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Pronator Teres Syndrome

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(Redirected from Pronator Syndrome)

Other Names

  • Pronator Syndrome
  • Pronator Teres Syndrome
  • Pronator teres entrapment syndrome
  • Pronator teres compression syndrome
  • Proximal Median Nerve Entrapment
  • Median Nerve Entrapment in the Proximal Forearm

Background

  • This page refers to pronator teres syndrome, a proximal median nerve entrapment neuropathy

History

  • First described in 1951 by the Norwegian neurologist Henrik Seyffarth[1]

Epidemiology

  • Consistently described as "rare" across the medical literature
  • There are no well-established population-based incidence or prevalence rates[2]

Introduction

Course of the median nerve at the elbow[3]

General

  • Relatively rare condition characterized by entrapment of the Median Nerve in the proximal forearm
  • This is a distinct clinical condition but is often mistaken for Carpal Tunnel Syndrome[4]
  • Presents with vague volar forearm pain, median nerve paresthesias in the thumb, index, middle, and radial half of the ring finger
  • Controversial diagnosis because electrodiagnostic studies are frequently normal
  • Develops insidiously over months to years, often in the setting of repetitive forearm pronation/supination activitie

Etiology

  • Causes
    • Forceful and repetitive pronation/supination motions and gripping activities are the most commonly cited[5]
    • Sports: Weightlifting, tennis (backhand swing), competitive driving
    • Occupation: repetitive hammering are recognized risk factors
    • Anatomical aberrations: Tight ligaments, fascial bands, fibrous arcades, and intramuscular tendinous bands
    • Iatrogenic and traumatic causes
    • Accessory muscles: An accessory flexor pollicis longus belly (Gantzer's muscle)[6]
  • Entrapment most commonly occurs[7]
    • Between humeral head and ulnar head of the Pronator Teres muscle
    • Can also occur at lacertus fibroseus (biceps aponeurosis) or under sublimis bridge
    • Other etiologies: local trauma, compression with schwanomma
  • Involves hypertrophied pronator-flexor mass

Patho-Anatomy of the Median Nerve

  • Can be compressed at five recognized anatomical sites in the proximal forearm region (listed proximal to distal)
  • Ligament of Struthers[8]
    • Rarely present fibrous band
    • Connects an anomalous supracondylar bony spur of the distal humerus to the medial epicondyle
    • When present, it can compress the median nerve proximal to the elbow
  • Lacertus fibrosus (bicipital aponeurosis)[9]
    • The fascial extension from the biceps tendon
    • crosses over the median nerve approximately 1.5 cm distal to the bi-epicondylar line
    • compression here is exacerbated by resisted elbow flexion with forearm supination
  • Between the two heads of the pronator teres[10]
    • Most commonly cited site of compression
    • Median nerve passes between the humeral (superficial) and ulnar (deep) heads of the pronator teres
    • Fibrous arcades between the two heads were found in 64% of cadaveric specimens
  • Deep fascia of the superficial head of the pronator teres[11]
    • Some authors consider this the primary compressive structure
    • Selective release of this fascia resolved symptoms in 93% of surgical cases in one series
  • Fibrous arch of the flexor digitorum superficialis (FDS)[12]
    • The proximal tendinous edge of the FDS lies approximately 4.5–7 cm distal to the bi-epicondylar line
    • can compress the median nerve as it passes beneath

Associated Conditions

Risk Factors

  • Gender: Male > female
  • Sports with repetitive forceful gripping or pronation
    • Throwing
    • Tennis
    • Archery
    • Arm Wrestling
    • Weight Lifting
    • Rowers
  • Occupations
    • Repetitive forearm pronation and supination
    • hammering, ladling food, cleaning dishes

Differential Diagnosis

Differential Diagnosis Wrist Pain

Differential Diagnosis Forearm Pain

Other Considerations

Clinical Features

History

  • Patients will report volar wrist pain
  • Often aggravated by pronation, elbow flexion
  • Report of parasthesias, numbness, tingling

Physical Exam: Physical Exam Wrist

Special Tests

Evaluation

Radiographs

EMG/NCS

  • Gold standard for diagnosis
  • EMG abnormalities can be seen in FPL, FDP, FDS, APB sparing PT

Ultrasound

  • Cross sectional area of median nerve between humeral and ulnar heads of PT correlates with severity and duration of symptoms[15]

MRI

  • Needs to be updated

Classification

Pronator Teres Morphological Classification[16]

  • Type I (~74%)
    • Median nerve passes between the humeral and ulnar heads
    • Classic configuration with entrapment risk from fibrous arcades between heads
  • Type II (~12%)
    • Median nerve passes beneath both heads
    • Higher entrapment potential due to complete muscular coverage
  • Type III (~14%)
    • Ulnar head absent; median nerve passes beneath the humeral head only
    • Entrapment from the deep fascia of the single head

Management

Nonoperative

  • First line for all cases, most cases will resolve with conservative measures
  • Avoidance of provocative activities
  • Protection from external compression
  • Night splint to prevent elbow flexion
  • Physical Therapy
  • Corticosteroid Injection at point of compression
  • Medications including NSAIDS

Operative

  • Indications:
    • Failure of conservative measures
    • Objective findings of weakness
    • Motor atrophy
    • Abnormal EMG/NCS
  • Procedure:
    • Release of pronator teres muscle and other compressive structures

Return to Play

  • Prognosis is generally favorable
  • For occupation-related disease
    • Most patients return to light duty at 3 weeks, full duty at 6 weeks[17]
    • Surgical cases have a longer recovery, up to 12 weeks at the discretion of the surgeon
  • For athletes, there are no clear guidelines
    • Typically, they can continue to play unless they develop prominent sensor or motor deficits

Complications

See Also

Internal

External

References

  1. ↑ Seyffarth, Henrik. "Primary myoses in the M. pronator teres as a cause of lesion of the N. medianus." Acta Psychiatr Scand 74.1 (1951): 251-254.
  2. ↑ Podlasińska, Marta, et al. "The Pronator Teres Muscle Revisited: Morphological Classification, Neurovascular Entrapment, and Surgical Implications." Journal of Clinical Medicine 14.21 (2025): 7474.
  3. ↑ Löppönen, Pekka, Sina Hulkkonen, and Jorma Ryhänen. "Proximal median nerve compression in the differential diagnosis of carpal tunnel syndrome." Journal of clinical medicine 11.14 (2022): 3988.
  4. ↑ Asheghan M, Hollisaz MT, Aghdam AS, Khatibiaghda A. The Prevalence of Pronator Teres among Patients with Carpal Tunnel Syndrome: Cross-sectional Study. Int J Biomed Sci. 2016 Sep;12(3):89-94.
  5. ↑ Bair, Marcus R., et al. "Differential diagnosis and intervention of proximal median nerve entrapment: a resident's case problem." journal of orthopaedic & sports physical therapy 46.9 (2016): 800-808.
  6. ↑ de Mont-Marin, Geoffroy Dubois, et al. "Topographic anatomy of structures liable to compress the median nerve at the elbow and proximal forearm." Orthopaedics & Traumatology: Surgery & Research 107.2 (2021): 102813.
  7. ↑ Olewnik Ł, Podgórski M, Polguj M, Wysiadecki G, Topol M. Anatomical variations of the pronator teres muscle in a Central European population and its clinical significance. Anat Sci Int. 2018 Mar;93(2):299-306.
  8. ↑ Wertsch, Jacqueline J., and John Melvin. "Median nerve anatomy and entrapment syndromes: a review." Arch Phys Med Rehabil 63.12 (1982): 623-7.
  9. ↑ de Mont-Marin, Geoffroy Dubois, et al. "Topographic anatomy of structures liable to compress the median nerve at the elbow and proximal forearm." Orthopaedics & Traumatology: Surgery & Research 107.2 (2021): 102813.
  10. ↑ de Mont-Marin, Geoffroy Dubois, et al. "Topographic anatomy of structures liable to compress the median nerve at the elbow and proximal forearm." Orthopaedics & Traumatology: Surgery & Research 107.2 (2021): 102813.
  11. ↑ Zancolli III, Eduardo R., Eduardo P. Zancolli IV, and Christian Jorge Perrotto. "New mini-invasive decompression for pronator teres syndrome." The Journal of hand surgery 37.8 (2012): 1706-1710.
  12. ↑ Wertsch, Jacqueline J., and John Melvin. "Median nerve anatomy and entrapment syndromes: a review." Arch Phys Med Rehabil 63.12 (1982): 623-7.
  13. ↑ Zancolli III, Eduardo R., Eduardo P. Zancolli IV, and Christian Jorge Perrotto. "New mini-invasive decompression for pronator teres syndrome." The Journal of hand surgery 37.8 (2012): 1706-1710.
  14. ↑ Hartz CR, Linscheid RL, Gramse RR, Daube JR. The pronator teres syndrome: compressive neuropathy of the median nerve. J Bone Joint Surg Am. 1981 Jul;63(6):885-90.
  15. ↑ Asheghan M, Hollisaz MT, Aghdam AS, Khatibiaghda A. The Prevalence of Pronator Teres among Patients with Carpal Tunnel Syndrome: Cross-sectional Study. Int J Biomed Sci. 2016 Sep;12(3):89-94.
  16. ↑ Podlasińska, Marta, et al. "The Pronator Teres Muscle Revisited: Morphological Classification, Neurovascular Entrapment, and Surgical Implications." Journal of Clinical Medicine 14.21 (2025): 7474.
  17. ↑ Carter GT, Weiss MD. Diagnosis and Treatment of Work-Related Proximal Median and Radial Nerve Entrapment. Phys Med Rehabil Clin N Am. 2015 Aug;26(3):539-49.
Created by:
John Kiel on 14 June 2019 08:37:49
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Last edited:
20 July 2026 20:30:04
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