Text Box: In order to increase the diagnostic yield of patients at risk of vestibular schwannoma and reduce the incidence of 'negative' findings on MRI scan ordered for patients with audiovestibular symptoms especially assymetric SNHL suspected to be VS, this study from the UK (Nouraei, Huys,  Chatrath et al, Clinical Otolaryngology, 32, 248–254) utilized a Gaussian Process Ordinal Regression Classifier   to differentiate between patients with and without vestibular schwannoma based on clinical and audiological data collected during a routine otolaryngological consultation, and observed that this decision support tool is more sensitive than previously reported audiological protocols.

Text Box: Editor’s choice :  Neural Network & SNHL in VS...?

Text Box: Olfactory Mediators or Modulators...?

Text Box: Recall the issue on odor coding and GABA (Vol6no3). To clear the air on the controversy surrounding events that happen between the appearance of odourants on the olfactory receptor cells surface and depolarization, eventually resulting in action potentials that are transmitted to the olfactory bulb, tracts, cortex, etc, this new study from Texas, Baltimore and Germany (T. Leinders-Zufall et al, PNAS, PNAS | September 4, 2007 | vol. 104 | no. 36 | 14507-14512) demonstrated that the main olfactory epithelium demonstrated the essential role of GC-D and CNGA3 in olfactory signal transduction.

Text Box: otolaryngologyinafrica.net Text Box: otolaryngologyinafrica.net Text Box: September 20 2007

Text Box: Volume 7, No 2

Text Box: Otorhinolaryngology news

Text Box: In this issue · Neural Network & SNHL in VS..? · Olfactory Mediators or Modulators…? · Tinnitus & Electro-Cortical Stimulation...? · Case of The Week

Text Box: Biodun Olusesi  Newsletter Editor View Page in FrenchText Box: Journal Watch: Primary Tumor Volume Calculation as a Predictive Factor in Nasopharyngeal Carcinoma, Lee CC et al, 2007    1.   Win fantastic gifts (soon to be announced) by guessing 3 of the outstanding diagnosis in our Clinical Case of The Week past series. Watch out for details...  2.  Otolaryngologyinafrica.net is experimenting with use of SMS notification of newsletter release. Feel free to air your view on this issue by emailing orl-mailer@otolaryngologyinafrica.net . 3.    Feel free to take our online poll - Click HERE  Till Next Week,  Biodun

Text Box: This recent study from Belgium ( de Ridder D. et al, Acta Neurochir Suppl. 2007;97(Pt 2):451-62) demonstrated that electrical stimulation of the auditory cortex significantly led to tinnitus suppression in unilateral pure tone tinnitus and posits that this could become a treatment option in selected patients with severe tinnitus

Text Box: Electro-Cortical Stimulation for Tinnitus...?...?

Text Box: ABSTRACT: Functional imaging techniques have demonstrated a relationship between the intensity of tinnitus and the degree of reorganization of the primary auditory cortex. Studies in experimental animals and humans have revealed that tinnitus is associated with a synchronized hyperactivity in the auditory cortex and proposed that the underlying pathophysiological mechanism is thalamocortical dysrhythmia; hence, decreased auditory stimulation results in decreased firing rate, and decreased lateral inhibition. Consequently, the surrounding brain area becomes hyperactive, firing at gamma band rates; this is considered a necessary precondition of auditory consciousness, and also tinnitus. Synchronization of the gamma band activity could possibly induce a topographical reorganization based on Hebbian mechanisms. Therefore, it seems logical to try to suppress tinnitus by modifying the tinnitus-related auditory cortex reorganization and hyperactivity. This can be achieved using neuronavigation-guided transcranial magnetic stimulation (TMS), which is capable of modulating cortical activity. If TMS is capable of suppressing tinnitus, the effect should be maintained by implanting electrodes over the area of electrophysiological signal abnormality on the auditory cortex. The results in the first patients treated by auditory cortex stimulation demonstrate a statistically significant tinnitus suppression in cases of unilateral pure tone tinnitus without suppression of white or narrow band noise. Hence, auditory cortex stimulation could become a physiologically guided treatment for a selected category of patients with severe tinnitus.

Text Box: Abstract: Objectives: Selecting patients with asymmetrical sensorineural hearing loss for further investigation continues to pose clinical and medicolegal challenges, given the disparity between the number of symptomatic patients, and the low incidence of vestibular schwannoma as the underlying cause. We developed and validated a diagnostic model using a generalisation of neural networks, for detecting vestibular schwannomas from clinical and audiological data, and compared its performance with six previously published clinical and audiological decision support screening protocols. Design: Probabilistic complex data classification using a neural network generalization. Settings: Tertiary referral lateral skull base and a computational neuroscience unit. Participants: Clinical and audiometric details of 129 patients with, and as many age and sex-matched patients without vestibular schwannomas, as determined with magnetic resonance imaging. Main outcome measures: The ability to diagnose a patient as having or not having vestibular schwannoma. Results: A Gaussian Process Ordinal Regression Classifier was trained and cross-validated to classify cases as ‘with’ or ‘without’ vestibular schwannoma, and its diagnostic performance was assessed using receiver operator characteristic plots. It proved possible to pre-select sensitivity and specificity, with an area under the curve of 0.8025. At 95% sensitivity, the trained system had a specificity of 56%, 30% better than audiological protocols with closest sensitivities. The sensitivities of previously-published audiological protocols ranged between 82–97%, and their specificities ranged between 15–61%. Discussion: The Gaussian Process ORdinal Regression Classifier increased the flexibility and specificity of the screening process for vestibular schwannoma when applied to a sample of matched patients with and without this condition. If applied prospectively, it could reduce the number of ‘normal’ magnetic resonance (MR) scans by as much as 30% without reducing detection sensitivity. Performance can be further improved through incorporating additional data domains. Current findings need to be reproduced using a larger dataset.

Text Box: © Copyright Dr 'Biodun Olusesi,  2005 - 2007

Otolaryngology in Africa FeedText Box: Reed Our Feed

Text Box: A 19 year old female presented with 16 months history pf nasal obstruction associated with difficulty in breathing especially at night. Clinical examination revealed the signs demonstrated in this picture >>> (Case Presentation by Dr Aminu Bakari, NECC, Kaduna)

Text Box: Case of the week

Text Box: Abstract: The mammalian main olfactory epithelium (MOE) recognizes and transduces olfactory cues through a G protein-coupled, cAMP-dependent signaling cascade. Additional chemosensory transduction mechanisms have been suggested but remain controversial. We show that a subset of MOE neurons expressing the orphan receptor guanylyl cyclase GC-D and the cyclic nucleotide-gated channel subunit CNGA3 employ an excitatory cGMP-dependent transduction mechanism for chemodetection. By combining gene targeting of Gucy2d, which encodes GC-D, with patch clamp recording and confocal Ca2+ imaging from single dendritic knobs in situ, we find that GC-D cells recognize the peptide hormones uroguanylin and guanylin as well as natural urine stimuli. These molecules stimulate an excitatory, cGMP-dependent signaling cascade that increases intracellular Ca2+ and action potential firing. Responses are eliminated in both Gucy2d- and Cnga3-null mice, demonstrating the essential role of GC-D and CNGA3 in the transduction of these molecules. The sensitive and selective detection of two important natriuretic peptides by the GC-D neurons suggests the possibility that these cells contribute to the maintenance of salt and water homeostasis or the detection of cues related to hunger, satiety, or thirst.

 

Pediatric Airway Obstruction

 

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