Effect of Return Electrode Placement at Apical Cochleostomy on Current Flow With a Cochlear Implant.
David M Landsberger, Christopher J Long, Jonathon R Kirk and 2 others
PMID 38047764WHAT IT FOUND
Placing the return electrode inside the cochlear apex shifted current flow apically in two cadaver heads.
This required a surgical cochleostomy; placing the electrode outside the cochlea had no effect. This confirms the technique is feasible but does not show it improves hearing.
Key findings
01Inserting the return electrode into the cochlear lumen at the helicotrema increased current leaving apically and decreased current leaving basally.
02Placing the return electrode outside the cochlea, even near the apex, did not alter current flow.
03The surgical approach to place the electrode in the apex was feasible in both specimens.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study used only two cadaveric specimens, not living patients. Cadaveric tissue does not fully replicate the electrical properties of living cochlear fluid and tissue. The study measured current flow, not hearing performance or speech recognition. The technique requires removing the incus bone, which causes conductive hearing loss. The electrode used in the cadavers (CI24RE) differs from newer models (CI632), which may affect applicability.
Declared interests
Two authors (Christopher J. Long and Jonathon R. Kirk) are employees of Cochlear Ltd., the manufacturer of the implant hardware used in the study.
The easy way to misread this
Do not interpret the shift in current flow as evidence of clinical benefit. The study only shows that the technique changes electrical fields in dead tissue; it does not show that this improves hearing or speech understanding in patients.