1,721,201 research outputs found
An Acute Spinal Intradural Hematoma after an Extraforaminal Wiltse Approach: A Case Report and Review of the Literature
No full textA nontraumatic spontaneous spinal acute subdural hematoma (sSDH) is a rare complication after spinal surgery. Although an sSDH is often associated with anticoagulation therapy, vascular malformations, or lumbar puncture, the pathogenesis of nontraumatic spontaneous sSDH remains unclear. We present the case of an intradural hematoma after an extraforaminal surgery through the Wiltse approach for an extraforaminal disk herniation at L5/S1. This 58-year-old woman experienced hypoesthesia and progressive motor dysfunction in the left leg several hours postoperation. Urgent magnetic resonance imaging revealed an intradural hematoma at the L1/L2 to L2/L3 level in the ventral dural sac proximal to the surgical level. Surgical decompression was performed. There was no evidence of trauma, coagulopathy, or anticoagulation therapy. To our knowledge, this case is the first to report an acute sSDH proximal to the surgery level after an extraforaminal spinal surgery through the Wiltse approach for an extraforaminal disk herniation. It illustrates that attentive postoperative neurologic monitoring, even in the absence of intraoperative irregularities, remains important to diagnose and treat this complication at the early stage.Plazier, M (corresponding author), Jessa Hosp, Dept Neurosurg, Campus Virga Jesse, B-3500 Hasselt, Limburg, Belgium.
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Rapid ventricular pacing in neurovascular surgery : effectiveness and safety
No full textAbstract: The prevalence in the adult population of unruptured aneurysms varies between 3% and 5%. The most feared complication of a cerebral aneurysm is rupture, leading to a subarachnoid hemorrhage (SAH). The incidence of a SAH, caused by the rupture of an aneurysm is less than 0,02 % a year. The therapy of a cerebral aneurysm is performed on a selective, case-by-case basis. The three main options are observation, endovascular coiling and microsurgical clipping. Several techniques have been proposed to decrease the intra-aneurysmal pressure, to prevent its premature rupture or to reduce the intraoperative bleeding in case of a rupture during clipping. The most widely used technique for facilitation of the dissection and a better visualisation of the aneurysm, branches and perforators is the temporary clipping of the feeding arteries. Our research project indicates that RVP is a technique well suited in those circumstances where short, repetitive flow arrests are adequate to allow the neurosurgeon to manipulate the aneurysm. Rapid ventricular pacing (RVP) enforces ventricular tachycardia, ventricular filling is compromised because of the high rate and the absence of atrioventricular synchrony, leading to decreased blood pressure without causing cardiac arrest and vasodilatation. We demonstrated that RVP is an effective blood pressure lowering technique operating as an on-off mechanism. Blood pressure and CBF dropped with 50% after RVP initiation, remained at that level during the pacing and rebounded to pre-pacing values immediately after RVP cessation. We analysed the effect of RVP on the heart. Our study results indicated that troponin levels increased slightly following RVP and normalised to pre-operative levels 24h after surgery. The intra- and post operatively impact of RVP on the brain was evaluated. We used PbtO2 and rScO2 intra-operatively as measures of cerebral oxygenation. Whereas blood pressure reacts in an on-off mode to RVP, the impact on cerebral oxygenation is delayed and extends beyond the pacing period. Postoperatively, we compared pre- and postoperative MRI to assess the impact of RVP on the brain. No new areas of restricted diffusion were observed in the contralateral hemisphere or posterior fossa. The safe application of RVP requires a concerted effort of the neuro- surgeon and anesthesiologist. Following the conclusion of this research project, the use of RVP in neurosurgical surgery has been reinstated and has been included in the standard intra- operative management of neurovascular clipping in our centre
Thoracic disc herniations : an underestimated disease in search for a surgical cure
No full textAbstract: Although still not widely acknowledged, thoracic disc herniations (TDHs) are not rare lesions that may be observed on MRI scans of asymptomatic individuals (37%; Wood, 1995). Even to date, symptomatic TDHs are underdiagnosed. Their pathogenesis and pathophysiology seems to be different from their cervical and lumbar counterparts, largely involving spinal cord rather than radicular compression. Patients may be incapacitated by myelopathy and/or crippling pain resisting medication, physiotherapy, even invasive pain therapy. Physicians including general practitioners, neurologists, neurosurgeons are insufficiently familiar with their diverse clinical presentation. I started this PhD work to make sure these patients receive the best possible care, regardless whether they are suffering myelopathy or merely pain. I set out to study their very diverse clinical presentation, defining different subgroups encountered in my growing practice, as well as their unique imaging characteristics. Also, after implementation of the thoracoscopic microdiscectomy (TMD) technique (Rosenthal, 1994), I set out to make this technique less invasive, safer, and more efficient. This thesis bundles several papers with regard to these intriguing lesions. First, TDH related acute myelopathy, usually caused by a large preexistent TDH causing important cord compression at the lower end of the thoracic spine, frequently preceeded by dorsalgia. Prognosis tends to be favorable when managed correctly. Second, persisting crippling upper back pain after whiplash and other motor vehicle collisions, caused by a preexistent asymptomatic TDH. Prognosis tends to be favorable when managed correctly. Third, T3-T4 DHs as a unique entity causing severe symptoms despite their usually small dimensions. They can be safely resected using a transaxillary approach. Fourth, a sutureless multi-layer technique to reconstruct the dura during TMD has a 97% success rate in preventing a possibly life-threatening subarachnoid-pleural fistula without converting to open surgery. Fifth, high-risk TDHs which are often giant or massive, calcified, close to the apex of (an accentuated) kyphosis, causing significant spinal canal occupation and spinal cord compression, often accompanied by intramedullary signal changes (myelomalacia). We demonstrate that in experienced hands they can be safely dealt with using TMD with motor evoked potential monitoring support. Finally, TMD-R (\u201cR\u201d meaning rib-preserving) as a safe and effective technique even for the most challenging TDHs, while preserving stability and minimizing acute and chronic postoperative pain, thus opening the door to a more widespread use including patients presenting with merely pain. At the end, some suggestions for future research covering clinical, radiologic, surgical and pathophysiological aspects are discussed
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
Optimizing use of the Glasgow Coma Scale : review of clinical application and clinimetric characteristics
No full textDispelling 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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