Upper trunk type thoracic outlet syndrome

Anatomically, the upper trunk is located between the bellies of the anterior and middle scalene muscles and has no basis for compression. However, the C5 and C6 nerve roots are surrounded by the crossing tendinous origin fibers of the anterior and middle scalene muscles at the intervertebral foramen, which is the basis for compression. Therefore, the author refers to upper trunk-type thoracic outlet syndrome as C5 and C6 nerve root compression. It was previously believed that upper trunk-type thoracic outlet syndrome was rare, accounting for only 4%-10% of thoracic outlet syndrome cases. In fact, this disease is quite common clinically. The main reason is that this type of thoracic outlet syndrome is mistakenly classified as cervical spondylotic radiculopathy. Both conditions involve nerve root compression, and the compression sites differ by only a few millimeters to one or two centimeters, making clinical differentiation truly difficult. With in-depth research on neck and shoulder pain, it has been found that C5 and C6 nerve root compression can not only exist independently but can also be combined with C5, C6, and C5-C6 spinal cord compression-type cervical spondylosis, as well as lower trunk-type thoracic outlet syndrome.