Introduction:
Triggered by the insertion trauma, connective tissue develops around the electrode.
The postoperatively measurable impedances seem to correlate with the extent and can
be used for interpreting measures to curb this. Previous publications have demonstrated
a positive effect of triamcinolone, at least in basal areas, when injected into the
round window prior to insertion. In order to achieve this reduction of impedances
even in apical areas, a catheter for intracochlear pharmacotherapies has been developed
together with Med-El (Innsbruck, Austria).
Methods:
The catheter consists of a 20 mm long, hollow silicone tube with the dimensions of
a standard electrode with an outlet for liquids at the top. In each case, 5 patients
without functional residual hearing (> 80 dB hearing loss at 250 Hz) were treated
with triamcinolone (low dose: 4 mg/ml vs. high dose: 20 mg/ml) with a cochlear catheter
before implantation with a Med-El Flex 28 electrode. Impedances, electric evoked compound
action potentials and amplitude growth function were measured intraoperatively and
at defined intervals after implantation and compared with a control group of patients
with the same electrode, similar residual hearing but without catheter application.
Results:
There were no adverse events during and after the intervention. While in the low dose
group the impedances decreased only in the first weeks compared to the control group,
the effect in the high dose group was detectable both basal and apical beyond first
fitting. 3 and 6 month data will be presented.
Conclusions:
The investigated method seems suitable as a safe and effective form of drug delivery
even for apical areas of the cochlea.
