Carpal tunnel syndrome, cubital tunnel syndrome, and radial tunnel syndrome are nerve compression syndromes. In these disorders, something (usually bone or connective tissue) presses on a nerve, causing abnormalities of sensation, movement, or both. Symptoms include tingling, pain, loss of sensation, weakness, or a combination. The diagnosis can often be made or confirmed by electromyography and nerve conduction studies (see Diagnosis of Brain, Spinal Cord, and Nerve Disorders: Electromyography and Nerve Conduction Studies). In these disorders, surgery may be necessary to relieve pressure on the nerve if symptoms are severe despite other treatments or if there is persistent loss of sensation or weakness.

Carpal Tunnel Syndrome

Carpal tunnel syndrome is a painful compression of the median nerve as it passes through the wrist.

• The side of the hand near the thumb can tingle and become numb.
• Symptoms can usually be relieved by use of a splint or injection of a corticosteroid.

Carpal tunnel syndrome results from compression of the median nerve, which is located at the palm side of the wrist (an area called the carpal tunnel). The median nerve serves the thumb side of the hand. The compression results when swelling or bands of fibrous tissue form for a variety of reasons on the palm side of the wrist.

Causes

Carpal tunnel syndrome is common—especially among women aged 30 to 50 years—and may affect one or both hands. At slightly increased risk are people whose work requires repeated forceful movements with the wrist extended, such as using a screwdriver. Another potential factor is use of a computer keyboard that is not positioned properly. Prolonged exposure to vibrations (for example, by using certain tools) has also been claimed to cause carpal tunnel syndrome. Pregnant women and people who have diabetes, an underactive thyroid gland, gout, or rheumatoid arthritis are at increased risk of developing carpal tunnel syndrome. However, most cases develop for unknown reasons.

Proper Keyboard Position Using a computer keyboard that is positioned improperly can result in carpal tunnel syndrome. To prevent injury, the user should keep the wrist in a neutral position. That is, the line from the hand to the forearm should be straight. The hand may be slightly lower than the forearm. But the hand should never be higher, and the wrist should not be cocked. The keyboard should be positioned relatively low, keeping the hand slightly lower than the elbow. A wrist pad can be used to support the wrist.

Symptoms

The symptoms, due to the nerve compression, are odd sensations, numbness, tingling, and pain in the first three fingers on the thumb side of the hand. Occasionally, there is also pain and a burning or tingling sensation in the arm. The pain may be more severe while the person is sleeping because of the way the hand is positioned. With time, the muscles in the hand on the thumb side can weaken and shrink through lack of use (atrophy).

Diagnosis

The diagnosis is made largely by examining the affected hand and wrist. A doctor may first perform nerve conduction studies (see Diagnosis of Brain, Spinal Cord, and Nerve Disorders: Electromyography and Nerve Conduction Studies) to be certain that the problem is carpal tunnel syndrome, particularly if surgery is considered.

Treatment

Avoiding positions that overextend the wrist or put extra pressure on the median nerve, including such measures as adjusting the angle of a computer keyboard, sometimes provide some relief. Wearing wrist splints that hold the hand in a neutral position (especially at night) and taking mild analgesics often help. Treating underlying disorders (such as rheumatoid arthritis or an underactive thyroid gland) can help to relieve symptoms.

Injections of a corticosteroid suspension into the carpal tunnel occasionally bring long-lasting relief. If pain is severe or if the muscle atrophies or weakens, surgery is the best way to relieve pressure on the median nerve. A surgeon can cut away the bands of fibrous tissue that place pressure on the nerve.

Cubital Tunnel Syndrome

(Ulnar Neuropathy)

Cubital tunnel syndrome (ulnar neuropathy) is a disorder caused by compression of the ulnar nerve at the elbow.

The ulnar nerve passes close to the surface of the skin at the elbow (“funny bone”) and is easily damaged by repeatedly leaning on the elbow, by bending the elbow for prolonged periods, or sometimes by abnormal bone growth in the area. Baseball pitchers are prone to cubital tunnel syndrome because of the extra twist of the arm required to throw a slider.

Symptoms include pain and numbness of the elbow and a pins-and-needles sensation of the ring and little fingers. Eventually, weakness of the ring and little fingers may develop. Weakness may also interfere with the ability to pinch using the thumb and index finger, because most of the small muscles in the hand are controlled by the ulnar nerve. Severe, chronic cubital tunnel syndrome can lead to muscle wasting (atrophy) and a clawlike deformity of the hand.

Nerve conduction studies (see Diagnosis of Brain, Spinal Cord, and Nerve Disorders: Electromyography and Nerve Conduction Studies) may be needed to help pinpoint the exact area of nerve damage. People with mild cases of cubital tunnel syndrome undergo physical therapy (including a splint at night to avoid overbending the elbow) and avoid pressure over the elbow. An elbow pad worn during the day can be helpful. About 85% of people who do not respond to splinting or who have more severe cases of nerve compression may benefit from surgery, which usually consists of releasing pressure on the nerve.

Radial Tunnel Syndrome

(Posterior Interosseous Nerve Syndrome)

Radial tunnel syndrome (posterior interosseous nerve syndrome) is a disorder resulting from compression of a branch of the radial nerve in the forearm or back of the arm or at the elbow.

Causes of compression of the radial nerve at the elbow include injury, ganglia, lipomas (noncancerous fatty tumors), bone tumors, and inflammation of the surrounding bursa or muscles.

Compression of the radial nerve results in cutting, piercing, or stabbing pain affecting the top of the forearm and back of the hand. Pain results when the person tries to straighten the wrist and fingers. There is no loss of sensation, because the radial nerve principally connects to muscles.

To reduce pressure on the nerve and speed healing, the person should wear a splint and avoid rotating the wrist and bending the arm at the elbow. If the wrist becomes weak and tends to droop (wristdrop), surgery may be needed to relieve pressure on the nerve.

Last full review/revision March 2008 by David R. Steinberg, MD