The Myelogram in Avulsion of the Brachial Plexus

Although avulsion of the brachial plexus is a well known condition and a not uncommon entity, little attention has been paid to its radiologic features. Murphey, Hartung, and Kirklin (11) published the first case of avulsing injury of the brachial plexus in which myelography was performed. They later presented additional cases before the Clinical Congress of the American College of Surgeons (12). Only recently two other reports have appeared. Whiteleather (16) presented several cases before the American Roentgen Ray Society in 1953, and Jaeger and Whiteley (7) reported 6 cases, with myelograms in 3. In the 6 cases to be reported here findings were obtained on myelography which are considered pathognomonic for avulsion of the brachial plexus. Incidence The exact incidence of various types of injury to the brachial plexus is difficult to determine. The Peripheral Nerve Registry of World War II (17) contains a total of 7,050 cases. Of these, 139 involved the brachial plexus, but the type of lesion is not stated in Woodhall's summary. From 2,500 cases of peripheral nerve injury seen in the center established for such injuries at Oxford during the war, Seddon (13) describes 52 cases in which autogenous grafts were employed. Only 6 of these were of the brachial plexus. Stevens (15) reviewed 710 cases of brachial plexus injury in the world literature up to 1932. Only 135 were verified by surgery or autopsy; 86 of these were supra-clavicular, but only 32 were proved to be ruptures or avulsions. The term avulsion is reserved for injuries with separation of nerve roots or rootlets from the spinal marrow itself. Separation elsewhere as a result of blunt or closed trauma constitutes rupture. Stevens discovered only 4 proved avulsions in the 710 cases reviewed. One of these (4) was the first case in which the seat of the lesion within the dural sac was demonstrated at operation. Mode of Injury Early writers believed that brachial plexus injury associated with shoulder dislocations, clavicular fractures, and other injuries of this region resulted from compression of the involved nerves. Gerdy in France and Horsley (8) in England are credited with expounding the traction theory of closed brachial plexus injury. Most patients are rendered unconscious as a result of an injury producing severe brachial plexus trauma. The exact direction of the force is therefore usually conjectural. Barnes (1) points out that when the head and shoulder are forcibly separated, with the arm by the side, the greatest stress falls on the upper roots, while the lower roots are not under tension. Abduction increases tension on the lower roots. Clinical Findings Traction injuries of the brachial plexus are usually divided into four main groups: Lesions of (a) C-5 and C-6; (b) C-5, C-6, and C-7; (c) C-8 and D-1, sometimes with C-7 also involved; (d) the entire plexus.