Lidocaine-induced Extraocular Myotoxicity after Local Anesthesia Techniques

Lee, Se Youp; Kim, Sang Pyo

Abstract

After retrobulbar, peribulbar and direct muscle injection of 2% lidocaine in rabbit eyes, we examined the ultrastructural changes of superior and inferior rectus muscles from 30 minutes to 30 days after injections. Physiologic saline was injected in control group as the same method. The purpose of this study is as followings : (1) to determine the myotoxic effect of the anesthetic and subsequent regeneration of muscle fibers; (2) to compare the myotoxic effects among retrobulbar, peribulbar and direct muscle injection; and (3) to evaluate toxic effect to optic nerve. The lesions of retrobulbar and peribulbar injection resulted in the degeneration of the muscle fibers on the surface of extraocular muscles. In contrast, large internal lesion were frequently observed in the muscles that received direct injections of 2% lidocaine. No ultrastructural damages of optic nerve were observed. With these anesthetic methods, initial damages were restored by regeneration up to 30 days. The myotoxic effects of retrobulbar and peribulbar injection seem to be less harmful than that of direct muscle injection of 2% lidocaine in rabbits. This results suggest that the intentional or accidental direct muscle injection of local anesthetics during surgery may cause strabismus especially in elderly patients who have poor muscle regeneration capacity.