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Bob S. Carter

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Low-grade gliomas

Mitchel S. Berger and Bob S. Carter

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Fredric B. Meyer

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Fred G. Barker II and Bob S. Carter

Systematic reviews and metaanalyses have become increasingly popular ways of summarizing, and sometimes extending, existing medical knowledge. In this review the authors summarize current methods of performing meta-analyses, including the following: formulating a research question; performing a structured literature search and a search for trials not published in the formal medical literature; summarizing and, where appropriate, combining results from several trials; and reporting and presenting results. Topics such as cumulative and Bayesian metaanalysis and metaregression are also addressed. References to textbooks, articles, and Internet resources are also provided. The goal is to assist readers who wish to perform their own metaanalysis or to interpret critically a published example.

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Bob S. Carter, Jonathan L. Brisman and Christopher S. Ogilvy

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Carlos E. Sanchez, Christopher S. Ogilvy and Bob S. Carter

✓Successfully measuring cerebrovascular neurosurgery outcomes requires an appreciation of the current state-of-the-art epidemiological instruments, their specific relevance to surgical treatments and the underlying pathological entity, and ultimately the right set of questions for the next generation of studies. In this paper the authors address these questions with specific attention to measurement targets, individual modeling scales, and types of studies, all within a conceptual framework for specific disease models in their current state of outcomes modeling in cerebrovascular neurosurgery.

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R. Loch Macdonald

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Javier M. Figueroa and Bob S. Carter

The detection of glioblastoma (GBM) in biofluids offers potential advantages over existing paradigms for the diagnosis and therapeutic monitoring of glial tumors. Biofluid-based detection of GBM focuses on detecting tumor-specific biomarkers in the blood and CSF. Current clinical research concentrates on studying 3 distinct tumor-related elements: extracellular macromolecules, extracellular vesicles, and circulating tumor cells. Investigations into these 3 biological classifications span the range of locales for tumor-specific biomarker discovery, and combined, have the potential to significantly impact GBM diagnosis, monitoring for treatment response, and surveillance for recurrence. This review highlights the recent advancements in the development of biomarkers and their efficacy for the detection of GBM.

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Brian L. Hoh, Christopher M. Putman, Ronald F. Budzik, Bob S. Carter and Christopher S. Ogilvy

Object. Certain intracranial aneurysms, because of their fusiform or complex wide-necked structure, giant size, or involvement with critical perforating or branch vessels, are unamenable to direct surgical clipping or endovascular coil treatment. Management of such lesions requires alternative or novel treatment strategies. Proximal and distal occlusion (trapping) is the most effective strategy. In lesions that cannot be trapped, alteration in blood flow to the “inflow zone,” the site most vulnerable to aneurysm growth and rupture, is used.

Methods. From 1991 to 1999 the combined neurosurgical—neuroendovascular team at the Massachusetts General Hospital (MGH) managed 48 intracranial aneurysms that could not be clipped or occluded. Intracavernous internal carotid artery aneurysms were excluded from this analysis. By applying a previously described aneurysm rupture risk classification system (MGH Grades 0–5) based on the age of the patient, aneurysm size, Hunt and Hess grade, Fisher grade, and whether the aneurysm was a giant lesion located in the posterior circulation, the authors found that a significant number of patients were at moderate risk (MGH Grade 2; 31.3% of patients) and at high risk (MGH Grades 3 or 4; 22.9%) for treatment-related morbidity. The lesions were treated using a variety of strategies—surgical, endovascular, or a combination of modalities. Aneurysms that could not be trapped or occluded were treated using a paradigm of flow alteration, with flow redirected from either native collateral networks or from a surgically performed vascular bypass. Overall clinical outcomes were determined using the Glasgow Outcome Scale (GOS). A GOS score of 5 or 4 was achieved in 77.1%, a GOS score of 3 or 2 in 8.3%, and death (GOS 1) occurred in 14.6% of the patients. Procedure-related complications occurred in 27.1% of cases; the major morbidity rate was 6.3% and the mortality rate was 10.4%. Three patients experienced aneurysmal hemorrhage posttreatment; in two patients this event proved to be fatal. Aneurysms with MGH Grades 0, 1, 2, 3, and 4 were associated with favorable outcomes (GOS scores of 5 or 4) in 100%, 92.8%, 71.4%, 50%, and 0% of instances, respectively.

Conclusions. Despite a high incidence of transient complications, intracranial aneurysms that cannot be clipped or occluded require alternative surgical and endovascular treatment strategies. In those aneurysms that cannot safely be trapped or occluded, one approach is the treatment strategy of flow alteration.

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Sepideh Amin-Hanjani, William E. Butler, Christopher S. Ogilvy, Bob S. Carter and Fred G. Barker II

Object. The authors assessed the results of extracranial—intracranial (EC—IC) bypass surgery in the treatment of occlusive cerebrovascular disease and intracranial aneurysms in the US between 1992 and 2001 by using population-based methods.

Methods. This is a retrospective cohort study based on data from the Nationwide Inpatient Sample (Healthcare Cost and Utilization Project, Agency for Healthcare Research and Quality, Rockville, MD). Five hundred fifty-eight operations were performed at 158 hospitals by 115 identified surgeons. The indications for surgery were cerebral ischemia in 74% of the operations (2.4% mortality rate), unruptured aneurysms in 19% of the operations (7.7% mortality rate), and ruptured aneurysms in 7% of the operations (21% mortality rate). Overall, 4.6% of the patients died and 4.7% of the patients were discharged to long-term facilities, 16.4% to short-term facilities, and 74.2% to their homes. The annual number of admissions in the US increased from 190 per year (1992–1996) to 360 per year (1997–2001), whereas the mortality rates increased from 2.8% (1992–1996) to 5.7% (1997–2001).

The median annual number of procedures was three per hospital (range one–27 operations) or two per surgeon (range one–21 operations). For 29% of patients, their bypass procedure was the only one recorded at their particular hospital during that year; for these institutions the mean annual caseload was 0.4 admissions per year. For 42% of patients, their particular surgeon performed no other bypass procedure during that year. Older patient age (p < 0.001) and African-American race (p = 0.005) were risk factors for adverse outcome. In a multivariate analysis in which adjustments were made for age, sex, race, diagnosis, admission type, geographic region, medical comorbidity, and year of surgery, high-volume hospitals less frequently had an adverse discharge disposition (odds ratio 0.54, p = 0.03).

Conclusions. Most EC—IC bypasses performed in the US during the last decade were performed for occlusive cerebrovascular disease. Community mortality rates for aneurysm treatment including bypass procedures currently exceed published values from specialized centers and, during the period under study, the mortality rates increased with time for all diagnostic subgroups. This technically demanding procedure has become a very low-volume operation at most US centers.