Central Nervous System Metabolic Activity after Cochlear Implantation in the Feline Neonatal Model

Abstract

OBJECTIVE: To determine the effects of deafening and cochlear implant stimulation on central nervous system (CNS) metabolic activity in the feline neonate model. BACKGROUND: Deafening of fetal animals has been shown to result in acute, profound depression of CNS glucose metabolism, in both auditory structures and the cerebral hemispheres. Preliminary studies have suggested that electrical stimulation of the auditory system may increase central nervous metabolic activity after deafening. The purpose of this study was to investigate this possibility. METHODS: This was a prospective, randomized, blinded, and controlled animal study of 13 random-source newborn kittens. It was set in an animal research facility for otologic disorders. OUTCOME: Deoxyglucose metabolism (assessed with autoradiograph densitometry) of brain cross-sections of normal, deafened, and deafened and cochlear-implanted animals after 6 weeks of auditory stimulation or deprivation. RESULTS: Chronic deafening did not result in a profound reduction in CNS metabolic activity. Cochlear implantation and electrical stimulation did not significantly raise the level of CNS metabolic activity within either auditory pathways or the cerebral hemispheres. CONCLUSIONS: Deafening is not associated with significant chronic reduction in CNS metabolic activity. Other parameters of CNS activity and maturation may be necessary to assess the effects of cochlear implantation and stimulation in animal models.