Background and objective We have assessed the analgesic efficacy and side-effects of neostigmine when added to lidocaine for axillary brachial plexus block, in a prospective, randomized, double-blind, placebo-controlled study.

Methods We studied 34 ASA I or II patients undergoing elective ambulatory carpal tunnel release. Axillary brachial plexus block was performed using a peripheral nerve stimulator to locate the median nerve. All patients were administered 1.5% lidocaine 450 mg and epinephrine 5 μg mL−1. Patients were allocated randomly to one of two groups. Neostigmine 500|ig was added in group N, and saline 1 mL in group S.

Results The duration of analgesia did not significantly differ between groups [mean (SD)]: 812.5 (456.9) for group S vs. 746.7 (474.1) min for group N (P >0.05). The need for supplementary analgesia did not significantly differ between groups: 4.4 (1.5) extra doses for group S vs. 3.8 (2.2) extra doses for group N (P>0.05). Visual analogue pain scores and occurrence of side-effects did not significantly differ between groups.

Conclusion Neostigmine does not seem to be of clinical value for peripheral nerve blocks.