title: Enhanced preservation of the auditory nerve following cochlear perfusion with nerve growth factors.
abstract: Survival of auditory neurons in the cochlea is thought to be an important factor in the success of cochlear implantations. Damage to the cochlear end-organ often produces loss of dendrites in the osseous spiral lamina. The authors have established a method that delivers water soluble pharmacologic agents to the cochlea using a mini osmotic pump with a polyethylene cannula that is inserted into the scala tympani via cochleostomy. The cannula is filled with an ototoxic agent, neomycin, that destroys the end-organ over the first 24 hours after insertion. Nerve growth factor (NGF), or a control substance, is placed in the pump reservoir and is pumped into the cochlea over a 2-week period. In this study, auditory nerve fibers in the osseous spiral lamina were counted in the apical, middle, and basal turns of the cochlea in 16 guinea pigs. At each location, fiber counts were significantly higher when neomycin was followed by perfusion with NGF, than when it was followed by infusion with control substances. The study demonstrates that NGF confers some protection against ototoxic induced degeneration of the auditory nerve in vivo.
authors.affiliation: Department of Otolaryngology--Head and Neck Surgery, Epstein Hearing Research Laboratory, University of California, San Francisco, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: Schindler
authors.forename: H B
authors.initials: HB
authors.lastname: Gladstone
authors.forename: N
authors.initials: N
authors.lastname: Scott
authors.forename: G T
authors.initials: GT
authors.lastname: Hradek
authors.forename: H
authors.initials: H
authors.lastname: Williams
authors.forename: S B
authors.initials: SB
authors.lastname: Shah
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents; D002470:Cell Survival; D003051:Cochlea / Q000187:drug effects* / Q000294:innervation / Q000502:physiology; D003054:Cochlear Implants; D003712:Dendrites / Q000187:drug effects; D004195:Disease Models, Animal; D006168:Guinea Pigs; D008297:Male; D009355:Neomycin; D009410:Nerve Degeneration / Q000187:drug effects*; D009414:Nerve Growth Factors / Q000008:administration & dosage / Q000494:pharmacology*; D010477:Perfusion; D000159:Vestibulocochlear Nerve / Q000187:drug effects* / Q000502:physiology
chemical_list: D000900:Anti-Bacterial Agents; D009414:Nerve Growth Factors; D009355:Neomycin