MRI diagnosis of occult ganglion compression of the posterior interosseous nerve and associated supinator muscle pathology

Posterior interosseous nerve entrapments: review of the literature. Is the entrapment distal to the arcade of Frohse a really rare condition?

INTRODUCTION

Spontaneous posterior interosseous nerve palsy is a rare condition. Entrapment is mostly at level of the arcade of Frohse, and a few cases of distal entrapment have been described.

METHODS

A case of entrapment distal to the arcade of Frohse is described here. Cases of distal entrapment have been reviewed from the published literature in order to evaluate the frequency of atraumatic mechanical palsy.

RESULTS

Seven cases of distal entrapment have been identified. Lesion is the cause of palsy in 58.7% of the cases and entrapment in 20.65%. The pathology is at the elbow in 33.7% of the cases, at the arcade of Frohse in 28.26%, and at the supinator canal in 10.33%. Entrapment is at the arcade of Frohse in 64.45%, proximal in 20%, and distal in 15.55%.

CONCLUSION

Posterior interosseous nerve distal entrapment is a rare condition; therefore, further investigation is needed when radiological images at the arcade of Frohse do not show any entrapment.

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.