1,720,986 research outputs found
DEGENERATIVE SPONDYLOLISTHESIS.II. SURGICAL TREATMENT
No full textThe authors analyze the results of operative treatment in 32 cases of degenerative spondylolisthesis with various degrees of compression of the nervous structures. Five types of surgery were performed: unilateral laminotomy; bilateral laminotomy with or without transverse process fusion; bilateral laminectomy with or without spinal fusion; and laminectomy, spinal fusion, and interspinous wiring. Satisfactory results were achieved in 84% of the cases. Seventy-six percent of the patients had further vertebral displacement, and 81% showed varying degrees of articular process regeneration more than two years after surgery; these findings concern both patients who had been treated with spinal fusion and those who had not. Bilateral laminotomy is indicated in patients with isolated nerve root canal stenosis; as the olisthesis is mild and lateral flexion-extension radiographs show no vertebral hypermobility, spinal fusion is not necessary. When central spinal canal stenosis is present, bilateral laminectomy, extensive lateral decompression, and spinal fusion are recommended. Interspinous wiring may be useful for immediate vertebral stabilization
POSTOPERATIVE INTERVERTEBRAL DISCITIS.EVALUATION OF 12 CASES AND STUDY OF ESR IN THE NORMAL POSTOPERATIVE PERIOD
No full textAbstract
Twelve cases of intervertebral discitis following lumbar discectomy were evaluated and ESR was assessed in 70 patients operated on and without evidence of postoperative infection. Six of the intervertebral discitis patients were studied retrospectively and 6 prospectively. In the retrospective group, patients reported that symptoms appeared on average 15 days after the operation. Antibiotic treatment generally began 31 days after the operation and lasted 62 days; symptoms regressed after 3.9 months. All patients showed long-term radiographic vertebral changes and osteolysis in the cases treated later. In the prospective group, the first symptoms appeared on average 5 days after the operation, treatment started after 8 days and lasted 41 days. Symptoms regressed after 1.8 months. There were only 3 cases of vertebral radiographic changes. In both groups, ESR was always more than 70. The most useful diagnostic imaging tests were conventional tomography and MRI. Needle biopsy had no effect on the length of treatment. In 14% of patients without infective complications, ESR increased noticeably a week after the operation but, in contrast to the intervertebral discitis patients, it did not then continue to increase. Close post-operative observation permitted early detection of intervertebral discitis. Early and high-dose antibiotic treatment, even if unspecific, can resolve this infection in a few weeks
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
Ligamenta flava in lumbar disc herniation and spinal stenosis. Light and electron microscopic morphology.
No full textLigamenta flava obtained from nine patients with lumbar disc herniation and ten patients with lumbar stenosis were studied at histologic, histochemical, and ultrastructural levels. Lumbar ligamenta flava removed from six patients who underwent surgeries for thoracolumbar fractures were used as controls.
RESULTS:
Ligamenta flava from control subjects consisted of large elastic fibers, thin bundles of collagen fibers, and few spindle-shaped fibroblasts. In proximity to the laminal insertion, the ligaments had fibrocartilagineous features. In the control subjects who were age 50 or older, the cells decreased in number and areas that had fewer and thinner elastic fibers and a more abundant collagen component were visible occasionally. In patients with disc herniation, the ligaments had similar morphologic features to those of the controls of similar ages. The ligamenta flava from patients with lumbar stenosis showed areas of fibrosis in which the cells were often represented by actively synthesizing fibroblasts and areas of chondroid metaplasia. Degenerating elastic fibers were seen occasionally, while calcified areas were observed often.
CONCLUSIONS:
Ligamenta flava undergo slight fibrotic and chondrometaplastic changes with aging. No peculiar changes occur in patients with disc herniation. In spinal stenosis, fibrotic changes, chondroid metaplasia, and calcification reduce the elasticity of the ligaments, which may thus bulge into the spinal canal in the standing position even if they are normal in thickness
The surgical treatment of central lumbar stenosis. Multiple laminotomy compared with total laminectomy.
Full text linkWe assigned 67 patients with central lumbar stenosis alternately to either multiple laminotomy or total laminectomy. The protocol, however, allowed multiple laminotomy to be changed to total laminectomy if it was thought that the former procedure might not give adequate neural decompression. There were therefore three treatment groups: group I consisting of 26 patients submitted to multiple laminotomy; group II, 9 patients scheduled for laminotomy but submitted to laminectomy; and group III, 32 patients scheduled for, and submitted to, laminectomy. The mean follow-up was 3.7 years. Bilateral laminotomy at two or three levels required a longer mean operating time than total laminectomy at an equal number of levels. The mean blood loss at surgery and the clinical results did not differ in the three groups. The mean subjective improvement score for low back pain was higher in group I but there was also a higher incidence of neural complications in this group. No patient in group I had postoperative vertebral instability, whereas this occurred in three patients in groups II and III, who had lumbar scoliosis or degenerative spondylolisthesis preoperatively. Multiple laminotomy is recommended for all patients with developmental stenosis and for those with mild to moderate degenerative stenosis or degenerative spondylolisthesis. Total laminectomy is to be preferred for patients with severe degenerative stenosis or marked degenerative spondylolisthesis
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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