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Journal of the Association for Research in Otolaryngology

15-04-2024 | Cochlear Implant | Original Article

Hampshire Sheep as a Large-Animal Model for Cochlear Implantation

Authors: Nicholas A. Waring, Alexander Chern, Brandon J. Vilarello, Yew Song Cheng, Chaoqun Zhou, Jeffrey H. Lang, Elizabeth S. Olson, Hideko Heidi Nakajima

Published in: Journal of the Association for Research in Otolaryngology

Abstract

Background

Sheep have been proposed as a large-animal model for studying cochlear implantation. However, prior sheep studies report that the facial nerve (FN) obscures the round window membrane (RWM), requiring FN sacrifice or a retrofacial opening to access the middle-ear cavity posterior to the FN for cochlear implantation. We investigated surgical access to the RWM in Hampshire sheep compared to Suffolk-Dorset sheep and the feasibility of Hampshire sheep for cochlear implantation via a facial recess approach.

Methods

Sixteen temporal bones from cadaveric sheep heads (ten Hampshire and six Suffolk-Dorset) were dissected to gain surgical access to the RWM via an extended facial recess approach. RWM visibility was graded using St. Thomas’ Hospital (STH) classification. Cochlear implant (CI) electrode array insertion was performed in two Hampshire specimens. Micro-CT scans were obtained for each temporal bone, with confirmation of appropriate electrode array placement and segmentation of the inner ear structures.

Results

Visibility of the RWM on average was 83% in Hampshire specimens and 59% in Suffolk-Dorset specimens (p = 0.0262). Hampshire RWM visibility was Type I (100% visibility) for three specimens and Type IIa (> 50% visibility) for seven specimens. Suffolk-Dorset RWM visibility was Type IIa for four specimens and Type IIb (< 50% visibility) for two specimens. FN appeared to course more anterolaterally in Suffolk-Dorset specimens. Micro-CT confirmed appropriate CI electrode array placement in the scala tympani without apparent basilar membrane rupture.

Conclusions

Hampshire sheep appear to be a suitable large-animal model for CI electrode insertion via an extended facial recess approach without sacrificing the FN. In this small sample, Hampshire specimens had improved RWM visibility compared to Suffolk-Dorset. Thus, Hampshire sheep may be superior to other breeds for ease of cochlear implantation, with FN and facial recess anatomy more similar to humans.

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Title: Hampshire Sheep as a Large-Animal Model for Cochlear Implantation
Authors: Nicholas A. Waring
Alexander Chern
Brandon J. Vilarello
Yew Song Cheng
Chaoqun Zhou
Jeffrey H. Lang
Elizabeth S. Olson
Hideko Heidi Nakajima
Publication date: 15-04-2024
Publisher: Springer US
Keyword: Cochlear Implant
Published in: Journal of the Association for Research in Otolaryngology
Print ISSN: 1525-3961
Electronic ISSN: 1438-7573
DOI: https://doi.org/10.1007/s10162-024-00946-1

At a glance: The STEP trials

Springer Medicine

Hampshire Sheep as a Large-Animal Model for Cochlear Implantation

Abstract

Background

Methods

Results

Conclusions

At a glance: The STEP trials

Springer Medicine

Abstract

Background

Methods

Results

Conclusions

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