Pronator Teres Syndrome (Pronator Syndrome).pptx

Pronator Teres Syndrome (Pronator Syndrome).pptx

1. Pronator Syndrome Dr. Mohammad Taqi Ehsani PGY2 of Orthopedics, FMIC July, 2024

2. Pronator teres syndrome (PTS), first described by Henrik Seyffarth in 1951, is caused by a compression of the median nerve (MN) by the pronator teres (PT) muscle in the forearm one of three common median nerve entrapment syndromes; the other two being anterior interosseous nerve syndrome and the far more common carpal tunnel syndrome. Signs and symptoms result from compression of the median nerve in the upper forearm

3. Etiology The median nerve can be involved at several locations around the elbow : Distal humerus :  avian spur and ligament of Struthers Proximal elbow: thickened biceps aponeurosis (a.k.a. lacertus fibrosus) Elbow joint : between humeral and ulnar heads of the  pronator teres muscle (most common cause)  Proximal forearm: thickened proximal edge of the flexor digitorum superficialis muscle Gantzer muscle Quick and repetitive grasping or pronation movements (prolonged hammering, ladling food, cleaning dishes, tennis) may cause PT muscle hypertrophy and entrapment of MN local trauma, compression with Schwannoma, and in patients undergoing anticoagulation therapy and renal dialysis

4. Epidemiology Incidence rare < 1 per 100,000 annually Demographics female > male common in 5th decade Risk factors associated with  well-developed forearm muscles  (e.g. weight lifters)

5. Clinical presentation Patients may present with:   volar pain of the proximal lower arm paresthesia of the volar forearm and the radial three digits and radial aspect of the fourth digit weakness, on the other hand, is variable, often with unspecified grip clumsiness the proximal volar forearm is painful to palpation, and Tinel’s sign can be elicited on palpation of the pronator teres muscle

6. Physical exam provocative tests   are specific for different sites of entrapment positive Tinel sign in the proximal anterior forearm but no Tinel sign at wrist nor provocative symptoms with wrist flexion as would be seen in CTS resisted forearm pronation with elbow extended  (compression at two heads of pronator teres) resisted contraction of FDS to middle finger  (compression at FDS fibrous arch) resisted elbow flexion with forearm supination (compression at  bicipital aponeurosis) possible coexisting medial epicondylitis Clinical presentation

7. Evaluation Radiographs elbow films are mandatory  may see supracondylar process EMG and NCV may exclude other sites of nerve compression or identify double-crush syndrome Ultrasound and MRI imaging modalities that best lend themselves to investigating entrapment syndromes visualizing direct causes [e.g. primary nerve or sheath tumors, ganglion cysts, osseous spurs, anatomical variants (e.g. Gantzer muscle) recognizing pathological muscle signal patterns on MRI can inversely point to the affected nerve.

8. Differential Diagnosis other median nerve entrapment syndromes carpal tunnel syndrome anterior interosseous nerve syndrome  (a.k.a.  Kiloh -Nevin Syndrome) cervical radiculopathy thoracic outlet syndrome brachial plexus neuritis ( Parsonage-Turner Syndrome)

9. Treatment Nonoperative: mild to moderate symptoms rest, splinting, and NSAIDS for 3-6 months modification of activities that exacerbate the symptoms, physical and occupational therapy, and local injections with corticosteroids or local anesthetic Splint: should avoid forearm rotation

10. Treatment Operative: surgical decompression of median nerve   indications only when  nonoperative management fails for 3-6 months technique decompression of the median nerve at all 5 possible sites of compression Outcomes 80% of patients having relief of symptoms

11. Complications Complications of surgical treatment are rare. In one study of 72 patients treated with pronator teres syndrome, no complications were recorded during the operations with an overall postoperative satisfaction rate (very satisfied  and  satisfied) of 59%. Theoretical complications from surgery include: Infection Seroma/hematoma formation Nerve injury Scar formation