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Search Results: 1 - 10 of 408916 matches for " Alejandro M. Spiotta "
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Y-Stenting for Bifurcation Aneurysm Coil Embolization: What is the Risk?
Alejandro M. Spiotta,Jonathan Lena,M. Imran Chaudry,Raymond D. Turner,Aquilla S. Turk
Stroke Research and Treatment , 2014, DOI: 10.1155/2014/762389
Abstract: The use of two stents in a “Y” configuration (Y-stenting) to assist with coil embolization of complex bifurcation aneurysms has been accepted as an alternative to clip reconstruction of a select subset of challenging aneurysms. We review the risks associated with Y-stenting, including its procedural complication rates, angiographic occlusion rates, rerupture, and retreatment rates. 1. Introduction Since the International Symptomatic Aneurysm Trial (ISAT) and the Barrow Ruptured Aneurysm Trial (BRAT) firmly established endovascular therapy as a valid method for treating intracranial aneurysms, development of new techniques has broadened the scope of practice to allow for the treatment of geometrically complex aneurysms. Until the introduction and widespread adoption of adjuncts to endovascular coil embolization, complex wide-necked bifurcation aneurysms had classically been treated with microsurgical clip reconstruction. Advances in endovascular techniques including balloon remodeling as well as the use of stents have allowed more of these challenging aneurysms to be treated with coil embolization. The use of two stents in a “Y” configuration (Y-stenting) to assist with coil embolization of complex bifurcation aneurysms was first described by Chow et al. in 2004 [1]. Since that time many reports have been published demonstrating low morbidity and mortality rates associated with Y-stenting [1–14] and it has been accepted as a safe and reasonable alternative to clip reconstruction of a select subset of challenging aneurysms. But what exactly are the risks associated with Y-stenting? To address this question a thorough understanding of the technical aspects of the procedure as well as the available reported rates of complications is required. 2. Stent Assisted Coiling The technique of stent assisted coiling in the clinical setting was first described in 1997 [15] Soon after, the availability of new flexible, self-expanding intracranial stents allowed for increasing application of this technique and observation of its benefits. Stents have been quickly adopted as promising adjuncts with potential mechanical, hemodynamic, and biologic properties, imparting an advantage over coil embolization alone [15]. Stent deployment provides mechanical support to prevent coil prolapse, may serve as a conduit to divert flow, and provides a scaffold for endothelial growth and vessel healing [15–17]. In addition, an implanted stent may incur subtle changes in the parent vessel-aneurysm geometry, imparting significant hemodynamic alterations which change the inflow
Elucidating General Equilibrium Multiplier Effects: A Differential Perspective  [PDF]
M. Alejandro Cardenete, Ferran Sancho
Theoretical Economics Letters (TEL) , 2013, DOI: 10.4236/tel.2013.35046
Abstract: Expenditure multipliers are routinely used to evaluate the effectiveness of government spending. When interested in disaggregated effects, interindustry models provide the necessary tools to be able to look at very detailed sectorial results. These models are theoretically simple and empirically operational, which makes them easily implementable and therefore popular with policy makers. They miss, however, quite a bit of the interaction that takes place at the micro level. On the one hand, they ignore the role exerted by supply constraints in primary factors; on the other hand, they look at the world as though it is fully linear. We overcome these limitations by using an opposite Walrasian general equilibrium model to compute marginal multipliers. By using differential calculus, we also offer some insights regarding the “under-the-hood” circuits of influence.
Bronquiolitis obliterante posinfecciosa
Colom,Alejandro J.; Teper,Alejandro M.;
Archivos argentinos de pediatr?-a , 2009,
Abstract: bronchiolitis obliterans is an uncommon and severe form of chronic obstructive lung disease that results from an insult to the lower respiratory tract. the bronchiolitis obliterans was described as a complication of graft versus host disease in bone marrow or lung transplant recipients. bronchiolitis obliterans is most commonly seen in children after severe viral lower respiratory tract infections. the understanding of pathology, pathogenesis and molecular pathology, as well as the best treatment in bronchiolitis obliterans remain the subject of ongoing investigations. this review discusses our current knowledge on the different areas of bronchiolitis obliterans associated to infectious disease.
Suddenly Last Summer de Tennessee Williams: un tributo a Eurípides en el teatro del siglo XX
Errecalde,Alejandro M.;
Circe de cl??sicos y modernos , 2006,
Abstract: this study aims at approaching to one of tennessee williams' dramatic texts (suddenly last summer) to observe every dionysiac element used by the autor there, taken from their essential intertext: euripides' bacchae. the analysis of the play will propose the way in which the particular cosmovision of this american playwright gives them a new signified, transforming his new creation in a 'tribute' to one of the most important greek tragedians.
EVOLUCIóN MINERALóGICA DEL CEMENTO PORTLAND DURANTE EL PROCESO DE HIDRATACIóN
GIRALDO M.,MANUEL ALEJANDRO;
DYNA , 2006,
Abstract: an investigation about mineralogical evolution during hydration process of the portland cement was carried out in this work using techniques of materials characterization, such as x ray diffraction (xrd) and scanning electron microscopy (sem) in order to understand the behaviour shown by the different minerals of the cement (alite, belite, celite and felite) and their transformation in the stables hydrate phases (tobermorite, portlandite, ettringite) it was found that, in general, the hydration process happens in a different way in each mineral either because of the reaction speed, or the crystalline changes experienced by them in the transformation from the anhydrous to the hydrated phase. the tobermorite gel (csh), portlandite and ettringitre formation and the changing in appearance of the paste during the hydration advances, could be appreciated.
Descripción, interpretación, análisis e importancia del nistagmus inducido por la hiperventilación en el estudio de patologías vestibulares periféricas y centrales
Pe?a M,Alejandro;
Revista de otorrinolaringología y cirugía de cabeza y cuello , 2012, DOI: 10.4067/S0718-48162012000100012
Abstract: recent clinical studies have revealed the usefulness of the hyperventilation-induced nystagmus in retrolabyrinthine and central vestibular diseases with the appearance either excitatory (ipsilateral) or paretic (contralateral) nystagmus. the objectives of this study have been: 1) to get to know the sensitivity of the exam, according to the best literature available; 2) to get to know the physiopathology of this hyperventilation-induced nystagmus, and 3) to carry out an analysis and interpretation of this exam in order to reach solid conclusions of the highest level in evidence based medicine. an exhaustive research of literature published on this topic in the last 25 years was carried out. the main source of information being the most important medical data-based publications and also a thorough revision of these texts. the scarce number of publications on this topic (not more than 40) is what strikes the attention most, as well as the very few studies of the physiopathology of the hyperventilation-induced nystagmus. the method of the test is a simple one; this fact makes its application an attractive one, with a low number of false positive. most of the studies published are focused on its application in the vestibular schwannoma and in the vestibular neuritis. as to what the vestibular schwannoma is concerned, ofa group of 107 patients studied, the test was positive in 80%% of the cases, with the appearance of ipsilesional or contralesional nystagmus. in vestibular neuritis the test was positive in 68 % of a number of272patients; this amount was in direct correlation with the time of evolution of the disease. in multiple sclerosis, in patients with vestibular symptoms, the test gave positive in 75%%, whereas in those patients without vestibular symptoms it was positive only in 7%%. in patients with cerebellar diseases, particularly degenerative ones this test was positive in 78%% of the cases. the search of hyperventilation-induced nystagmus was a statistically no
Homologación lingüística nacional del Dizziness Handicap Inventory (test de discapacidad vestibular)
Pe?a M,Alejandro;
Revista de otorrinolaringología y cirugía de cabeza y cuello , 2011, DOI: 10.4067/S0718-48162011000100013
Abstract: the symptoms of dizziness syndromes are mainly subjective and difficult to evaluate by the physician. it is thus highly useful to count on elements that allow standardization of the patient's symptoms, and to have an available measurement of vestibular disability the disease may cause. in order to achieve this, jacobson and newman published some time ago the so called dizziness handicap inventory. this test has been later validated by several studies, which gave it high veracity and statistical reliability. this paper translates the test into everyday chilean spanish in order to have a reliable tool that allows an ent specialist to determine the patient's degree of discapacity.
Una breve historia de la invención del espejillo laríngeo y del espejo frontal
Pe?a M,Alejandro;
Revista de otorrinolaringología y cirugía de cabeza y cuello , 2008, DOI: 10.4067/S0718-48162008000100013
Abstract: a brief history of the laryngeal and head mirrors and of the people that participated in their invention is presented. the main credit for having thought of a system to perform a laryngoscopy is on manuel v. garcia, a spanish music professor. in 1854, he used a dental speculum, a hand mirror and sunlight to observe vocal chords movements for the first time. a couple of years later, in 1856, the method spread among european doctors thanks to an austrian neurologist: ludwig türck. his technique was not very widely accepted because of its dependence on sunlight. türck s idea was perfected by johann czermack, a czech physiologist. he modified the concave hand mirror with a central hole, which at the time was used by otologists to examine the tympanum, adding a headband in order to attach it to the forehead. in this way he managed to easily observe the vocal chords using light from a lamp, and reported his technique in a 1858 paper
El examen vestibular abreviado, descripción, interpretación y análisis
Pe?a M,Alejandro;
Revista de otorrinolaringología y cirugía de cabeza y cuello , 2011, DOI: 10.4067/S0718-48162011000200006
Abstract: introduction: caloric tests play a very important role in a patient's vestibular exam. but these exams, along with the new test brought about by both technology and computing in medicine, have turned these examinations into very long and expensive procedures. taking all this into account, it seems suitable the realization of a preliminary vestibular exam performed in the doctor's consultation office. this will allow a diagnostic guideline with solid foundations. aim: to describe, interpret, and carry out a critical analysis of the so called "10 minute vestibular examination of the dizzy patient" in order to get to some conclusions about sensitivity and specificity of this short exam. material and method: using the available bibliography, particularly medical studies based on evidence, the following test are described, interpreted and analyzed : spontaneous nystagmus, gaze nystagmus, smooth pursuit, saccades, halmagyi test, head shake test, , dynamic visual acuity test, fixation suppression test, dix-hallpike maneuver, aural pressure/sound test, cerebellar limbs, somato-sensation test, romberg test, and gait test. since most of these tests are performed in the classic vestibular examination, only non-routine ones are analyzed and discussed. results: most analyzed test show low sensitivity, under 50%%, but good specificity. with some basic training they are easy to carry out, and they require a short length of time, but over 10 minutes. discussion: taking into consideration the long time the specialist needs for a vestibular examination, a basic vestibular study is highly necessary to guide the dizzy patient's clinical investigation. the tests suggested in this examination have a low sensitivity individually considered. but carrying out all of these together, added to a solid anamnesis with a pre-established structured questionnaire, gives the study strength and reliability. conclusion: the abbreviated vestibular examination is a good study. although the various tests
Estudio sobre la divulgación, presencia y prestigio de la Revista de Otorrinolaringología y Cirugía de Cabeza y Cuello, a?o 2006
Pe?a M,Alejandro;
Revista de otorrinolaringología y cirugía de cabeza y cuello , 2007, DOI: 10.4067/S0718-48162007000200008
Abstract: introduction.besides an excellent quality of the papers published, medical journals require good diffusion to reach potential readers. goal.to investigate the actual situation of the rev otorrinolaringol cir cabeza cuello, in terms of levels of national and international diffusion, presence and prestige. materials and methods.review and analysis of the journal' presence in several of well known bibliometric indexes: national impact factor, citation reports, indexation in biomedical databases, e-journal rate of diffusion via internet, existence of an english version and use of abstracts or summaries. results.the calculated national impact factor for 2006 was a very low: 0.101. analyses of citation reports for 2006 showed an overwhelming presence of american journals (86%), a few chilean and european journals and none from other latin american countries. review of biomedical databases indexation showed that the journal is indexed only in lilacs, a database that is notcommonly used by researchers. the electronic version of the journal has a lowvisibility, because it can be only accessed via the website of the sociedad chilena de otorrinolaringología, it does not have an english version and neither abstracts nor summaries are published. conclusions: this study showed that, at the present time, the rev otorrinolaringol cir cabeza cuello has a poor diffusion and very little national and international presence. a substantial improvement on this condition seems urgent. several action lines are proposed: first, indexation in widely used databases, such as scielo and medline/pubmed; secondly, make access to the journal by foreign researchers easier; in third place, publish in the near future the electronic version of the journal in both english and spanish, similar to other latin american journals on the area; and finally, propose to the editorial committee to add the word ?chilena? to the journal title, in order to improve the international identification of the journal
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