2025 Workshop Handout Bundle-W109RTC Unusual Upper Limb NCS

W109RTC Unusual Upper Limb NCS - Duplechan

Pdf Summary

This 2024 presentation by Dr. Lester S. Duplechan provides an in-depth review of unusual upper limb nerve conduction studies (NCS) aimed at technologists, residents, and students. The focus is on less commonly tested nerves such as the dorsal ulnar cutaneous (DUC), radial motor, anterior interosseous (AIN), medial and lateral antebrachial cutaneous (MAC, LAC), axillary, and suprascapular nerves.<br /><br />Key objectives include reviewing accepted NCS protocols for these nerves, discussing the use of hybrid evaluation techniques combining needle electrodes and surface electrodes (notably to confirm absent motor responses), and exploring electrode placement strategies.<br /><br />The presentation emphasizes challenges posed by volume conduction—where action potentials from multiple muscle areas blend—especially notable in ulnar and radial nerve studies. For instance, the ulnar response may appear double-peaked due to contributions from hypothenar and deep ulnar branch muscles, complicating amplitude interpretation. Similarly, radial motor compound muscle action potentials (CMAP) reflect summated signals from several muscles, limiting the utility of measurements like conduction block.<br /><br />Specific nerve evaluations are detailed: AIN can be studied via surface electrodes on flexor pollicis longus or needle electrodes in pronator quadratus; MAC and LAC sensory nerves have defined measurement techniques; axillary nerve assessment focuses on deltoid muscle recordings with side-to-side comparison to identify impairments; suprascapular nerve studies involve recordings over infraspinatus to capture potential entrapment sites.<br /><br />The presentation also highlights the importance of averaging to reduce noise in small sensory responses and describes dynamic assessment of ulnar neuropathy at the elbow—including compression sites and nerve subluxation.<br /><br />References include authoritative texts on nerve conduction and electrodiagnosis. Attendees are encouraged to provide feedback via the AANEM app and to claim continuing education credits.<br /><br />Overall, this work provides valuable guidance on specialized nerve conduction techniques in the upper limb, addressing methodological nuances needed for accurate diagnosis beyond commonly tested median and ulnar nerves.

Keywords

upper limb nerve conduction studies

dorsal ulnar cutaneous nerve

radial motor nerve

anterior interosseous nerve

medial antebrachial cutaneous nerve

lateral antebrachial cutaneous nerve

axillary nerve assessment

suprascapular nerve studies

volume conduction challenges

dynamic ulnar neuropathy assessment