Thoracic Outlet Syndrome

Thoracic outlet syndrome (TOS) is a condition caused by compression of the nerves and blood vessels as they exit the chest to supply the arm. This triangular region, bordered by the neck muscles, first rib, and clavicle is referred to as the thoracic outlet.

There are three main types:

• Neurogenic TOS is the most common and presents with pain, weakness, and occasionally muscle wasting
• Venous TOS results in swelling, pain, and discolouration of the arm
• Arterial TOS results in pain, coldness, and altered blood flow

Any condition that causes encroachment of the space for the nerves and vessels at the thoracic outlet can lead to thoracic outlet syndrome, including poor posture. It is more common in females. Other factors include:

• Congenital: developmental abnormalities around the vessels and nerves
• Post-Traumatic: history of trauma to the area (e.g. clavicle fracture, whiplash, shoulder)
• Functional: Repetitive lifting of the arm above the head (e.g. painter, swimmer)

Symptoms of TOS depend on the region of compression . Nerve pain is the most common presentation and occurs predominantly in women aged 20–40 years. Swelling and pain from deep vein thrombosis (DVT) are the most common symptoms of venous compression. Those with arterial symptoms present with pain especially during exercise or cold, pale fingers. Arterial aneurysms may be formed by compression on the vessel.

Arterial and venous duplex ultrasound with provocation manoeuvres is used to dynamically assess vascular compression within the thoracic outlet. Other investigations can include nerve tests, such as Electromyography (EMG) and plain X-ray of the region. MRI is of limited value except when a tumour is suspected. The use of ultrasound in different arm positions can show problems in flow or an aneurysm caused by pressure in the shoulder.

• Surgical
  Open surgical treatment to free the space and release the pressure on the nerves, artery or vein is the treatment of choice. The blood vessel can also be repaired at the same time.

• Medical
  Muscle injections also play a role as a therapeutic tool in patients with nerve compression. Trauma patients who receive this treatment, particularly those treated soon after onset of symptoms, experience better results.

• Rehabilitation
  Despite the high rate of success with minimal complications associated with surgery, other options such as physiotherapy, modifications to daily activities and medications are all options in treatment.

Thoracic Outlet Syndrome remains a challenging entity to diagnose but treatment outcomes can be very successful and long-lasting given the correct patient selection.