Thoracic outlet syndrome (TOS) involves compression at the thoracic inlet, which is known clinically as the superior thoracic outlet, resulting from excess pressure placed on the neurovascular bundle passing between the anterior scalene and middle scalene muscles.
TOS can affect one or more of the nerves that innervate the upper limb and/or blood vessels as they pass between the chest and upper extremity, specifically in the brachial plexus, the subclavian artery, and rarely, the subclavian vein. TOS can be caused by a variety of factors, including repetitive arm and shoulder movements, trauma, or anatomical abnormalities.
Symptoms of TOS may include pain, weakness, numbness, and tingling in the arms and hands, especially when performing overhead activities or carrying heavy objects. Treatment for TOS depends on the underlying cause and severity of the condition, and may include medications like corticosteroids, or even surgery.