Fax +41 61 306 12 34 E-Mail karger@karger.ch www.karger.com Audiol Neurotol 2006;11(suppl 1):49–56 DOI: 10.1159/000095614 Ipsilateral Electric Acoustic Stimulation of the Auditory System: Results of Long-Term Hearing Preservation Wolfgang K. Gstoettner a Silke Helbig a Nicola Maier a Jan Kiefer b Andreas Radeloff a Oliver F. Adunka c a Department of Otolaryngology, Johann Wolfgang Goethe University Frankfurt am Main, Frankfurt am Main, b Department of Otolaryngology, Klinikum rechts der Isar, Technical University Munich, Munich, Germany; c Department of Otolaryngology, University of North Carolina at Chapel Hill, Chapel Hill, N.C., USA ly lost residual hearing during or immediately after surgery. Freiburger Monosyllabic word understanding scores in a group of patients with complete hearing preservation in- creased from 13.1% preoperatively to 75% in the electric acoustic stimulation condition. Conclusion: This study doc- uments that complete and partial preservation of ipsilateral hearing after cochlear implantation can be achieved in about 70% of cases over an average period of 27.25 months when using 360° electrode insertions. Copyright © 2006 S. Karger AG, Basel Introduction Until 1993, when Lehnhardt first described the soft surgery technique for inserting intracochlear implants [Lehnhardt, 1993], little effort has been made to protect and preserve inner ear structures during cochlear im- plantation. Initially, the goal of soft surgery was to ensure the presence of sufficient excitable neuronal structures for electrostimulation. A few years later, Hodges et al. [1997] described measurable residual acoustic hearing af- ter cochlear implantation in about 50% of cases. Although soft surgery techniques were already used by many sur- geons at that time, preoperative- and thus postoperative residual hearing were small and did not improve overall Key Words Cochlear implants  Acoustic stimulation  Electric stimulation  Hearing loss  Electric acoustic stimulation  Hearing preservation Abstract Objective: To evaluate long-term ipsilateral hearing preser- vation in patients who underwent cochlear implantation for the combined electric acoustic stimulation of the auditory system. Methods: This was a prospective observational study conducted at a tertiary referral center. Twenty-three subjects were implanted with the MED-EL C40+ standard or C40+ medium electrode using an atraumatic surgical proto- col via an anterior-inferior cochleostomy approach. The de- sired insertion depth was 18–24 mm or 360°. All patients showed significant low-frequency hearing prior to surgery and monosyllabic word scores did not exceed 40% in the best aided condition. Pure-tone audiometry was performed prior to implantation and at distinct intervals after surgery. Results: Nine patients (39.1%) showed complete pure-tone audiometric hearing preservation (0–10 dB) over an average of 29 months. Seven subjects (30.4%) showed partial preser- vation of residual hearing (hearing loss 15–40 dB) until an average of 25 months. Delayed loss of residual hearing was observed in 5 cases (21.7%) and 2 patients (8.6%) complete- Received: January 25, 2006 Accepted after revision: August 2, 2006 Published online: October 6, 2006 Neurotology Audiology Prof. Wolfgang K. Gstoettner, MD, PhD Department of Otolaryngology, J.W. Goethe University Frankfurt am Main Theodor-Stern-Kai 7 DE–60590 Frankfurt am Main (Germany) Tel. +49 69 6301 5163, Fax +49 69 6301 5435, E-Mail gstoettner@em.uni-frankfurt.de © 2006 S. Karger AG, Basel 1420–3030/06/0117–0049$23.50/0 Accessible online at: www.karger.com/aud