Phalen's Test evaluates compression of which nerve in Carpal Tunnel Syndrome?

• A. Median nerve compression in CTS
• B. Ulnar nerve compression at elbow
• C. Radial nerve entrapment
• D. Axillary nerve compression

Answer: (A)

Phalen's test is used to detect compression of the median nerve as it travels through the carpal tunnel. When the wrists are flexed and pressed together, the space in the carpal tunnel narrows, and if the median nerve is irritated, symptoms such as numbness or tingling appear in its distribution (thumb, index, middle fingers, and the radial half of the ring finger). A positive result supports the presence of carpal tunnel syndrome due to median nerve compression. Nerve issues in the ulnar distribution at the elbow, radial nerve entrapment, or axillary nerve compression produce different patterns of numbness or weakness and are not specifically invoked by this wrist-flexion position.