Pronator Syndrome

synonyms:

Pronator Syndrome ICD-9

Pronator Syndrome Etiology / Epidemiology / Natural History

• Proximal compression of the median nerve related to the pronator teres or adjacent anatomic structures.
• Much less common than carpal tunnel syndrome.
• More common in patients with well developed forearm muscles: weight lifters.

Pronator Syndrome Anatomy

• Entrapment usually at pronator teres(resisted pronation with forearm extention. 
• Other sites=supracondlyar process, ligament of Struthers, bicipital aponeurosis(resisted elbow flexion with forearm suppination).
• Bicital aponeurosis = lacertus fibrosus
• See Elbow anatomy.

Pronator Syndrome Clinical Evaluation

• Symptoms similar to CTS.
• Differences from CTS=pain/numbness in the palm in the distribution of the palmar cutaneous branch of median N, anterior proximal forearm pain, Tinels anterior forearm, usually no night pain. Negative Phalen's and Tinel's sign.
• Pronator sign=resisted pronation with elbow extended=compression at heads of pronator teres
• Resisted pronation with elbow flexed=compression at bicipital aponeurosis(less common).
• Prominent supracondylar process and tenderness along the medial distal arm indicates compression around the ligament of Struthers.
• Pain with resisted Long finger IP flexion indicates compression deep to the flexor digitorum superficialis.
• MF PIP flexion=compression at FDS

Pronator Syndrome Xray / Diagnositc Tests

• A/P & Lat of forearm, P/A, Lat, oblique of wrist usually normal
• EMG positive for PQ and FPL

Pronator Syndrome Classification / Treatment

• Non-operative: activity modifications/rest, splinting(elbow at 90°/slight forearm pronation/slight wrist flexion), NSAIDS.  50% succcessful.
• Operative: proximal decompression. Indicated only after failure or non-operative treatment. Release ligament of Struthers, lacertus fibrosus, split the heads of the pronator teres and release between the arcade of the flexor digitorum superficialis.

Pronator Syndrome Associated Injuries / Differential Diagnosis

• Carpal tunnel syndrome
• Ulnar tunnel syndrome(commonly coexist, release of transverse carpal ligament adequetely decompresses Guyons canal).
• Cervical radiculopathy
• Thoracic outlet syndrome
• Brachial plexus palsy
• Parsonage-Turner syndrome
• Pancoast's tumor
• Vascular pathology
• Tumor
• HNPP

Pronator Syndrome Complications

• Failure of decompression
• Persistent numbness
• Median nerve palsy
• Wound dehiscence
• Infection

Pronator Syndrome Follow-up Care

Pronator Syndrome Review References

• Greens Hand Surgery