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Radial Tunnel Syndrome

 

synonyms:

Radial Tunnel Syndrome ICD-9

Radial Tunnel Syndrome Etiology / Epidemiology / Natural History

  • etiology=fibrous bands, recurrent radial vessels, ECRB, Archade of Frohse, distal suppinator

Radial Tunnel Syndrome Anatomy

  • Radial nerve Origin: fibers from the sixth, seventh, and eighth roots of the brachial plexus.  Posterior divisions of the upper, middle, and lower trunks–posterior cord–radial nerve 
  • Radial nerve Course: passes anterior to the subscapularis, teres major, and latissimus dorsi muscles.  Passing through the triangular space and then through the lateral head of the triceps.  Courses distally along the humerus and passes from the posterior to the anterior compartment of the arm. Travels along the deep surface of the brachioradialis and the extensor carpi radialis longus muscles, the radial nerve bifurcates into a superficial branch and deep branch.  
  • Superficial branch of the radial nerve:  contains sensory fibers.  Travels beneath the brachioradialis into the forearm, passing between the brachioradialis and the flexor carpi radialis in the distal third of the forearm to lie superficial and subcutaneous.
  • Posterior Interosseous Nerve (deep branch of radial nerve): passes through the radial tunnel to the supinator muscle.  Divides into the superficial branch of the PIN (innervates:extensor digitorum, extensor digiti minimi, extensor carpi ulnaris) and the deep branch of the PIN (innervates: abductor pollicis longus, the extensor pollicis brevis, extensor indicis proprius, extensor pollicis longus).
  • Radial tunnel:  the anatomic structures between the radiohumeral joint and the distal extent of the supinator muscle.
  • Sites of Radial nerve compression: accessory subscapularis-teres-latissimus, penetration of the nerve directly by the subscapular artery, at the lateral head of the triceps, genetic defect in Schwann cell myelin metabolism, lateral intermuscular septum, radial tunnel.
  • Radial tunnel syndrome sites of compression: fibrous margin of the extensor carpi radialis brevis muscle, fibrous bands at the level of the radiocapitellar joint, the radial recurrent artery, the arcade of Frohse proximally. 

Radial Tunnel Syndrome Clinical Evaluation

  • vague arm pain, no PIN dysfunction
  • Localized pain without objective findings. 
  • Point of maximal tenderness is present at the site of compression, usually located over the anterior radial neck
  • Pain may be increased by compression of the “mobile wad” and/or resistance to active extension of the middle finger and/or Active wrist extension and forearm supination against resistance
  • Symptoms may be worse with the elbow extended, the forearm pronated, and the wrist flexed.
  • Radial Tunnel Syndrome Xray / Diagnositc Tests
  • Forearm xray generally normal
  • EMG is negative in most cases of radial tunnel syndrome, but positive in posterior interosseous nerve syndrome.

Radial Tunnel Syndrome Classification / Treatment

  • Nonoperative (6-12 months):  activity modification to avoid provocative positions,  rest, stretching exercise, and splinting.  Second line treatment: corticosteroid injection placed adjacent to, but not within, the nerve.  
  • Surgical: decompression of the radial nerve generally through an extensile incision from the lateral epicondyle to the supinator muscle. Identify all potential sites of compression and release the entire supinator, including its distal edge.
  • surgery=50-80% improvement.

Radial Tunnel Syndrome Associated Injuries / Differential Diagnosis

Radial Tunnel Syndrome Complications

Radial Tunnel Syndrome Follow-up Care

  • Postoperative management: long-arm posterior splint with the wrist in neutral position.  Begin gradual range-of-motion exercise and extensor muscle stretching program at 1-2 weeks.  Return to unlimited activities at  6 to 12 weeks. 

Radial Tunnel Syndrome Review References

  • Lubahn JD, JAAOS 1998;6:378

 

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