Long-term degeneration and regeneration of the rabbit facial nerve blocked with conventional lidocaine and bupivacaine solutions.

The alterations due to the long-term degeneration and regeneration of the rabbit facial nerve were investigated. The facial nerve was blocked with conventional lidocaine and bupivacaine solutions. The rabbits were sacrificed and facial nerves were removed 2, 4, 6 and 8 weeks after the administration of normal saline, lidocaine and bupivacaine. The samples were then processed for electron microscopic observation. Degenerations were seen 2-4 weeks after the injection of normal saline, lidocaine and bupivacaine. In the normal saline group the regeneration process was observed after 6 weeks, whereas in the lidocaine and bupivacaine groups this process was first noticed after 8 weeks. In the lidocaine and bupivacaine groups, regeneration was not completed at the end of 8 weeks; however, it was faster in the bupivacaine group. Bupivacaine is therefore suggested as the drug of choice for neural blockade as it caused less damage and a faster regeneration.