Tip Fold-over in Cochlear Implantation: Case Series.

Zuniga MG, Rivas A, Hedley-Williams A, Gifford RH, Dwyer R, Dawant BM, Sunderhaus LW, Hovis KL, Wanna GB, Noble JH, Labadie RF
Otol Neurotol. 2017 38 (2): 199-206

PMID: 27918363 · PMCID: PMC5584995 · DOI:10.1097/MAO.0000000000001283

OBJECTIVE - To describe the incidence, clinical presentation, and performance of cochlear implant (CI) recipients with tip fold-over.

STUDY DESIGN - Retrospective case series.

SETTING - Tertiary referral center.

PATIENTS - CI recipients who underwent postoperative computed tomography (CT) scanning.

INTERVENTION(S) - Tip fold-over was identified tomographically using previously validated software that identifies the electrode array. Electrophysiologic testing including spread of excitation or electric field imaging (EFI) was measured on those with fold-over.

MAIN OUTCOME MEASURE(S) - Location of the fold-over; audiological performance pre and postselective deactivation of fold-over electrodes.

RESULTS - Three hundred three ears of 235 CI recipients had postoperative CTs available for review. Six (1.98%) had tip fold-over with 5/6 right-sided ears. Tip fold-over occurred predominantly at 270 degrees and was associated with precurved electrodes (5/6). Patients did not report audiological complaints during initial activation. In one patient, the electrode array remained within the scala tympani with preserved residual hearing despite the fold-over. Spread of excitation supported tip fold-over, but the predictive value was not clear. EFI predicted location of the fold-over with clear predictive value in one patient. At an average follow-up of 11 months, three subjects underwent deactivation of the overlapping electrodes with two of them showing marked audiological improvement.

CONCLUSION - In a large academic center with experienced surgeons, tip fold-over occurred at a rate of 1.98% but was not immediately identifiable clinically. CT imaging definitively showed tip fold-over. Deactivating involved electrodes may improve performance possibly avoiding revision surgery. EFI may be highly predictive of tip fold-over and can be run intraoperatively, potentially obviating the need for intraop fluoroscopy.

MeSH Terms (18)

Adolescent Adult Child Cochlea Cochlear Implantation Cochlear Implants Female Hearing Hearing Loss Hearing Tests Humans Male Middle Aged Postoperative Period Reoperation Retrospective Studies Tomography, X-Ray Computed Young Adult

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