Pronator syndrome, also referred to as pronator teres syndrome (PTS), is a neuropathy caused by compression of the median nerve as it passes through the 2 heads of the pronator teres muscle in the proximal forearm. Distally, median nerve entrapment at the wrist is called carpal tunnel syndrome (CTS).

PTS is usually caused by repetitive physical activity involving quick pronation and grasping movements:

• Manual labor – mechanics, chopping wood, carpentry
• Physical activity – weight lifting, playing racquet sports, throwing balls, rowing, skiing, holding the handlebars of a bicycle
• Activities of daily living – carrying books, pouring drinks, cleaning dishes, raking leaves, shoveling snow 

Other conditions that cause adjacent forearm or elbow structures to hypertrophy, swell, or become inflamed can also cause PTS by impinging on the median nerve. Examples include:

• Trauma
• Compressive tumors
• Hypertrophy of bicipital aponeurosis

This condition affects both men and women, although women aged 40-50 years are most commonly affected. Risk factors include female biological sex, occupational or recreational physical activity, hypothyroidism, diabetes, and medical conditions requiring dialysis or anticoagulation.

Because it can be mistaken for more common conditions such as CTS, the incidence of pronator syndrome is rare, occurring in less than 1 in 100 000 people annually.

Impingement of the median nerve can occur at several locations in pronator syndrome: elbow joint (most common cause), distal humerus, proximal elbow, proximal forearm, or due to the Gantzer muscle (accessory head of the flexor pollicis longus muscle).