Radial Tunnel Syndrome
An aching pain in the muscles of the outer aspect of the forearm part of the elbow is the main feature of this condition. It tends to remain constant, with increased pain in response to sustained forceful twisting to the elbow, or repeated twisting movements. Some therapy treatments can make it feel a bit better for a while, but it usually returns again after exercise challenge. It has many features in common with tennis elbow: but that condition tends to settle with time and therapy treatment.
A deep branch of the radial nerve, that carries messages to the muscles that straighten the wrist and fingers, travels deeply under those muscle bellies, and between two parts of one muscle: the ‘supinator’. A soft tissue injury to that muscle can cause swelling, or increased fibrous scarring that then presses on the nerve and squashes it. That produces a deep ache, which is felt somewhere in the outer elbow region (poorly localised).
This can be difficult. A lot of doctors are familiar with tennis elbow: not many know of the subtle difference with this condition. Many hand therapists are very familiar with this condition.
Ultrasound can be helpful in diagnosis: but again the changes are subtle and need an experienced radiologist to pick. Nerve conduction studies can be helpful: but do not always help and do need to record muscle activity which requires small needles to be placed.
A combination of tests and a careful examination with a surgeon or physician familiar with the condition remains the best method of diagnosis.
The pressure on the nerve (posterior interosseous nerve) needs to be relieved. Careful surgical exposure of the nerve throughout its passage under the covering muscle is needed: release of all tight compressing tissues must be performed. I then irrigate with a scar inhibiting steroid solution to soften the scar that forms after the surgery.
Therapy to assist scar softening and recover full elbow and wrist motion then follows over the next 6 weeks.
Full function is expected at 8 weeks after surgery, depending on your scar response.
- Philip A. Griffin, FRACS