1,720,984 research outputs found
Neuroendoscopic options in the treatment of mesencephalic expanding cysts: Report of four cases and review of the literature
No full textObjective Mesencephalic expanding cysts, also called lacunae, are rare intraparenchymal, multilobulated cavities of variable diameter mostly localized in the thalamo-mesencephalic region. In symptomatic cases, usually presenting with hydrocephalus or midbrain syndrome, surgical treatment is required and, considering their position, a minimally invasive approach should be preferred. Methods Four cases of expanding mesencephalic cysts endoscopically treated in three different Italian centers are described. Other possible causes of intracerebral cyst were excluded in all cases by complete neuroimaging and laboratory screening. All patients presented with signs and symptoms of midbrain compression and a slight to moderate ventricular dilation was present in three cases. Results All patients underwent endoscopic cyst fenestration into the ventricle, associated with endoscopic third-ventriculostomy (ETV) in two cases and with cyst wall biopsy in one case. One patient suffered from transient worsening of her hemiparesis due to intraoperative bleeding. All patients showed clinical improvement and a reduction in cyst size on follow-up magnetic resonance images (MRI). Conclusion Neuroendoscopy appears to be an effective, probably definitive surgical option in the treatment of symptomatic mesencephalic expanding cysts. Associating ETV with cyst fenestration seems to offer more complete treatment. Deep intracystic navigation and cyst wall biopsy should be avoide
Third ventriculostomy site as a neuroreceptorial area
Full text linkPurpose: Endoscopic third ventriculostomy is an established method for treating hydrocephalus. The third ventriculostomy site is considered a safe area that can be disrupted during surgical endoscopic procedures. The question of the clinical consequences of an apparently unavoidable injury to the floor of the third ventricle has been sporadically addressed in the literature. The aim of this study is to describe our anatomical and operative findings during endoscopic procedures performed in fluorescent mode after intravenous fluorescein injection and address the possible role of fluorescein-enhanced visualization of the median eminence as an accessory tool in order to partially spare this functional structure when performing ventriculostomy. Methods: We prospectively administered intravenously 500 mg of fluorescein sodium in 12 consecutive endoscopic surgery cases. A flexible scope equipped with dual observation modes for both white light and fluorescence was used. Taking into account the position of the basilar apex and the need for a conveniently sized stoma, a perforation area was chosen and dilated using a Fogarty balloon, guided by fluorescein-enhanced visualization of the median eminence. Results: After a mean of 20 s in the fluorescent mode, the fluorescein enhanced the visualization of the median eminence-tuber cinereum complex. In our preliminary experience, by opening the stoma in the fluorescence mode, almost half of the visible median eminence surface can be spared from iatrogenic sacrifice. Conclusions: Tailoring fluorescence-guided ventriculostomy is a feasible way of trying to preserve the median eminence and may have implications for the site and safety of this common surgical procedur
External ventricular drainage alone versus endoscopic surgery for severe intraventricular hemorrhage: a comparative retrospective analysis on outcome and shunt dependency
No full textObject
Massive intraventricular hemorrhages (IVHs) require aggressive and rapid management to decrease intracranial hypertension, because the amount of intraventricular blood is a strong negative prognostic predictor on outcome. Neuroendoscopy may offer some advantages over more traditional surgical approaches on outcome and may decrease the number of shunt procedures that need to be performed.
Methods
The authors retrospectively reviewed the clinical and radiological data in 96 patients treated for massive IVH who were admitted between January 1996 and June 2008 to the neurosurgery unit after undergoing emergency CT scanning. Forty-eight patients (Group A) were treated with endoscopic aspiration surgery using a flexible endoscope with a “freehand” technique. A historical group of 48 patients (Group B) treated using external ventricular drain (EVD) placement alone was used as a comparison. The authors compared the radiological results with the clinical outcomes at 1 year according to the modified Rankin Scale and the need for internal CSF shunt treatment in the 2 groups.
Results
Endoscopic aspiration did not significantly affect the outcome at 1 year as determined using the modified Rankin Scale. Patients who underwent endoscopy had an EVD in place for 0.18 days fewer than patients treated with an EVD alone. Patients undergoing external ventricular drainage alone had a 5 times greater chance of requiring a shunting procedure than those treated using neuroendoscopy and external ventricular drainage. Neuroendoscopy plus external drainage reduces shunting rates by 34% when compared with external drainage alone.
Conclusions
The reduction in internal shunt surgery encourages the adoption of neuroendoscopic aspiration of severe IVH as a therapeutic tool to decrease shunt dependency
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
Fluorescein-Enhanced Characterization of Additional Anatomical Landmarks in Cerebral Ventricular Endoscopy
Full text linkBACKGROUND:: Fluorescein enhancement to detect retinal disorder or differentiate cancer tissue in situ is a well-defined diagnostic procedure. It is a visible marker of where the blood-brain barrier is absent or disrupted. Little is reported in the contemporary literature on endoscopic fluorescein-enhanced visualization of the circumventricular organs, and the relevance of these structures as additional markers for safe ventricular endoscopic navigation remains an unexplored field. OBJECTIVE:: To describe fluorescein sodium-enhanced visualization of circumventricular organs as additional anatomic landmarks during endoscopic ventricular surgery procedures. METHODS:: We prospectively administered intravenously 500 mg fluorescein sodium in 12 consecutive endoscopic surgery patients. A flexible endoscope equipped with dual observation modes for both white light and fluorescence was used. During navigation from the lateral to the fourth ventricle, the endoscopic anatomic landmarks were first inspected under white light and then under the fluorescent mode. RESULTS:: After a mean of 20 seconds in the fluorescent mode, the fluorescein enhanced visualization of the choroid plexus of the lateral ventricle, median eminence-tuber cinereum complex, organum vasculosum of the lamina terminalis, choroid plexus of the third and fourth ventricles, and area postrema. CONCLUSION: Fluorescein-enhanced visualization is a useful tool for helping neuroendoscopists recognize endoscopic anatomic landmarks. It could be adopted to guide orientation when the surgeon deems an endoscopic procedure unsafe or contraindicated because of unclear or subverted anatomic landmarks. Visualization of the circumventricular organs could add new insight into the functional anatomy of these structures, with possible implications for the site and safety of third ventriculostomy
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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