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Home , Cholesteatoma, Ototoxicity

ABSTRACTS PAPERS – 2 68th Annual Meeting, May 11-13, 2014, OTTAWA

Additional Factors in Topical - B. Blakley, E. Kim, Winnipeg, MB

Learning Objectives: After this presentation the participant will have greater understanding of the possibility that factors other than the principal ingredient in otic drops may cause .

OBJECTIVE: To demonstrate some possible explanations for discrepant results in the literature regarding the ototoxicity of drops. INTRODUCTION: This paper will examine the possibility that factors other than the principal ingredient play a role in ototoxicity. Dose, duration of exposure, concentration, pH and preservatives are the additional factors that we considered that may be critical but partial determinants of ototoxicity. METHODS: A systematic literature review of ototoxicity was conducted after agreeing on inclusion criteria for papers that studied hearing loss due to -containing drops in humans or animals. RESULTS: Five hundred fifty-four papers were identified that addressed one or more “additional factors” including dose (56), duration (28), concentration (54), pH (248), and preservative (8). There was considerable variability in techniques. There were no formal randomized, controlled human trials but some findings suggest that: 1. Low concentrations of the preservatives (antioxidants) such as benzalkonium chloride may be protective against ototoxicity whereas in higher concentrations the opposite may be true. 2. Oxidation-reduction chemistry may be involved in ototoxicity. CONCLUSIONS: While the principal agent is important in ototoxicity methods of application also can affect the expression of hearing loss for aminoglycoside-containing otic drops.

Diffusion Weighted MRI versus Second Look Surgery in Residual and Recurrent - A Cost Analysis - D. Choi, J. Archibald, M. Gupta, R. Rebello, Toronto, ON

Learning Objectives: 1) By the end of the session, the audience will gain an understanding of the evidence surrounding imaging techniques in the role of recurrent and residual cholesteatoma.2) By the end of the session, the audience will be able to consider using diffusion-weighted MRI in diagnosing residual or recurrent cholesteatoma.

Objectives: Surveillance of residual or recurrent cholesteatoma following combined approach tympanomastoidectomy is traditionally performed through a second look tympanotomy, nine to twelve months following primary surgery. Traditional MRI sequences have been inadequate at detecting cholesteatoma recurrence. However, recent literature has shown diffusion-weighted imaging (DWIMRI) to be a viable alternative to second look surgery, particularly the non-echo planar imaging (non-EPI) sequence. The goal of this study is to perform a cost analysis of DWIMRI versus second look surgery. Methods: A decision tree model was created to compare second look surgery with DWIMRI. Inputs were obtained from the Ontario Case Costing Initiative, the Ontario Health Insurance Plan (OHIP) schedule of benefits and fees, and a systematic review of the current literature. Costs were reported in 2013 Canadian dollars and a payer perspective was adopted. A deterministic sensitivity analysis was performed. Results: The cost difference between second-look surgery and echo planar imaging (EPI) is CAD561.16 in favour of second look surgery. For non-EPI imaging, the more sensitive DWIMRI technique, the cost difference is CAD224.22 in favour of non-EPI imaging. Conclusion: Magnetic resonance imaging, particularly non-EPI MRI, is an effective economic alternative to second look surgery in the detection of residual or recurrent .

The Impact of Erdosteine on -Induced Ototoxicity: A Proteomics Approach - S. Waissbluth, O. Akinpelu, P. Salehi, S. Daniel, Montreal, QC

Learning Objectives: Cognitive, knowledge: By the end of this session, otolaryngologists will be able to describe a procedure for a large-scale study of cochlear proteins when presented with a molecular biology case. Cognitive, knowledge: By the end of this session, first year otolaryngology residents will be able to list genes found within the that have an impact on cochlear immunology when presented with a clinical case. Cognitive, problem-solving: By the end of this session, the third year medical student will be able to evaluate the benefits of an antioxidant in ototoxicity when presented with evidence from the literature.

Objectives: Cisplatin is a commonly used chemotherapeutic agent and causes serious side effects including sensorineural hearing loss. No treatment is currently available for cisplatin-induced ototoxicity. We have previously demonstrated that erdosteine, a potent antioxidant, partially protected the cochlea against cisplatin in vivo. The aims of this study were to evaluate the protein profile of the cochlea following cisplatin administration and evaluate the impact of erdosteine using a proteomics-based approach. Methods: Sprague-Dawley rats were injected intraperitoneally with saline (n=10), cisplatin (n=10) or with cisplatin and erdosteine (n=10). The cisplatin dosage was 14 mg/kg and for erdosteine, 500 mg/kg. Protein lysates were obtained from fresh-frozen cochleae and were processed for mass spectrometry and western blotting. Results: Proteins with decreased levels of expression after cisplatin treatment included ras-related protein Rab-2A, ribosomal protein S5 and myelin basic protein. Following erdosteine treatment, the expression of ras-related protein Rab-2A, ribosomal protein S5 and collagen (type IX, alpha 2) increased. The data was further validated by western blotting analysis. Conclusion: In this study, we discuss the proteins that expressed the greatest ABSTRACTS PAPERS – OTOLOGY 2 68th Annual Meeting, May 11-13, 2014, OTTAWA fold changes as a result of cisplatin administration and the impact, on the proteome, of an antioxidant. Emphasis will be placed on describing the steps necessary for establishing a successful and productive collaborative research program and fostering research relationships for OHNS. Finally, the benefits of such a program are described.

Optical Coherence Tomography Imaging of the Human Tympanic Membrane and Ex Vivo - J. Rainsbury, M. Bance, R. Adamson, D. MacDougall, Halifax, NS

Learning Objectives: By the end of this session, members of the audience will be able to:-1. Describe how Optical Coherence Tomography (OCT) works and understand its applications in medical imaging.2. Observe a selection of normal and pathological middle ear structures on OCT images.

Objective-Optical Coherence Tomography (OCT) is a cross-sectional imaging technique that can acquire micrometer-resolution, three-dimensional images from biological tissues. The images it produces are very similar in appearance to ultrasound images, although OCT images the tissue’s optical reflectivity rather than its acoustic scattering strength. Good quality OCT imaging of the middle ear would allow assessment of the ossicular chain, ossiculoplasty/stapedotomy prostheses, and other structures behind an intact tympanic membrane (TM). We present images of human cadaveric middle with a variety of simulated ossicular . Method-OCT of fresh frozen human cadaveric temporal bones under the following conditions: intact ossicular chain; ossicular discontinuity; ossicular reconstruction prosthesis (partial/total, intact/displaced).Results-High resolution OCT images of the TM and middle ear structures from human cadaveric temporal bones under a variety of conditions will be presented. Conclusion-Although there are still limitations, OCT has the potential to be a valuable diagnostic tool in otology, and may become particularly useful in pre- and postoperative assessment of patients with ossicular chain .

Tympanic Membrane Perforations with Anterior Wall Bulging: Endoscopic Hyaluronic Acid Fat Graft vs Overlay Myringoplasty - E. Thibaudeau, I. Saliba, M. Alzahrani, A. Naim, Montreal, QC

Learning Objectives: To present a new surgical technique for the reparation of the anterior tympanic membrane perforations partially hidden by an anterior auditory can wall bulging. To compare the results of this technique to those obtained with traditional methods. To review the principles of tympanic membrane perforation healing.

Objectives: 1. To compare the closure success rates of different sizes of tympanic membrane perforations (TMPs) with anterior external auditory canal (EAC) bone bulging between the Endoscopic hyaluronic acid fat graft myringoplasty (E-HAFGM) and the overlay tympanoplasty. 2. To assess the hearing improvement post operatively at 1 year. Methods: A prospective study in a tertiary care center. All the patients operated on for different sizes of TMPs with anterior bony bulging of the EAC were included. They were divided according into: overlay tympanoplasty group and E-HAFGM group. Complete closure was considered a success. Audiometric parameters were evaluated pre and post operatively. Results: One hundred and twelve patients were included in the study. Forty-one patients underwent overlay tympanoplasty and seventy-one patients underwent E-HAFGM. The global success rate was 85.3% and 70.0% for the Overlay and the E-HAFGM, respectively (p=0.07). The size of the TMP did not influence the success rate. By repeating the E-HAFGM for the residual perforation of this group, success rate reach 83%. A significant improvement in the pure tone and the air bone gap was found in all patients (p<0.05).Conclusion: E-HAFGM is an effective procedure for TMPs with hidden margins due to anterior EAC bone bulging.