P51-T A new approach to the radial nerve conduction block determination in the upper arm

Background There are technical limitations in the radial nerve studies in the upper arm using surface electrodes. One of the limitations is that stimulation at the axilla and Erb‘s point stimulates the entire brachial plexus along with the radial nerve. Material and methods Twenty-one healthy volunteers, 55 patients with compressive neuropathies of the radial nerve in the spiral groove and 22 patients with complete radial nerve injuries were studied. Control group (65 radial nerves) consisted of healthy subjects and patients with the undamaged side. Stimulation was carried out at: (1) the distal part of lateral brachium (distal point); (2) Erb’s point (proximal point); (3) the middle part of medial brachium – median and ulnar nerves (additional point). CMAP area recorded from the extensor digitorum was analyzed. Conduction block (CB) in percentage was calculated using the formula: ((distal CMAP + additional CMAP) − (proximal CMAP)) × 100/(distal CMAP + additional CMAP). Results In control group and patients with complete nerve injury CB was not registered (4.2 ± 9.8% and −1.7 ± 11.7% respectively), whereas in patients with compressive radial nerve neuropathy CB was 61.2 ± 11.2% (P Conclusion Median and ulnar nerves stimulation in the middle part of medial brachium is recommended as an additional brachium diagnostic point for radial nerve CB determination.