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William J. Kemp III, Daniel H. Fulkerson, Troy D. Payner, Thomas J. Leipzig, Terry G. Horner, Erin L. Palmer and Aaron A. Cohen-Gadol

A small percentage of patients with intracranial aneurysms will develop a second, new aneurysm, anatomically unrelated to their initial lesion. These aneurysms are termed “de novo.” 12 , 16 , 25 , 38 , 41 By definition, a de novo aneurysm is a lesion that develops from a vessel that had been normal on previous imaging studies. A number of published studies have estimated the risk of forming a de novo aneurysm to range between 0.37% and 4.15% per year after discovery of an original aneurysm. 3 , 7 , 16 , 25 , 38 Previous studies have consistently

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Benjamin Pulli, Christopher J. Stapleton, Brian P. Walcott, Matthew J. Koch, Scott B. Raymond, Thabele M. Leslie-Mazwi, James D. Rabinov and Aman B. Patel

symptomatic stroke or death by 33 months’ follow-up compared with 10.1% of patients in the medical management group. In ARUBA, 32% of patients were treated with embolization alone and 16% with combined embolization and radiosurgery, whereas only 17% of patients were treated with microsurgery (with or without embolization). All patients in the study were stratified by Spetzler-Martin grade (SMG); the SM classification system is designed to assess microsurgical risk, regardless of the intended treatment modality. 13 , 14 However, the factors that inform risk stratification

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Hieronymus D. Boogaarts, Jasper H. van Lieshout, Martinus J. van Amerongen, Joost de Vries, André L. M. Verbeek, J. André Grotenhuis, Gert P. Westert and Ronald H. M. A. Bartels

rupture as is feasible to reduce the rate of rebleeding. 8 Currently, ultra-early treatment, considered to be within 24 hours, is advised for patients in good clinical condition. 34 Although nonmodifiable causes, such as transfer from other hospitals and late diagnosis, might delay treatment, ultra-early treatment can also be difficult due to internal logistics issues like limited 24/7 surgical coverage and access to operating theaters and anesthetic and nursing staff. 34 Recognizing risk factors for aneurysmal rebleeding is particularly relevant and might help to

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Ian K. White, Kashif A. Shaikh, Reilin J. Moore, Carli L. Bullis, Mairaj T. Sami, Thomas J. Gianaris and Daniel H. Fulkerson

potentially more susceptible to the damaging effects of radiation. The National Academies' Biological Effects of Ionizing Radiation (BEIR) VII report related the risk of cancer with radiation exposure from military sources (Japanese patients exposed to nuclear fallout in World War II), therapeutic radiation treatment (treatment of tinea capitis), and nuclear facility workers. 10 Various models and anthropomorphic phantom simulations provide estimates for the effective radiation dose to organs based on the type of CT scanning study. 3 , 7 , 9 , 14 , 18 Authors have then

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Bengt Karlsson, Arne V. Johansson, Huai-Che Yang, Hidefumi Jokura, Masaaki Yamamoto, Roberto Martínez-Álvarez, Jun Kawagishi, Wan-Yuo Guo, Guus Beute, David H. C. Pan, Wen-Yuh Chung, Michael Söderman, Hitoshi Aiyama and Tseng Tsai Yeo

M any studies estimating the annual risk for hemorrhage of unruptured arteriovenous malformations (AVMs) have been published. 2 , 4 , 5 , 8 , 10–13 , 15–17 , 20 , 23 , 25 With few exceptions, the studies are retrospective and analyze patients in whom, for various reasons, the AVM has been left untreated for longer or shorter periods of time. In most reports, the risk of rupture varies between 2% and 4%, but a rate exceeding 30% was reported for select ruptured AVMs. 20 , 31 Several factors have been suggested to influence the risk for hemorrhage, such as AVM

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Nardin Samuel and Ivan Radovanovic

I ntracranial aneurysms (IAs) are pathological dilatations of cerebral vasculature, most commonly occurring at bifurcations of major intracranial arteries, and are estimated to occur in up to 6% of adults worldwide. 54 Approximately 2% of these aneurysms ultimately rupture, as inferred from the cumulative incidence of aneurysmal subarachnoid hemorrhage (aSAH). 54 Unruptured aneurysms may be detected incidentally through cranial imaging for trauma or alternate pathologies, or through deliberate screening of high-risk individuals, such as those with a family

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Waleed Brinjikji, John Huston III, Alejandro A. Rabinstein, Gyeong-Moon Kim, Amir Lerman and Giuseppe Lanzino

C arotid artery stenosis is a well-established risk factor for ischemic stroke, contributing to 10%–20% of strokes or transient ischemic attacks (TIAs). 28 Randomized clinical trials comparing medical therapy with surgical intervention have primarily selected patients by degree of stenosis. 8 , 27 , 37 , 41 , 72 , 116 Because current guidelines have established degree of stenosis as the primary surrogate for stroke risk and indication of intervention, much research has been dedicated to determining sensitive, specific, and cost-effective techniques to

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Felicitas J. Detmer, Sara Hadad, Bong Jae Chung, Fernando Mut, Martin Slawski, Norman Juchler, Vartan Kurtcuoglu, Sven Hirsch, Philippe Bijlenga, Yuya Uchiyama, Soichiro Fujimura, Makoto Yamamoto, Yuichi Murayama, Hiroyuki Takao, Timo Koivisto, Juhana Frösen and Juan R. Cebral

to decide whether to treat the patient or to conservatively follow up the IA since the risk associated with interventions aimed at preventing future aneurysm rupture outweighs the natural aneurysm rupture risk. 12 , 17 , 23 The pathophysiological mechanisms leading to aneurysm rupture are not yet fully understood; however, a plethora of risk factors have been suggested in the literature. 13 These risk factors include patient-related variables such as sex or smoking status, genetics, geometric factors describing the shape of an IA, and hemodynamic factors

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Nima Alan, Andreea Seicean, Sinziana Seicean, Duncan Neuhauser and Robert J. Weil

A nemia , defined as low hematocrit, may be viewed as merely a laboratory abnormality byproduct of an underlying condition, thereby suggesting that anemia may not be an independent predictor of outcomes in surgical patients. 21 However, anemia is a common, and often clinically significant, condition. In patients undergoing a variety of nonneurosurgical procedures, anemia has been identified as an independent risk factor for postoperative outcomes. 3 , 10 , 16 , 19 , 20 , 21 , 30 Given the sensitivity of the central nervous system to suboptimal oxygen

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Stephen I. Ryu and Krishna V. Shenoy

eye on this field, and significant fiscal support and encouragement, the field is now in a unique position to answer this question. In short, translation of human cortical prostheses will only result when their benefits clearly outweigh the risks. Here we discuss some of the obstacles that currently concern human cortical prostheses, which if unaddressed, may doom their realization. Motor and Communication Prostheses Existing BMIs strive to restore normal function in patients suffering from neurological impairments. Two successful examples include cochlear