COMPARATIVE STUDY BETWEEN ULTRASOUND AND NERVE STIMULATOR GUIDED SCIATIC NERVE BLOCK THROUGH THE ANTERIOR APPROACH.

Introduction: The aim of the current study was to compare block of the sciatic nerve through the anterior approach by two methods, namely, the nerve-stimulator guided and ultrasound-guided, with or without nerve stimulation, with regard to the ease of performance, reliability and safety of this approach.

Patients and methods: 36 adult patients were randomly allocated equally into one of 2 main groups: "Nerve Stimulator-Guided Group (NSG)" where the nerve was located by nerve stimulator only and "Ultrasound guided group (USG)" where the sciatic nerves were blocked by a stimulated needle under guidance of the ultrasound. Assessment of performing each technique, sensory and motor blockades, occurrence of acute systemic toxicity and haematoma formation were compared.

Results: Only one-third of the sciatic nerves could be visualized by US. This did not affect the block execution time but caused less number of needle passes in a statistically significant value. Sensory and motor block showed significant differences between the 2 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. 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 anisotropy of the nerve.