Since it is possible to have sensory nerve contact and not elicit a motor response, the use of a nerve stimulator does not prevent nerve injury in the anesthetized patient. In addition, the elicited motor response does not distinguish between stimulation of a peripheral nerve, a plexus, spinal root or spinal cord. First, the safety of regional anes-thesia performed on anesthetized pediatric patients is not readily applied to adults. Needle and catheter placement associated with administration of neuraxial opioids at the lumbar level only appears safe. However, techniques performed above the termination of the cord or injection of local anesthetics, which have the potential for neurotoxicity, should be avoided until proven safe.
Few data exist on the relative risk of peripheral techniques.
It may be that the cases of intracord injection following interscalene block reflect the number of neural structures present within needle contact and that other plexus of peripheral blocks are not as dangerous when performed in the presence of heavy sedation or general anesthesia. The increasing popularity of lower extremity techniques will no doubt be associated with subsequent case reports of neurologic complications. We must be honest in reporting these cases in order to evaluate the risks and benefits. Major complications after regional anesthetic techniques are rare but can be devastating to the patient and the anesthesiologist. Prevention of regional anesthesia-related complications begins during the preoperative visit with a careful evaluation of the patient s medical history and an appropriate discussion of the risks and benefits of the available anesthetic techniques.