Twenty-two patients were included in this study and were separated into two groups according to the surgical indication. Knee arthroscopy (group 1; n = 16) and other procedures (group 2; n=6). The sciatic nerve blocks were performed immediately after a paravascular three-in-one block. Patients were placed in the prone position with monitors, including blood pressure, electrocardiography and pulse oximetry. Sedation was achieved using 50-100 mg of intravenous fentanyl combined with 1-4 mg of intravenous midazolam or propofol 20-30 mg, or both.

To specify anatomical landmarks, a line was drawn between the inferior border of the anterior superior iliac spine and a superior angle of this pubic symphysis tubercle with the patient in the supine position and the lower extremity in the neutral position. From this anterior superior iliac spine pubic symphysis line, a perpendicular dissector line was drawn in the middle and extended 8 cm caudad to define the site of introduction of the needle. A sterile 15 cm insulated b-beveled Stimuplex needle connected to a Stimuplex digital nerve stimulator and introduced perpendicular to the skin after subcutaneous local anesthesia with lidocaine 1%. The needle has the potential of coming into proximity with the femoral nerve and the nerve stimulator was initially at 1 mA. Within a depth of 9.5-13 cm, the sciatic nerve was identified via a motor response related to the stimulation of its common peroneal nerve component or its tibial nerve component. The current was then decreased and the needle orientation was optimized to obtain the same response with a current equal to or lower than 0.7 mA. Patients either received 30 ml of mepivacaine 1.5% or a combination of 15 ml mepivacaine 1.5% plus 15 ml ropivacaine 0.75%.

Determination of the appropriate landmarks required 1.1 minutes. The sciatic nerve was identified in all patients within 2.9 minutes after two attempts and the sciatic nerve was found at a depth of approximately 10.5 cm. In 13 patients the common peroneal nerve was the first stimulated, whereas stimulation of the tibial nerve was elicited in nine patients. A complete sensory block developed faster in the common peroneal nerve than in the tibial territory. The overall onset time for complete sensory block in both the common peroneal and tibial territories was 12.5 minutes. However, the onset time varied according to the anesthetic solutions. The overall duration of the block was five hours. The block lasted 4.6 hours with mepivacaine alone compared to 13.8 hours after the mixture of mepivacaine and ropivacaine.

The authors concluded that this technique represented an easy and reliable anterior technique for performing sciatic nerve blocks. These blocks are an example of an alternative to the more traditional approaches, especially in patients with limited mobility. This approach, therefore, facilitated the performance of sciatic nerve blocks.

The performance of peripheral nerve blocks to provide regional anesthesia is steadily growing. The ability to provide a dense block and avoid the need for a general anesthetic, combined with profound postoperative analgesia and the ability to avoid opiates has been demonstrated in numerous studies. This provides improved patient satisfaction and decreases discharge times, as nausea and pain are well controlled. The performance of upper extremity blocks is widely accepted and utilized by anesthesia practitioners throughout the United States. The performance of lower extremity blocks, on the other hand, has suffered from a lack of familiarity by many practitioners and as a result has been underutilized. The description and teaching of techniques that have simple landmarks and reliable results will improve the performance of lower extremity blocks and should facilitate the introduction of these techniques into more wide-spread practice in the outpatient setting. I congratulate the authors on their efforts to improve our understanding of the anatomy associated with the performance of sciatic nerve blocks and to facilitate its utilization in a larger number of patients by providing a simple anatomical aproach.