment failure was preceded by clinical symptoms in 14 of 15 patients. Most tumor growths appeared within 2.5 years. Only one third grew later (range, 6-20 yr). The complication rate was 6.0%: optic neuropathy (2), pituitary dysfunction (3), worsening of diplopia (1), and radiation edema (1). Mortality was 0. At last follow-up, 88.0% were able to live independent lives. CONCLUSION: GKS gives long-term growth control and has a low complication rate. Most tumor growths manifest within 3 years following treatment. However, some appear late, emphasizing the need for long-term follow-up.

Transcranial Doppler pulsatility index: not an accurate method to assess intracranial pressure.

Abstract: BACKGROUND: Transcranial Doppler sonography (TCD) assessment of intracranial blood flow velocity has been suggested to accurately determine intracranial pressure (ICP). OBJECTIVE: We attempted to v ...

Pericranial flap for endoscopic anterior skull-base reconstruction: clinical outcomes and radioanatomic analysis of preoperative planning.

Abstract: Background One of the major challenges of cranial base surgery is reconstruction of the dural defect and prevention of postoperative cerebrospinal fluid (CSF) fistula. The introduction of endoscopic techniques and an endonasal approach to the ventral skull base has created new challenges for reconstruction. Objective We have developed an endoscopic pericranial flap (PCF) for skull base reconstruction and hereby present the initial cohort of patients who had endonasal reconstruction with a PCF after endoscopic skull base resection. We also demonstrate a method to radiographically incorporate anticipated skull base defects for preoperative planning of PCF length. Methods Dural defects after endonasal skull base resection of invasive tumors were reconstructed with an onlay PCF (n = 10). We performed radiological studies to assist preoperative planning for where to make incisions while harvesting a PCF for anterior skull base, sellar, and clival defects. Results Each of the 10 patients had excellent healing of their skull base and had no evidence of any postoperative cerebrospinal fluid leaks. Eight patients had radiation therapy without flap complications. Radiographic studies demonstrate that the adequate PCF length, covering defects of the anterior skull base, sellar, and clival defects are 11.31 to 12.44 cm, 14.31 to 15.57 cm, and 18.5 to 20.42 cm, respectively. Conclusion The PCF provides an option for endonasal reconstruction of cranial base defects and can be harvested endoscopically. Pre-operative radiographic evaluation may guide surgical planning. There is minimal donor site morbidity, and the flap provides enough surface area to cover the entire ventral skull base.

Endoscopic transsphenoidal pituitary surgery: evidence of an operative learning curve

Abstract: BACKGROUND: The use of the fiberoptic endoscope is a recent innovation in pituitary surgery. OBJECTIVE: To investigate the evidence of an operative learning curve after the introduction of endoscopic transsphenoidal surgery in our unit. METHODS: The first 125 patients who underwent endoscopic transnasal transsphenoidal surgery for pituitary fossa lesions between 2005 and 2007 performed by 1 surgeon were studied. Changes in a number of parameters were assessed between 2 equal 15-month time periods: period 1 (53 patients) and period 2 (72 patients). RESULTS: There were 67 patients (54%) with nonfunctioning adenomas, 22 (18%) with acromegaly, and 10 (8%) with Cushing's disease. Between study periods 1 and 2, there was a decrease in the mean duration of surgery for nonfunctioning adenomas (from 120 minutes to 91 minutes; P < .01). This learning effect was not apparent for functioning adenomas, the surgery for which also took longer to perform. The proportion of patients with an improvement in their preoperative visual field deficits increased over the study period (from 80% to 93%; P < .05). There were nonsignificant trends toward improved endocrine remission rates for patients with Cushing's disease (from 50% to 83%), but operative complications, notably the rates of hypopituitarism, did not change. Overall length of hospital stay decreased between time periods 1 and 2 (from 7 to 4 days median; P < .01). CONCLUSION: The improvements in the duration of surgery and visual outcome noted after about 50 endoscopic procedures would favor the existence of an operative learning curve for these parameters. This further highlights the benefits of subspecialization in pituitary surgery.