Radial tunnel syndrome is a compressive neuropathy where there is pressure on the radial nerve near the elbow. There is resulting weakness of the forearm muscles and possible numbness and tingling in the hand. Treatment is aimed at relieving the compressive forces on the nerve.
Supinator
The supinator is a muscle in the forearm that allows the forearm to perform the action of supination. Supination refers to rotating the forearm so that the palm of the hand faces up. The supinator is not the only muscle involved in supination---the biceps can supinate the forearm when the elbow is bent.
Radial Nerve
The radial nerve is an important nerve for the upper extremity for both function and sensation. In the forearm, it supplies muscles that can move the elbow, wrist and fingers.
Radial Nerve and Supinator
The radial nerve splits into different branches in order for it to supply many different structures. One of the branches is known as the deep branch of the radial nerve, which pierces the supinator muscle. Some refer to this nerve as the posterior interosseous nerve, or PIN. The tightness of the proximity of the structures at this anatomic location near the elbow allow for compression on the nerves at a variety of locations. Due to the location on the lateral elbow, the syndrome is often confused with lateral epicondylitis or tennis elbow and also posterior interosseous nerve compression syndrome.
Radial Tunnel Syndrome
Radial tunnel syndrome is a form of compressive neuropathy. The muscles and other structures surrounding the radial nerve at the level of the elbow put pressure on the nerve, altering its function. The most common site of compression leading to radial tunnel syndrome is at the supinator muscle, according to Wheeless' Textbook of Orthopaedics. Other possible locations of nerve compression leading to radial tunnel syndrome are from the fibrous bands at the start of the radial tunnel, from the blood vessels or from the extensor carpi radialis brevis muscle tendon origin.
Radial Tunnel Syndrome Symptoms
When the radial nerve is compressed in radial tunnel syndrome, patients will have a deep aching pain in the forearm that radiates from the outside/lateral elbow to the top/dorsum of the wrist. There may be tenderness directly over a spot on the elbow near the supinator muscle, which would be around the lateral elbow. Numbness and tingling may occur on the top of the hand. There is generally pain with any resistance to supination and wrist extension. Pain can also be present with pronation, or palms up, and wrist flexion.
Diagnosis
A physician may order X-rays, MRIs or nerve studies to help find the source of the pain. The clinical presentation of radial tunnel compression syndrome is often misdiagnosed as resistant tennis elbow, lateral epicondylitis or posterior interosseous nerve syndrome. It can be very difficult to differentiate among the three conditions due to similar symptoms.
Treatment
Treatment for radial tunnel compression syndrome is aimed at relieving the compression forces on the nerve. An initial trial with nonoperative methods such as splinting and physical therapy can be tried. If splinting and physical therapy fail, the radial nerve can be surgically decompressed. According to the AAOS Comprehensive Orthopaedic Review, treatment for posterior interosseous nerve compression and radial tunnel syndrome involves the same surgical decompression techniques. During the operation, lateral epicondylitis/tennis elbow can also be treated surgically.
References
- Wheeless' Textbook of Orthopaedics: Radial Nerve
- "AAOS Comprehensive Orthopaedic Review"; Dr. Jay Lieberman (Editor); 2008
- "Current Diagnosis and Treatment: Orthopaedics"; Dr. Harry Skinner (Editor); 2006
