A modified mid-femoral approach to the sciatic nerve block: a correlation between evoked motor response and sensory block.

BACKGROUND: The lateral sciatic mid-femoral block (LSMF), proved to be reliable, safe, and effective on both branches of the sciatic nerve with a single injection. However, we do not know which component of the sciatic nerve (the tibial [T] or the common peroneal [CP]) produces a better success rate when performing a LSMF with a single injection technique. In this prospective study we compared the success rate of the T motor response with the CP motor response. METHODS: Ninety-five patients undergoing ankle or foot surgery were enrolled. Thirty milliliters of 0.475% ropivacaine was injected at the first evoked motor response, either T or CP, with a minimal intensity between 0.3 and 0.5 mA. RESULTS: Seventy-two patients were included in group T and 23 in group CP. The block was considered a success when a complete sensory block of the sciatic nerve was obtained. The success rate was 90% (65) for the T response and 70% (16) for the CP response (P < 0.05). Time to perform the block (CP: 4.5 +/- 3 min vs T: 4.5 +/- 4 min; P = NS) as well as sensory and motor onset times were not significantly different between groups. No complications were observed in either group. CONCLUSION: We conclude that the evoked motor response of the T branch is associated with a higher success rate than a CP response using the modified LSMF block.

A comparison between double-injection axillary brachial plexus block and midhumeral block for emergency upper limb surgery.

In this prospective and randomized study, we compared a double-injection axillary (median and radial nerves) block with a midhumeral block in 90 patients undergoing emergency upper limb surgery. Time to perform the block, success rate, and patient tolerance were evaluated. The time to perform the block was 5 min longer in the midhumeral group. The success rate was similar in both groups (80% and 91% in groups axillary and midhumeral respectively), except for the musculocutaneous nerve. Patient tolerance was better in the axillary group. Double-injection axillary brachial plexus block is superior to midhumeral block for emergency hand surgery.

[Neurostimulation does not increase the success rate of saphenous nerve blocks]. / La neurostimulation n'augmente pas le taux de succes du bloc du nerf saphene.

PURPOSE: To evaluate neurostimulation of motor components of the vastus medialis muscle and the rectus femoris muscle, with a view to blocking the medial sensory fibres of the saphenous nerve. METHOD: First we dissected four femoral trigones, in order to select our puncture point. We were able to observe that, at the flexion crease of the thigh, the different fibers that make up the femoral nerve were clustered together and the saphenous nerve and the vastus medialis nerve had not yet separated from the femoral stem. Secondly, we conducted a prospective clinical study among 71 patients who had undergone surgery on the lower third of the leg with a sciatic block and a saphenous nerve block. The saphenous nerve block was performed using 10 mL of local anesthetic, by puncturing the flexion crease of the thigh in a bid to obtain one of two muscle responses: medial (contraction of the vastus medialis muscle) or anterior (contraction of the rectus femoris muscle and elevation of the patella). RESULTS: There was an overall success rate of 80% with the saphenous nerve block, with no statistical difference existing between the two response types. Average duration for the block to be completed was two minutes and it took an average of 15 min before the anesthesia took effect. No complications were encountered, apart from a puncture of the femoral artery, which was clinically inconsequential. CONCLUSION: Neurostimulation of the vastus medialis muscle has the same effect as neurostimulation of the rectus femoris muscle with respect to anesthesia of the saphenous nerve. Neurostimulation of the medial compartment of the femoral nerve saves local anesthetic, compared to a standard femoral block.