2025 Workshop Handout Bundle-W23RFC Unusual NCS

W23RFC Unusual NCS - Robinson

Pdf Summary

This document is a comprehensive workshop syllabus prepared for the American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM), detailing unusual sensory nerve conduction studies and techniques for diagnosing Carpal Tunnel Syndrome (CTS).<br /><br />The first section, "Unusual Sensory Conduction Studies," authored by Dr. Lawrence Robinson and colleagues, reviews the history and importance of sensory nerve conduction studies, initially described in 1956. Sensory studies are crucial as some peripheral nerve lesions affect only sensory fibers, and sensory conduction parameters are often more sensitive than motor studies in detecting nerve pathology. The document details anatomical considerations, sensitivity issues (like aging, limb temperature), and technical challenges such as electrode placement and minimizing artifacts. It provides protocols, normative data, and stimulation/recording techniques for various sensory nerves including the dorsal cutaneous branch of the ulnar nerve, superficial radial nerve, medial and lateral antebrachial cutaneous nerves, posterior antebrachial cutaneous nerve, medial and lateral plantar nerves, superficial peroneal nerve, saphenous nerve, and lateral femoral cutaneous nerve. Data tables report latency, conduction velocity, and amplitude values, with methodological notes on orthodromic vs antidromic techniques and methods to optimize signal detection in clinical electrodiagnostic labs.<br /><br />The second section focuses on "Carpal Tunnel Syndrome: Techniques for Diagnosis," discussing the limitations of relying solely on symptoms for CTS diagnosis and emphasizing electrodiagnostic studies to quantitatively assess median nerve conduction. The text reviews both standard and newer, more sensitive nerve conduction techniques that involve comparing median nerve latencies to ulnar and radial nerves and evaluating short segments of the median nerve across the carpal tunnel ("inching"). Techniques include median-ulnar mixed nerve latency differences to the palm, median-radial sensory latency differences to the thumb, median-ulnar sensory latency differences to the ring finger, median mid-palmar latency, and motor latency differences to intrinsic hand muscles. The document provides normative data, sensitivity and specificity statistics, diagrams of electrode placements, and discusses statistical considerations like false positive rates and data transformation for improved analysis. A combined "Combined Sensory Index" (CSI) summing three latency differences improves diagnostic accuracy by increasing sensitivity and specificity while reducing false positives. The document underscores the importance of using multiple tests in conjunction with clinical assessment to confirm CTS.<br /><br />Throughout, the guides emphasize careful technique, understanding nerve anatomy, and interpretation mindful of technical and physiological variables, aiming to equip electromyographers with advanced tools to improve diagnostic precision in sensory neuropathies and CTS.

Keywords

Sensory nerve conduction studies

Carpal Tunnel Syndrome diagnosis

Electrodiagnostic techniques

Median nerve latency

Ulnar nerve comparison

Radial nerve sensory latency

Combined Sensory Index (CSI)

Peripheral nerve lesions

Electrode placement protocols

Nerve conduction velocity