With radial tunnel syndrome, the radial nerve is pinched when passing through a tunnel near the elbow. The symptoms of radial tunnel syndrome are very similar to the symptoms of tennis elbow and there are very few helpful tests making it hard to diagnose.
The radial nerve starts at the side of the neck, where the individual nerve roots leave the spine. The nerve roots exit through small openings between the vertebrae.
The nerve roots join together to form three main nerves that travel down the arm to the hand. One of these nerves is the radial nerve. The nerve passes down the back of the upper arm. It then spirals outward and crosses the outside (the lateral part) of the elbow before it winds its way down the forearm and hand.
On the lateral part of the elbow, the radial nerve enters a tunnel formed by muscles and bone. This is called the radial tunnel.
Passing through the radial tunnel, the radial nerve runs below the supinator muscle. The supinator muscle lets you twist your hand clockwise.
After passing under the supinator muscle, the radial nerve branches out and attaches to the muscles on the back of the forearm.
Pressure on the radial nerve causes pain. Several spots along the radial tunnel can pinch the nerve. If the tunnel is too small, it can squeeze the nerve and cause pain. Repetitive, forceful pushing and pulling, bending of the wrist, gripping, and pinching can also stretch and irritate the nerve. Sometimes a direct blow to the outside of the elbow can injure the radial nerve.
The symptoms of radial tunnel syndrome are tenderness and pain on the outside of the elbow. Pain from radial tunnel syndrome often starts near the bony point on the outside of your elbow joint (lateral epicondyle). The pain gets worse when you bend your wrist backward, turn your palm upward, or hold something with a stiff wrist or straightened elbow.
Radial tunnel syndrome may cause a dull pain or fatigue in the muscles of the forearm. Nerve pressure inside the radial tunnel leads to weakness in the muscles on the back of the forearm and wrist, making it difficult to steady the wrist when grasping and lifting. It can even lead to wrist “drop,” meaning the back of the hand can’t be raised.
Diagnosing radial tunnel syndrome can be difficult. Many cases are initially diagnosed as tennis elbow, a condition affecting the elbow joint tendons. Tests don’t always help tell the two conditions apart.
A doctor will take a detailed medical history asking questions about your pain, activities, and any past injuries to the elbow.
A doctor will perform a physical examination looking for the most painful spot. Pinpointing the source of the pain will be most helpful in determining whether you have radial tunnel syndrome or tennis elbow.
A doctor may order some tests of the radial nerve. An electromyogram (EMG) tests to see if the muscles of the forearm are working properly. If the test shows a problem with the muscles, the cause may be a radial nerve problem. The nerve conduction velocity (NCV) test measures the speed of an electrical impulse as it travels along the radial nerve. If the speed is too slow, the nerve is probably pinched.
These tests are not always accurate in diagnosing radial tunnel syndrome. Many people who have radial tunnel syndrome will have normal EMG and NCV test results. A doctor will consider the entire examination and test results in diagnosing whether or not you have radial tunnel syndrome.
Getting symptoms under control and helping you regain the use of your elbow can be a challenge.
The most important part of your treatment is avoiding the activities causing the problem. Avoid repetitive activities requiring your wrist to be bent backwards. Repeated twisting motions of the wrist (such as using a screwdriver) also make the problem worse. If work tasks caused your condition, it is crucial to modify your work site or your duties for successful treatment. Take frequent breaks and limit heavy pushing, pulling, and grasping.
If symptoms are worse at night, you may need to wear a lightweight plastic arm splint while sleeping. Limiting elbow movements at night eases further irritation. Resting the elbow may give the nerve time to recover from irritation and pressure.
Doctors commonly have patients with radial tunnel syndrome work with a physical or occupational therapist. At first, the therapist will give tips on how to rest the elbow and do activities without extra strain. Your therapist may apply ice and electrical stimulation to ease pain. Exercises are used to gradually stretch and strengthen the forearm and muscles.
When conservative treatments have not worked, surgery may be the best treatment option.
The goal of surgery for radial tunnel syndrome is to relieve any abnormal pressure on the nerve where it passes through the radial tunnel. The surgeon begins by making an incision along the outside of the elbow and down the forearm, near the spot where the radial nerve goes under the supinator muscle.
Soft tissues are gently moved aside so the surgeon can check where the radial nerve is being squeezed within the radial tunnel. The nerve can be pinched in many spots, so it is important to check all areas potentially causing problems.
Any parts of the tunnel pinching the nerve are cut, expanding the tunnel and relieving pressure on the nerve. At the end of the procedure, the skin is stitched together.
Radial tunnel surgery can usually be done as an outpatient. Surgery can be done using a general anesthetic, which puts you to sleep, or a regional anesthetic. A regional anesthetic blocks nerves in only one part of your body.
If conservative treatment is successful, you may see improvement in four to six weeks. You may continue wearing your wrist strap during the day and the elbow pad or splint at night to control symptoms. Try doing activities using healthy body and wrist alignment. Limit activities requiring repeated hand and forearm motions, heavy grasping, and twisting motions of the arm and hand.
If you have surgery for radial tunnel syndrome, your elbow will be placed in a removable splint and wrapped in a bulky dressing following surgery. You will probably need to attend occupational or physical therapy sessions for six to eight weeks, and should expect full recovery to take three to four months depending on your specific medical condition.
You’ll begin active forearm range-of-motion exercises one week after surgery. Ice packs, soft-tissue massage, and hands-on stretching may also be used to improve range of motion.
When the stitches are removed, you may start carefully strengthening the hand and forearm by squeezing and stretching special putty. Therapists also use isometric exercises to improve forearm and hand strength without straining the tissues near the radial tunnel.
As you progress, the therapist will give you exercises to help strengthen and stabilize the muscles and joints in the wrist, elbow, and shoulder. Other exercises are used to improve fine motor control and dexterity of the hand.
Some of the exercises are designed to get your elbow working in ways similar to your work tasks and sport activities. The therapist will help find ways to do your tasks that don’t put too much stress on your elbow. Before your therapy sessions end, you will learn a number of ways to try to avoid future problems.