Intracochlear Drug Delivery Using a Catheter and Dexamethasone-Eluting Electrode Preserves Residual Hearing...

Area of Science:

• Otolaryngology
• Neuroscience
• Pharmacology

Background:

• Cochlear implantation (CI) can lead to hearing loss and oxidative stress.
• Developing safe methods for inner ear drug delivery during CI is crucial for otoprotection.
• L-N-acetylcysteine (L-NAC) has shown anti-apoptotic potential.

Purpose of the Study:

• To assess the feasibility and safety of a cochlear catheter for drug delivery during CI.
• To evaluate the otoprotective effects of L-NAC delivered via cannula, combined with a dexamethasone-eluting CI (Dexel).

Main Methods:

• An animal model was used with 8 experimental groups, including CI, Dexel, and various cannula injections (artificial perilymph, Ringer, L-NAC).
• Hearing thresholds were measured using auditory brainstem responses (ABRs) at baseline, POD 7, and POD 30.
• Organ of Corti dissections assessed hair cell (HC) viability and oxidative stress via immunostaining.

Main Results:

• The group receiving L-NAC (2 mM) via cannula with a Dexel implant showed significantly better hearing thresholds compared to standard CI, L-NAC alone, or Dexel alone.
• This combined treatment group also demonstrated enhanced HC viability and reduced oxidative stress.
• Intracochlear cannula delivery did not cause additional hearing loss.

Conclusions:

• An intracochlear cannula is a feasible and safe tool for delivering pharmaceutical interventions during cochlear implantation.
• L-NAC exhibits significant anti-apoptotic properties.
• Co-administration of L-NAC via cannula with Dexel implantation provides a synergistic otoprotective effect, improving hearing outcomes and cochlear health.