1,721,000 research outputs found
The anterior interhemispheric approach : a safe and effective approach to anterior skull base lesions
No full textMany approaches to the anterior skull base have been reported. Frequently used are the pterional, the unilateral or bilateral frontobasal, the supraorbital and the frontolateral approach. Recently, endoscopic transnasal approaches have become more popular. The benefits of each approach has to be weighted against its complications and limitations. The aim of this study was to investigate if the anterior interhemispheric approach (AIA) could be a safe and effective alternative approach to tumorous and non-tumorous lesions of the anterior skull base. We screened the operative records of all patients with an anterior skull base lesion undergoing transcranial surgery. We have used the AIA in 61 patients. These were exclusively patients with either olfactory groove meningioma (OGM) (n = 43), ethmoidal dural arteriovenous fistula (dAVF) ( n = 6) or frontobasal fractures of the anterior midline with cerebrospinal fluid (CSF) leakage ( n = 12). Patient records were evaluated concerning accessibility of the lesion, realization of surgical aims (complete tumor removal, dAVF obliteration, closure of the dural tear), and approach related complications. The use of the AIA exclusively in OGMs, ethmoidal dAVFs and midline frontobasal fractures indicated that we considered lateralized frontobasal lesions not suitable to be treated successfully. If restricted to these three pathologies, the AIA is highly effective and safe. The surgical aim (complete tumor removal, complete dAVF occlusion, no rhinorrhea) was achieved in all patients. The complication rate was 11.5 % (wound infection (n = 2; 3.2 %), contusion of the genu of the corpus callosum, subdural hygroma, epileptic seizure, anosmia and asymptomatic bleed into the tumor cavity (n = 1 each). Only the contusion of the corpus callosum was directly related to the approach (1.6 %). Olfaction, if present before surgery, was preserved in all patients, except one (1.6 %). The AIA is an effective and a safe approach to tumorous, vascular and traumatic pathologies of the midline anterior skull base. This approach should be part of the armamentarium of skull base surgeons
Die Symptomentwicklung nach transsphenoidaler Hypophysenadenomresektion in Abhängigkeit von Tumorausdehnung und klinischem Erscheinungsbild
No full textEinfluß der intrakraniellen Blutverteilung auf den klinischen Verlauf nach Subarachnoidalblutung
No full textStandard open microdiscectomy versus minimal access trocar microdiscectomy: results of a prospective randomized study
No full textOBJECTIVE: Minimal access surgery as a less invasive alternative to standard macro- and microsurgical approaches is becoming increasingly popular in the management of traumatic and degenerative spine diseases. However, data is lacking if minimal access spine surgery is indeed beneficial. This prospective randomized study was conducted to compare efficiency, safety, and outcome of standard open microsurgical discectomy (SOMD) for lumbar disc herniation with microsurgical discectomy using an 11.5 mm trocar system for minimal access to the spine. METHODS: Sixty patients were randomized to two groups of 30 patients each. Group I was treated by SOMD, and Group 2 was treated by minimal access microsurgical discectomy (MAMD). Perioperative parameters and pre- and postoperative clinical findings including sensory or motor deficits and pain according to the visual analog scale, Oswestry Disability index scores, and Short Form-36 results were assessed. All patients were followed for at least 6 months postoperatively (mean, 16 mo). RESULTS: Preoperatively, no statistically significant intergroup differences could be detected proving the comparability of both groups. Postoperatively, significant improvement of neurological symptoms and pain as measured by the visual analog scale, Oswestry Disability Index, and Short Form-36 scores could be achieved in both groups. In regard to operative time, intraoperative blood loss, and complication rate, slightly better results were observed in the MAMD group. CONCLUSION: SOMD and MAMD allow achievement of significant improvement of pain and neurological deficits in patients with lumbar disc herniations. Differences in operative time, blood loss, and complication rates were statistically not significant in MAMD compared with SOMD, indicating that, at least in lumbar disc surgery, minimal access trocar techniques are a viable alternative to standard spinal approaches
How useful is the 3-dimensional, surgeon's perspective-adjusted visualisation of the vessel anatomy during aneurysm surgery? A prospective clinical trial
No full textWe hypothesized that neuronavigational 3-dimensional display of vessel and aneurysm anatomy, which is adjusted to the actual surgeon's view, could be helpful during the critical steps of aneurysm treatment. A total number of 32 patients with 42 aneurysms entered this prospective clinical trial. With a neuronavigational system, a 3-dimensional image of the arterial vascular anatomy was generated by autosegmentation of a computerized tomography (CT) angiographic data set. The 3-dimensional image was then adjusted to the surgeon's perspective by rotation. The neurosurgeon linked the 3-dimensional image information with the vascular structures in his surgical field by a neuronavigational pointer. He had the opportunity to further rotate the image with the displayed pointer for visualization of hidden structures. After operation, the neurosurgeon had to define with which expectations neuronavigation was applied and to evaluate if these expectations were fulfilled. The expectations with which the neurosurgeon used neuronavigation were to localize the aneurysm (n=24), to understand the branching anatomy (n=18), to visualize hidden structures (n=8), to evaluate the projection of the aneurysm dome (n=5) and to tailor the approach (n=2). In 5 of the 42 aneurysms that were either very small or located in close vicinity to the skull base, the neurosurgeon's expectations were not fulfilled. A favorable outcome was achieved in 29 of the 32 patients (91%). Neuronavigational 3-dimensional display of the vessel anatomy was considered useful by the vascular neurosurgeon. Possibly, this technique has the potential to improve operative results by reduction of the surgical trauma and avoidance of intraoperative complications
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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