Effects of perineural application of glycerol on the facial nerve: an experimental study

Current procedures for treating hemifacial spasm control its symptoms but the condition is often complicated by facial weakness. We undertook this study using a rat facial nerve model to determine whether peripheral glycerol injection could be recommended as a feasible and safe technique in the management of hemifacial spasm. The animals were given a perineural application of glycerol on the facial nerve and killed at 3 days or 2 or 4 weeks after operation. The facial nerves were then examined with light and electron microscopy. Our results show that myelin disintegration and axolysis occurred after glycerol application and both the myelinated and unmyelinated fibers were affected at random, although the most striking histological changes were seen in the myelinated fibers. No evidence of persistent facial weakness in the animals was associated with this method.