physical examination signs indicative of CTS. How do they compare with other diagnostic testing?
In CTS, numbness commonly affects the index, middle, and radial side of the ring finger. The thumb is less often symptomatic. A positive Tinel’s sign occurs when tapping the nerve at the site of entrapment produces pain and dysesthesias radiating into the sensory distribution of the nerve distally. In CTS, this test has a pooled sensitivity of 50% and specificity of 77%. Phalen’s test is positive when passive wrist flexion to 90 degrees for 1 minute produces or worsens paresthesias in the median nerve distribution. It has a pooled sensitivity of 68% and specificity of 73% for CTS. The direct median nerve compression test is positive when pain and paresthesias occur within 30 seconds of pressure exerted over the carpal tunnel by the examiner’s thumb. The “volar hot dog” (swelling at the wrist on the ulnar side of the palmaris longus tendon) has been reported in over 90% of patients with CTS. In addition to provocative maneuvers, two-point discrimination (sensitivity 25%, specificity 90%), grip strength, and thenar muscle function and atrophy should be examined. Electrodiagnostic studies have a sensitivity of 85% and specificity of 95% for CTS. Ultrasonography and magnetic resonance imaging (MRI) can be useful in patients with equivocal electrodiagnostic studies.