History of thoracic outlet syndrome.

Thoracic outlet syndrome (TOS), a condition in which neurovascular structures in the thoracic outlet region are compressed, can be caused by anatomical abnormalities or acquired changes in the soft tissues and bony structures in the region. The brachial plexus is the most frequently affected structure. TOS is one of the most difficult neurovascular compressions in the upper extremity to manage because of the variability of complaints and the high risk associated with surgical treatment.