Specific evoked motor response for supraclavicular brachial block

Objective: To assess and evaluate the accuracy ofindividual types of evoked motor responses (EMRs)for prediction of successful surgical anesthesiafollowing peripheral nerve stimulator (PNS) assistedsupraclavicular block.Methods: A prospective study was carried out overa period of one and half years from August 2004 toJanuary 2006, at J. N. Medical College, Aligarh MuslimUniversity, Aligarh, India, in 60 patients who underwentvarious elective operative procedures on the upper limb.Any of the EMR, such as forearm flexion or extension,carpal flexion, or extension, prono-supination, or fingerflexion, at a definite current of 0.25 mA for 2 ms wastaken as an end point for prediction of successful block,and a local anesthetic solution (0.375% Bupivacaine,30 ml) was administered at that level.Results: Complete surgical anesthesia was observed inthose cases where EMR included: flexion of only secondand third fingers (n=15/15) or flexion of all 4 fingerswith thumb opposition (n=14/14) or uncommonflexion of all 4 fingers without movement of any otherjoint of the upper limb (n=2/2), suggesting a sensitivityof 100%. However, thumb opposition to the tip of theflexed little finger revealed a success rate of only 83%(n=5/6), and other EMRs were followed by high ratesof inadequate surgical anesthesia or total failure.Conclusion: Specific EMR of flexion of second andthird fingers, or all the 4 fingers are reliable predictorsof complete surgical anesthesia following PNS assistedsingle injection supraclavicular nerve block with noincidence of pneumothorax and nerve damage.