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

• Published in: Otology & neurotology Vol. 40; no. 5; p. e518
• Main Authors: Shaul, Chanan, Bester, Christofer W, Weder, Stefan, Choi, June, Eastwood, Hayden, Padmavathi, K V, Collins, Aaron, O'Leary, Stephen J
• Format: Journal Article
• Language: English
• Published: United States 01.06.2019
• Subjects: Adult; Aged; Biomarkers; Cochlear Implantation - adverse effects; Cochlear Implants - adverse effects; Ear, Inner - diagnostic imaging; Ear, Inner - injuries; Electric Impedance; Electrodes; Female; Hearing Loss - diagnostic imaging; Hearing Loss - epidemiology; Hearing Loss - etiology; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Monitoring, Intraoperative; Postoperative Complications - diagnostic imaging; Postoperative Complications - epidemiology; Retrospective Studies; Tinnitus - diagnostic imaging; Tinnitus - epidemiology; Tinnitus - etiology; Tomography, X-Ray Computed; Vertigo - diagnostic imaging; Vertigo - epidemiology; Vertigo - etiology
• ISSN: 1537-4505
• DOI: 10.1097/MAO.0000000000002227

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. 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 kΩ across all intracochlear electrodes from baseline measurements taken 2 weeks after switch-on. Medical records were analyzed from 189 of the 770 patients. 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 slim-straight 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. 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.