1,720,963 research outputs found
Electrocochleography: development of metrics and optimized recording techniques
No full textIntroduzione: Tradizionalmente, gli interventi chirurgici otologici, in cui l'integrità dell'orecchio interno è
compromessa, sono considerati demolitivi per l’udito, sebbene siano efficaci nel trattare alcune disabilitanti
malattie. L'elettrococleografia (ECochG) è una tecnica che consente la misurazione dei potenziali evocati
uditivi che derivano dall'orecchio interno e dal ganglio spirale grazie alla prossimità dell'elettrodo di
registrazione. Questa tesi ha l’obiettivo di indagare i potenziali meccanismi di perdita/preservazione
dell'udito mediante ECochG eseguita durante diversi tipi di procedure chirurgiche otologiche e della base
cranica laterale (es. impianto cocleare, IC, malattia di Ménière, MD, resezione di schwannoma vestibolare,
VS, ecc.). Inoltre, è stato utilizzato un modello animale per isolare le componenti del potenziale di
sommazione (SP) al fine di consentirne una migliore interpretazione clinica.
Materiali e metodi: I pazienti inclusi sono stati sottoposti a ECochG dalla finestra rotonda durante
l'intervento chirurgico: gli stimoli presentati sono stati tone burst da 95 a 110 dB SPL. Anche nel modello
animale è stata eseguita l'ECochG della finestra rotonda. Infine, un gruppo di pazienti programmati per
ricevere un IC “lateral wall” sono stati sottoposti a ECochG direttamente attraverso il multielettrodo durante
il suo inserimento, con il monitoraggio intraoperatorio attivo (AIM, Advanced Bionics, Advanced Bionics
LLC, Valencia, CA).
Risultati: I risultati ECochG nei pazienti con VS e MD hanno evidenziato una riduzione nell'ampiezza della
risposta all’aumentare della frequenza dello stimolo. In un caso di rimozione di un tumore del forame
giugulare, il potenziale d'azione composto è aumentato a tutte le frequenze (p<0.01) e la preservazione
dell'udito è stata confermata dall’esame audiometrico post-operatorio. Nonostante l'esiguo numero di
pazienti, sono stati osservati pattern di risposta ECochG eterogenei all'interno del gruppo con tip-fold-over,
mentre tutti i controlli hanno mostrato una diminuzione della risposta ECochG-totale. Il modello animale ha
evidenziato che il SP presenta almeno quattro componenti, di cui due neurali, con una miscela di polarità e
ampiezze.
Conclusioni: L'ECochG intraoperatoria può consentire il monitoraggio uditivo in tempo reale durante
chirurgie complesse della base cranica laterale, di minimizzare il trauma durante l’inserimento del
multielettrodo e di ridurre alcune complicanze come il tip-fold-over durante la chirurgia dell'IC. Segni di
patologia cocleare sono risultati presenti nei pazienti con VS e MD. Infine, dovrebbe essere annoverata
l’intricata origine cocleare e neurale nell’interpretazione clinica del SP.Introduction: Traditionally, ear surgeries where the integrity of the inner ear is compromised are considered
destructive procedures. While these operations can be very successful for threatening certain inner ear
diseases, they always determine a complete loss of hearing. Electrocochleography (ECochG) is a technique
that allows for the measurement of the auditory evoked potentials that arise from the inner ear and spiral
ganglion. As opposed to far-field recording techniques, ECochG is considered a near-field recording
montage, mainly due to the proximity of the recording electrode to the source generators in the inner ear. The
aims of these thesis were to investigate the potential mechanisms of hearing loss/preservation via
electrophysiological measures during several types of otologic and skull base procedures (i.e., cochlear
implantation, CI, Ménière’s disease, MD, resection of vestibular schwannoma, VS, etc.). Additionally, an
animal model was used to isolate the complex sources of the summating potential (SP) for better
interpretation for clinical purposes.
Materials and methods: Patient interventions consisted of intraoperative round window ECochG during
surgery: tone burst stimuli were presented from 95 to 110 dB SPL. Round window ECochG to tones and
clicks was also performed in the animal model. Lastly, a group of patients scheduled to receive a lateral wall
electrode underwent ECochG recorded directly from a CI electrode array during its insertion, with the Active
Intraoperative Monitoring (AIM, Advanced Bionics, Valencia, CA).
Results: ECochG findings in VS and MD patients evidenced a reduced trend in amplitude of the ongoing
response with increased stimulus frequency. In a case of jugular foramen tumor removal, the compound
action potential magnitudes increased at all test frequencies (p<0.01) and serviceable hearing was confirmed
by audiometric testing after tumor resection. Despite the small number of patients, heterogeneous ECochG
response patterns were observed within the CI fold-over group, while regarding the ECochG-total response,
all controls showed a decrease in the magnitude. The animal model evidenced that the sources of the SP
include at least four components presenting a mixture of polarities and magnitudes.
Conclusions: Intraoperative ECochG may allow for real-time monitoring of auditory function during
complex skull base surgery, minimizing trauma for electrode insertion and reducing complications such as
tip fold-over during CI surgery. Findings of cochlear pathology were likely present in patients with VS and
MD. Finally, the complex mixture of cochlear and neural sources should be acknowledged when interpreting
the SP for clinical purposes
Traumatic sensorineural hearing loss
No full textHearing loss is one the commonest disabling diseases affecting populations of all ages worldwide. The impairment of hearing may be the cause of impaired language development in children, the cause of scholarly issues in adolescents, the cause of worsening of quality of life in the adults, and the cause of isolation of aged people. In this book, the authors present the hearing loss in all its facets, starting from the basis of pathophysiology and anatomy, passing through the clinical and instrumental diagnosis and, finally, describing the most important diseases causing hearing loss with reasonable treatment options.
A section was dedicated to the imaging of the ear with about 100 original figures. The readers will find a complete classification of genetic hearing loss and all information related to congenital deafness as well. A wide section was reserved to the description and discussion of the most important pathology leading to hearing loss (Meniere’s disease, otosclerosis, trauma and occupational hearing impairment, etc.). The treatment of hearing loss is continuously evolving with the progress of technology, and the authors gave a wide space to describe all treatment options available for the patients, providing all information useful to manage hearing disease correctly
COVID-19: the difference between the nose and the lung
No full textTo the Editor An elegant study reported dysmorphic cells and syncytia in the deceased's lungs for COVID-19. The authors reasonably considered that most of these syncytia-forming cells were pneumocytes, as identified by specific biomarkers. However, cellular dysmorphism and syncytia are pathological features common in other respiratory infections caused by different viruses, including the human respiratory syncytial virus (HRSV) and Epstein-Barr virus (EBV), as correctly documented..
Update of endoscopic classification system of adenoid hypertrophy based on clinical experience on 7621 children
No full textINTRODUCTION: Nasal endoscopy is likely to be the method of choice to evaluate nasal obstruction and adenoid hypertrophy (AH) in children given its excellent diagnostic accuracy and low risk for the patient. The aim of this study was to update the previous classification of AH to guide physicians in choosing the best therapeutic option. MATERIALS AND METHODS: This is a retrospective observational study including 7621 children (3565 females; mean age 5.92; range: 3-14 years) who were managed for adenoid hypertrophy at our institution between 2003 and 2018. All patients were initially treated with medical therapy and then with surgery if not adequately controlled. We performed a specific analysis based on the presence or absence of comorbidities. RESULTS: In 1845 (24.21%) patients, adenoid obstruction was classified as Grade I when the fiberoptic endoscopy showed adenoid tissue occupying < 25% of choanal space. In 2829 of 7621 (37.12%) patients, the adenoid tissue was scored as Grade II since it was confined to the upper half of nasopharynx, with sufficiently pervious choana and visualisation of tube ostium. In 1611 of 7621 (21.14%) cases, adenoid vegetation occupied about 75% of the nasopharynx with partial involvement of tube ostium and considerable obstruction of choanal openings, and was classified as Grade III. Finally, 1336 of 7621 (17.53%) patients were scored as Grade IV due to complete obstruction with adenoid tissue reaching the lower choanal border without allowing the visualisation of the tube ostium. Based on resolution of symptoms in Grade III obstruction after medical therapy (that was mostly seen in patients without comorbidities), we divided patients in two subclasses: Grade IIIA was not associated with comorbidities, while Grade IIIB was correlated with important comorbidities. CONCLUSIONS: These results can be useful to guide medical or surgical therapeutic intervention. In patients with class IIIB AH, surgical treatment offered adequate control not only of nasal symptoms but also of associated comorbidities
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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