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Pronator syndrome
Other Resources UpToDate PubMed

Pronator syndrome

Contributors: Anusha Patil BA, Aabra Ahmed MD, Danielle Wilbur MD
Other Resources UpToDate PubMed


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).


G56.10 – Other lesions of median nerve, unspecified upper limb

230628008 – Pronator syndrome

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Differential Diagnosis & Pitfalls

Other median nerve entrapment syndromes:
PTS differs from CTS in:
  • PTS lacks nocturnal paresthesias, unlike CTS.
  • PTS involves sensory deficits of the palm and thenar eminence (palmar cutaneous nerve distribution), which is usually spared in CTS.
  • While both CTS and PTS symptoms are exacerbated with wrist flexion, PTS is also exacerbated with pronation and supination of the forearm.
  • PTS has positive Tinel sign at the proximal forearm but not at the wrist, as in CTS.
PTS differs from AIN syndrome in that PTS has minimal motor deficits, whereas AIN is primarily a motor palsy of the flexor pollicis longus (FPL) and flexor digitorum profundus (FDP) to the index and lacks sensory deficits.

PTS differs from brachial plexus injury and cervical radiculopathy in that these conditions often cause weakness to structures not innervated by the median nerve. They also involve neck pain radiating into the arm.

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Last Reviewed:02/20/2023
Last Updated:03/27/2023
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Pronator syndrome
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