Dose-Dependent Transient Decrease of Impedances by Deep Intracochlear Injection of Triamcinolone With a Cochlear Catheter Prior to Cochlear Implantation–1 Year Data

Abstract

Administration of low-dose steroids via a catheter inserted into the cochlea to apply pharmaceuticals to more apical regions was previously shown not to be sufficient for long-term reduction of electrode impedances. The aim of the present study was to investigate the effect of intra-cochlear high-dose triamcinolone application on impedances in cochlear implant recipients. Patients received low-dose (4 mg/ml; n = 5) or high-dose (20 mg/ml; n = 5) triamcinolone via a cochlear catheter just prior to the insertion of a Med-El Flex28 electrode. Impedances were measured at defined time points from intra-operatively up to 12 months after first fitting and retrospectively compared with a control group (no steroid application). Patients who received a high-dose application of crystalloid triamcinolone showed significantly reduced impedances in the first fitting measurements compared to the control group. This effect was no longer detectable in patients of the low-dose group at that time. Looking at the different regions of the electrode, the impedance values were lowered significantly only at the basal and medial contacts. At later time points, there were no significant differences between any of the groups. This is the first study to demonstrate a dose-dependent reduction of impedances by deep intra-cochlear injection of triamcinolone in cochlear implant patients. With a high-dose, single application of triamcinolone using a cochlear catheter prior to insertion of a Flex28 electrode, the impedances can be significantly reduced up to and including the first fitting. Although the effect was longer lasting than when compared to low-dose triamcinolone, it was also not permanent.

A PLLA Coating Does Not Affect the Insertion Pressure or Frictional Behavior of a CI Electrode Array at Higher Insertion Speeds

“…These agents are mainly glycocorticoids, which are administered locally or systemically [26][27][28]. A wide variety of systems are used to inhibit insertion trauma or to deliver drugs directly into the cochlea, such as intraoperative administration using catheters, longer-acting pump systems, or drug depots either in the silicone of the electrode array or in separate coatings [24][25][26][27][28][29][30][31][32][33][34]. The effect of polymer coatings without drug loading was tested by Hadler et al [29].…”

Microimaging of a novel intracochlear drug delivery device in combination with cochlear implants in the human inner ear

“…Prenzler et al used an intracochlear catheter made of material with similar soft characteristics as a CI electrode array carrier for delivering drugs closer to the cochlear apex. The catheter was used to apply triamcinolone during CI surgery before insertion of the electrode array [ 19 , 20 ]. However, the usage of such a catheter carries a risk of mechanical trauma to the inner ear comparable to CI insertion itself.…”

Comparison of Drug Availability in the Inner Ear After Oral, Transtympanic, and Combined Administration

“…Intracochlear administration through an opening in the cochlear bony wall is more efficient than intratympanic administration but is rather invasive, and performed only during surgery in current clinical practice. For example, Prenzler NK used a cochlear catheter to inject the steroid into the cochlea and achieved the decrease of the electrical impedance during human cochlear implantation ( 19 , 20 ). Although additional routes of delivery have been explored, including a comparison of round window injections vs. placement of drug-delivering materials on the surface of the round window membrane, intralabyrinthine injections to the semicircular canal or vestibule, and local activation following systemic delivery ( 21 , 22 ), conventional oral route of administration, intratympanic injection of liquid solutions and combination of these two routes that we used in this study are still widely performed clinically and closely resemble the projected route of administration to humans.…”