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Bones & Joints
Pronator syndrome is compression of the median nerve in the upper forearm near the elbow, causing forearm pain, thumb/index/middle finger numbness, and hand weakness that mimics carpal tunnel syndrome but with key differences—pain worsens with repetitive gripping and forearm pronation (rotating palm down), and symptoms extend to the forearm and palm unlike carpal tunnel which spares the palm and causes nocturnal symptoms. The median nerve can be compressed at four potential sites in the proximal forearm: ligament of Struthers (uncommon bony abnormality 1cm above elbow), lacertus fibrosus (fascial band from biceps tendon), between the two heads of pronator teres muscle (most common site 60-70%), or beneath the fibrous arch of flexor digitorum superficialis (FDS). Diagnosis is clinical with provocative tests (resisted pronation reproducing symptoms, tenderness over pronator teres) and nerve conduction studies showing focal slowing. Treatment is initially conservative with activity modification, NSAIDs, splinting, and physiotherapy achieving success in 50-70% of mild cases, while surgical decompression (releasing all four potential compression sites) is reserved for failed conservative treatment or severe cases with motor weakness, achieving 80-85% good-excellent outcomes with 3-6 month recovery.
What it is and why it happens
Pronator syndrome is compression of the median nerve in the upper forearm near the elbow, causing forearm pain, thumb/index/middle finger numbness, and hand weakness that mimics carpal tunnel syndrome but with key differences—pain worsens with repetitive gripping and forearm pronation (rotating palm down), and symptoms extend to the forearm and palm unlike carpal tunnel which spares the palm and causes nocturnal symptoms. The median nerve can be compressed at four potential sites in the proximal forearm: ligament of Struthers (uncommon bony abnormality 1cm above elbow), lacertus fibrosus (fascial band from biceps tendon), between the two heads of pronator teres muscle (most common site 60-70%), or beneath the fibrous arch of flexor digitorum superficialis (FDS). Diagnosis is clinical with provocative tests (resisted pronation reproducing symptoms, tenderness over pronator teres) and nerve conduction studies showing focal slowing. Treatment is initially conservative with activity modification, NSAIDs, splinting, and physiotherapy achieving success in 50-70% of mild cases, while surgical decompression (releasing all four potential compression sites) is reserved for failed conservative treatment or severe cases with motor weakness, achieving 80-85% good-excellent outcomes with 3-6 month recovery.