Radial tunnel syndrome (RTS) is the name given to a condition when the radial nerve is compressed in the proximal forearm, usually by muscle or ligament. It is sometimes called supinator syndrome.  If you have RTS, you are likely to experience pain in the proximal radial forearm, particularly in the muscles which supinate the forearm (rotate so the palm faces up) and extend the wrist and fingers. It is often aggravated with use of the hand and arm. Heavy gripping, working with the elbow extended, repetitive or prolonged positions of supination or pronation (palm facing down) often provoke symptoms. What about pain caused from RTS?

Pain across the back of the wrist or hand may also occur, due to a small sensory branch of the radial nerve which terminates over the wrist. Some people find they experience symptoms at night time and it is not uncommon to be woken up by symptoms.  In radial tunnel syndrome, the nerve is compressed which causes irritation. There are varying causes of compression, though the most common are slight changes or abnormalities in the surrounding tissues. A little anatomy....

The Arcade of Frohse is a fibrous band originating on the proximal edge of the supinator muscle, and it is a common culprit; the distal edge of the supinator muscle may also have fibrous bands which compress the nerve. The supinator muscle has two separate ‘heads’ which attach at the proximal end; the nerve passes between these two layers and muscle tightness can cause compression at this site. Fibrous bands from the radiocapitellar capsule or from the deep surface of the ECRB muscle may also cause compression. Less common causes may include abnormal ligaments, lesions, fracture or dislocation around the elbow, or tight muscles. In some instances, repetitive postures demanded by your occupation may contribute to the nerve’s compression and subsequent irritation.

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(Images courtesy of summitortho.net)

There are many other conditions in the upper limb which can produce pain around the proximal forearm or elbow. Lateral epicondylitis (often called tennis elbow) is a common condition which shares some of the same symptoms. To further complicate the matter, lateral epicondylitis can often occur in the presence of RTS. PIN (Posterior Interosseous Nerve) syndrome is another syndrome which involves compression of the deep branch of the radial nerve through the radial tunnel. PIN syndrome is associated with motor weakness of the wrist extensors, whereas RTS does not present with weakness.

The subtle differences that distinguish RTS require an experienced assessor to detect them. Fortunately, you’re in good hands with us here at Riverina Hand Therapy.