Ultrasound-aided unilateral epidural block for single lower-extremity pain.

We report an ultrasound-aided unilateral epidural block, employed in two patients, to provide better analgesia and motor function for lower-extremity pain. The patient in case 1 was a 72-year-old woman who suffered pain arising from Herpes zoster rash on the left leg (the second lumbar nerve area). A left-dominant continuous unilateral epidural block was performed to reduce her pain. After confirming the L2/3 epidural space and needle direction using ultrasound imaging, epidural cannulation was performed. Continuous infusion of 4 ml h(-1) of 1% lidocaine through the epidural catheter eliminated the herpetic pain in the left leg, maintaining motor function and normal sensation in her right leg. The patient in case 2 was a 35-year-old man whose complaint was postoperative pain in his left knee during passive movement. Dependent-side (left-side) dominant ultrasound-aided continuous unilateral epidural block, the same procedure as that used in case 1, was performed at the L3/4 intervertebral space. His left knee pain was clearly reduced, with partial paralysis, but motor function in his right leg was completely normal during the continuous epidural block with 4 ml h(-1) of 0.2% ropivacaine. Ultrasound imaging around the epidural space facilitated effective unilateral epidural block for single lower-extremity pain in both patients. This technique could decrease possible side effects and improve patient satisfaction during continuous nerve block by maintaining motor function and sensation in the nondependent side.