Electrical Impedance as a Biomarker for Inner Ear Pathology Following Lateral Wall and Peri-modiolar Cochlear Implantation

Chanan Shaul, Christofer W. Bester, Stefan Weder, June Choi, Hayden Eastwood, K. V. Padmavathi, Aaron Collins, Stephen J. O'Leary

Research output: Contribution to journalArticlepeer-review

35 Citations (Scopus)

Abstract

Objectives/Hypothesis: Spikes in cochlear implant impedance are associated with inner ear pathology after implantation. Here, we correlate these spikes with episodes of hearing loss and/or vertigo, with a comparison between lateral wall and peri-modiolar electrode arrays. Methods: Seven hundred seventy recipients of Cochlear's slim-straight, lateral wall electrode (CI422), or peri-modiolar (CI512) electrode were investigated for impedance spikes. Impedance fluctuations were defined as a median rise of ≥ 4 kV across all intracochlear electrodes from baseline measurements taken 2 weeks after switch-on. Medical records were analyzed from 189 of the 770 patients. Results: The slim straight, lateral wall electrode was found to spike in impedance at a significantly higher rate than the peri-modiolar array (17% vs 12%). The peri-modiolar electrode tended to spike in impedance earlier than the slimstraight electrode. Impedance spikes were found to significantly correlate with medical events (hearing loss, vertigo, or tinnitus). Overall, in the "spike"group, 42 of 75 patients (56%) demonstrated a clinical event during the impedance spike, whereas 26 of 114 patients (22%) of the "non-spike"group had a clinical event. This significant difference existed with both implant types. Conclusion: These results demonstrate a small, but significant increase in impedance spikes in lateral wall electrodes, and support the relationship between spikes in cochlear implant impedances and postoperative inner-ear events, including the loss of residual hearing and vertigo. Monitoring cochlear implant impedance may be a method for early detection, and so the prevention, of these events in the future.

Original languageEnglish
Pages (from-to)E518-E526
JournalOtology and Neurotology
Volume40
Issue number5
DOIs
Publication statusPublished - 1 Jun 2019
Externally publishedYes

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