We investigated distortion product otoacoustic emissions (DPOAE) as a prognostic factor in idiopathic sudden sensorineural hearing loss (ISSHL) patients with the time-dependent Cox proportional-hazards model. We also compared the importance of the prognostic factors that are reported in the literature. 108 patients with ISSHL were included. Both DPOAE and pure tone audiometry were performed everyday for a maximum of 7 days during admission and followed every other week or monthly after discharge. All DPOAE amplitudes were analyzed at 2f1-f2 – namely 1093, 1375, 1750, 2187, 2781, 3500, 4375, and 5500 Hz. The average of two series of DPOAE intensity corrected for the noise level in eight frequencies was coded as dichotomous at ≧6 or <6 dB. We selected the most updated DPOAE at 3 days or more before the assessment of recovery into the analysis. The potential confounders including age, sex, history of vertigo at onset, history of hypertension, diabetes, coronary arterial disease, and stroke, configuration and severity of initial pure tone audiometry, the duration from onset to treatment, auditory brainstem response (ABR), vestibular evoked myogenic potential (VEMP), and plasma triglyceride and cholesterol levels, hemoglobin level, and erythrocyte sedimentation rate were collected for evaluation. The results showed that a better DPOAE amplitude was a significantly good prognostic indicator both in univariate analysis (recovery rate ratio = 3.626, 95% CI = 2.119–6.205, p < 0.0001) and multivariate analysis (recovery rate ratio = 2.94, 95% CI = 1.537–5.624, p = 0.0011). The Kaplan-Meier estimates showed that the younger age group (≤40 years) with better initial pure tone audiometry (<65 dB) represented a better prognosis that was compatible with previous literature (log-rank test, p = 0.0297 and p = 0.0019 respectively). In the univariate analysis, normal ABR and VEMP waveforms were associated with a better prognosis (ABR: recovery rate ratio = 2.984, 95% CI = 1.742–5.112, p < 0.0001; VEMP: recovery rate ratio = 1.978, 95% CI = 1.183–3.305, p = 0.0093). The configuration of initial audiometry was also a significant prognostic factor that patients with scale-out type (recovery rate ratio = 0.228, 95% CI = 0.089–0.584, p = 0.002) and tent type (recovery rate ratio = 0.081, 95% CI = 0.008–0.778, p = 0.0295) were associated with a poorer prognosis than those with the flat type in the multivariate analysis. In this study, the time-dependent Cox proportional-hazards model established the prognostic value of DPOAE for ISSHL patients. This model can also be used for comparison of different treatment protocols. In addition, the further development of a predictive model based on this method is worthy of being investigated.

Keywords:
Distortion product otoacoustic emissions, Prognosis of ISSHL patients, Proportional-hazards models, Sudden hearing loss
1.
Byl FM Jr: Sudden hearing loss: eight years’ experience and suggested prognostic table. Laryngoscope 1984;94:647–661.
2.
Fetterman BL, Saunders JE, Luxford WM: Prognosis and treatment of sudden sensorineural hearing loss. Am J Otol 1996;17:529–536.
3.
Hoth S: On a possible prognostic value of otoacoustic emissions: a study on patients with sudden hearing loss. Eur Arch Otorhinolaryngol 2005;262:217–224.
4.
Ito S, Fuse T, Yokota M, Watanabe T, Inamura K, Gon S, Aoyagi M: Parognosis is predicted by early hearing improvement in patients with idiopathic sudden sensorineural hearing loss. Clin Otolaryngol 2002;27:501–504.
5.
Kiris M, Cankaya H, Ichi M, Kutluhan A: Retrospective analysis of our cases with sudden hearing loss. J Otolaryngol 2003;32:384–387.
6.
Laird N, Wilson WR: Predicting recovery from idiopathic sudden hearing loss. Am J Otolaryngol 1983;4:161–164.
7.
Lalaki P, Markou K, Tsalighopoulos MG, Daniilidis I: Transiently evoked otoacoustic emissions as a prognostic indicator in idiopathic sudden hearing loss. Scand Audiol Suppl 2001;52:141–145.
8.
Mattox DE, Lyles CA: Idiopathic sudden sensorineural hearing loss. Am J Otol 1989;10:242–247.
9.
Nakamura M, Yamasoba T, Kaga K: Changes in otoacoustic emissions in patients with idiopathic sudden deafness. Audiology 1997;36:121–135.
10.
Park HM, Jung SW, Rhee CK: Vestibular diagnosis as prognostic indicator in sudden hearing loss with vertigo. Acta Otolaryngol Suppl 2001;545:80–83.
11.
Sakashita T, Minowa Y, Hachikawa K, Kubo T, Nakai Y: Evoked otoacoustic emissions from ears with idiopathic sudden deafness. Acta Otolaryngol Suppl 1991;486:66–72.
12.
Whitaker S: Idiopathic sudden hearing loss. Am J Otol 1980;15:244–246.
13.
Wilson WR, Byl FM, Larid N: The efficacy of steroids in the treatment of idiopathic sudden hearing loss. A double-blind clinical study. Arch Otolaryngol 1980;106:772–776.
14.
Yamamoto M, Kanzaki J, Ogawa K, Ogawa S, Tsuchihashi N: Evaluation of hearing recovery in patients with sudden deafness. Acta Otolaryngol (Stockh) Suppl 1994;514:37–40.
15.
Zadeh MH, Storper IS, Spitzer JB: Diagnosis and treatment of sudden-onset sensorineural hearing loss: a study of 51 patients. Otolaryngol Head Neck Surg 2003;128:92–98.
© 2006 S. Karger AG, Basel
2006
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.