Human Otopathologic Findings in Cases of Folded Cochlear Implant Electrodes

UMMS Affiliation

Department of Otolaryngology; School of Medicine; Senior Scholars Program

Faculty Mentor

Aaron Remenschneider

Publication Date


Document Type



Medical Education | Otolaryngology | Otorhinolaryngologic Diseases


HYPOTHESIS: We hypothesize that human cases of cochlear implantation (CI) with folding of the electrode array will demonstrate greater degrees of intracochlear ossification, lower spiral ganglion neuron (SGN) counts, and poorer audiometric outcomes.

BACKGROUND: CI electrode array folding, such folding of the proximal array, is a relatively common surgical complication that can occur with forceful electrode insertion and may be an important and avoidable factor affecting implant outcomes. However, otopathologic findings and audiologic outcomes of human cases where folding of the implant electrode array is observed remain undefined.

METHODS: Specimens from a human temporal bone repository having undergone CI during life were evaluated. Specimens with folding of the electrode array on histological analysis constituted study cases. Electrode-matched specimens without array folding constituted controls. All specimens were examined by light microscopy and histopathologically described. Intracochlear fibrosis and osseous tissue, and SGN counts were measured. Pre- and postoperative word recognition scores were also compared.

RESULTS: Cases with folded electrodes showed greater volumes of intracochlear osseous tissue than controls, which was most prominent in areas adjacent to array folding. Both cases and controls demonstrated similar amounts of fibrous tissue. Folded cases showed decreased SGNs when compared with the contralateral ear, whereas controls showed stable SGN populations between ears. In this small cohort, postoperative hearing outcomes were similar between groups.

CONCLUSION: Atypical fibro-osseous changes and lower SGN counts are observed in cases of CI electrode folding. Future studies are necessary to determine if recognition and correction of folding can prevent long-term intracochlear changes.


Cochlear implantation, Electrode folding, Human temporal bone, Otopathology

DOI of Published Version



Trakimas DR, Kozin ED, Ghanad I, Nadol JB Jr, Remenschneider AK. Human Otopathologic Findings in Cases of Folded Cochlear Implant Electrodes. Otol Neurotol. 2018 Sep;39(8):970-978. doi: 10.1097/MAO.0000000000001886. PMID: 30020265; PMCID: PMC6095746. Link to article on publisher's site

Journal/Book/Conference Title

Otology and neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology


Danielle Trakimas participated in this study as a medical student in the Senior Scholars research program at the University of Massachusetts Medical School.

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Link to Article in PubMed

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