Ultrasonographic appearance of idiopathic radial nerve constriction proximal to the elbow.

ltrasonography not only permits a detailed assessment of peripheral nerves but also is useful for intrinsic nerve abnormality detection, as in peripheral nerve enlargement (eg, in trauma, peripheral nerve sheath tumors, and nerve compression). Ultrasonography can also be used to locate nerve compression due to an extrinsic factor (eg, compression of the posterior interosseous nerve by the arcade of Frohse, ganglionic cysts, vessels, rheumatoid nodules, lipoma, or hemangioma). We report a case of a closed radial nerve injury at the distal part of the humerus in which ultrasonography was instrumental in revealing a severe injury without a definite cause. Ultrasonography also allows specification of the nature of a radial nerve impediment and identification of its exact location. These elements were very useful in deciding on surgical treatment. We compare this recently observed radial nerve palsy with other intermediate injuries of the radial nerve previously described in the literature. Finally, we emphasize the role of ultrasonography in the treatment of radial nerve palsies.