Thoracic Outlet Syndrome-Part 1
Thoracic outlet syndrome cannot be described as one condition but is the agreed name for a variety of symptoms which are explained by being assumed to be due to compression of the blood vessels and nerves as they go through the area called the thoracic outlet. The outlet is made up of a triangle the boundaries of which are the scalene muscles, the first rib and the collar bone or clavicle, through which the nerves and vessels go to get to the axilla and then to the arm. Patient diagnosis is very difficult in this field and little agreement exists about the 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.
The repetitive movement of the shoulder towards the ends of its ranges makes the onset of thoracic outlet syndrome more likely, increasingly so if shoulder abduction (moving the arm out to the side) and outward rotation are involved at end ranges. A common occurrence is for swimmers to complain of pain during their stroke and this should raise the suspicion of thoracic outlet problems. Repetitive shoulder movements towards the end of the available movement make this more likely to occur in many sports or activities. Symptoms may present as neurological difficulties or as problems connected with blood supply to the arm.
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.
If the arterial flow is disrupted the arm can change colour, there can be pain on muscle use due to their not getting enough blood and an overall pain in the hand and the arm. Mild onset is typical as blood can often get round a blockage, but when the block is large patients attend for medical review independently. Thoracic outlet syndrome from neurological compression involves compression of some of the brachial plexus, a nerve crossroads in the neck which supplies the arms. Nerve compression does not usually occur alone but presents with awkwardness holding a ball or a racket and loss of muscle bulk in the small hand muscles.
Compression of nerve structures can present with loss of feeling and pins and needles, with pain reported at times but not a typical problem. Aggravating activities again are mostly in the realm of repeated overhead actions, usually in sports. The third type of thoracic outlet syndrome is the more difficult group as a large number of patients present with pain in the arm, neck and shoulder blade regions. A traumatic onset from an incident of some kind is typical and the meaning of these symptoms is not clear, with much disagreement as to whether these conditions are part of thoracic outlet syndrome.
Jonathan Blood Smyth, editor of the Physiotherapy Site, writes articles about physiotherapy, physiotherapy, Physiotherapy London, back pain, orthopaedic conditions, neck pain and injury management. Jonathan is a superintendant physiotherapist at an NHS hospital in the South-West of the UK.