Tests and diagnosis of carpal tunnel syndrome

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Carpal tunnel syndrome is caused by the compression of the median nerve which runs through the carpal tunnel in the wrist. Its causes are uncertain, but it’s generally assumed that any position that causes stress on the nerve can be a cause. It is often worse from flexing the wrist.

The syndrome causes a feeling of numbness and pain in the thumb, pointer finger, long finger and parts of the ring finger. The only digit unaffected is the pinkie finger.

Carpal tunnel syndrome is diagnosed largely from the presence of suspect symptoms, like pain and numbness in the hand. To increase certainty, the syndrome does not have a blood test, but there are physical tests that a doctor will ask you to perform. The doctor actually also has some electrical tests that he or she can use as well.

Nerve Conduction velocity test

This isn’t a test specifically for carpal tunnel syndrome, but it is used to check for abnormalities in nerve responses that might indicate the presence of the syndrome. In this test, an electrical current is introduced to the nervous system and the speed with which it reaches nerves “downstream” is measured. A slow response is indicative of some kind of issue with the nervous system. The electrical stimulus is generally introduced through electrodes placed on the patient’s skin.

Electromyogram test

This is often conducted at the same time as the Nerve Conduction Velocity test. It is a test specifically designed to find any muscular conditions that may be mimicking nervous conditions. Muscles also produce electrical signals when they are active, and so electrical abnormalities might also point to muscular issues rather than nervous conditions like carpal tunnel syndrome.

carpal tunnel syndrome test

Blood tests

While, as mentioned, there isn’t a specific blood test to test for carpal tunnel, there are tests to check related issues. There is something thyroid hormone levels, a test to check blood sugar and protein analysis. As stated, none of these will be definitive of carpal tunnel, but they can point to it being more or less likely.


Again, because carpal tunnel syndrome is a nervous condition, X-rays will not be able to find it specifically. However, they can find bone and joint abnormalities in the bones of your wrist and therefore are able to give an indication that the syndrome exists.

Physical examination

However, the main indication that is used for diagnosis of carpal tunnel syndrome is the existence and medical examination of physical symptoms. This will include a general examination of the area as well as more specific physical tests.

A physical exam with a focus on your neck, arms, wrists, and hands is done if there is tingling, numbness, weakness, or pain of the fingers, thumb, or hand. The exam is to help find out whether your symptoms are caused by compression of the median nerve as it passes through the carpal tunnel in the wrist.

During this examination, a doctor will also examine your wrists and hands to compare the strength and appearance of both sides. You will then be asked to pinch an object so your doctor can see and check your thumb for strength and movement during this movement.

Not only is it important to isolate issues you are having in your hand from muscular or other physiological problems, it is also necessary to ensure that your pain is being caused by the median nerve rather than a different nerve in another part of your body. The neck, especially, can mimic carpal tunnel issues, so if your doctor suspects neck-related problems, he or she will also check your neck for possible nerve compression.

Tinel’s sign test

This test dates back to the early 1900s when physiologist Paul Hoffman found that mild percussion of an injured nerve could illicit the sensation of “pins and needles,” or a feeling like an electrical shock.

Your doctor taps on the inside of your wrist over the median nerve. If you feel tingling, numbness, “pins and needles,” or a mild “electrical shock” sensation in your hand when tapped on the wrist, you may have carpal tunnel syndrome.

Phalen’s sign test

This test dates to the 1950s when physiologist George S. Phalen describe a new method for diagnosing carpal tunnel syndrome. The sensations caused by Tinel’s test might be caused by different nerves and not necessarily the median nerve which is affected by carpal tunnel syndrome. Therefore, by using Phalen’s test as well, you could be more specific with your diagnosis.

In the test, you will hold your arms out in front of you and then flex your wrists, letting your hands hang down for about 60 seconds. If you feel tingling, numbness, or pain in the fingers within 60 seconds, you may have carpal tunnel syndrome.

Two-point discrimination test

This test is used when severe carpal tunnel syndrome is suspected. It is not very accurate for mild carpal tunnel syndrome. To do the test, your doctor has you close your eyes and then uses small instruments, such as the tips of two opened paper clips, to touch two points (fairly close together) on your hand or finger. Typically, you would feel separate touches if the two points are at least 0.5 cm (0.2 in.) apart. In severe carpal tunnel syndrome, you may not be able to tell the difference between the two touches, so it may feel as though only one place is being touched.

Given our modern dependence on typing, carpal tunnel syndrome has become a more common issue. While treatment may be as straightforward as simply stopping the activity which causes the syndrome, sometimes more serious measures are required. These can include surgery to alleviate your symptoms, so it is good to be aware and catch the syndrome early, before it becomes severe enough to require more drastic measures to treat.

Further Reading

“Diseases and Conditions: Carpal Tunnel Syndrome.” by Mayo Clinic Staff. Mayo clinic. http://www.mayoclinic.org/diseases-conditions/carpal-tunnel-syndrome/basics/definition/con-20030332.

“Carpal Tunnel Syndrome and Tarsal Tunnel Syndrome.” by William C. Shiel, Jr. Medicinenet.com. http://www.medicinenet.com/carpal_tunnel_syndrome/article.htm.


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