Arterial thoracic outlet compression syndrome: a differential diagnosis of painful right supraclavicular swelling?

The narrow triangle described by the first rib inferiorly, the scalenus medius posteriorly and the scalenus anterior anteriorly confines the neurovascular structures of the upper extremities as they exit from the mediastinum and the spinal canal. In patients with cervical ribs or abnormal congenital fibrous connections between the cervical transverse process and the first rib, the base of the triangle maybe raised to the height of the vertebrae resulting in the angulation or compression of the neurovascular structures. This compression and angulation results in the syndrome known as thoracic outlet compression syndrome (TOCS) (Mann et al, 1995).