Median nerve - pronator teres syndrome

Causes

• Thickened lacertus fibrosus (fibrous aponeurosis over the median nerve proximal to its passage between pronator teres heads).
• Pronator teres hypertrophy.
• Entrapment by tight fibrous band of flexor digitorum superficialis.

Symptoms & signs

• Similar symptoms to carpal tunnel syndrome but nocturnal exacerbation is not seen.
• Flexion impairment of first three digits results in hand of benediction.
• Weakness in hand grip.
• Sensory deficit and paresthesias in median nerve distribution.
• Tenderness over pronator teres.
• Occasionally pronator teres, flexor carpi radialis, palmaris longus and flexor digitorum muscles are spared because they are innervated by branches that branch off more proximally than the compression site.
• Muscles innervated by anterior interosseous nerve are spared.
• Thenar atrophy may exist.
• Tinnel sign may be seen.