An improved cochlear implant electrode array for use in experimental studies

Experimental studies play an important role in establishing the safety and efficacy of cochlear implants and they continue to provide insight into a new generation of electrode arrays and stimulation strategies. One drawback has been the limited depth of insertion of an electrode array in experiment...

Full description

Saved in:
Bibliographic Details
Published in:Hearing research 2011-07, Vol.277 (1), p.20-27
Main Authors: Shepherd, Robert, Verhoeven, Kristien, Xu, Jin, Risi, Frank, Fallon, James, Wise, Andrew
Format: Article
Language:English
Subjects:
Acoustic Stimulation
Animals
Auditory Threshold
Biological and medical sciences
Cadavers
Cats
Cochlea
Cochlea - diagnostic imaging
Cochlea - surgery
Cochlear Implantation - adverse effects
Cochlear Implantation - instrumentation
Cochlear Implants
Data processing
Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation
Ear, auditive nerve, cochleovestibular tract, facial nerve: diseases, semeiology
Electric Stimulation
Electrodes
Evoked potentials
Evoked Potentials, Auditory, Brain Stem
Fundamental and applied biological sciences. Psychology
Hearing
Ionizing radiation
Ligaments
Materials Testing
Medical sciences
Models, Animal
Otorhinolaryngology. Stomatology
Prosthesis Design
Radiography
Time Factors
Trauma
Tumors
Vertebrates: nervous system and sense organs
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Experimental studies play an important role in establishing the safety and efficacy of cochlear implants and they continue to provide insight into a new generation of electrode arrays and stimulation strategies. One drawback has been the limited depth of insertion of an electrode array in experimental animals. We compared the insertion depth and trauma associated with the insertion of Cochlear Ltd’s Hybrid-L (HL) array with a standard 8 ring array in cat cochleae. Both arrays were inserted into cadaver cochleae and an X-ray recorded their anatomical location. The implanted cochlea was serially sectioned and photographed at 300 μm intervals for evidence of electrode insertion trauma. Subsequently two cats were chronically implanted with HL arrays and electrically-evoked potentials recorded over a three month period. Mean insertion depth for the HL arrays was 334.8° (SD = 21°; n = 4) versus 175.5° (SD = 6°; n = 2) for the standard array. This relates to ∼10.5 mm and 6 mm respectively. A similar insertion depth was measured in a chronically implanted animal with an HL array. Histology from each cadaver cochleae showed that the electrode array was always located in the scala tympani; there was no evidence of electrode insertion trauma to the basilar membrane, the osseous spiral lamina or the spiral ligament. Finally, evoked potential data from the chronically implanted animals exhibited significantly lower thresholds compared with animals implanted with a standard 8 ring array, with electrical thresholds remaining stable over a three-month observation period. Cochlear Ltd’s HL electrode array can be safely inserted ∼50% of the length of the cat scala tympani, placing the tip of the array close to the 4 kHz place. This insertion depth is considerably greater than is routinely achieved using a standard 8-ring electrode array (∼12 kHz place). The HL array evokes low thresholds that remain stable over three months of implantation. This electrode array has potential application in a broad area of cochlear implant related research. ► New Hybrid-L24 and Hybrid-L16 arrays can be inserted further into the cochlea. ► Arrays can be inserted up to 50% the length of cochlea. ► Deeper insertion can be achieved with no trauma. ► HL electrode arrays exhibit significantly lower thresholds than a standard 8 ring array. ► Evoked potential thresholds remain stable over a three month chronic stimulation period.
ISSN:0378-5955
1878-5891
1878-5891
DOI:10.1016/j.heares.2011.03.017