Review Question - QID 407

The patient has radial tunnel syndrome, which often presents with insidious onset of pain and tenderness several centimeters distal to the lateral epicondyle, and pain elicited with active extension of the long finger against resistance can help differentiate the condition from lateral epicondylitis.

Radial tunnel syndrome is a compressive neuropathy that can occur between the mobile wad laterally and the biceps aponeurosis and brachialis insertion medially as the nerve courses over the radiocapitellar joint into the forearm. Patients usually have diffuse pain over the site of the radial tunnel, sometimes have radiating pain in the distribution of the superficial radial nerve, and occasionally have subtle weakness or fatigue of the wrist and extrinsic finger extensors. Initial treatment should include conservative measures such as stretching, activity modification, and NSAIDS; Injections can be performed for both diagnostic and therapeutic reasons. Surgical intervention is indicated if pain persists despite exhausting conservative measures. The most common anatomic causes of radial tunnel syndrome are fibrous adhesions between the brachialis and brachioradialis, the Leash of Henry (radial recurrent vessels), the fibrous edge of the ECRB, the arcade of Fröhse (supinator arch), and fibrous bands of the leading edge of the supinator muscle.

Dang et al. discuss compression neuropathies of the upper extremity in their 2009 review article. They highlight the importance of the clinical exam in diagnosing radial tunnel syndrome, especially the location of pain, which is distal to that of lateral epicondylitis. Additionally ruling out other less common diagnoses on the differential can be assisted by EMG (radiculopathy or plexopathies), MRI (tumor or other causes of mass effect), and diagnostic injections.

Illustration A shows the anatomy of the five common sites of compressing in the radial tunnel.

Incorrect Answers:

1. Radiocapitellar arthritis would not be antagonized by stretch of the common extensors of the wrist
3. Carpal tunnel syndrome is diagnosed by evidence of nerve compression of the median nerve at the wrist and should not be associated with pain near the origin of the wrist extensors
4. Lateral epicondylitis can very much mimic radial tunnel syndrome; however, the location of the pain and tenderness on exam can be a very helpful
5. Intersection syndrome is a chronic tenosynovitis of the ECRL and ECRB characterized by pain at the intersection of the 1st and 2nd dorsal compartments of the wrist