Thoracic outlet syndrome occurs when the nerves, veins, and arteries in the space between the collarbone and the first rib (the thoracic outlet) become compressed and irritated as they travel to the arm and hand. This can cause headache, pain in the shoulders, chest, and neck and along the arm. It can also cause numbness and weakness in the hand and fingers with or without loss of grip strength and dexterity. There are three types of thoracic outlet syndrome:
- Neurogenic thoracic outlet syndrome is caused by compression of the nerves of the brachial plexus (a network of nerves that originate near the neck and shoulders). This is by far the most common form of thoracic outlet syndrome and can be overlooked because of its varied symptoms, mostly pain and weakness of the arm and hand.
- Venous thoracic outlet syndrome is caused by an obstruction or clotting of the main vein from the arm (subclavian vein). This is most often associated with repetitive activity such as weightlifting, sports, or intense manual labor with repetitive tasks. This can cause severe swelling in the arm.
- Arterial thoracic outlet syndrome occurs when the artery leading to the arm (the subclavian artery) is compressed by an additional rib (cervical rib) or an abnormality of the first rib. This condition is very rare and can cause blood clots in the artery leading to the hand.