Is Thoracic Outlet Syndrome Serious?

The chest x-ray shows the compression of the nerves and blood vessels in the thoracic outlet.

Thoracic outlet syndrome refers to a group of conditions caused by the compression of nerves and blood vessels (neurovascular structures) in the thoracic outlet, which is the area of the upper chest between the collarbone and the first rib. 

There are three types of thoracic outlet syndrome:

• Neurogenic thoracic outlet syndrome, which affects the nerves – most common type, majority of cases
• Venous thoracic outlet syndrome, which affects the veins – second-most common type, about 3% of cases
• Arterial thoracic outlet syndrome, which affects the arteries – least common type, about 1% of cases

Symptoms of thoracic outlet syndrome depend on the neurovascular structure that is compressed. 

Symptoms of neurogenic thoracic outlet syndrome that affects the nerves include: 

• Pain
• Abnormal sensations such as burning or itching
• Numbness
• Weakness
• Symptoms are worsened by activities that require sustained use of the arms or hands or raising the arms or hands, such as reaching or lifting overhead and prolonged working at a computer or driving. Turning the neck, tilting the head, and extending or rotating the arm may also cause symptoms.
• Prolonged, severe compression can lead to muscle atrophy (rare) 

Symptoms of venous thoracic outlet syndrome that affects the veins include:

• Frequently occurs in people who perform vigorous repetitive actions of the arms, usually when the arms are above shoulder level
• Forearm fatigue within minutes of performing an activity
• Swelling of arms and hands
• Pain
• Bluish color to the skin of the affected extremity due to low oxygen
• Numbness and tingling in the fingers (usually due to swelling)
• Visible veins in the skin overlying the shoulder, neck, and chest wall
• Deep vein thrombosis (DVT)

Symptoms of arterial thoracic outlet syndrome that affects the arteries include:

• Usually associated with a cervical rib or anomalous rib (extra ribs that are a congenital abnormality)
• Loss of blood supply to the hand that causes pain, pallor, numbness, and tingling, and cold sensation
• Arm pain

There are two main causes of thoracic outlet syndrome - bony and soft-tissue factors. 

Bony factors include:

• Abnormalities such as anomalous cervical ribs (extra rib that is present from birth)
• Underdeveloped first thoracic ribs
• Abnormal bone growth of the first rib or clavicle, usually hereditary

Soft-tissue factors include:

• Abnormal fibrous muscular bands near the brachial plexus (congenital – present from birth)
• Enlarged muscles in athletes and weight lifters
• Lesions that take up space such as tumors or cysts
• Inflammatory processes in the soft tissues 

Trauma and stress to the neck, shoulders, or upper arms can also cause thoracic outlet syndrome.

After a physical exam, some tests may be ordered to rule out other conditions that can cause similar symptoms.

Blood tests to help exclude other diseases and causes of inflammation include:

• Blood glucose level
• Complete blood cell (CBC) count
• Erythrocyte sedimentation rate (ESR)
• Basic metabolic panel
• Thyrotropin level
• Rheumatologic workup

Imaging studies to help diagnose thoracic outlet syndrome may include:

• X-rays
• Computed tomography (CT) scans
• Magnetic resonance imaging (MRI)  
• Magnetic resonance angiography (MRA) 
• Arteriography/venography and duplex scanning 
• Ultrasound

A scalene muscle test injection may be used to help diagnose neurogenic thoracic outlet syndrome. 

Treatment for thoracic outlet syndrome depends upon the type, and is only needed in patients who experience symptoms of the condition. 

Treatment for neurogenic thoracic outlet syndrome may include:

• Physical therapy 
• Rest and passage of time 
• Weight loss
• Interscalene injection of anesthetic agents, steroids, or botulinum toxin type A (BTX-A)  

Treatment for venous neurogenic thoracic outlet syndrome may include:

• Anticoagulation/thrombolysis 
• Surgical decompression 

Treatment for arterial neurogenic thoracic outlet syndrome may include:

• Catheter-directed thrombolysis 
• Surgical embolectomy (with or without intraoperative thrombolysis) in conjunction with thoracic outlet decompression
• Arterial stenting

Complications of thoracic outlet syndrome may include:

• Blood flow problems (ischemic changes) 
• A blood clot in the lungs (pulmonary embolism)
• Upper extremity phlegmasia cerulea dolens 
• Nerve injury (e.g., brachial plexus neurapraxia) is a serious postoperative complication after thoracic outlet decompression
• Need for chronic anticoagulation
• Bleeding problems from the subclavian vessels and lymph leakage from the thoracic duct (uncommon)