Change in endocochlear potential during experimental insertion of a simulated cochlear implant electrode in the guinea pig

Hidetoshi Oshima, Ryoukichi Ikeda, Kazuhiro Nomura, Muneharu Yamazaki, Hiroshi Hidaka, Yukio Katori, Takeshi Oshima, Tetsuaki Kawase, Toshimitsu Kobayashi

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

OBJECTIVE: Preservation of residual hearing during cochlear implantation is important. This study investigated changes in endocochlear potential (EP) during simulated cochlear implant (CI) electrode insertion. STUDY DESIGN: Laboratory animal study. SETTING: Academic hospital laboratory. SUBJECTS AND METHODS: Guinea pigs were divided into 4 groups: cochleostomy only (4 animals), suction after cochleostomy (5 animals), simulated CI electrode insertion parallel to the longitudinal axis of the scala tympani without suctioning (7 animals), and simulated CI electrode insertion toward the modiolus without suctioning (7 animals). The EP was measured from the second turn of the cochlea, and the values after 20 minutes were compared. RESULTS: The EP showed little change at 20 minutes after cochleostomy with a nearly normal value of 84.83 ± 2.12 mV. Suctioning of the perilymph from the cochleostomy site caused a slight acute reduction in EP by about 6 mV, and the value at 20 minutes after cochleostomy was 78.64 ± 4.42 mV. Insertion of the simulated CI electrode parallel to the longitudinal axis of the scala tympani caused a slight decrease in EP to 78.91 ± 5.06 mV. Insertion toward the modiolus caused a marked decrease in EP to 54.13 ± 4.42 mV at 20 minutes after the treatment, significantly lower compared with the other 3 groups. CONCLUSION: EP was well preserved during carefully performed surgical procedures of simulated CI electrode insertion, but it decreased significantly if the simulated CI electrode was inserted toward the modiolus. Careful attention is necessary to ensure the correct direction of CI electrode insertion to preserve residual hearing. Use of suction should be minimized if possible.

Original languageEnglish
Pages (from-to)234-240
Number of pages7
JournalOtology and Neurotology
Volume35
Issue number2
DOIs
Publication statusPublished - 2014 Feb

Keywords

  • Cochlear implantation
  • Cochleostomy
  • Electrical and acoustic stimulation
  • Endocochlear potential
  • Residual hearing

ASJC Scopus subject areas

  • Otorhinolaryngology
  • Sensory Systems
  • Clinical Neurology

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