Abstract
We report a patient who developed involuntary movement of the lower limbs, probably caused by spinal myoclonus, after bolus injection of a local anesthetic into the epidural space. An 86 year-old woman with postherpetic neuralgia received a bolus epidural injection of 1 % mepivacaine 6 ml via an indwelling epidural catheter. Involuntary movement of the right lower limb began 30 min after the injection. The intensity and frequency of this movement increased, and the same abnormal movement of the left lower limb also developed 45 min after the mepivacaine injection. The patient was alert during the episode; however, she could not restrain the abnormal movements, which began to subside in each limb after one hour, gradually resolved, and completely disappeared 3 hr after the injection. She could ambulate after the episode, and MRI of the spinal cord disclosed no abnormalities around the epidural catheter. However, syringomyelia was found in the cervical spinal cord (C4 to C7). We conclude that the cause of the involuntary movement of the lower limbs of this patient was spinal myoclonus, because no mechanical stimulation was caused by the epidural catheter, hematoma, or nerve damage.
