title: Effects of glycerin, hyaluronic acid, and hydroxypropyl methylcellulose on the spiral ganglion of the guinea pig cochlea.
abstract: A cochlear lubricant may facilitate the surgeon's ability to place the electrode array deep within the cochlea. Patient performance with the multichannel cochlear implant may be enhanced with a deeper electrode insertion. Theoretically, deeper insertion and stimulation will recruit and activate more surviving spiral ganglion neurons. Several studies have shown that neuron survival is a factor for cochlear implant success, especially in the postmeningitis patient. We studied the histologic and electrophysiologic effects of the intracochlear injection of three potential lubricants in the guinea pig: glycerin, hyaluronic acid, and hydroxypropyl methylcellulose. All three have approved medical uses, reduce friction, and are readily available. Results show that when compared to surgical controls (cochleostomy without injection), there is no significant reduction in the spiral ganglion neuronal count at 2 and 8 weeks postinjection, and the dendrite and axon histology is well preserved. Injection of any of the substances within the cochlea causes severe hearing loss (detected by direct round window electrocochleographic responses to auditory stimuli) that only partially recovers with time. These findings suggest that any of the three tested substances could be considered as lubricants for intracochlear electrode insertion.
authors.affiliation: Department of Otolaryngology, New York University Medical Center, New York, USA.
authors.forename: J T
authors.initials: JT
authors.lastname: Roland
authors.forename: T M
authors.initials: TM
authors.lastname: Magardino
authors.forename: J T
authors.initials: JT
authors.lastname: Go
authors.forename: D E
authors.initials: DE
authors.lastname: Hillman
mesh_terms: D000818:Animals; D001300:Audiometry, Evoked Response; D003054:Cochlear Implants; D004567:Electrodes, Implanted; D005990:Glycerol / Q000494:pharmacology*; D006168:Guinea Pigs; D006820:Hyaluronic Acid / Q000494:pharmacology*; D065347:Hypromellose Derivatives; D008153:Lubrication; D008747:Methylcellulose / Q000031:analogs & derivatives* / Q000494:pharmacology; D013136:Spiral Ganglion / Q000187:drug effects* / Q000473:pathology
chemical_list: D065347:Hypromellose Derivatives; D006820:Hyaluronic Acid; D008747:Methylcellulose; D005990:Glycerol