20The Cochlear Implant of the Future and Choosing a Device

TThe totally implantable CI

The leading near-term frontier is the totally implantable cochlear implant (TICI), burying the microphone, processor and rechargeable battery so nothing is worn externally (early human experience: Briggs et al. 2008). Two problems remain unsolved: a battery lasting ~5–10 years between surgeries, and an implantable microphone with adequate SNR that rejects body and chewing noise (cross-ref Ch.22 Emerging Technology).[2022]

COptical and optogenetic stimulation

Optogenetic and infrared (optical) stimulation aim to replace current with light to sharpen frequency selectivity. Because light can be confined far more tightly than current in conductive perilymph, optical approaches target dozens of independent channels versus the ~8 effective electrical channels — viral transfection of spiral-ganglion neurons with light-gated channels, activated by micro-LED or fibre arrays; hurdles are gene-therapy safety, fast-enough opsin kinetics and chronic light-source reliability (cross-ref Module 11).[2008]

TConverging incremental advances

Converging incremental strategies include drug-eluting (dexamethasone) electrodes to blunt fibrosis and protect residual hearing, ever-thinner robotically inserted arrays (sub-mm/s, force-feedback controlled) for atraumatic lateral-wall placement, and intraneural/intramodiolar electrodes that penetrate the nerve for far finer selectivity at higher surgical risk (cross-ref Module 16, Ch.15).[2006]

CMRI as a design driver

MRI compatibility is a persistent design driver because malformation, NF2 and aging recipients need lifelong imaging; modern receiver-stimulators use removable or self-aligning rotatable magnets to permit 1.5 T and increasingly 3.0 T scanning, and future TICI/optical systems must solve the same constraints (cross-ref Module 15, Ch.12).[2022]

TChoosing a device

Choosing a device synthesises the whole chapter: contact count and channel philosophy (Cochlear 22, AB 16 with current steering, MED-EL 12 with fine structure), array family and length matched to the patient's cochlear duct length and goal, hearing-preservation/EAS candidacy, MRI needs, processor connectivity, and reliability — all weighed against the ~4–8 effective-channel ceiling that no current device escapes.

CNo universally best array

The recurring lesson across families is that there is no universally best array: perimodiolar buys efficiency and selectivity in the basal turn, lateral-wall buys atraumatic depth and hearing preservation, mid-scala splits the difference — and the right choice is the one whose trade-offs best fit this cochlea, this audiogram and this patient's imaging (cross-ref Module 12, Ch.11 Candidacy, Ch.12 Imaging).