Magnetic resonance microscopy imaging of posterior interosseous nerve palsy.

Posterior interosseous nerve palsy, also called deep radial nerve syndrome, is a neuropathy caused by radial nerve entrapment or compression at the level of the supinator muscle. Although imaging studies are not necessary for diagnosing this syndrome because of its characteristic clinical manifestations, the causes of palsy, which include mass lesions, or precise anatomical findings can sometimes be demonstrated by imaging. Magnetic resonance (MR) findings of posterior interosseous nerve palsy have been described as involving atrophy of related muscles caused by denervation, a common secondary change of this nerve disorder. We present a case in which the swollen posterior interosseous nerve itself could be directly depicted by MR imaging using a 4.7-cm microscopy coil in a patient with neuropathy.