1,721,012 research outputs found
Auditory brainstem implants for neurofibromatosis type 2.
No full textAbstract
PURPOSE OF REVIEW: Neurofibromatosis type 2 (NF2) produces benign Schwann cell tumors on many cranial nerves, in particular on the vestibular portions of the VIIIn bilaterally. Removal of these vestibular schwannomas usually severs the auditory portion of the VIIIn, thus deafening the patients. The auditory brainstem implant (ABI) was designed to provide prosthetic electric stimulation of the cochlear nucleus in the brainstem to restore some hearing sensations to patients deafened by bilateral removal of vestibular schwannomas. This study will review the new developments and improving outcomes of the ABI.
RECENT FINDINGS: From its initial application in 1979 until about 2005, the ABI provided modest but useful auditory sensations to NF2 patients. However, application of the ABI in non-NF2 populations and in children with congenital malformations demonstrated better results, showing that the ABI could provide high levels of speech recognition. Recent results show excellent speech recognition in NF2 patients as well. This study will discuss the potential causes of the variability in ABI outcomes.
SUMMARY: ABIs activate neurons in the cochlear nucleus to recreate hearing sensations in people who have become deaf as a result of the loss of the auditory nerve. Most NF2 patients show functional hearing benefit from the ABI, with awareness and recognition of environmental sounds and enhancement of lipreading. It is now clear that ABIs can produce excellent speech recognition in some patients with NF2, allowing even conversational telephone use. Although the factors leading to this improved performance are not completely clear, these new results show that excellent hearing is possible for NF2 patients with the ABI
Nervus intermedius guides auditory brainstem implant surgery in children with cochlear nerve deficiency
No full textObjective To investigate the anatomic features of the nervus intermedius and cranial nerve VII in children with cochlear nerve deficiency and to verify whether the nervus intermedius can provide an additional landmark to help guide placement of the auditory brainstem implant electrode. Study Design Case series with chart review. Setting Tertiary referral center. Subjects and Methods High-definition video was captured during retrosigmoid surgery in 64 children (mean age, 3.91 ± 2.83 years) undergoing auditory brainstem implant placement. These videos were examined with particular reference to the number and variety of nervus intermedius bundles and any associated facial nerve anomalies. Results Absence of cranial nerves VI, VII, and VIII was observed in 3, 6, and all 64 children, respectively. Fifteen children had several abnormalities of the facial nerve in the cerebellopontine angle. Anatomic identification of the facial nerve and the bundles composing the nervus intermedius was possible in 46 children. In 12 children, identification was possible with the assistance of intraoperative monitoring. The number of bundles composing the nervus intermedius varied from 1 to 6. The nervus intermedius and cranial nerve IX were useful landmarks for identifying the foramen of Luschka of the lateral recess. Conclusion The nervus intermedius provides an additional landmark during auditory brainstem microsurgery since it was identified in all subjects. The nervus intermedius anatomy and its topographic relationship with the neurovascular structures around the foramen of Luschka have been described for the first time in children with cochlear nerve deficiency
Electrocochleography during cochlear implantation for hearing preservation.
No full textAbstract
OBJECTIVE: To determine whether intraoperative electrocochleography during cochlear implant surgery provides online feedback to modify surgical procedure, reduce trauma, and increase preservation of residual hearing.
STUDY DESIGN: Prospective cohort study.
SETTING: Tertiary referral center, Otolaryngology Department, University of Verona.
SUBJECTS AND METHODS: Twenty-seven adult patients undergoing cochlear implant surgery who had low- to mid-frequency (0.25-2 kHz) auditory thresholds measured preoperatively were enrolled. Fifteen subjects had compound action potentials measured to assess cochlear function during surgery. In those patients, surgery was modified according to electrocochleographic feedback. Twelve control subjects underwent cochlear implant surgery with blinded electrocochleographic monitoring.
RESULTS: The average preoperative pure-tone audiometry thresholds (0.25-2 kHz) were 74.3 ± 10.2 and 81.5 ± 12.7 dB hearing level (HL) in the electrocochleographic feedback and control cohorts, respectively (P > .05). Compound action potential recordings showed a mean maximum latency shift of 0.63 ± 0.36 ms and normalized amplitude deterioration of 59% ± 19% during surgery. All of these changes reverted to normal after electrode insertion in all but 1 subject in the electrocochleographic feedback group. The average shifts in postoperative pure-tone average threshold (0.25-2 kHz), evaluated before activation, were 8.7 ± 4.3 and 19.2 ± 11.4 dB HL in the electrocochleographic feedback and control cohorts, respectively (P = .0051). Complete hearing preservation (loss of ≤10 dB) at 1 month before activation was achieved in 85% (11/13) of electrocochleographic feedback subjects and in 33% (4/12) of control patients (P = .0154).
CONCLUSION: Monitoring cochlear function with electrocochleography gives real-time feedback during surgery, providing objective data that might help in modifying the surgical technique in ways that can improve the rate of hearing preservation
Surgical visual reference for auditory brainstem implantation in children with cochlear nerve deficiency
No full text
Training Prospective Primary and Kindergarten Teachers on Electric Circuits Using Conceptual Metaphors
Full text linkThe awareness and use of conceptual metaphors available in ordinary language should be a relevant part of teaching strategies, yet it is still rather neglected in teacher education. With a specific activity, we integrated a class of prospective kindergarten and primary school teachers on electric circuits with a reflection on the cognitive and linguistic aspects of metaphor. To understand how effective this integration proved to be, both in terms of learning and in terms of developing teaching skills, we conducted a single case study with a mixed qualitative–quantitative methodology. Student teachers were invited to analyze and discuss expressions on electric circuits selected from those they themselves had formulated at an earlier time. Here, we present some relevant results from the analysis of the students’ elaborations, highlighting how they worked with metaphors. They demonstrated a better understanding of the subject matter and greater awareness of teaching as well, in particular for what concerns the use of language and identifying and overcoming implicit ideas
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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