Radial tunnel syndrome

Radial tunnel syndrome is an entrapment neuropathy of the radial nerve as it passes through the radial tunnel, from the level of the head of the radius to the distal edge of the supinator muscle. There are four potential sites of compression within the radial tunnel. The first is by fibrous bands lying anterior to the radial head at the entrance to the tunnel. The second site occurs at the radial recurrent vessels, lying across the radial nerve. The third potential site of compression occurs at the tendinous margin of the extensor carpi radialis brevis muscle. The fourth, and most common site, is at the arcade of Fröhse. Recently a fifth site has been identified: a fascial arcade is often present lining the deep surface of the superficial head of the supinator muscle and this band can exert pressure on the posterior interosseous branch of the radial nerve just before it emerges from beneath that muscle. The diagnosis is confirmed by diagnostic nerve block and surgical decompression is an effective form of treatment.