Median nerve - anterior interosseous nerve lesions

Causes

• Compression by fibrous band.
• Compression by accessory head of the flexor pollicis longus muscle (Gantzer muscle).
• Injury by strenous excercise.
• Iatrogenic injury by venipuncture or cutdown procedure.
• Injury by supracondular humerus fracture.
• Parsonage-Turner neuralgic amyotrophy.
• Compression by tumor or vascular anomaly.
• Infection by CMV.

Symptoms & signs

• Flexion weakness of the terminal phalanges because of flexor digitorum profundus paresis.
• Flexion weakness of the interphalangeal joint of the thumb because of flexor pollicis longus paresis.
• Abnormal thumb-index pinch attitude.
• Mild pronation weakness because of pronator quadratus paresis.
• Normal sensation
• Aching pain in volar wrist may exist.