The diagnosis of carpal tunnel syndrome is suspected based on the symptoms and the distribution of the hand numbness. Examination of the neck, shoulder, elbow, pulses, and reflexes can be performed to exclude other conditions that can mimic carpal tunnel syndrome. The wrist can be examined for swelling, warmth, tenderness, deformity, and discoloration. Sometimes tapping the front of the wrist can reproduce tingling of the hand and is referred to as Tinel's sign of carpal tunnel syndrome. Symptoms can also at times be reproduced by the examiner by bending the wrist downward (referred to as Phalen's maneuver).Picture of carpal tunnel syndromeThe diagnosis is strongly suggested when a nerve conduction velocity test is abnormal. This test involves measuring the rate of speed of electrical impulses as they travel down a nerve. In carpal tunnel syndrome, the impulse slows as it crosses through the carpal tunnel. A test of muscles of the extremity, electromyogram (EMG), is sometimes performed with the nerve conduction velocity test to exclude or detect other conditions that might mimic carpal tunnel syndrome.Blood tests may be performed to identify medical conditions associated with carpal tunnel syndrome. These tests include thyroid hormone levels, complete blood counts, and blood sugar and protein analysis. X-ray tests of the wrist and hand might also be helpful to identify abnormalities of the bones and joints of the wrist.