Also known as Resistant Tennis Elbow, Radial Tunnel Syndrome is considered an overstress or repetitive stress condition caused when the nerve instrumental in the function of several muscles around the wrist and hand (a branch of the radial nerve) is compressed, or pinched at the forearm or the elbow. This results in weakness of the affected muscles and pain over the compressed area.
Compression can take the form of an injury, ganglia, lipomas, bone tumors and inflammation of the surrounding bursa or muscles. Patients suffering from the condition report a piercing pain at the top of the forearm and back of the hand when straightening the wrist and fingers.
Since the radial nerve primarily connects to muscle, there is no loss of sensation. The radial nerve begins at the side of the neck, where individual nerve roots leave the spine. The nerve roots exit through small openings (called foramen) between the vertebrae. The nerve roots join to form the three main nerves responsible for arm and hand function (radial, ulnar and median) – and travel down the arm to the hand. The radial nerve passes down the back of the upper arm, around the outside of the lateral portion of the elbow and down the forearm and hand.
Through the radial tunnel, the radial nerve passes below the supinator muscle, which allows clockwise twisting of the hand. It then fans out and attaches to the muscles on the back of the forearm.
Though the symptoms of radial tunnel syndrome are similar to those of tennis elbow, the cause is not. It is most similar to the nerve compression experienced in carpal tunnel syndrome – though a different nerve is compressed.
Those at Risk
It is believed that radial tunnel syndrome is caused by repetitive stress. Those involved in repetitive, forceful pushing and pulling, gripping, bending, or twisting of the arm, are at risk of stretching and irritating the nerve. Though, sometimes a direct blow to the outside of the elbow can also injure the radial nerve.
Diagnosis of radial tunnel syndrome can be difficult, as few tests have been effective in identifying it. Following a complete patient history and physical examination that may involve an assessment of pain in various arm positions, an electromyogram (EMG) may be indicated. An EMG will test to verify that muscles of the forearm are working properly or not. Improper functioning of the muscle is generally caused by the improper function of the supervising nerve.
A nerve conduction velocity (NCV) test may also be used, in order to measure the speed of an electrical impulse as it travels along the radial nerve. A slow speed indicates a compressed, or pinched nerve.
The first phase of treatment for radial tunnel syndrome is conservative and includes refraining from the activity responsible for the condition, as well as those irritating the condition. A lightweight plastic removable arm splint may be indicated at night if pain worsens during sleep. A patient-specific physical or occupational therapy is established in order to increase the success of the other conservative treatment plans.
When the condition is non responsive to conservative treatment and symptoms persist, an outpatient procedure that helps to decompress the nerve may be indicated.
And following all treatment options is a rehabilitation program that demonstrates correct alignment and positions during activity. It also includes active forearm range of motion and stretching exercises – possibly combined with a soft-tissue massage. Isometric exercises following a surgical procedure helps to improve forearm hand strength while placing minimal stress on the tissues near the radial tunnel.