Carpal tunnel syndrome is usually diagnosed from the results of a:

• Medical history, including any medical conditions or illnesses, prior injuries, current symptoms, or daily activities that may be causing your symptoms.
• Hand diagram. You may be asked to help fill in a diagram of your hand to show where you have numbness, tingling, or pain.
• Physical exam, including the tests for Tinel's sign, Phalen's sign, and two-point discrimination. Although many other tests have been developed for diagnosing carpal tunnel syndrome, there is no convincing evidence of their accuracy.²

Additional testing

If your symptoms are severe, if nonsurgical treatment has not improved symptoms, or if your symptoms are not clearly caused by carpal tunnel syndrome, your health professional may recommend:

• Nerve testing (electromyogram [EMG] and nerve conduction studies), to evaluate any loss of normal functioning in the median nerve. Nerve testing for carpal tunnel syndrome is used in specific situations, such as when surgery is being considered or the diagnosis is unclear.
• X-rays, to check for bone problems caused by past injury, arthritis, recently broken or dislocated bones, or tumors. X-rays are not used to diagnose carpal tunnel syndrome, but they can be helpful for identifying signs of arthritis or an old or new wrist or neck injury that may be contributing to your symptoms.
• Ultrasound, to look at the size of the median nerve. It is inexpensive, comfortable, and quick. However, its use for carpal tunnel syndrome diagnosis is still unproven and relatively uncommon.
• MRI (magnetic resonance imaging), to look for swelling of the median nerve, narrowing of the carpal tunnel, or problems with circulation of blood through the carpal tunnel.
• Blood tests, which are occasionally done to check for a thyroid problem, rheumatoid arthritis, or other medical problem. If the cause of your symptoms is unclear and your medical history suggests other possible conditions, your health professional may order blood tests.