Locally applied drugs can protect residual hearing following cochlear implantation. The influence of cochlear implantation on drug levels in the scala tympani (ST) after round window application was investigated in guinea pigs using the marker trimethylphenylammonium (TMPA) measured in real time with TMPA-selective microelectrodes. TMPA concentration in the upper basal turn of the ST rapidly increased during implantation and then declined due to cerebrospinal fluid entering the ST at the cochlear aqueduct and exiting at the cochleostomy. The TMPA increase was found to be caused by the cochleostomy drilling if the burr tip partially entered the ST. TMPA distribution in the second turn was less affected by implantation procedures. These findings show that basal turn drug levels may be changed during implantation and the changes may need to be considered in the interpretation of therapeutic effects of drugs in conjunction with implantation.

1.
Adunka O, Kiefer J, Unkelbach MH, Lehnert T, Gstoettner W: Development and evaluation of an improved cochlear implant electrode design for electric acoustic stimulation. Laryngoscope 2004;114:1237-1241.
2.
Baumgartner WD, Jappel A, Morera C, Gstöttner W, Müller J, Kiefer J, Van De Heyning P, Anderson I, Nielsen SB: Outcomes in adults implanted with the FLEXsoft electrode. Acta Otolaryngol 2007;127:579-586.
3.
Briggs RJ, Tykocinski M, Stidham K, Roberson JB: Cochleostomy site: implications for electrode placement and hearing preservation. Acta Otolaryngol 2005;125:870-876.
4.
Chang A, Eastwood H, Sly D, James D, Richardson R, O'Leary S: Factors influencing the efficacy of round window dexamethasone protection of residual hearing post-cochlear implant surgery. Hear Res 2009;255:67-72.
5.
Cipolla MJ, Iyer P, Dome C, Welling DB, Bush ML: Modification and comparison of minimally invasive cochleostomy techniques: a pilot study. Laryngoscope 2012;122:1142-1147.
6.
Coulson CJ, Taylor RP, Reid AP, Griffiths MV, Proops DW, Brett PN: An autonomous surgical robot for drilling a cochleostomy: preliminary porcine trial. Clin Otolaryngol 2008;33:343-347.
7.
Doménech J, Carulla M, Traserra J: Sensorineural high-frequency hearing loss after drill-generated acoustic trauma in tympanoplasty. Arch Otorhinolaryngol 1989;246:280-282.
8.
Eastwood H, Pinder D, James D, Chang A, Galloway S, Richardson R, O'Leary S: Permanent and transient effects of locally delivered n-acetyl cysteine in a guinea pig model of cochlear implantation. Hear Res 2010;259:24-30.
9.
Enticott JC, Eastwood HT, Briggs RJ, Dowell RC, O'Leary SJ: Methylprednisolone applied directly to the round window reduces dizziness after cochlear implantation: a randomized clinical trial. Audiol Neurotol 2011;16:289-303.
10.
Eshraghi AA: Prevention of cochlear implant electrode damage. Curr Opin Otolaryngol Head Neck Surg 2006;14:323-328.
11.
Fishman AJ, Moreno LE, Rivera A, Richter CP: CO2 laser fiber soft cochleostomy: development of a technique using human temporal bones and a guinea pig model. Lasers Surg Med 2010;42:245-256.
12.
Gantz BJ, Turner CW: Combining acoustic and electrical hearing. Laryngoscope 2003;113:1726-1730.
13.
Gantz BJ, Turner C: Combining acoustic and electrical speech processing: Iowa/Nucleus hybrid implant. Acta Otolaryngol 2004;124:344-347.
14.
Gantz BJ, Turner C, Gfeller KE, Lowder MW: Preservation of hearing in cochlear implant surgery: advantages of combined electrical and acoustical speech processing. Laryngoscope 2005;115:796-802.
15.
Gstoettner WK, van de Heyning P, O'Connor AF, Morera C, Sainz M, Vermeire K, Mcdonald S, Cavallé L, Helbig S, Valdecasas JG, Anderson I, Adunka OF: Electric acoustic stimulation of the auditory system: results of a multi-centre investigation. Acta Otolaryngol 2008;128:968-975.
16.
Gudis DA, Montes M, Bigelow DC, Ruckenstein MJ: The round window: is it the ‘cochleostomy' of choice? Experience in 130 consecutive cochlear implants. Otol Neurotol 2012;33:1497-1501.
17.
James DP, Eastwood H, Richardson RT, O'Leary SJ: Effects of round window dexamethasone on residual hearing in a guinea pig model of cochlear implantation. Audiol Neurotol 2008;13:86-96.
18.
Jayawardena J, Kuthubutheen J, Rajan G: Hearing preservation and hearing improvement after reimplantation of pediatric and adult patients with partial deafness: a retrospective case series review. Otol Neurotol 2012;33:740-744.
19.
Kiefer J, Gstoettner W, Baumgartner W, Pok SM, Tillein J, Ye Q, von Ilberg C: Conservation of low-frequency hearing in cochlear implantation. Acta Otolaryngol 2004;124:272-280.
20.
Kiefer J, Ye Q, Tillein J, Adunka O, Arnold W, Gstöttner W: Protecting the cochlea during stapes surgery: is there a role for corticosteroids? Adv Otorhinolaryngol 2007;65:300-307.
21.
King EB, Salt AN, Eastwood HT, O'Leary SJ: Direct entry of gadolinium into the vestibule following intratympanic applications in guinea pigs and the influence of cochlear implantation. J Assoc Res Otolaryngol 2011;12:741-751.
22.
Kylén P, Arlinger S: Drill-generated noise levels in ear surgery. Acta Otolaryngol 1976;82:402-409.
23.
Lenarz T, Stover T, Buechner A, Paasche G, Briggs R, Risi F, Pesch J, Battmer RD: Temporal bone results and hearing preservation with a new straight electrode. Audiol Neurotol 2006;11(suppl 1):34-41.
24.
Lehnhardt E: Intracochlear placement of cochlear implant electrodes in soft surgery technique (in German). HNO 1993;41:356-359.
25.
Mynatt R, Hale SA, Gill RM, Plontke SK, Salt AN: Demonstration of a longitudinal concentration gradient along scala tympani by sequential sampling of perilymph from the cochlear apex. J Assoc Res Otolaryngol 2006;7:182-193.
26.
Ohyama K, Salt AN, Thalmann R: Volume flow rate of perilymph in the guinea-pig cochlea. Hear Res 1988;35:119-129.
27.
Pau HW, Just T, Bornitz M, Lasurashvilli N, Zahnert T: Noise exposure of the inner ear during drilling a cochleostomy for cochlear implantation. Laryngoscope 2007;117:535-540.
28.
Plontke SK, Mynatt R, Gill RM, Salt AN: Concentration gradient along scala tympani following the local application of gentamicin to the round window membrane. Laryngoscope 2007;117:1191-1198.
29.
Plontke SK, Biegner T, Kammerer B, Delabar U, Salt AN: Dexamethasone concentration gradients along scala tympani after application to the round window membrane. Otol Neurotol 2008;29:401-406.
30.
Salt AN, Ma Y: Quantification of solute entry into cochlear perilymph through the round window membrane. Hear Res 2001;154:88-97.
31.
Salt AN, Hartsock JJ, Gill RM, Piu F, Plontke SK: Perilymph pharmacokinetics of markers and dexamethasone applied and sampled at the lateral semi-circular canal. J Assoc Res Otolaryngol 2012a;13:771-783.
32.
Salt AN, King EB, Hartsock JJ, Gill RM, O'Leary SJ: Marker entry into vestibular perilymph via the stapes following applications to the round window niche of guinea pigs. Hear Res 2012b;283:14-23.
33.
Skarzynski H, Lorens A, Piotrowska A, Anderson I: Preservation of low frequency hearing in partial deafness cochlear implantation (PDCI) using the round window surgical approach. Acta Otolaryngol 2007;127:41-48.
34.
von Ilberg C, Kiefer J, Tillein J, Pfenningdorff T, Hartmann R, Stürzebecher E, Klinke R: Electric-acoustic stimulation of the auditory system. New technology for severe hearing loss. ORL J Otorhinolaryngol Relat Spec 1999;61:334-340.
35.
Ye Q, Tillein J, Hartmann R, Gstoettner W, Kiefer J: Application of a corticosteroid (triamcinolone) protects inner ear function after surgical intervention. Ear Hear 2007;28:361-369.
36.
Zou J, Pyykkö I, Bjelke B, Dastidar P, Toppila E: Communication between the perilymphatic scalae and spiral ligament visualized by in vivo MRI. Audiol Neurotol 2005a;10:145-152.
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.