Thoracic outlet syndrome, also known as TOS, is a condition that causes symptoms in the arm due to pressure on the structures running between the collarbone and the first rib (the thoracic outlet). Generally, it is confused with other conditions that cause pressure on nerves and blood vessels in the neck and arm. One cause of TOS is cervical rib syndrome, but there are other causes. What is thoracic outlet syndrome, and how do we treat it?
What is a cervical rib?
Ususally, the rib cage contains 12 ribs. A cervical rib is an extra rib from the cervical spine that sits above the first rib. These extra bone growths form from the transverse processes of the C7 vertebrae. They occur in less than 1% of the population. Most of these extra bones don’t cause problems. However, in some cases, they compress the thoracic outlet, contributing to the development of thoracic outlet syndrome.
Thoracic outlet syndrome
A complex set of nerves and vessels passes through a hole or ‘outlet.’ The boundaries of the hole are the first rib of the chest wall, the collarbone, and the muscles of the neck (called the scalene muscles). Pressure on these structures can cause symptoms ranging from a pinched nerve (leading to numbness, pins and needles, and weakness) to pinched vessels (causing swelling, discolouration, and changes in temperature).
Causes
Causes of pressure in the outlet can be traumatic or overuse. Examples of trauma include a break in the collarbone, leading to pressure from a bone sticking into the outlet. Overuse conditions include repetitive overhead movements or participation in certain sports. Sometimes, people with an extra rib, called a cervical rib, can narrow the outlet.
How to diagnose thoracic outlet syndrome
Symptoms depend on the type of compression you have. Generally, we think there are three varieties of compression:
- Neurogenic compression is caused by the pinching of the brachial plexus nerves, leading to symptoms such as pins and needles, numbness, clumsiness, or weakness in the hand. Sometimes pain can extend to the chest, under the armpit, or to the head.
- Arterial compression is caused by the compression of a large artery or the subclavian vein, resulting in coldness, numbness, and pain in the finger.
- Venous compression caused by pressure on the vein leads to swelling of the arm, an increase in the size of chest veins, and a heavy sensation in the arm.
Generally, we recommend a thorough examination to confirm our assessment and rule out other potential causes. Firstly, we begin with a comprehensive evaluation of the neck, arm, and wrist. Pressing on the compressed structures in the neck or chest can produce symptoms. Next, we use a group of tests, including Roos’ and Adson’s tests, to assess the strength of the wrist pulse in various arm positions. A loss of a wrist pulse suggests TOS. Additionally, nerve testing is crucial for identifying a pinched nerve and other potential causes of your symptoms.
Generally, tests such as MRI of the neck and outlet, nerve studies, and vascular studies are performed. Sometimes, a local anaesthetic injection near the neck can help localise the pressure site.
Difficult diagnosis
Often, making a diagnosis can be challenging. Early symptoms are similar to other conditions, such as
- Pinching of the nerves in the arm or wrist, such as carpal tunnel syndrome or cubital tunnel syndrome
- Nerve pinching in the neck from a herniated disc
- Inflammation of the nerves of the brachial plexus is also called brachial neuritis.
Thoracic outlet syndrome vs. cervical radiculopathy
Differentiating between these two conditions is challenging. Generally, people with cervical radiculopathy have a painful neck, and movement of the neck brings on the pain. Additionally, a herniated disc does not typically cause vascular problems, such as discolouration, swelling of the arm, or fatigue with arm movement. Nonetheless, it remains challenging to distinguish between these conditions.
Treatment
Cervical rib syndrome
If a cervical rib is causing compression of the thoracic outlet, physiotherapy can help improve neck mobility and reduce muscle tension in the affected area. Other treatments include injections, such as Botox or local anaesthetic, into the scalene muscles to reduce muscle tension.
Surgical excision is performed if these methods fail to reduce pressure on the nerves or vessels. Sometimes, excision of the scalene muscles is also used to open the outlet further and relieve pressure. Some surgeons think you need to excise both the cervical and the first rib to get the best results.
Thoracic outlet obstruction
Generally, simple treatments are tried first, particularly in the neurogenic type of condition.
Examples of simple treatments that your physiotherapist may try include soft tissue massage and stretching of the muscles surrounding the outlet. Targets include the pectoral, trapezius, and scalene muscles. Additionally, strengthening the shoulder and rotator cuff muscles can improve posture and reduce pressure in the outlet. Finally, nerve gliding techniques for the upper limb will help loosen the nerves and prevent them from becoming entangled.
Secondly, medications for nerve pain might help reduce pain symptoms. Examples include amitriptyline or duloxetine.
Thoracic outlet syndrome sleeping position
It is important to avoid sleeping positions that increase the pressure on the outlet. Generally, we recommend sleeping on your back or with two pillows on the affected side to prevent compression of the outlet.
Thoracic outlet syndrome Surgery
If left untreated, permanent damage can occur to the nerves and vessels of the outlet. Sometimes, blood clots can form in the veins, putting your life in danger. Generally, we recommend surgery if 3-6 months of physiotherapy fail or you develop signs of vessel compression.
Final word from Sportdoctorlondon on cervical rib and thoracic outlet syndrome
Thoracic outlet obstruction is a complex condition to diagnose. It is often confused with other conditions, such as a herniated disc in the neck or carpal tunnel syndrome. But, significantly, early diagnosis can reduce permanent damage to the nerves and vessels.
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