Experimental Facial Nerve Paralysis

Facial nerve paralysis was produced by inoculating rabbits with herpes simplex virus. Inoculations were made through the stylomastoid foramen into the facial nerve canal, the subarachnoid space, and the common carotid artery. Subarachnoid and common carotid artery inoculation caused encephalomeningitis, but facial nerve paralysis failed to develop. Inoculation through the stylomastoid foramen produced facial nerve weakness on the third day and severe paralysis on the sixth day. No improvement was noticed after 223 days of follow-up. Regeneration was extremely poor and the nerve tissues were totally replaced by collagen fibers in some animals. Even if regeneration was present, markedly proliferated collagen fibers surrounded the regenerated nerve. In some cases, a typical labyrinthine disturbance resulted which could be ascribed to interneuron spread of the virus.