Radial tunnel syndrome
Radial tunnel syndrome (RTS) is caused by increased pressure on the radial nerve as it travels from the upper arm (the brachial plexus) to the hand and wrist.

Symptoms and signs
Radial tunnel syndrome causes posterolateral elbow pain that is similar to tennis elbow and may sometimes occur in conjunction with that condition. Patients may typically have weakness of extension at the wrist and third digit. The pain is often reproduced upon resisted supination of the forearm, and pain at the radial tunnel on resisted hyperextension of the wrist.

Cause
The theory is that the radial nerve becomes irritated and/or inflamed from friction caused by compression by muscles in the forearm.Some speculate that radial tunnel syndrome is a type of repetitive strain injury (RSI), but there is no detectable pathophysiology and even the existence of this disorder is questioned.The term "radial tunnel syndrome" is used for compression of the posterior interosseous nerve, a division of the radial nerve, at the lateral intermuscular septum of arm, while "supinator syndrome" is used for compression at the arcade of Frohse.The "radial tunnel" is the region from the humeroradial joint past the proximal origin of the supinator muscle. Some scientists believe the radial tunnel extends as far as the distal border of the supinator. The radial nerve is commonly compressed within a 5 cm region near the elbow, but it can be compressed anywhere along the forearm if the syndrome is caused by injury (e.g. a fracture that puts pressure on the radial nerve). The radial nerve provides sensation to the skin of posterior arm, posterior and lateral forearm and wrist, and the joints of the elbow, wrist and hand. The nerve also provides sensory branches that travel to the periosteum of the lateral epicondyle, the anterior radiohumeral joint, and the annular ligament. It provides motor function through innervation to most extensor muscles of the posterior arm and forearm. Therefore, it is extremely important in upper body extremity movement and can cause significant pain to patients presenting with radial tunnel syndrome. Unlike carpal tunnel syndrome, radial tunnel syndrome does not present tingling or numbness, since the posterior interosseous nerve mainly affects motor function.This problem is often caused by: bone tumors, injury (specifically fractures of the forearm), noncancerous fatty tumors (lipomas), and inflammation of surrounding tissue.

Diagnosis
The diagnosis is based on symptoms and signs alone and objective testing is expected to be normal. This syndrome may be clinically tested by flexing the patients long finger while the patient extends the wrist and fingers. Pain is a positive finding.
The chief complaint of this disease is usually pain in the dorsal aspect of the upper forearm, and any weakness described is secondary to the pain. Tenderness to palpation occurs over the area of the radial neck. Also, the disease can be diagnosed by a positive "middle finger test", where resisted middle finger extension produces pain. Radiographic evaluation of the elbow should be performed to rule out other diagnoses.

Treatment
Non-surgical treatment of radial tunnel syndrome includes rest, NSAID, therapy with modalities, work modification, ergonomic modification, injection if associated with lateral epicondylitis.Patients whose conditions are more adapted to surgical intervention are those who do not respond to prolonged conservative treatment. The patient must have pain with resisted supination, positive middle finger test, positive electrodiagnostic findings, and pain relief after anesthetic injection into the radial tunnel. Based on 2002 data, surgical decompression leads to 60–70% good or excellent results.

See also
Golfers elbow
Repetitive strain injury
Tennis elbow

References
Further reading
Books
Rind, Libi; Pobre, Thomas; Weiss, Frederick; Magyar, Yasha; Ruotolo, Charles; Aldad, Tamir; Mahboubian, Shahab; Knijnikov, Alexander; Asheld, Wilbur J. (2010). "Radial tunnel syndrome and supinator syndrome".  In Weiss, Lyn D.; Weiss, Jay M.; Pobre, Thomas (eds.). Oxford American Handbook of Physical Medicine & Rehabilitation. Oxford University Press. pp. 96–7. ISBN 978-0-19-536777-5.
Wertsch, Jacqueline J.; Hoch, Anne Zeni (2009). "Radial Tunnel Syndrome".  In Akuthota, Venu; Herring, Stanley A. (eds.). Nerve and Vascular Injuries in Sports Medicine. Berlin: Springer. pp. 79–80. ISBN 978-0-387-76599-0.
Russell, Stephen M. (2006). "Radial Tunnel Syndrome". Examination of peripheral nerve injuries: an anatomical approach. Stuttgart: Thieme. p. 62. ISBN 978-3-13-143071-7.
Saladin, Kenneth S. (2012). Anatomy & Physiology: The Unity of Form and Function. McGraw Hill. p. 496. ISBN 978-0-07-337825-1.

Journals
Dickerman, Rob D.; Stevens, Qualls E. J.; Cohen, Anders J.; Jaikumar, S. (2002). "Radial tunnel syndrome in an elite power athlete: a case of direct compressive neuropathy". Journal of the Peripheral Nervous System. 7 (4): 229–32. doi:10.1046/j.1529-8027.2002.02030.x. PMID 12477169.
Huisstede, Bionka; Miedema, Harald S.; van Opstal, Twan; de Ronde, Manon T.; Verhaar, Jan A.; Koes, Bart W. (2008). "Interventions for Treating the Radial Tunnel Syndrome: A Systematic Review of Observational Studies". The Journal of Hand Surgery. 33 (1): 72–8. doi:10.1016/j.jhsa.2007.10.001. PMID 18261668.
Henry, Mark; Stutz, Christopher (2006). "A Unified Approach to Radial Tunnel Syndrome and Lateral Tendinosis". Techniques in Hand and Upper Extremity Surgery. 10 (4): 200–5. doi:10.1097/01.bth.0000231580.32406.71. PMID 17159475. S2CID 9709553.
Cleary, C (2006). "Management of Radial Tunnel Syndrome: A Therapists Clinical Perspective". Journal of Hand Therapy. 19 (2): 186–91. doi:10.1197/j.jht.2006.02.020. PMID 16713866.
Sarris, Ioannis K.; Papadimitriou, Nikolaos G.; Sotereanos, Dean G. (2002). "Radial Tunnel Syndrome". Techniques in Hand and Upper Extremity Surgery. 6 (4): 209–12. doi:10.1097/00130911-200212000-00010. PMID 16520604.
Smola, C. (2004). "Zur Problematik des algetischen Supinatorsyndroms oder Wo hört der Tennisarm auf und wo fängt das Supinatorsyndrom an?" [About the problem of radial tunnel syndrome or where does the tennis elbow end and where does the radial tunnel syndrome begin?]. Handchirurgie, Mikrochirurgie, Plastische Chirurgie (in German). 36 (4): 241–5. doi:10.1055/s-2004-817947. PMID 15368151.
Loh, YC; Lam, WL; Stanley, JK; Soames, RW (2004). "A new clinical test for radial tunnel syndrome—the Rule-of-Nine test: A cadaveric study" (PDF). Journal of Orthopaedic Surgery. 12 (1): 83–6. doi:10.1177/230949900401200115. PMID 15237127. S2CID 14049155.
Rosenbaum, Richard (1999). "Disputed radial tunnel syndrome". Muscle & Nerve. 22 (7): 960–7. doi:10.1002/(SICI)1097-4598(199907)22:7<960::AID-MUS26>3.0.CO;2-C. PMID 10398221.
Portilla Molina, A. E.; Bour, C.; Oberlin, C.; Nzeusseu, A.; Vanwijck, R. (1998). "The posterior interosseous nerve and the radial tunnel syndrome: an anatomical study". International Orthopaedics. 22 (2): 102–6. doi:10.1007/s002640050218. PMC 3619716. PMID 9651775.
Jebson, Peter J. L.; Engber, William D. (1997). "Radial tunnel syndrome: Long-term results of surgical decompression". The Journal of Hand Surgery. 22 (5): 889–96. doi:10.1016/S0363-5023(97)80086-X. PMID 9330150.
Sarris, Ioannis K.; Papadimitriou, Nikolaos G.; Sotereanos, Dean G. (2002). "Radial Tunnel Syndrome". Techniques in Hand and Upper Extremity Surgery. 6 (4): 209–212. doi:10.1097/00130911-200212000-00010. PMID 16520604.


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