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Wheeless' Textbook of Orthopaedics

Entrapment of Median nerve at the Elbow and Forearm


- See: Anterior Interosseous Nerve Sydrome:
       
- Site of Proximal Forearm Compression;
    - supracondylar process of the humerus and struther's ligament:
          - median nerve may be compressed as it passes under the bondy spur
          - pt c/o of weak hand grip and in pronating, & tingling in lateral digits;
          - there may be objective weakness in the pronator teres, FCR, FPL, FDS, and lateral half of FDP, and thenar mucles;
          - presence of pronator weakness distinguishes this syndrome from pronator and anterior interosseous syndromes;
          - nerve conduction studies may have shown slowing in the conduction velocity in the median nerve in the arm;
          - ref: Images in clinical medicine. Processus supracondylaris humeri.
    - lacertus fibrosus:
          - at front of elbow, median nerve lies behind bicipital aponeurosis (lacertus fibrosus) and in front of the brachialis;
          - one must suspect the lacertus fibrosis with pain in the forearm w/ resisted elbow flexion beyond 120 deg;
                 - it can also be caused by pressure from the origin of the FDS;
    - pronator teres: (pronator teres compression syndrome)
                 - w/ compression at this site, pts may complain of pain following resisted flexion of the FDS to the long finger;
                 - one should suspect compression of meidan nerve by head of pronator teres when a patient complains of pain with increased activity;
                 - check this with forced pronation and wrist flexion;
                 - elarged median artery can also cause the pronator syndrome as well as compress the median nerve at the wrist;
    - sublimis bridge:
                 - median nerve then passes under the fibrotendinous arcade that represents the origin of the FDS muscle;
                 - median nerve descends in the forearm adherent to the undersurface of FDS and lying superficial to the FDP;


- EMG may show denervation potentials in median innervated muscles in the forearm and hand;
    - clinical syndrome may be associated with symptoms and signs of ischemia in the distribution of the brachial artery;
    - bony process may or may not be palpable;
    - tangential or oblique views of humerus may show supracondylar process to greater advantage than routine AP & lateral views;
    - brachial arterogram may be necessary if vascular comprimise is possible
    - surgical therapy consists of excision of Struther's ligament and removal of the bony spur



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Thursday, May 31, 2012 1:03 pm