Thoracic outlet syndrome also known as TOS is a term that refers to a group of conditions where either the subclavian vein, artery or the nerves of the brachial plexus are compressed in an anatomical location called the ‘Thoracic Outlet’. The thoracic outlet refers to the space between the left and right first rib, the sternum at the front and the spine at the back.
The main artery, vein and nerves supplying the arm passes over the top of the first rib. The space through which these structures pass is quite narrow and can be further compressed if some of the large muscles of the neck are enlarged due to exercise. The nerves can also be irritated by scarring as a result of trauma to the area. The symptoms of Thoracic Outlet syndrome are dependent on the type of TOS neurogenic, venous or arterial.
Symptoms of thoracic outlet syndrome
Arterial thoracic outlet typically has symptoms of pain in the arm when exercising, coolness, pins and needles in the fingers or a pale arm. This is due to a lack of blood supply getting into the arm.
Venous thoracic outlet tends to present with a painful swollen engorged arm. This is due to the significant compression on the vein causing a clot in the vein also known as a deep venous thrombosis (DVT).
The symptoms of neurogenic thoracic outlet syndrome are more varied but usually involve pain or tingling and numbness in the upper arm especially with certain movements. There is usually a history of significant trauma to the lower portion of the neck prior to the symptoms styling.
Thoracic outlet syndrome often affects healthy active young people as it is caused by either significant muscle size or trauma.
Diagnosing Thoracic Outlet Syndrome
A thorough medical history and a physical examination will be performed particularly focusing on upper limb symptoms. A history of pain when using the arm as well as DVT will need to be elicited.
Depending on the type of thoracic outlet syndrome that is suspected further investigations will likely need to be explored.
Arterial venous thoracic outlet
Vascular ultrasound – ultrasound of the veins and arteries is performed to look for compression when the arm is moved into different positions.
MRI – to assess the structures of the neck for anatomical variants that may be the underlying cause
CT – to look for other anomalies within the arteries
Anterior scalene muscle injection test – this may be performed if the diagnosis is uncertain and is used to mimic temporarily the outcomes from surgery.
Neurogenic thoracic outlet
Neurogenic thoracic outlet is typically much more difficult to diagnose.
Nerve conduction studies – performed to locate where the issue is in the nerves of the upper arm
MRI scan – to look for anatomical variants that may be the underlying cause
Scalene or pectoralis minor muscle block – this is performed to confirm the diagnosis if there is any uncertainty.
Treatment
Treatment for thoracic outlet syndrome depends on the type that is suspected.
Most patients are able to be treated with conservative measures however first rib resection may be recommended in some cases. The purpose of the first rib resection is to relieve the compression on the structures as they pass over the first rib.
Arterial thoracic outlet syndrome
Often arterial thoracic outlet syndrome has an abnormality. Removal of the first rib and/or other abnormal structures will often give excellent results in this situation. If there has been damage to the artery this will need to be repaired at the same time as the rib resection.
Venous thoracic outlet syndrome
Resection of the first rib is reserved for patients who have had an upper limb DVT in the setting of venous thoracic outlet syndrome. Many patients are found to have venous thoracic outlet on an ultrasound scan however many of these remained asymptomatic in the long term and can be managed conservatively.
Neurogenic thoracic outlet
Neurogenic thoracic outlet syndrome can often be managed conservatively. Specialist physiotherapy is indicated in all patients with suspected neurogenic thoracic outlet syndrome. First rib resection is reserved for a smaller subset of patients in whom it is suspected will have the best benefit from the surgery.
Consultation
During your initial consultation Dr McGlade will take a thorough history and examination in an attempt to diagnose your thoracic outlet syndrome. You may need to progress onto further investigations such as ultrasound or nerve conduction studies following this. Once the results of all your investigations are returned Dr McGlade will tailor a treatment plan specific to your needs and this may include medications for pain relief, physiotherapy or surgery.