2026 Workshop Handout Bundle-W109RG - Unusual Upper Limb Nerve Conductions

W109RG - Unusual Upper Limb Nerve Conductions - Duplechan

Pdf Summary

Dr. Lester S. Duplechan’s 2024 workshop reviews nerve conduction study (NCS) techniques for less commonly tested upper-limb nerves. Unlike median and ulnar hand-intrinsic recordings, many of these studies are complicated by greater volume conduction, less accessible muscles, and small responses. Muscle disease or disuse can also reduce compound muscle action potential (CMAP) amplitude.<br /><br />The presentation discusses two approaches to evaluating the anterior interosseous nerve: surface recording over flexor pollicis longus, which may be affected by volume-conducted median-nerve activity, and needle recording in the deep head of pronator quadratus. It also covers sensory studies of the medial and lateral antebrachial cutaneous nerves, emphasizing averaging to improve small responses. Because averaging changes amplitude, averaged responses should not be compared directly with normative values.<br /><br />For axillary nerve testing, deltoid recording is preferred; side-to-side amplitude and latency comparisons may help identify impairment, though a single stimulation site prevents assessment of conduction velocity or block. For suprascapular studies, recording over infraspinatus can help evaluate potential entrapment at both the suprascapular and spinoglenoid notches.<br /><br />Radial motor CMAPs sum activity from multiple muscles, producing substantial volume conduction and larger proximal responses. This makes conduction block and temporal dispersion difficult to assess, but side-to-side comparisons and evaluation of distal conductivity may be useful.<br /><br />The workshop also addresses ulnar neuropathy at the elbow, including compression sites and dynamic subluxation or luxation. Recording from first dorsal interosseous can directly assess the deep ulnar branch and may reveal fascicular involvement not apparent in hypothenar recordings. The dorsal ulnar cutaneous nerve is also included.

Keywords

nerve conduction study

ncs

ncv

upper-limb nerves

anterior interosseous nerve

medial antebrachial cutaneous nerve

lateral antebrachial cutaneous nerve

axillary nerve

suprascapular nerve

radial motor CMAP

ulnar neuropathy at the elbow

dorsal ulnar cutaneous nerve