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Radial Tunnel Syndrome

(Posterior Interosseous Nerve Syndrome)

By

David R. Steinberg

, MD, Perelman School of Medicine at the University of Pennsylvania

Last full review/revision May 2020| Content last modified May 2020
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Radial tunnel syndrome is a disorder resulting from compression (pinching) of a branch of the radial nerve in the forearm or back of the arm or at the elbow.

The radial tunnel is called a tunnel because it is a narrow area through which the radial nerve passes around the elbow and through the forearm to the hand. The tunnel is made of the surrounding muscles, tendons, and ligaments. Causes of compression of the radial nerve at the elbow include injury, ganglia Ganglia Ganglia are swellings that occur over joints or on coverings of tendons in the hands and wrists and that contain a jellylike fluid. It is not known why ganglia develop. Ganglia usually do not... read more Ganglia , lipomas Lipomas Lipomas are soft deposits of body fat that grow under the skin, causing round or oval lumps. (See also Overview of Skin Growths.) Lipomas are very common. They appear as smooth, soft bumps under... read more Lipomas (noncancerous fatty tumors), bone tumors Overview of Bone Tumors Bone tumors are growths of abnormal cells in bones. Bone tumors may be cancerous (malignant) or noncancerous (benign). Cancerous tumors may start in the bone (primary cancer) or start in other... read more , and inflammation of the surrounding bursae Tendons and Bursae Tendons are tough bands of connective tissue made up mostly of a rigid protein called collagen. Tendons firmly attach each end of a muscle to a bone. They are often located within sheaths, which... read more (small fluid-filled sacs that can lie under a tendon) or muscles Muscles There are three types of muscles: Skeletal Smooth Cardiac (heart) Two of these kinds—skeletal and smooth—are part of the musculoskeletal system. read more .

Compression of the radial nerve results in cutting, piercing, or stabbing pain affecting the top of the forearm and back of the hand and side of the elbow. Pain results when the person tries to straighten the wrist and fingers. There is no numbness because the radial nerve carries more fibers that control movement rather than sensation. In advanced cases, the muscles that straighten the thumb and fingers become weak.

Doctors base the diagnosis of radial tunnel syndrome on an examination.

Treatment of Radial Tunnel Syndrome

  • A splint

  • Sometimes surgery

To reduce pressure on the nerve, the person should wear a splint on the wrist and/or the elbow and avoid rotating the wrist and bending the arm at the elbow.

If the wrist becomes weak and tends to droop (wristdrop) or if symptoms are not relieved after 3 months of nonsurgical treatment, surgery may be needed to relieve pressure on the nerve.

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