Posterior Interosseous Nerve Syndrome

Original Editor - Your name will be added here if you created the original content for this page.

Lead Editors - Your name will be added here if you are a lead editor on this page.  Read more.

Clinically Relevant Anatomy

add text here relating to clinically relevant anatomy of the condition

The posterior interosseus nerve is a continuation of the radial nerve as it passes down the posterior side of the forearm. The radial nerve wraps around the posterior aspect of the arm to the anterior side of the lateral epicondyle of the humerus. As it passes below the lateral epicondyle the radial nerve splits into the superficial and deep radial nerves. The continuation of the deep radial nerve passes through the supinator muscle to become the posterior interosseus nerve. The posterior interosseus nerve can become entrapped with this course through the supinator muscle in the arcade or canal of Froshe in approximately 30% of the population. The role of the posterior interosseus nerve is motor only to the wrist and finger extensors as well as all of the supinator.

Mechanism of Injury / Pathological Process

add text here relating to the mechanism of injury and/or pathology of the condition

Compression of the posterior interosseus nerve may arise from activities that promote repetitive gripping activities that are combined with supinatory movements. This diagnosis may be associated with lateral epicondylitis.

Clinical Presentation

add text here relating to the clinical presentation of the condition

A patient who presents with this diagnosis of posterior interosseus syndrome may have a history of vague proximal posterior forearm pain with no weakness in more mild cases. In more severe cases, the patient may present with weakness in the wrist and finger extensors. Because the extensor carpi radialis longus and brevis are innervated before the radial nerve passes into the supinator, there is usually some sparring of wrist extension. Also because of lack of extensor carpi ulnaris, there may some radial deviation of the wrist with extension with the remaining innervated ECRL and ECRB. There will be no sensory loss as this nerve carries motor fibers only. In mild cases posterior interosseus syndrome may be difficult to delineate from lateral epicondylitis and may be considered only after a failed resolution of lateral epicondylitis. There will be no vhanges with electro diagnostic studies with lateral epicondylitis.

Diagnostic Procedures

add text here relating to diagnostic tests for the condition

Diagnosis of posterior interosseus syndrome can be identified with EMG studies of the nerve. Differentiation of the lateral aspect of the nerve can be made with delays with the lateral aspect innervated musculature with involvement of the abductor pollicis longer, extensor pollicis longus, extensor pollicis brevis, and extensor indicis. The medial aspect of the nerve will have involvement of all the other extensors. Differentiation of posterior interosseus syndrome from lateral epicondylitis may be achieved with lidocaine injection at the lateral epicondyle. This should relieve lateral epicondyle pain however it will not change compression pain distally at the supinator.

Outcome Measures

add links to outcome measures here (see <a href="Outcome Measures">Outcome Measures Database</a>)

Management / Interventions

add text here relating to management approaches to the condition

Differential Diagnosis

add text here relating to the differential diagnosis of this condition

Key Evidence

add text here relating to key evidence with regards to any of the above headings

Resources

add appropriate resources here

Case Studies

add links to case studies here (case studies should be added on new pages using the case study template)

References

References will automatically be added here, see adding references tutorial.

.