“Thoracic outlet” is the medical term for the space between the collarbone and first rib (lower neck and upper chest). The nerves and blood vessels that serve the arms and hands run through these spaces. If the neighboring muscles or bones press too hard against these nerves or blood vessels, thoracic outlet syndrome (TOS) occurs.

TOS symptoms vary depending on what is being compressed:

If nerves are compressed, this can cause shooting pain down the arms and numbness. This is called neurogenic TOS, which is most common.

If the subclavian vein is compressed, the entire arm will swell considerably. This is called venous TOS, and it’s less common but much more serious.

If the subclavian artery is compressed, it can block blood flow to the affected arm. This is extremely dangerous and requires emergency surgery to restore circulation. Fortunately, arterial TOS is very rare.

What causes this compression?

According to Virtua vascular surgeon Ashish Bedi, MD, the vast majority of TOS sufferers are young, active people, particularly weight lifters (building up the chest/shoulder muscles) or those playing sports that involve the arms frequently going above the head (such as in baseball or volleyball). Other TOS risk factors include certain anatomical defects, pregnancy, repetitive job-related activities, and trauma (such as a car accident).

Dr. Bedi performs surgery on people affected by venous and arterial TOS, but only rarely on those with neurogenic TOS. This is because surgery is not necessarily effective in treating neurogenic TOS. “Surgery provides long-term relief of neurogenic TOS symptoms in only about half of those affected,” says Dr. Bedi. Conservative treatments like physical therapy and medication are preferable alternatives for most people with neurogenic TOS.

Surgery, however, is essential for treating venous or arterial TOS, and can be an option for more severe cases of neurogenic TOS that don’t improve with conservative treatment.

What you need to know about TOS surgery

• TOS surgery involves removing a portion of the first rib.
• For venous and arterial TOS, the surgeon also repairs the affected blood vessel during the procedure.
• The incision to access the thoracic outlet is made in one of three places: the armpit, above the collarbone, or below the collarbone.
• Nerve damage is the most notable risk of TOS surgery.

After a successful procedure, however, recovery is usually swift. “My patients almost always go home the day after surgery,” says Dr. Bedi. As for the piece of rib that’s removed: “There won’t be any detectable physical deformity. You’ll never notice it’s gone.”