The thoracic outlet is a part of the body between the neck and the arm. Three major structures pass through this – the nerves of the arm (the brachial plexus), the subclavian vein, and the subclavian artery. Compression of the thoracic outlet structures often occurs by a muscle, muscular band or a cervical rib. When any of these structures is compressed or squeezed, a person may develop symptoms of pain, color change, or numbness. Sometimes these symptoms occur with specific arm positions. This condition is known as thoracic outlet syndrome (or TOS).
Vascular thoracic outlet syndrome is a rare condition caused by compression of the subclavian artery or subclavian vein. Sometimes these are referred to as arterial or venous TOS. They may cause symptoms of swelling or bluish color change, pain in the fingers, coldness or pale coloration in the fingers, or poor oxygen supply to the fingers. When compression of the vein or artery is confirmed, vascular surgery treatment is recommended.
Neurogenic thoracic outlet syndrome is a more common condition. It may be related to a history of trauma or repetitive movement. Symptoms of neurogenic TOS may include pain and weakness in the hand, pain in the neck or the back of the head, and tingling. Coldness and color change may also occur, but this can be caused by nerve irritation rather than vascular changes. No arm swelling or pulse changes are present with neurogenic TOS.
The symptoms of neurogenic thoracic outlet syndrome can sometimes be triggered by movement of the head or arms. Rotating and tilting the head is one way to trigger the symptoms. Another way is to raise the arms to the level of the shoulders , extend the wrists and tilt the head towards one side. Sometimes this is a useful test during an office evaluation. Congestion of veins on the chest or absence of a radial artery pulse with positioning of the arm is a helpful clue for vascular TOS.
Because TOS is affected by positioning of the arm, diagnostic testing for this can be misleading. A chest xray will evaluate for the presence of an extra rib at the bottom of the neck. The cervical rib is sometimes present at birth and it may influence symptoms of TOS. In many patients, EMG or nerve conduction tests are normal. The EMG is most helpful because it can assess for other conditions that mimic TOS. MRI or MRA testing results can be variable, and often they are not helpful.
Treatment of TOS may benefit from physical therapy, medications, injection of anesthetic into a muscle that causes TOS, or sometimes surgery. Surgery is rarely necessary for neurogenic TOS.
The following is a link to a thorough discussion of TOS, its diagnosis, and treatment at a TOS treatment center.