Does antidromic activation of nociceptors play a role in sciatic radicular pain?

Abstract

We describe a case where transcutaneous electrical stimulation of the right sciatic nerve in a patient with right L5 radiculopathy reproduced the patient's pathological pain in the leg. Following a right ankle block with 0.5% bupivacaine, the sciatic nerve stimulation induced pain in the thigh and the calf but not in the foot. Despite an increase in the magnitude of stimulation by 50% (compared with the stimulation before the block) the pain was not perceived below the level of blockade. We suggest that in this case the electrical stimulation generated impulses propagated antidromically into the leg and activated nociceptors in it. The bupivacaine blockade prevented antidromic propagation of impulses into the foot, therefore pain in this region was not perceived.