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Pronator Teres Compression Syndrome – median nerve compression

- Discussion:
    - see: compression of the median nerve at the elbow and forearm;
    - compression of median nerve where it passes between the two heads of the pronator teres;

- Differential Dx:
    - lacertus fibrosus:
         - draws tightly across the median nerve when the forearm is held in resisted supination and flexion;
         - independent flexion of the middle finger flexion (FDS) localizes the level of entrapment to the fibrous arcade of the FDS;
    - flexor superficialis crossover syndrome:
         - resisted flexion of flexor superficialis of long finger combined w/ parasthesias in forearm & hand while pronating wrist, clinical test for
                 median nerve entrapment at pronator teres & flexor superficialis cross over;
    - C6 / C7 radiculopathy:
         - involvment of these levels will cause numbeness of thumb, index, and long fingers, and the median nerve innervated muscles of the forearm;
         - correct diagnosis is made by establishing the function of the muscles innervated by the C6-C7 portions of the radial nerve (ie the
                 function of the wrist entensors and the triceps);
         - supracondylar process:
                 - An Unusual Case of Pronator Syndrome With Ipsilateral Supracondylar Process and Abnormal Muscle Mass  

- Exam:
    - see: exam for carpal tunnel;
    - Phalen and tunnel test are negative;
    - pain in wrist and forearm;
    - weakness of thenar muscles;
    - thenar muscles are weak but muscles of ain (fpl, fdp, quad) are spared;
    - dysesthesia in "palmar triangle;"
         - pronator teres can be implicated when arm is held in resisted pronation and flexion and then gradually extended while in pronated position;

- EMG:
    - when EMG does not confirm pronator teres syndrome but clinical evidence is suggestive, then wait 4-6 wks and repeat the EMG;

- Treatment:
    - realease of humeral head of pronator teres and the superficialis bridge as well as associated compressing structures

Abnormal musculoaponeurotic tunnel in the arm: possible entrapment of the median nerve and brachial artery with high origin of nerve to pronator teres within the tunnel.

The pronator teres syndrome: compressive neuropathy of the median nerve.