1,720,960 research outputs found
A true minimally invasive approach for cochlear implantation: High accuracy in cranial base navigation through flat-panel-based volume computed tomography
No full textObjective: High-precision intraoperative navigation using high-resolution flat-panel volume computed tomography makes feasible the possibility of minimally invasive cochlear implant surgery, including cochleostomy. Conventional cochlear implant surgery is typically performed via mastoidectomy with facial recess to identify and avoid damage to vital anatomic landmarks. To accomplish this procedure via a minimally invasive approach-without performing mastoidectomy-in a precise fashion, image-guided technology is necessary. With such an approach, surgical time and expertise may be reduced, and hearing preservation may be improved. Interventions: Flat-panel volume computed tomography was used to scan 4 human temporal bones. A drilling channel was planned preoperatively from the mastoid surface to the round window niche, providing a margin of safety to all functional important structures (e.g., facial nerve, chorda tympani, incus). Main Outcome Measures: Postoperatively, computed tomographic imaging and conventional surgical exploration of the drilled route to the cochlea were performed. Results: All 4 specimens showed a cochleostomy located at the scala tympani anterior inferior to the round window. The chorda tympani was damaged in I specimen-this was preoperatively planned as a narrow facial recess was encountered. Conclusion: Using flat-panel volume computed tomography for image-guided surgical navigation, we were able to perform minimally invasive cochlear implant surgery defined as a narrow, single-channel mastoidotomy with cochleostomy. Although this finding is preliminary, it is technologically achievable
Water Swallow Screening Test for Patients After Surgery for Head and Neck Cancer: Early Identification of Dysphagia, Aspiration and Limitations of Oral Intake
No full textPatients with head and neck cancer (HNC) are at high risk for oropharyngeal dysphagia (OD) following surgical therapy. Early identification of OD can improve outcomes and reduce economic burden. This study aimed to evaluate the validity of a water screening test using increasing volumes postsurgically for patients with HNC (N=80) regarding the early identification of OD in general, and whether there is a need for further instrumental diagnostics to investigate the presence of aspiration as well as to determine the limitations of oral intake as defined by fiberoptic endoscopic evaluation of swallowing. OD in general was identified in 65%, with aspiration in 49%, silent aspiration in 21% and limitations of oral intake in 56%. Despite a good sensitivity, for aspiration of 100% and for limitations of oral intake of 97.8%, the presented water screening test did not satisfactorily predict either of these reference criteria due to its low positive likelihood ratio (aspiration=2.6; limitations of oral intake=3.1). However, it is an accurate tool for the early identification of OD in general, with a sensitivity of 96.2% and a positive likelihood ratio of 5.4 in patients after surgery for HNC
Image-guided minimal-invasive cochlear implantation - Experiments on cadavers
No full textBackground: The accuracy of navigation systems can be improved significantly by using high-resolution flat panel-based Volume Computed Tomography (fpVCT) so that new surgical therapeutic concepts become feasible. A navigation-guided minimally-invasive cochleostomy places highest requirements on the accuracy of intraoperative navigation. Methods: A flat-panel Volume Computed Tomograph (fpVCT) was used to scan four human temporal bones. The isometric voxel size was 200 pm. The preoperative planning was used to define an optimized drilling channel from the mastoid surface to the round window niche and the scala tympani providing a safety margin to critical anatomical structures such as facial nerve, chorda tympani, sigmoid sinus and posterior wall of auditory canal. The canal was drilled hand-operated with a navigated drill following the previously planned trajectory. Afterwards the drilled canal was imaged by fpVCT. Conventional dissection including mastoidectomy and posterior tympanotomy assured correct localization of the cochleostomy. Results: Path planning took an average of 54 minutes (range 35-85 minutes). Installation took an average of 16 minutes (range 14-19 minutes). The drilling procedure itself took an average of 7.75min (range 5-12 minutes.) The RMSE-values varied between 0.1 and 0.2mm (Table 1). All four specimens showed a cochleostomy located at the scala tympani anterior inferior to the round window. The chorda tympani was damaged in one specimen - this was preoperatively planned as a narrow facial recess was encountered. The time needed for planning and system-installation could be reduced continuously. Conclusions: This feasibility study demonstrates that using current image-guided surgery technology in combination with fpVCT allows drilling of a minimally invasive channel to the cochlea with loco typico cochleostomy. The necessary accuracy of intraoperative navigation can be achieved by use of fpVCT (technical accuracy between 0.1 and 0.2 mm). Our results demonstrate the feasibility of a navigation-guided minimally-invasive cochleostomy loco typico. While we are enthused by this preliminary work, we recognize the barriers which exist in translation to clinical application. These include surgical issues (e.g. control of unexpected bleeding) and electrode issues (e.g. development of insertion tools)
A true minimally invasive approach for cochlear implantation: High accuracy in cranial base navigation through flat-panel-based volume computed tomography
No full textObjective: High-precision intraoperative navigation using high-resolution flat-panel volume computed tomography makes feasible the possibility of minimally invasive cochlear implant surgery, including cochleostomy. Conventional cochlear implant surgery is typically performed via mastoidectomy with facial recess to identify and avoid damage to vital anatomic landmarks. To accomplish this procedure via a minimally invasive approach-without performing mastoidectomy-in a precise fashion, image-guided technology is necessary. With such an approach, surgical time and expertise may be reduced, and hearing preservation may be improved. Interventions: Flat-panel volume computed tomography was used to scan 4 human temporal bones. A drilling channel was planned preoperatively from the mastoid surface to the round window niche, providing a margin of safety to all functional important structures (e.g., facial nerve, chorda tympani, incus). Main Outcome Measures: Postoperatively, computed tomographic imaging and conventional surgical exploration of the drilled route to the cochlea were performed. Results: All 4 specimens showed a cochleostomy located at the scala tympani anterior inferior to the round window. The chorda tympani was damaged in I specimen-this was preoperatively planned as a narrow facial recess was encountered. Conclusion: Using flat-panel volume computed tomography for image-guided surgical navigation, we were able to perform minimally invasive cochlear implant surgery defined as a narrow, single-channel mastoidotomy with cochleostomy. Although this finding is preliminary, it is technologically achievable
Predictability of Oral and Laryngopharyngeal Function for Aspiration and Limitation of Oral Intake in Patients After Surgery for Head and Neck Cancer
No full textSwallowing disorders are common in patients after surgery for head and neck cancer. The clinical assessment of oral and laryngopharyngeal abilities is widely used as a dysphagia assessment tool in this patient group, despite a lack of research. The goal of this study was to assess the predictability of clinical parameters for aspiration and limitation of oral intake. A swallowing disorder with the need for further intervention was identified by fiberoptic endoscopic evaluation of swallowing (FEES) in 65%, with aspiration in 49%, silently in 21%, and limited oral intake with tube dependency in 56% of studied patients. Four clinical parameters (dysglossia, wet voice, tongue motility, and tongue strength) correlated significantly with aspiration and limitation of oral intake. However, none of these clinical parameters was able to predict one of our two reference criteria, due to low positive likelihood ratios, mostly less than two. Clinical assessment is therefore inappropriate for early detection of swallowing disorders in such patients
Predictability of Oral and Laryngopharyngeal Function for Aspiration and Limitation of Oral Intake in Patients After Surgery for Head and Neck Cancer
No full textSwallowing disorders are common in patients after surgery for head and neck cancer. The clinical assessment of oral and laryngopharyngeal abilities is widely used as a dysphagia assessment tool in this patient group, despite a lack of research. The goal of this study was to assess the predictability of clinical parameters for aspiration and limitation of oral intake. A swallowing disorder with the need for further intervention was identified by fiberoptic endoscopic evaluation of swallowing (FEES) in 65%, with aspiration in 49%, silently in 21%, and limited oral intake with tube dependency in 56% of studied patients. Four clinical parameters (dysglossia, wet voice, tongue motility, and tongue strength) correlated significantly with aspiration and limitation of oral intake. However, none of these clinical parameters was able to predict one of our two reference criteria, due to low positive likelihood ratios, mostly less than two. Clinical assessment is therefore inappropriate for early detection of swallowing disorders in such patients
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
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