Radial tunnel syndrome

Last revised by Yuranga Weerakkody on 13 Dec 2022

Radial tunnel syndrome is an entity that refers to entrapment (tunnel syndrome) of the radial nerve in the forearm, as it occurs in the supinator syndrome. Some authors believe this is an early form of the posterior interosseous nerve syndrome 5.

There may be a female predilection and most commonly occurring in those around 30-50 years of age 6.

The syndrome is characterized by pain along the radial aspect of the proximal forearm and, despite it being compression of a motor nerve, it is characterized by the absence of neurologic deficits. Pain on resisted supination of the forearm and pain on resisted middle finger extension is common 2. Pain may radiate up to the shoulder and neck and is aggravated by the use of the hand 1.

Electromyographic findings that might suggest or confirm the diagnosis are typically absent.

It is a result of compression of the posterior interosseous nerve (deep motor branch of the radial nerve) as it passes through the lateral muscular septum 1.

Evidence of muscle denervation (edema or atrophy) along the posterior interosseous nerve distribution is the most common finding on MRI 4.  This is typically seen within the supinator muscle, followed by the proximal forearm extensor muscles. 

MRI may also identify alternative conditions that may explain the patient's symptoms, such as lateral epicondylitis, or may identify compressive lesions that may be amenable to surgical resection or decompression 2

Treatment is usually conservative. Some authors suggest surgical decompression to avoid permanent nerve damage.

Clinically, the radial tunnel syndrome can occasionally be confused with tennis elbow (lateral epicondylitis).

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