Anterior interosseous syndrome

Anatomy: Few inches distal to the cubital fossa, the median nerve gives a branch named anterior interosseous nerve, which travels on the interosseous membrane and supplies the flexor pollicis longus (flexor of the thumb), the flexor digitorum profundus to the radial 2 digits, and the pronator quadratus at its termination. The nerve innervates the pronator teres, flexor capri radialis, the flexor digitorum sublimis, and the 2 radial flexor digitorum profundus tendons.

Symptoms: include pain in the proximal forearm and weakness of the thumb and index finger. Affected persons cannot form a circle by pinching their thumb and index finger (ie, hyperextension of index distal interphalangeal joint and thumb interphalangeal joint).

Treatment: Medical treatment includes rest, NSAIDs (Non Steroidal Anti Inflammatory Drugs), and splints. Surgical treatment includes exploration and release.