Evaluation of sciatic nerve damage following intraneural injection of bupivacaine, levobupivacaine and lidocaine in rats.

OBJECTIVE: The local anesthetics may cause neurotoxicity. We aimed to compare the neurotoxic potential of different local anesthetics, local anesthetic induced nerve damage and pathological changes of a peripheral nerve. METHODS: Sixty Wistar rats weighing 200-350g were studied. Rats were assigned into 3 groups and 26-gauge needle was inserted under magnification into the left sciatic nerve and 0.2mL of 0.5% bupivacaine, 5% levobupivacaine, and 2% lidocaine were injected intraneurally. An individual who was blind to the specifics of the injection monitored the neurologic function on postoperative 1st day, and daily thereafter. Neurologic examination included assessment for the presence and severity of nociception and grasping reflexes. At the 7th day sciatic nerve specimen was taken for evaluation of histopathologic changes. RESULTS: There was no statistical difference detected among groups regarding grasping reflex and histopathologic evaluation. Two cases in bupivacaine group, 1 case in levobupivacaine group and 2 cases in lidocaine group had slight grasping, while 1 case in lidocaine group had no grasping reflex on the seventh day. Severe axonal degeneration was observed in all groups, respectively in bupivacaine group 4 (20%), levobupivacaine group 3 (15%), and lidocaine group 6 (30%). CONCLUSION: In all groups, histopathological damage frequency and severity were more than the motor deficiency.