Pronator syndrome

This is an uncommon entrapment neuropathy of the median nerve occurring in the elbow region. Entrapment can occur typically at four sites. 1. The first occurs at the site of the ligament of Struthers. This ligament represents an anatomical variant and when present connects a small supracondyloid spur of bone to an accessory origin of pronator teres. The median nerve can be compressed as it passes under this ligament. 2. The nerve may also be trapped as it passes deep to the bicipital aponeurosis; 3. the aponeurotic edge of the deep head of pronator teres muscle; 4. or the tendinous aponeurotic arch forming the proximal free edge of the radial attachment of flexor digitorum superficialis.

The syndrome presents with pain on the volar aspect of the distal arm and proximal forearm. The symptoms may be aggravated by flexing the elbow against resistance, pronating the forearm against resistance, or flexion of superficialis to the middle finger against resistance, depending on the precise cause of the entrapment. If the anterior interosseous nerve is also compressed there is weakness of all the muscles innervated by the median nerve, including abductor pollicis brevis and the long finger flexors, and sensory impairment on the palm of the hand.

The treatment is exploration of the nerve and surgical decompression.