The thoracic outlet describes the bones that permit structures to pass from the chest to the neck and arms. It comprises the clavicle (collar bone), the 1st rib, the scapula and the vertebral column. Imagine a ring of bones sitting at the top of your chest – this is your thoracic outlet. It is a tight space, and things tend to get squashed in some people!
Some patients have anatomical abnormalities predisposing them to thoracic outlet syndromes, such as additional ribs (a cervical rib) or, anatomical abnormalities in which certain muscles specific from the neck to the ribs (scalene muscles) or abnormal fibrous bands are born with. These patients are more likely to develop thoracic outlet syndrome.
Arterial thoracic outlet syndrome (ATOS)
Venous thoracic outlet syndrome (VTOS)
Neurogenic thoracic outlet syndrome (NTOS)
Arterial thoracic outlet syndrome is a rare condition. In ATOS, there is damage to the large vessel that delivers blood from your heart to either arm (the subclavian artery). It passes over the first rub and under the clavicle. When you raise your arm overhead, the space between your first rib and clavicle narrows, which can squash the artery. After years of repeated squashing, the artery wall can get damaged and form an aneurysm. These aneurysms can damage the blood flow down the arm. They can block and mean your arm doesn’t have enough blood, or the aneurysm can burst and cause massive bleeding. Usually, patients with ATOS have some anatomical abnormality, such as an additional rib mentioned in the introduction.
It is such a rare presentation that there is no standard pattern. The main presenting symptoms are:
All patients require surgery to repair the damaged artery and free up space in the thoracic outlet by removing some bony and muscular structures. Surgical correction is invasive surgery that carries significant risk.
A similar issue occurs with the sizeable subclavian vein as does with the subclavian artery. It gets squashed repeatedly and develops scarring and webs within the vein, which prevent the blood from returning to the heart from the arm. Eventually, if someone spends a prolonged time with their arm over their head, the vein may stay blocked for long enough that they develop a large blood clot in their arm.
The decision to have surgery on a venous thoracic outlet syndrome is a discussion that takes around 30 minutes and is best untaken face to face.
In an attempt to summarise, the options are:
This condition describes numbness and pain to the nerve trunks that exit the spine up in the neck and traverse down the arms through the thoracic outlet.
Many people develop symptoms of NTOS. However, there are many causes unrelated to the tight space. Generally, physiotherapy and a conservative approach are preferred, as surgery for the issue is aggressive and can lead to problems.
Three bedside examination tests are used to elicit symptoms and point towards the diagnosis of NTOS, as listed below. They are performed by a vascular surgeon when you have your consultation.
Nerve conduction studies are usually used to rule out other nerve compression issues, such as carpal tunnel syndrome
A local anaesthetic block of the scalene muscle (muscle in the neck that sits between the spine and the collar bone) can be used to help diagnose the condition, as complete resolution of symptoms after injection of the anaesthetic confirms the likely benefit of decompressing the nerve at that level with surgery.
The first rib is removed through one or two incisions, either above the clavicle, below the clavicle, or a combination. Some vascular surgeons use an incision through the armpit as another way of getting to the first rib.
Multiple structures need to be navigated in the procedure. There is a nerve that makes one-half of your diaphragm move. If this is damaged, only one lung will inflate when you breathe. Other nerves are involved in your arm’s function and can rarely be damaged from retraction. The large subclavian artery and vein can be injured, which can lead to severe bleeding. The lining of the lung sits right beneath the first rib. This can sometimes be torn when removing the rib, which causes air to on the outside of the lung and collapses a portion of the lung, requiring a tube in the chest to drain the air (pneumothorax). There are lymphatic vessels that traverse the space, particularly on the left, which, if damaged, can lead to an accumulation of milky lymph fluid, which can take months to resolve.
Consulting locations
WOLLONGONG
Artery and Vein Clinic
402 Crown St
Wollongong
NSW 2500
GREGORY HILLS
Artery and Vein Clinic
Soma Centre
Suite 8/7, Gregory Hills drive
Gregory hills
NSW 2557
Orange
Artery and Vein Clinic
117 Molder st
Orange
NSW 2800
Contact Info
Wollongong
Phone: (02) 4226 9333
Fax: (02) 4229 4006
Gregory Hills
Phone: (02) 4601 1055
Fax: (02) 4601 1058
Orange
Phone: (02) 4601 1055
Fax: (02) 4601 1058
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