The radial tunnel is the space containing the radial nerve as it courses from the humeroradial joint, proximal to the insertion of the supinator muscle, to the distal border of the supinator, just below the elbow. This space also comprises the two main radial nerve branches, the posterior interosseous nerve and superficial radial nerve.
Symptoms arise from compression of the radial nerve branches by the supinator muscle. This may be caused by repeated forceful supination or pronation, or by inflammation of supinator muscle attachments (as in tennis elbow).
Radial Tunnel Syndrome specifically refers to compression of the posterior interosseous nerve at the lateral intermuscular septum of arm, while Supinator Syndrome refers to compression of the posterior interosseous nerve at the arcade of Frohse, although these terms are used interchangeably.
Patients usually present complaining of pain in the dorsal aspect of the upper forearm. Diagnosis can be made with a positive “middle finger test,” in which resisted middle finger extension produces pain. First-line treatment is conservative management, including rest, work modification, NSAIDs for pain control, and physical therapy. Surgical intervention is rarely required, although nerve decompression may be necessary in some cases.
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- Tubbs RS, Mortazavi M, Farrington WJ, Chern JJ, Shoja MM, Loukas M, Cohen-Gadol AA. Relationships between the posterior interosseous nerve and the supinator muscle: application to peripheral nerve compression syndromes and nerve transfer procedures. J NeurolSurg A Cent EurNeurosurg.2013; 74(5): 290-3.