Thoracic outlet syndrome is a pain syndrome of the upper extremities. Doctors use the abbreviation ‘TOS’ instead of the full name of the disease, ‘Thoracic Outlet Syndrome.’ TOS patients suffer pain, tingling, numbness, weakness, or abnormal blood flow in one or both upper extremities. TOS can range from an emergent surgical condition to a progressive, chronic pain syndrome that alters the lives of TOS patients.
Three vital structures pass from the neck and chest to reach each upper extremity. When compression of these vital structures causes symptoms, TOS is present.