Thoracic Outlet Syndrome-Part 1
Thoracic outlet syndrome is not one condition but the overall name for a number of different conditions thought to be related to compression of the nerves and blood vessels as they travel through the anatomical area known as the thoracic outlet. The thoracic outlet is an area in the neck which has as its boundaries the collar bone or clavicle, the first rib and the scalene muscles, through which the vessels and nerves must pass to reach the armpit and so the arm. It is often not clear what the patient is suffering from and there is little agreement about this condition.
The wide variation in signs and symptoms of sufferers with thoracic outlet syndrome and the absence of any test to confirm or deny its presence means that correct diagnoses of patients with thoracic outlet syndrome is difficult. The numbers of people who suffer from this syndrome is as a consequence not clear although it is known that higher numbers of women occur in this group, especially if they have poor muscle tone and posture.
The bundle of blood vessels and nerves which travels down from the neck to the arm has to go through three anatomical, more or less triangular, areas. The bundles can be compressed in any one of the spaces and they are small when the arm is at rest by the side, becoming smaller still when the arm is moved into various positions. These tight positions are used to increase compression during diagnostic testing to give a better idea of which structures are being compressed and which structures might be doing the compressing. Physiotherapists and doctors place the patients’ arms into potentially aggravating positions and ask them to perform repetitive muscle actions such as clenching the fist to increase neurological or vascular demand.
Risk factors for developing thoracic outlet syndrome are seen in patients who perform repetitive actions at the end of the shoulder''s movements, particularly of abduction (moving the arm away from the side) and external rotation (turning the arm outwards). This occurs often in swimmers and this condition should be suspected if they complain of pain during their stroke. Any sport which demands repeated activity involving the shoulder in extreme positions increases the likelihood of developing this problem and patients can present with either neurological symptoms or symptoms of abnormalities of blood supply.
How patients present initially with thoracic outlet syndrome depends on if the compression is mostly neurological, vascular or both combined. Symptoms can be mild and intermittent or severe and continuous and disabling. Typically there tends to be three types of normal presentation involving the blood supply, the nerve supply and the remainder which are non-specific. Direct compression of the main artery or vein is uncommon and more likely in young athletes who indulge in strong activities overhead such as throwing.
Obstruction of the artery involves changes in colour of the arm, pain on using the muscles due to insufficient blood flow and general widespread arm and hand pain. It may start off mildly but if the obstruction becomes severe patients are usually forced to seek medical advice. Nerve related thoracic outlet syndrome is secondary to compression of part of the brachial plexus, the complex web of major nerves travelling from the neck to the arms. Symptoms are rarely of nerve compression on its own, with loss of muscle bulk in hand muscles and problems holding rackets or balls a common complaint.
Neurological compromise may also cause pins and needles or loss of feeling, with some reports of pain but this tends not to be a major issue. Overhead actions with the arm repetitively tend again to be the aggravating factors. The third group is the contentious one, with a large number of patients who complain of pain in the neck, shoulder blade and arm. Often starting after an accident of some type, this kind of pain is not well understood and there is little medical agreement as to whether this is thoracic outlet syndrome or not.
Author: Jonathan Blood-Smyth