Carpal Tunnel Diagnosis

How Do I Know if I Have Carpal Tunnel Syndrome?

Your doctor may use a handful of tests to diagnose carpal tunnel syndrome and rule out other causes of hand and wrist pain.

They’ll probably start with questions about your medical history. Then they’ll examine your hands, arms, shoulders, and neck to figure out if your pain results from another condition, like an injury or arthritis. They’ll also make sure your daily activities aren’t to blame.

The doctor may focus on your wrist to see if the area is tender, swollen, warm, or discolored. They’ll probably test each finger to see if you’ve lost any feeling. And they’ll check the strength of the muscles in your hand.

After that, they may do tests focusing on the median nerve, which runs through your forearm into your hand. When that nerve gets pressed or squeezed through the carpal tunnel, it causes carpal tunnel syndrome.

Carpal Tunnel Tests

Tinel’s Sign

The doctor will tap or press on the median nerve in your wrist with a reflex hammer. If your fingers tingle or if you feel an electric-shock-like sensation, the test is positive. You may have carpal tunnel syndrome.

Phalen’s Maneuver

This is also known as the wrist-flexion test. The doctor will tell you to press the backs of your hands and fingers together with your wrists flexed and your fingers pointed down. You’ll stay that way for a minute or two. If your fingers tingle or get numb, you have carpal tunnel syndrome.

Two-Point Discrimination Test

This means you can tell if two objects touching your skin are two distinct points instead of just one. The doctor may use a gadget called a 2-point disk-criminator, a small, flat, eight-sided tool with needle-like prongs sticking out from all sides.

They might do the test several times on each finger. They’ll start with two points touching your skin a few centimeters apart and move them closer together until you feel just one point of pressure.

The distance at which you can feel only one point will help them figure out nerve function and compression -- two important components of carpal tunnel syndrome.

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Nerve Conduction Velocity Test

This test provides some of the strongest evidence of carpal tunnel syndrome. It measures how fast an electrical signal can travel along a nerve or from the nerve to a muscle.

The doctor places a small electrode on your skin near your elbow. It sends a mild electrical current down your median nerve. The more time it takes for the current to travel from your elbow to your fingers, the more damage to your median nerve.

Electromyogram

This works like the second part of the nerve conduction velocity test. It measures how well the muscle around your median nerve works. The doctor places a small needle electrode into muscles in your hand and arm that get impulses from the median nerve. The needle sends electric impulses into the muscle. You relax and flex your hand several times. The doctor can tell if your median nerve is damaged or being squeezed.

The needles might hurt a little, but it should stop once the doctor takes them out. You may feel twitches or spasms from the electrical current. You could have some bruising where the electrode went in, but that should go away within a few days.

Ultrasound, X-ray, and MRI

Your doctor may order one of these tests to rule out other causes of wrist and hand pain. An X-ray can show arthritis or a broken bone. An ultrasound or MRI will show a swollen or compressed median nerve. They’ll also tell the doctor why it is being squeezed, whether it’s arthritis, carpal tunnel syndrome, or another reason.

They might also order lab tests, like blood work, to look for diseases like diabetes that can damage your nerves.

Other Physical Examination

Your doctor will also ask you about any patterns with your symptoms. For example, if you have tingling or numbness in your little finger, it may not be carpal tunnel syndrome since the median nerve doesn’t provide feeling to that finger. The doctor may also ask if you have a history of symptoms:

  • While holding your phone or a newspaper
  • At night
  • In the morning

These are all signs of carpal tunnel.

WebMD Medical Reference Reviewed by Hansa D. Bhargava, MD on September 22, 2020

Sources

SOURCES:

National Institutes of Health: “Carpal Tunnel Syndrome Fact Sheet.”

Washington University School of Medicine in St. Louis: “Peripheral Nerve Surgery: A Resources for Surgeons.”

American College of Rheumatology: “Carpal Tunnel Syndrome.”

Mayo Clinic: “Carpal tunnel syndrome: Diagnosis,” “Electromyography: “What you can expect.”

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