Merck Manual

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Radial Tunnel Syndrome

(Posterior Interosseous Nerve Syndrome)


David R. Steinberg

, MD, Perelman School of Medicine at the University of Pennsylvania

Reviewed/Revised Apr 2022 | Modified Sep 2022

Radial tunnel syndrome is compression of the radial nerve in the proximal forearm. Symptoms include forearm and elbow pain. Diagnosis is clinical. Treatments include splinting and sometimes surgical decompression.

Symptoms and Signs of Radial Tunnel Syndrome

Symptoms of radial tunnel syndrome include lancinating pain in the dorsum of the forearm and lateral elbow. Pain is precipitated by attempted extension of the wrist and fingers and forearm supination. Sensory loss is rare because the radial nerve is principally a motor nerve at this level. This disorder is sometimes confused with backhand tennis elbow (lateral epicondylitis Lateral Epicondylitis Lateral epicondylitis results from inflammation and microtearing of fibers in the extensor tendons of the forearm. Symptoms include pain at the lateral epicondyle of the elbow, which can radiate... read more ). When weakness of the extensor muscles is the primary finding, the condition is referred to as posterior interosseus nerve palsy.

Diagnosis of Radial Tunnel Syndrome

  • Clinical evaluation

Lateral epicondylitis can cause similar tenderness around the lateral epicondyle but does not cause the Tinel sign (paresthesia elicited by percussion over a nerve) or tenderness along the course of the radial nerve (which travels under the mobile wad group of muscles in the proximal radial forearm).

Treatment of Radial Tunnel Syndrome

  • Splinting

Splinting allows avoidance of the forceful or repeated motion of supination or wrist dorsiflexion, reducing pressure on the nerve.

If wristdrop or weakened digital extension develops, or conservative treatment fails to provide relief after 3 months, surgical decompression may be needed.

NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
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