In vitro modifications of the scala tympani environment and the cochlear implant array surface.
OBJECTIVE
To investigate the influence of alterations of the scala tympani environment and modifications of the surface of cochlear implant electrode arrays on insertion forces in vitro.


METHODS
Research experimental study.


METHODS
Fibroblasts producing neurotrophic factors were cultivated on the surface of Nucleus 24 Contour Advance electrodes. Forces were recorded by an Instron 5542 Force Measurement System as three modified arrays were inserted into an artificial scala tympani model filled with phosphate-buffered saline (PBS). The recorded forces were compared to control groups including three unmodified electrodes inserted into a model filled with PBS (unmodified environment) or Healon (current practice). Fluorescence microscopy was used before and after the insertions to identify any remaining fibroblasts. Additionally, three Contour Advance electrodes were inserted into an artificial model, filled with alginate/barium chloride solution at different concentrations, while insertion forces were recorded.


RESULTS
Modification of the scala tympani environment with 50% to 75% alginate gel resulted in a significant decrease in the insertion forces. The fibroblast-coated arrays also led to decreased forces comparable to those recorded with Healon. Fluorescence microscopy revealed fully cell-covered arrays before and partially covered arrays after the insertion; the fibroblasts on the arrays' modiolar surface remained intact.


CONCLUSIONS
Modifications of the scala tympani's environment with 50% to 75% alginate/barium chloride and of the cochlear implant electrode surface with neurotrophic factor-producing fibroblasts drastically reduce the insertion forces. As both modifications may serve future intracochlear therapies, it is expected that these might additionally reduce possible insertion trauma.
Department of Otolaryngology, Hanover Medical School, Hanover, Germany. gkontorinis@gmail.com
Georgios
G
Kontorinis
Verena
V
Scheper
Kirsten
K
Wissel
Timo
T
Stöver
Thomas
T
Lenarz
Gerrit
G
Paasche
D000464:Alginates / Q000494:pharmacology*; D019929:Cochlear Implantation / Q000379:methods*; D003054:Cochlear Implants; D004567:Electrodes, Implanted; D005471:Fluoroscopy; D005782:Gels / Q000494:pharmacology; D020723:Glucuronic Acid / Q000494:pharmacology; D006603:Hexuronic Acids / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008962:Models, Theoretical; D012016:Reference Values; D012533:Scala Tympani / Q000187:drug effects* / Q000601:surgery; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D013499:Surface Properties / Q000187:drug effects
D000464:Alginates; D005782:Gels; D006603:Hexuronic Acids; D020723:Glucuronic Acid