Text Box: Hitherto, the explanation of the cellular mechanism of salicylate-induced tinnitus has focused on the peripheral auditory system (cochleotoxicity). But based on the fact that tinnitus is often accompanied with changes in neural activities of the central auditory system, Wang et al from China in a recent study (Hearing Research, Volume 215, Issues 1-2 , May 2006, Pages 77-83  ) designed to determine whether the lateral inhibition of the auditory cortex is directly influenced by salicylate reported that salicylate significantly depressed both evoked inhibitory postsynaptic currents (eIPSCs) and miniature inhibitory postsynaptic currents (mIPSCs) in neurons of rat auditory cortex, and suggested a central mechanism of salicylate-induced tinnitus is also possible. 
 
Abstract: Sodium salicylate (SS) is a medicine for anti-inflammation and for chronic pain relief with a side effect of tinnitus. To understand the cellular mechanisms of tinnitus induced by SS in the central auditory system, we examined effects of SS on evoked and miniature inhibitory postsynaptic currents (eIPSCs and mIPSCs) recorded from layer II/III pyramidal neurons of rat auditory cortex in a brain slice preparation with whole-cell patch-clamp techniques. Both eIPSCs and mIPSCs recorded from the auditory cortex could be completely blocked by bicuculline, a selective GABA(A) receptor antagonist. SS did not change the input resistance of neurons but was found to reversibly depress eIPSCs in a concentration-dependent manner. SS reduced eIPSCs to 82.3% of the control level at 0.5 mM (n = 7) and to 60.9% at 1.4 mM (n = 12). In addition, SS at 1.4 mM significantly reduced the amplitude of mIPSCs from 24.12 ± 1.44 pA to 19.92 ± 1.31 pA and reduced the frequency of mIPSCs from 1.34 ± 0.23 Hz to 0.89 ± 0.13 Hz (n = 6). Our results demonstrate that SS attenuates inhibitory postsynaptic currents in the auditory cortex, suggesting that the alteration of inhibitory neural circuits may be one of the cellular mechanisms for tinnitus induced by SS in the central auditory region.
Text Box: Editor's Choice: Salicylate & Tinnitus, What Mechanism...?
Text Box: Abreast of Ear, Nose, Throat, Head & Neck Advances

Text Box: Volume 3, N0. 7
Text Box: May 21, 2006

Text Box: Otorhinolaryngology News

Text Box: Inside This Issue
· Salicylate & Tinnitus
· OK-432 & Branchial Cyst
· Otitis Externa & Guidelines
*     Case of the Week

 

 

 Case Review

 Clinical Photo of The Week

An 11-year old female was referred from the paediatric outpatient on account of right hemi-cranial pain, right otalgia, drooping of right eyelid and leakage of saliva from the right angle of the mouth all of 2 months duration. She had initial steroid therapy at the Paediatric OP with little improvement. Examination revealed right conjuctival hyperemia with good visual acuity, and the signs shown in this picture. MRI showed post nasal space narrowing by a soft tissue mass, as well as cloudy ipsilateral sphenoid sinus, and poorly pneumatized ipsilateral mastoid air cells. . EUA revealed heaped-up firm mass plastered to the post-nasal space. Histology report of the curretage biopsy specimen was negative for malignancy. The attending surgeon received a phone call that the patient suddenly died at home, 2 days before the histology report was expected.

What is the Diagnosis?

Text Box: Coming Events of Importance to Otorhinolaryngologists in Africa

1.          8th International Otology Course of the Jean Causse Ear Clinic June 22-24, 2006; Béziers, France

2. 110th American Academy of ORL, Head & Neck Surgery Annual Meeting & OTO EXPO, September 17-20, 2006; Toronto, Canada.

3. 42nd South African ENT Congress joint meeting with the British Association of Otolaryngology - Head & Neck Surgery, October 29-November 1, 2006; Cape Town, South Africa.

A multi-disciplinary committee set up to promote appropriate use of topical and systemic antibiotimicrobials as well as highlight the need for acute pain control in acute otitis externa recently published their recommendation (Rosenfeld RM et al, Otolaryngol Head Neck Surg. 2006 Apr;134(4 Suppl):S4-23.) as an evidence based guideline to guide clinicians managing this condition

Abstract: OBJECTIVE: This guideline provides evidence-based recommendations to manage diffuse acute otitis externa (AOE), defined as generalized inflammation of the external ear canal, which may also involve the pinna or tympanic membrane. The primary purpose is to promote appropriate use of oral and topical antimicrobials and to highlight the need for adequate pain relief. STUDY DESIGN: In creating this guideline, the American Academy of Otolaryngology-Head and Neck Surgery Foundation (AAO-HNSF) selected a development group representing the fields of otolaryngology-head and neck surgery, pediatrics, family medicine, infectious disease, internal medicine, emergency medicine, and medical informatics. The guideline was created with the use of an explicit, a priori, evidence-based protocol. RESULTS: The group made a strong recommendation that management of AOE should include an assessment of pain, and the clinician should recommend analgesic treatment based on the severity of pain. The group made recommendations that clinicians should: 1) distinguish diffuse AOE from other causes of otalgia, otorrhea, and inflammation of the ear canal; 2) assess the patient with diffuse AOE for factors that modify management (nonintact tympanic membrane, tympanostomy tube, diabetes, immunocompromised state, prior radiotherapy); and 3) use topical preparations for initial therapy of diffuse, uncomplicated AOE; systemic antimicrobial therapy should not be used unless there is extension outside of the ear canal or the presence of specific host factors that would indicate a need for systemic therapy. The group made additional recommendations that: 4) the choice of topical antimicrobial therapy of diffuse AOE should be based on efficacy, low incidence of adverse events, likelihood of adherence to therapy, and cost; 5) clinicians should inform patients how to administer topical drops, and when the ear canal is obstructed, delivery of topical preparations should be enhanced by aural toilet, placing a wick, or both; 6) when the patient has a tympanostomy tube or known perforation of the tympanic membrane, the clinician should prescribe a nonototoxic topical preparation; and 7) if the patient fails to respond to the initial therapeutic option within 48 to 72 hours, the clinician should reassess the patient to confirm the diagnosis of diffuse AOE and to exclude other causes of illness. And finally, the panel compiled a list of research needs based on limitations of the evidence reviewed. CONCLUSION: This clinical practice guideline is not intended as a sole source of guidance in evaluating patients with AOE. Rather, it is designed to assist clinicians by providing an evidence-based framework for decision-making strategies. It is not intended to replace clinical judgment or establish a protocol for all individuals with this condition and may not provide the only appropriate approach to the diagnosis and management of this problem. SIGNIFICANCE: This is the first, explicit, evidence-based clinical practice guideline on acute otitis externa, and the first clinical practice guideline produced independently by the AAO-HNSF.

 


                 Journal Watch : Cost of Tracheo-oesopahgeal prosthesis in developing countries. Stafierri et al, 2006

  1.  Reviewers wanted for otolaryngology news journal's watch page. If you are an Otolaryngologist in Africa and will like to be our journal reviewer, please feel free to email orl-mailer@otolaryngologyinafrica.net

  2.   DODA 2006, capable of advanced hearing measure, and also paediatric hearing assessment is being developed. If you requested for and got a free copy of DODA, you may also look out for this latest version dubbed DODA-i, as well as for an additional page on outcome of hearing assessment using DODA.

 3.  You may want to check out this new site dedicated to early detection of hearing loss in developing countries

 Till Next Week,

 Biodun

 

 

 

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