Radial Tunnel Syndrome

Radial tunnel syndrome is caused by a pinched nerve, called the radial nerve, that runs through the muscles on the top of the elbow and forearm. The radial nerve is one of the five major nerves of the upper extremity. It powers the muscles that straighten your elbow, wrist, and fingers. It also powers the muscles that rotate the forearm so the palm is facing up or down. Finally, it gives feeling or sensation to the back of the arm, forearm, and hand.

The area where the muscles overlap on the top of the forearm is called the radial tunnel. Within the tunnel, the radial nerve divides into two branches: one branch provides sensation, and the other powers the forearm muscles. Pain and weakness can occur if the nerve is compressed by swelling or tightness in the tunnel.

Radial tunnel syndrome can coexist with tendinitis at the outer elbow, also called lateral epicondylitis or tennis elbow. Radial tunnel syndrome is common, but diagnosis and treatment can be controversial because there is no single clear test to diagnose it. The patient's history and physical exam help determine the diagnosis.

Causes

Radial tunnel syndrome is not considered an inherited or genetic condition. It can be more common in people who have:

• A history of overuse in a single event or repetitive activities
• A history of activities involving forearm rotation
• A history of tight-grip activities

Symptoms

Symptoms of radial tunnel syndrome can include:

• Pain deep in the back or top of the forearm
• Forearm pain described as dull or burning
• Pain that may extend from near the elbow down to the wrist
• Pain with rotation of the forearm
• Pain with straightening the wrist
• Pain that may be more noticeable at night or the day after use
• Feelings of wrist weakness due to pain

Diagnosis and Treatment

Diagnosis

The symptoms described above, along with findings during a physical examination, help determine the diagnosis. There are no clear tests that definitively diagnose radial tunnel syndrome. Electromyography (EMG) and nerve conduction studies (NCS) are often normal, but they may still be useful to rule out other diagnoses.

A magnetic resonance image (MRI) may sometimes help identify a reason the nerve is being pinched. It can also identify other muscle, ligament, tendon, bone, artery, or cartilage sources of pain. Injections around the nerve can be helpful for both diagnosis and treatment. These injections usually include a numbing medication. Temporary pain relief can support the diagnosis by showing that medication in the area decreases the pain. Steroid injections may decrease inflammation in some cases.

Surgical Treatment

Patients with a suspected diagnosis who do not improve after months or years of nonsurgical treatment may be candidates for surgery. There are many surgical techniques for radial tunnel syndrome, and surgical outcomes can vary.

A common approach is to make a cut between the forearm muscles to open the space where the nerve passes through. The surgeon removes all sites of compression on the nerve. This is an outpatient surgery. Some surgeons may also treat tennis elbow during the same procedure if it is present.

Recovery may take three to six months and may benefit from therapy so muscles and nerves can recover and to help prevent scarring. Risks of surgery include general anesthesia risks, nerve injury, persistent pain, scarring, and weakness.

This mobile-friendly version is adapted from patient education content originally provided by the American Society for Surgery of the Hand.