1,720,992 research outputs found
sEVD-smartphone-navigated placement of external ventricular drains.
Full text linkBACKGROUND
Currently, the trajectory for insertion of an external ventricular drain (EVD) is mainly determined using anatomical landmarks. However, non-assisted implantations frequently require multiple attempts and are associated with EVD malpositioning and complications. The authors evaluated the feasibility and accuracy of a novel smartphone-guided, angle-adjusted technique for assisted implantations of an EVD (sEVD) in both a human artificial head model and a cadaveric head.
METHODS
After computed tomography (CT), optimal insertion angles and lengths of intracranial trajectories of the EVDs were determined. A smartphone was calibrated to the mid-cranial sagittal line. Twenty EVDs were placed using both the premeasured data and smartphone-adjusted insertion angles, targeting the center of the ipsilateral ventricular frontal horn. The EVD positions were verified with post-interventional CT.
RESULTS
All 20 sEVDs (head model, 8/20; cadaveric head, 12/20) showed accurate placement in the ipsilateral ventricle. The sEVD tip locations showed a mean target deviation of 1.73° corresponding to 12 mm in the plastic head model, and 3.45° corresponding to 33 mm in the cadaveric head. The mean duration of preoperative measurements on CT data was 3 min, whereas sterile packing, smartphone calibration, drilling, and implantation required 9 min on average.
CONCLUSIONS
By implementation of an innovative navigation technique, a conventional smartphone was used as a protractor for the insertion of EVDs. Our ex vivo data suggest that smartphone-guided EVD placement offers a precise, rapidly applicable, and patient-individualized freehand technique based on a standard procedure with a simple, cheap, and widely available multifunctional device
Comment (on Comparative effectiveness of PEEK rods versus titanium alloy rods in lumbar fusion: a preliminary report)
No full textComment (on Conjunctival oedema as a potential objective sign of intracranial hypertension: a short illustrated review and three case reports)
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
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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