Deep intracochlear injection of triamcinolone-acetonide with an inner ear catheter in patients with residual hearing

Abstract

IntroductionIn a previous study, an inner ear catheter was used to deliver low- and high-dose steroids into the cochlea prior to cochlear implant electrode insertion. With this approach, more apical regions of the cochlea could be reached and a reduction of electrode impedances in the short term was achieved in cochlear implant recipients. Whether intracochlear application of drugs via the catheter is a safe method also for patients with residual hearing has not been investigated hitherto. The aim of the present study was therefore to investigate the effect of intracochlear triamcinolone application in cochlear implant recipients with residual hearing.Patients and methodsPatients with residual hearing were administered triamcinolone-acetonide (4 mg/ml; n = 10) via an inner ear catheter just prior to insertion of a MED-EL FLEX28 electrode. Impedances were measured at defined time points (intra-operatively, post-operatively and at first fitting) and retrospectively compared with a control group (no steroid application) and low- and high-dose group. Hearing thresholds were measured preoperatively, 3 days after surgery and at first fitting by pure tone audiometry. Pre- to postoperative hearing loss was determined at first fitting and compared to results from a previous study.ResultsThe median hearing loss after implantation (125–1,500 Hz) was 20.6 dB. Four patients (40%) showed a median hearing loss of less than 15 dB, three patients (30%) between 15 and 30 dB and three patients (30%) more than 30 dB. The median hearing loss was similar to the results obtained from our previous study showing a median hearing loss of 24 dB when using FLEX28 electrode arrays.ConclusionNo difference in residual hearing loss was found when comparing application of triamcinolone-acetonide using an inner ear catheter prior to the insertion of a FLEX28 electrode array to the use of the FLEX28 electrode array without the catheter. Thus, we conclude that application of drugs to the cochlea with an inner ear catheter could be a feasible approach in patients with residual hearing.

Insertion trauma of a novel inner ear catheter for intracochlear drug delivery

“…Prenzler et al ( 16 ) used the IEC for deep intracochlear injections of triamcinolone prior to cochlear implantation resulting in significantly reduced impedances on short-term follow up. Further, steroid application using the IEC followed by cochlear implantation in patients with residual hearing turned out to be a safe and atraumatic drug delivery strategy to the inner ear, since no difference in residual hearing loss between IEC-implanted and untreated controls could be observed ( 17 ). However, it should be kept in mind that potential trauma caused by the insertion of the IEC to the basal cochlear turn may not manifest as a hearing threshold shift in those patients, since cochlear implant recipients already display little to no residual hearing in the high frequency regions.…”

“…Recent studies have successfully utilized an inner ear catheter (IEC) as a novel drug delivery tool ( 15 – 17 ). The silicone-based IEC possesses dimensions comparable to those of a cochlear implant and features a small opening at the catheter tip enabling deep intracochlear drug administration.…”