Thoracic outlet syndrome (TOS) is a broad term that refers to compression by bony structures and muscles of the nerves, veins and arteries that leave the chest in order to supply the arm. The condition is thought to affect 0.8% of the population and is seen 3 times more frequently in women.
Onset of symptoms is usually between the ages of 20 – 50 and the nature of the complaint is dictated by which structure is pressed upon though there may be some degree of overlap:
Patients may also find that symptoms only manifest when the arm is moved into certain positions or that certain actions can precipitate problems. This is an important feature and should be mentioned to your Vascular Alliance consultant. The vast majority of TOS symptoms are present on only 1 side.
95% of confirmed Thoracic Outlet Syndrome (TOS) cases are neurogenic in nature. Though the symptoms are uncomfortable or unpleasant it is safe to investigate and treat these patients in an out–patient setting.
The remaining 5% of cases (4% venous and 1% arterial) require an urgent review by a vascular surgeon. Any patients with symptoms suggestive of this should attend their nearest emergency department. If investigations confirm the diagnosis, treatment can be planned/initiated at that hospital and then subsequently performed/completed by Vascular Alliance.
What is it?
Thoracic outlet syndrome (TOS) is a condition which causes a broad range of symptoms through compression of the nerves, arteries and veins which supply the arms. The precise nature of the complaint is determined by which of the 3 structures is predominantly compressed. 95% of patients present with symptoms in keeping with nerve compression, 4% with vein compression and 1% with artery compression.
Anatomy of the Thoracic Outlet
The thoracic outlet is the region where the neck meets the chest. All structures supplying the head, neck and arms must get from the heart to their final destination through this opening. The most common site of abnormal compression lies between the collar bone and first rib at the base of the neck. Here the subclavian artery, subclavian vein and branches of the “brachial plexus” (nerves supplying the arm) run between the first rib and important muscles called the “scalene muscles”. It is a relatively congested area and it is not hard to visualise how even small changes could result in compression of major vessels and nerves. Various factors can predispose to development of TOS. They include:
History of neck trauma or strain – often as a result of motoring accidents and work based repetitive strain injuries. This is the most common reason for development of neurogenic symptoms (nerve compression).
Cervical Rib – an extra rib that arises from the lowest part of the spine in the neck. It is found in 0.2% of the population and when present may cause compression of the nerves and vessels between itself and the scalene muscles.
Fibrous Band – an abnormal band of strong inelastic tissue that may be present from birth or develop after an injury.
Anatomical variability – the anatomy of this region is variable between all individuals. In some people placement and orientation of their bones, muscles, nerves and vessels can predispose to TOS.
Excessive exercise – People who exercise heavily increase the bulk of their muscles and this includes the scalene muscles which help with breathing. Over time and in a small percentage of these patients, the muscle can begin to compress the subclavian vein which causes turbulent blood flow within it at the point of compression. This allows clot to start to build up, which in time can partially or completely block the vein. This is known as “effort induced thrombosis” or “Paget Schroetter’s syndrome” which are both types of deep vein thrombosis affecting the arm. It can also happen to people with a natural anatomical narrowing of the subclavian vein which causes turbulent blood flow.
How is Thoracic Outlet Syndrome diagnosed?
At your initial clinic visit, a thorough history of your symptoms will be obtained. Your consultant will ask questions about the type, severity and duration of your symptoms. They will need to know if certain movements or actions bring on these problems as well as your other medical problems and tablets that you take regularly.
Your consultant will then examine you. This will involve a neurological examination of the arms to look for any signs of injury or damage to the nerves supplying it. You may be asked to perform some specific movements that could bring on your symptoms. The pulses in your wrist and arm will be examined manually and with a small hand–held Doppler machine (painless). Your neck, shoulders and chest wall should also be examined to rule out other causes of your symptoms. Physical examination is normal in many cases and your consultant may then request some further tests for you. They include:
A Chest X–ray – to look for a cervical rib.
Nerve Conduction Studies – to more accurately assess the function of the nerves supplying the arm. This is non–invasive and painless.
Doppler Ultrasound of the arm – to more closely map the blood vessels and establish if there is a narrowing present. This is non–invasive and painless.
Angiography/Venography – an invasive test that looks at flow in the arteries and veins respectively. This may be necessary in cases where Doppler ultrasound cannot look at very deep vessels adequately.
CT/MRI scans of the neck – may be required to rule out spinal causes of your symptoms.
95% of confirmed Thoracic Outlet Syndrome (TOS) cases are neurogenic in nature meaning there is compression of the nerves supplying the arm. Though the symptoms are uncomfortable or unpleasant it is safe to investigate and treat these patients in an out-patient setting.
Treatment methods in these cases include:
Physiotherapy and Posture advice.
Surgical removal of the 1st rib or cervical rib in cases resistant to other treatment methods.
The remaining 5% of cases (4% venous and 1% arterial) require an urgent review by a vascular surgeon. Any patients with symptoms suggestive of this should attend their nearest emergency department. If investigations confirm the diagnosis, treatment can be planned/initiated at that hospital and subsequently performed/completed by Vascular Alliance.
Treatment methods in these cases include:
Thrombolysis +/- Stent placement.
Surgical removal of the 1st rib or cervical rib.
In all cases your consultant will advise you on the most appropriate form of treatment for you. They will answer your questions and explain the procedures to you.
Physiotherapy and Posture advice
TOS is commonly caused by poor posture and repetitive strain injuries. Physiotherapy increases the range of motion of the neck and shoulders, strengthens muscles and promotes better posture through stretching and exercises. Most patients experience an improvement in symptoms after undergoing physioptherapy. Your Vascular Alliance consultant will discuss the results of any investigations you may have had and organise a referral to a physiotherapist if that is the most appropriate treatment for you.
What is it?
Anticoagulation is used as a treatment for partial or complete blockage of the subclavian or axillary vein (a form of “deep vein thrombosis” – DVT) as a result of TOS. It is the use of medications to reduce the formation of further clots in the blood and is commonly referred to as “thinning the blood”. Different types of drug can be used including Warfarin and Heparin. They do not break down the clot in the vein but help prevent it increasing in size or forming new clots. They also greatly reduce the risk of a pulmonary embolus (PE – blood clot in the lung) developing. Your body will naturally break down the blood clot over the coming months. All patients with evidence of venous TOS should be started on some form of anticoagulation which may or may not precede further surgical treatment.
How is it given?
Warfarin – is the most commonly used anticoagulant. It is a tablet that takes a few days to work fully. To provide some protection early on until warfarin is totally effective, heparin injections (usually given just under the skin) are used concurrently for up to 5 days.
Once you have started warfarin you will need regular blood tests to check your “INR” which is a measure of clotting. A normal INR is 1.0. The higher the INR the thinner the blood, and the lower the INR the more sticky it is. You need the tests quite often at first, but then less frequently once the correct dose is found. An INR of 2.5 is the aim if you have warfarin for a DVT, though anywhere in the range 2 – 3 is ok. If you have had recurrent DVTs, or have had a PE whilst on warfarin, you might need a higher INR (2.5 – 3.5). A specialist nurse and your GP will oversee your blood tests and warfarin dosing.
If you are pregnant, regular heparin injections rather than warfarin tablets may be used. This is because warfarin can potentially cause harm (birth defects) to the unborn child.
Heparin – can be given in 2 forms:
Injections under the skin given once a day. Often used to provide immediate blood thinning whilst warfarin takes a few days to become effective.
Intravenous infusion. This requires hospital admission and is often used in more serious cases where patients need to be closely monitored.
How long will you require Anticoagulation?
Duration of anticoagulant therapy is dependent upon a number of factors. These include where the clot is, whether risk factors are permanent or temporary and whether this is a first–time or recurrent clot. As a rule:
Deep vein thrombosis of the arm requires 3 months of anticoagulation.
Deep vein thrombosis of the arm + clotting defects requires 6 months of anticoagulation.
Recurrent deep vein thrombosis of the arm requires lifelong warfarin OR until surgical treatment (e.g removal of 1st rib or cervical rib) is performed.
Success rates with Anticoagulation
The clot seen in deep vein thrombosis is broken down by your body over time. Anticoagulation is not a treatment as such but has been proven to be effective in reducing the risk of further DVTs and pulmonary emboli.
Risks of Anticoagulation
The main risk of anticoagulation is that the blood is thinned too much so that patients bleed easily. This can present in a range of ways including bruising easily, nose bleeds, bleeding from the bowel and in a minority of cases severe bleeds within the brain. Studies have shown that 8% of patients on anticoagulation will develop bleeding complications at some point. Anybody started on anticoagulation should be counselled about possible side–effects. Warfarin in particular can interact with other medications and foods. Your consultant will provide guidance but you will also be given a patient information leaflet that has lots of information to help you.
Thrombolysis +/- Stent placement
This procedure is known as “catheter directed thrombolysis”. You will be taken into the radiology treatment room and asked to lie down for the procedure. Some local anaesthetic will be injected around the site where the small tube (catheter) is to be inserted. This may sting but the area will quickly go numb. The radiologist will then insert the catheter into an easily accessible vein of the ankle, groin or elbow.
The catheter allows x–ray dye called “contrast” to be administered into the vein. A series of x–rays are then taken to confirm the position and extent of the DVT. The contrast will give you a warm feeling each time it is given which is entirely normal.
A fine guide wire is placed down the catheter and x–rays are used to guide its passage along the vein and through the clot. A small tube is then fed over the guide wire till it is sitting in position. It has a series of small holes in its tip so that once connected a thrombolytic drug can be slowly administered directly to the clot. This drug is given for up to 72 hours in order to dissolve the clot. Consequently, the tube delivering the drug is left in place for this time period. The guide wire and catheter are removed.
Once the procedure is complete, a stitch will be placed in the skin of the puncture site to hold the tube delivering thrombolytic agent in place. It will be covered with a dressing and you will return to the ward.
After the Procedure
The tube delivering thrombolytic agent will stay in place until treatment is complete or for up to a maximum of 3 days.
During this time, an ultrasound scan (venous duplex) will be repeated to assess clot breakdown and blood flow within the affected vein.
Once treatment is complete the tube is removed (painless) and pressure applied to the puncture site for a few minutes to stop any bleeding.
You should drink plenty of water for 2 days after the procedure to flush the contrast dye out of your kidneys.
You can shower 24 hours after treatment but should avoid baths for the first 3 days.
When you get home, you should check your wound regularly. You may have some bruising, but if swelling develops, or the area becomes hard to the touch or painful you should contact your doctor. If your wound starts to bleed, you should press firmly on it. If it persists you should contact the hospital immediately.
Most patients can return to work and after a week.
You can drive when you are comfortable to perform an emergency stop. This is usually 1 week after the procedure.
You will need to continue anticoagulation treatment for a period of time after thrombolysis. This is usually in the form of warfarin but your consultant will advise you appropriately.
Your consultant will organise a follow–up appointment with you after 3 weeks to discuss your treatment and assess your recovery.
Success rates with Thrombolysis
Thrombolysis is successful in 70 – 80% of cases. Medical trials have shown that thrombolysis has certain advantages over anticoagulation. Thrombolysis dissolves clots more effectively so that complete clot breakdown occurs more often than with standard anticoagulant therapy. Blood flow in the affected vein is also better maintained. Two trials continued for over six months found that fewer people developed post–thrombotic syndrome when treated with thrombolysis, 48% compared to 65% in the standard anticoagulation treatment group. However, those receiving thrombolysis have more bleeding complications than with standard anticoagulation (10% versus 8%).
Risks of Thrombolysis
Thrombolysis is an effective treatment but complications can happen in up to 10% of patients. Potential risks can be divided into the following categories:
The puncture site:
Some bruising is common after a vein puncture.
Some oozing of bloody fluid around the puncture site can occur which responds to firm pressure or redressing of the site.
Very rarely significant bleeding from the vein or blockage of the vein can occur which may require firm pressure. In 1% of cases a large amount of blood collects under the skin (known as a “haematoma”) and this may require a small operation to remove it.
Related to the contrast::
Some patients experience an allergic reaction to the X–ray contrast. In most cases this is minor but very rarely (1 in 3000) a reaction may be severe and require urgent treatment with medicines.
The x–ray contrast can, in some patients, affect the kidney function. If you are likely to be at risk of this, special precautions will be taken to reduce the chances of this problem occurring. If you are a diabetic on Metformin tablets, you should not take this on the day of the procedure and for 48 hours after the procedure.
Related to the treatment:
The procedure may not work in a small number of cases.
The clot can re–accumulate after thrombolysis has finished in a very small number of cases. This risk is greatly reduced by continuing anticoagulation treatment.
Despite the tube being sited within the clot some of the thrombolytic drug still escapes into general circulation. This can cause bleeding from a number of locations.
A stent is a tube that can be placed inside a vein or artery and is designed to hold it open. They are used after thrombolysis in some cases because veins that have been compressed for a long period of time are at high risk of forming recurrent clots. The stent holds the vein open ensuring normal flow of blood along the vein which greatly reduces the formation of further DVTs. A stent can be placed in a procedure identical to thrombolysis except that the guide wire helps place the stent across the narrowed vein.
Surgical removal of the 1st rib
What is it?
This is a surgical procedure that detaches one of the scalene muscles from the 1st rib and then removes a section of the rib completely. By doing this any compression that these structures were causing is relieved and symptoms resolve. It is performed under a general anaesthetic and takes approximately 1 hour to complete. Most patients will go home in the day or two after surgery.
Before your Operation
You will be seen several weeks before your treatment for a pre–operative assessment. A number of blood tests will be taken and you will have a chest x–ray and an ECG (tracing of the heart rhythm).
You will be admitted to the ward the day before or the morning of your surgery. As you will have a general anaesthetic, you should not eat for 6 hours prior to treatment. However, you may drink “clear fluids” like water up to 2 hours before.
Your surgeon will visit you before the operation and ask you to sign a consent form once he has explained the procedure to you.
How is surgical excision of the 1st rib performed?
Once you are asleep you will be taken into the operating theatre. A small cut about 3 – 5cm long is made in the hairline of the armpit. The surgeon carefully dissects into deeper tissues to expose the 1st rib, scalene muscles, blood vessels and nerves. One of the scalene muscles is then cut off the first rib. A 5cm section of the first rib is then carefully removed. Once any bleeding is controlled the wound is closed with stitches of which those in the skin dissolve and do not require removal. A small drainage tube may be left in the wound and held in place with a stitch in the skin. Once complete you will wake up in the recovery room.
After your Operation
It takes a couple of hours to recover from the anaesthetic. You will be given painkillers and anti–sickness medications if required.
You will be given something to eat and drink soon after the operation and encouraged to get up and about when you are comfortable.
A chest x–ray will be performed routinely after the operation to look for any air sitting between the lung and chest wall (a pneumothorax).
The drainage tube will be removed the morning after surgery provided it has not collected too much fluid.
Most patients will go home the day after the procedure.
The procedure causes some discomfort where incisions have been made. Most patients can get back to work 2 – 5 days after the procedure.
You can shower 2 days after the procedure. If the wound is clean and dry no further dressings are required.
Gentle exercise can be undertaken after 3 – 4 days or when you are comfortable.
You can fly 2 weeks after your procedure.
Success rates with 1st rib removal
Removal of the 1st rib is a very important treatment that definitively excises one of the major structural causes of TOS. Symptom recurrence rates have been quoted as 10% at 5 years and these were mostly neurogenic cases. The recurrence of venous or arterial symptom recurrence is much lower. Given these are much more serious forms of the condition this represents an excellent treatment modality.
Complications with 1st rib removal
Risks that are standard for any form of surgery include post operative bleeding and wound infections which affect up to 5% of patients. These are easily treated in the vast majority of cases. Patients will also be left with a small scar in the arm pit. It is usually placed in the hairline or in a skin crease and infrequently causes cosmetic issues. Serious complications are very rare but patients should be aware of them:
Pneumothorax – Seen in 10% of patients, a pneumothorax is a residue of air remaining between the lung and the chest wall. Small amounts of air are generally reabsorbed naturally over the following days and need no further treatment (the patient should, however, avoid taking a flight during the next day or as long as the pneumothorax persists). Greater amounts (very infrequent) may require suction drainage for a day or two.
Haematoma – A blood clot within the soft tissues is uncommon. It may be associated with bruising and will be naturally reabsorbed by the body over time.
Injury to the major Veins and Arteries – this occurs very rarely during the operation and can lead to significant bleeding. It will be dealt with appropriately whilst you are still asleep. In a tiny percentage of cases a blood transfusion may be required.
Injury to Nerves – Some of the small nerves supplying the skin around the armpit and chest wall may be cut during the operation. This can result in numbness or tingling in small areas of skin which will resolve in the coming 1 – 2 months. Injury to other major nerves in the armpit and the field of surgery is more serious but rare.
Failure of the Procedure – occurs in under 5% of cases and is usually due to not enough of the 1st rib being removed. The procedure can be repeated if required.