One hundred sciatic nerve blocks: a comparison of localisation techniques.

One hundred sciatic nerve blocks performed for surgery related to lower limb vascular disease were prospectively audited with respect to the techniques used for sciatic nerve localisation and the success rates achieved. Utilising a 22 gauge Quincke point needle, sciatic nerve localisation was performed by initially searching for paraesthesia, followed by the use of a low powered peripheral nerve stimulator. Overall there were 89 successful blocks. Paraesthesia was found in only 44 cases of which 41 were subsequently judged to be successful blocks. A positive response to the nerve stimulator was achieved in 95 cases of which 87 went on to have successful blocks. Our findings suggest that either eliciting paraesthesia or a positive response to the peripheral nerve stimulator carries a high correlation with subsequent successful block, but that the use of the nerve stimulator provides a more consistent and reliable technique for nerve localisation.