title: Ipsilateral electric acoustic stimulation of the auditory system: results of long-term hearing preservation.
abstract: OBJECTIVE
  To evaluate long-term ipsilateral hearing preservation 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 protocol via an anterior-inferior cochleostomy approach. The desired insertion depth was 18-24 mm or 360 degrees. 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 preservation 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%) completely lost residual hearing during or immediately after surgery. Freiburger Monosyllabic word understanding scores in a group of patients with complete hearing preservation increased from 13.1% preoperatively to 75% in the electric acoustic stimulation condition.
  
  
  CONCLUSIONS
  This study documents 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 degrees electrode insertions.
authors.affiliation: Department of Otolaryngology, Johann Wolfgang Goethe University Frankfurt am Main, Frankfurt am Main, Germany. gstoettner@em.uni-frankfurt.de
authors.forename: Wolfgang K
authors.initials: WK
authors.lastname: Gstoettner
authors.forename: Silke
authors.initials: S
authors.lastname: Helbig
authors.forename: Nicola
authors.initials: N
authors.lastname: Maier
authors.forename: Jan
authors.initials: J
authors.lastname: Kiefer
authors.forename: Andreas
authors.initials: A
authors.lastname: Radeloff
authors.forename: Oliver F
authors.initials: OF
authors.lastname: Adunka
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods*; D000328:Adult; D000368:Aged; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold; D003054:Cochlear Implants; D004558:Electric Stimulation / Q000295:instrumentation; D004567:Electrodes, Implanted; D005260:Female; D006312:Hearing Loss, Bilateral / Q000175:diagnosis / Q000601:surgery; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D012720:Severity of Illness Index