Information regarding the condition, procedure s and advice
The following information is designed to supplement what your surgeon tells you about the condition and procedures involved. Please do ask any questions during discussions or after reading this.
Thoracic outlet syndrome
The thoracic outlet is the space that the nerves to the arm (the brachial plexus), the artery carrying blood to the arm (the subclavian artery) and the vein carrying blood from the arm pass through. It is bounded by the collarbone on the top and the first rib below, and the breast bone at the front. There are muscles (scalenus anterior and medius muscles) attached to the first rib that divide the thoracic outlet into compartments.
The thoracic outlet is a tight space in everyone. It can be made smaller by certain manoeuvres such as raising the shoulder up and turning the arms away from the floor. This manoeuvre can pinch, the vein, artery or nerve in about 5% of the population.
In some circumstances there are anatomical reasons why the thoracic outlet is smaller and causes impingement of the vein, artery and nerve to a greater degree than in many others. These include an abnormal cervical rib (present in 0.3% of the population), previous fracture of the rib or collar bone, musculoskeletal and connective tissue disorders that cause the nerve, artery and vein to be pulled over the rib and hypertrophy (bulking ) of the neck muscles which increase the size of the scalenus anterior and medius muscles and restrict the space even further.
In some, who have impingement of the nerve, artery and vein, there are significant symptoms that can lead to decreased quality of life and complications. These can be treated with various conservative manoeuvres and occasionally surgery is warranted.
Venous thoracic outlet syndrome
In this condition the vein is constricted in various arm positions and may become scarred and narrowed permanently. When this happens there may be swelling of the arm, especially after exercise, bluish discolouration and tightness and aching. This may be mild or in some circumstances quite severe.
If the blood flow out of the arm is severely compromised there may be clotting inside the vein and deep vein thrombosis. This may in fact be the first sign of venous thoracic outlet syndrome. The presentation is with a swollen, blue or reddened, painful, tender arm.
In this scenario the most important treatment is anticoagulation to stop propagation of the clot and generation of fragile clot that may break off and travel to the lungs – this is called a pulmonary embolism and can be very serious causing acute shortness of breath and even death. Once anti coagulated the risk of pulmonary embolism is low.
In some cases where there may be a benefit, thrombolysis is considered. This is a treatment where a sheath is place in the vein and a small tube is pushed up the vein using X-Ray control, into the clot itself. A drug to break down the clot is injected and then continued via a drip for 24 hour or more, with regular check X-Ray examinations to check progress. Where there is good clearance of the clot, immediate relief of symptoms of venous blockage occurs. Further treatment to relieve thoracic outlet compression may be considered if this is thought to be the primary cause for the deep vein thrombosis.
Arterial thoracic outlet syndrome
This is less common than the venous and neurological type but may be more serious if left unchecked. In this case there is compression and damage to the artery.
This may present with arterial blockage and acute profound ischaemia (lack of blood supply) to the hand. There is a risk of ulcers, gangrene, and loss of fingers. The hand is cold, painful, numb and there is loss of movement. Fortunately, this is rare.
Sometimes there is damage to the artery and narrowing that causes claudication, a cramping sensation on exercise of the arm that is relieved by rest. On other occasions there is symptoms of Raynaud’s syndrome where there is a reaction to the cold with the development of white fingers, which then turn blue and deep red on warming. Lastly, there may be a dilatation of the artery after damage and clot may form in the dilated portion and embolism (break off and travel down the arm) causing areas of ischaemia in the hand and fingers.
In these cases, often the only treatment is release of the thoracic outlet and repair of the artery directly, through an incision above the collar bone in the base of the neck.
Neurological thoracic outlet syndrome.
In this case there is stretching and pressure on the lower fibres of the brachial plexus. Classically there is pain on the inside of the hand and forearm that is much worse on raising the arms above the head. Sometimes there is permanent pins and needles, numbness and rarely loss of movement and strength of the arm.
The symptoms may be mild, and all that is needed is reassurance that there is not a progressive nerve damage occurring or anywhere along a range to severe, where there is permanent pain and severe loss of quality of life.
In the case of neurological thoracic outlet syndrome there is an emphasis on investigation for other causes of neurological issues in the arm (it is sometimes two places where a nerve is crushed and causing symptoms) and then there are various treatment options, but a conservative course is often preferred with specialist physiotherapy.
Investigations for thoracic outlet syndrome
- Duplex (ultrasound) examination of the artery and vein of the arm with thoracic outlet provocation views, to show any damage to the artery and vein and how these are pinched at the level of the thoracic outlet.
- MRI of the thoracic outlet which will show abnormalities of the artery and vein (which may show narrowing in the chest where the ultrasound can’t see) as well as the nerve plexus. The scan may also identify a band of scarring that might cause restriction of the structure in the thoracic outlet.
- Nerve conduction studies – to see if there is any nerve damage at the thoracic outlet level or affecting nerves elsewhere.
- Chest X-Ray to examine for a cervical rib.
Treatments for thoracic outlet syndrome
Physiotherapy – This must be specialist physiotherapy for thoracic outlet syndrome. For pain and neurological disease this can be very useful. The physiotherapist will teach postural correction and manoeuvres to relieve impingement of the nerve, artery, and vein.
Botox injection – In some cases to relieve symptoms and also useful as a diagnostic test, Botox can be injected into the scalenus anterior and medius muscles to paralyse the muscle (it is only used for a small percentage of the effective breathing mechanism in extreme circumstances). The first rib drops, and the thoracic outlet widens relieving some of the symptoms.
Operative intervention – This is first rib (or cervical rib if present) removal and decompression of the thoracic outlet. There are various approaches to this procedure. One approach is for above the collar bone where the incision is made above the collar bone, the fat pad is retracted, and nerves preserved. There is then division of the scalenus anterior muscle and isolation of the rib with resection of the rib under the nerve, artery and bone.