oa Comparative study between ultrasound and nerve stimulation guided sciatic nerve block through the anterior approach

Background: Performing a sciatic nerve block on trauma patients unable to be positioned in lateral or prone position is difficult, hence the anterior approach is better in such cases¹. Using blind nerve stimulation has more risk of nerve trauma². The aim of the current study was to compare block of the sciatic nerve with regards to the ease of performance, reliability and safety through the anterior approach by two methods; the first being the nerve stimulator guided approach and the second being ultrasound guided³. Methods: 36 adult patients were randomly allocated equally into two main groups: “Nerve Stimulator-Guided Group (NSG)” where the nerve was located by nerve stimulator only. “Ultrasound guided group (USG)” where the sciatic nerves were blocked by a stimulated needle under guidance of the ultrasound (Figure 1). Assessment of performing each technique, sensory and motor blockades, occurrence of acute systemic toxicity and hematoma formation were compared. Results: Results are shown in Table 1. Only one-third of the sciatic nerves could be visualized by ultrasound. This did not affect the block execution time but caused a statistically significant smaller number of needle passes. Sensory and motor block showed significant differences between the two groups. Criteria of acute systemic toxicity and occurrence of hematoma were not reported in both groups. Conclusion: Results of the current study showed that the addition of ultrasound to nerve stimulator in the anterior approach to the sciatic nerve block added only little to the ease of performance, reliability, and safety of the procedure. This was because only one-third of the nerves could be seen. More practice, better machines, and new blocking techniques may be needed to overcome the problem of visualizing the nerve.