Electrodiagnostic Testing for Carpal Tunnel Syndrome When Routine Median Sensory and Thenar Motor Responses Are...

Area of Science:

• Neurology
• Electromyography
• Nerve Conduction Studies

Background:

• Carpal tunnel syndrome (CTS) is a common condition characterized by median nerve compression at the wrist.
• Cardinal symptoms include hand pain, but electrodiagnostic findings in severe cases can be challenging.
• The median/second lumbrical nerve (Med2ndL) has been suggested as a potentially preserved pathway in severe CTS.

Purpose of the Study:

• To evaluate the utility of Med2ndL nerve stimulation in diagnosing markedly severe CTS.
• To determine the prevalence of hand pain in patients with electrophysiologically severe CTS.
• To assess the diagnostic value of Med2ndL response preservation when routine electrodiagnostic tests are absent.

Main Methods:

• Retrospective analysis of 208 hands from 183 patients with electrophysiologically severe CTS.
• Stimulation of Med2ndL and ulnar/second dorsal interosseous (Uln2ndDIn) nerves.
• Comparison of Med2ndL distal latency with Uln2ndDIn latency; recording of hand pain data.

Main Results:

• Med2ndL response was preserved in 83.7% of hands meeting criteria for severe CTS.
• Among hands with available pain data, 77.1% reported no pain.
• In hands without pain, 79.3% showed preserved Med2ndL response.

Conclusions:

• Med2ndL response preservation is common in markedly severe CTS.
• Med2ndL assessment aids electrophysiological diagnosis when standard median nerve responses are absent.
• Most patients with severe CTS, as defined by electrophysiology, may not experience hand pain.