Constraints on the use of a nerve stimulator in peripheral conduction blocks when there is disturbance in the neuromuscular junction

An 81-year-old woman with right lower limb ischemia was scheduled for revascularization of a femoropopliteal bypass grafted 10 years earlier. A popliteal blockade, attempted as part of regional anesthesia with the aid of a nerve stimulator, was not achieved because the posterior tibial nerve could not be located. After surgery, the patient mentioned symptoms in the region of the right knee consistent with complex regional pain syndrome (Ducke's stage 3); the symptoms appeared after the first operation and would explain the absence of response to the nerve stimulator. Using a nerve stimulator to facilitate location of the various nerve trunks for anesthesia involves obtaining a motor response to electrical stimulation. The procedure is becoming more and more frequent because of its many advantages over other more traditional methods. However, it may be impossible to locate a nerve for a variety of reasons.