Electrocochleography (ECochG) patterns observed during cochlear implant (CI) electrode insertion may provide information about scalar location of the electrode array.
Conventional CI surgery is performed without actively monitoring auditory function and potential damage to intracochlear structures. The central hypothesis of this study was that ECochG obtained directly through the CI may be used to estimate intracochlear electrode position and, ultimately, residual hearing preservation.
Intracochlear ECochG was performed on 32 patients across 3 different implant centers. During electrode insertion, a 50-ms tone burst stimulus (500 Hz) was delivered at 110 dB SPL. The ECochG response was monitored from the apical-most electrode. The amplitude and phase changes of the first harmonic were imported into an algorithm in an attempt to predict the intracochlear electrode location (scala tympani [ST], translocation from ST to scala vestibuli [SV], or interaction with basilar membrane). Anatomic electrode position was verified using postoperative computed tomography (CT) with image processing.
CT analysis confirmed 25 electrodes with ST position and 7 electrode arrays translocating from ST into SV. The ECochG algorithm correctly estimated electrode position in 26 (82%) of 32 subjects while 6 (18%) electrodes were wrongly identified as translocated (sensitivity = 100%, specificity = 77%, positive predictive value = 54%, and a negative predictive value = 100%). Greater hearing loss was observed postoperatively in participants with translocated electrode arrays (36 ± 15 dB) when compared with isolated ST insertions (28 ± 20 dB HL). This result, however, was not significant (p = 0.789).
Intracochlear ECochG may provide information about CI electrode location and hearing preservation.
*Research and Technology, Advance Bionics LLC, Valencia, California
†Department of Otolaryngology–Head and Neck Surgery, The Ohio State University, Columbus, Ohio
‡Department of Otolaryngology–Head and Neck Surgery, Vanderbilt University and Medical Center, Nashville, Tennessee
§Department of Otolaryngology–Head and Neck Surgery, Washington University School of Medicine, St. Louis, Missouri
||Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin
¶Department of Otolaryngology–Head and Neck Surgery, University of North Carolina, Chapel Hill, North Carolina
Address correspondence and reprint requests to Kanthaiah Koka, Ph.D., Advanced Bionics LLC, Valencia, CA; E-mail: email@example.com
Research reported in this publication was supported by the National Institute of Deafness and Other Communication Disorders within the National Institutes of Health, through the “Development of Clinician/Researchers in Academic ENT” training grant, award number T32DC000022. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Disclosures: K.K. and L.L. are employees of Advanced Bionics Corp. O.F.A., C.A.B., R.F.L. are consultants for Advanced Bionics Corp., Med-El Corp., Cochlear Corporation, and MSH is a consultant with Advanced Bionics Corp. OFA and CAB have an ownership interest in Advanced Cochlear Diagnostics, LLC.
The authors disclose no conflicts of interest.