Effects of semicircular canal electrode implantation on hearing in chinchillas

Acta Otolaryngol. 2009 May;129(5):481-6. doi: 10.1080/00016480802252243.


Conclusion: Implantation of vestibular prosthesis electrodes in chinchilla semicircular canal ampullae can be accomplished without significant loss of cochlear function; however, the risk of hearing loss with the current surgical technique is high.

Objectives: To determine if it is possible to implant vestibular prosthesis electrodes into the labyrinth without damaging hearing, and to quantify the extent of hearing loss due to implantation.

Materials and methods: The left semicircular canals of six chinchillas were implanted with three bipolar pairs of electrodes using a transmastoid approach. Right ears, which served as controls, were subjected to the same mastoid approach without fenestration and implantation. Auditory brainstem response hearing thresholds to free-field clicks and tone pips at 2, 4, 6, and 8 kHz were measured bilaterally 3-9 weeks after implantation. Hearing thresholds were compared between sides and against data from six normal chinchillas.

Results: Four implanted ears suffered severe hearing loss, with thresholds ranging from 5 to 11 SD above the mean threshold of sham surgery control ears across all tested stimuli. Two implanted ears had preserved hearing, with thresholds remaining within 1 SD of the mean threshold of sham surgery control ears across nearly all stimulus frequencies.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chinchilla
  • Cochlear Implants*
  • Electrodes, Implanted / adverse effects*
  • Hearing Loss / etiology*
  • Hearing Loss / rehabilitation*
  • Otologic Surgical Procedures / adverse effects*
  • Semicircular Canals / surgery*