Experimental grafting of the auditory nerve.

The auditory nerve of five cats was sectioned unilaterally. Its proximal stump was immediately sutured to the proximal stump of the simultaneously severed facial nerve to study afferent sensory nerve regeneration. After time intervals of nine to 18 months, the nerve anastomosis was tested by electrical stimulation of the anastomosis and by recording evoked cortical responses at the auditory cortex. Electrophysiologic evidence of both fiber regeneration within the sectioned auditory nerve and of the reestablishment of a functional synapse at the cochlear nucleus was obtained. Further support of the concept of a possible auditory nerve grafting was added by the histologic examination of the nerve anastomosis and of the cochlear nuclei, which showed signs of the outspreading of axons from the facial nerve through the auditory nerve and through the barrier of the brain stem into the areas of the cochlear nuclei.