Morphologic effects of glycerol on the mental nerve.

OBJECTIVE

In recent years, injection of pure glycerol has been used successfully for the treatment of trigeminal neuralgia. However, the mode of action of this therapy remains unclear. The present experiment was undertaken to examine histologically the morphologic changes produced by extraneural injections of pure glycerol into the dog mental nerve.

METHODS

Under direct vision, glycerol was injected extraneurally into the mental foramen on one side of the lower jaw of each of nine dogs. Physiologic saline solution was the control on the contralateral side of each animal. Animals were killed at 1, 3, and 7 days after the application of glycerol, and the mental nerve specimens were examined by light microscopy.

RESULTS

Results showed that extraneural application of pure glycerol in the vicinity of the dog mental nerve is not associated with structural changes. No signs of nerve degeneration or other morphologic changes were observed for any of the experimental and control specimens in any of the time intervals studied.

CONCLUSIONS

It can be concluded that despite the encouraging clinical results related to extraneural application of pure glycerol for treatment of trigeminal neuralgia, glycerol produces its effect without inducing any morphologic or destructive changes in the peripheral nerve. A probable explanation of the temporary clinical effectiveness of glycerol in relieving trigeminal neuralgia is discussed.