Thoracic Outlet Syndrome (TOS)

Thoracic Outlet Syndrome

Thoracic Outlet Syndrome Overview

The thoracic outlet, the space between your lower neck and upper chest, can at times become compressed, injured, or irritated, as a result leading to complications with the nerves and blood vessels that run through this outlet.

Types of Thoracic Outlet Syndrome 

  1. Neurogenic Thoracic Outlet Syndrome: Characterized by compression and irritation of the brachial plexus, this is the most common type of Thoracic Outlet Syndrome (TOS) disorder, representing 95% of cases. The brachial plexus which derives from the spinal cord is responsible for controlling muscle movement and feeling in the arm, shoulder, and hand. Symptoms include include weakness or numbness in the neck, chest, arms, and/or hands, as well as decreased muscle size in the hand.
  2. Vascular Thoracic Outlet Syndrome: This condition can be broken down into 2 subcategories and is not very common, making up 2-5% of cases. Venous thoracic outlet syndrome, which is caused by damage to the veins (venous) in the lower neck and upper chest region and arterial thoracic outlet syndrome, which is caused by bony abnormalities in the lower neck and upper chest present at birth which leads to compression of the artery.TOS


A variety of factors can lead to compression of the thoracic outlet:

  • Anatomical Defects: For instance, an extra rib that is present at birth leads to increased compression on the nerves and blood vessels.
  • Poor Posture: Rounded shoulders and increased flexion of the cervical and thoracic spine can lead to compression of the thoracic outlet.rounded shoulders
  • Injury: A car accident or trauma to the neck region can cause changes to the anatomical layout of your bones leading to increased compression.
  • Repetitive Shoulder Movement: Swimmers, baseball players, golfers, and volleyball players are all examples of athletes who are at risk of TOS due to repeated movement of the arm and shoulder, for instance.
  • Pregnancy: Due to the joints loosening during pregnancy, Thoracic Outlet Syndrome may start to develop.
  • Tumors: Both tumors and large lymph nodes in the upper chest area can lead to Thoracic Outlet Syndrome.


Signs and symptoms of Thoracic Outlet Syndrome will differ depending on the type of disorder present:

Neurogenic Symptoms:

  • Numbness or tingling in the arm or fingers
  • Pain in neck, shoulder, or hand
  • Weak grip
  • Decreased size of hand muscles

TOSVascular Symptoms:

  • Swelling in hands, fingers, and arms
  • Heavy and weak neck and arms
  • Swollen or dilated veins in the anterior chest wall
  • Poor blood circulation in the arms, hands, and fingers
  • Numbness in hands and fingers
  • Cold sensitivity
  • Discoloration of the hand
  • Possible pain due to blood clots
  • Weak or no pulse in the affected arm
  • Arm fatigue
  • Throbbing lump near the collarbone

Risk Factors 

A couple of risk factors that seem to increase the odds of developing TOS are sex and age. Both females and young adults between 20 and 40 years of age are more likely to develop TOS.

In addition, poor muscle development and poor posture result in an increased risk of developing Thoracic Outlet Syndrome.

Lastly, jobs or sports activities that require repetitive overhead movements may result in an increased risk of developing Thoracic Outlet Syndrome.


If TOS goes untreated for a lengthy period of time, a few complications can develop:

  • Nerve damage
  • Permanent arm swelling
  • Permanent pain in the arm
  • Blood clot blood clot
  • Pulmonary embolism (obstruction in the blood vessel)
  • Gangrene (death of body tissue due to the lack of blood flow)

Diagnosis & Test

Tests used to properly diagnose TOS include:

  • Physical exam
  • Imaging and nerve study
    • X-Ray (checks for abnormalities such as an extra rib)
    • CT or MRI scan (checks for compression of blood vessels)
    •  Venogram (uses dye to make blood vessels more visible in order to check blood flow)
    • Nerve conduction study (test for nerve damage by using a small amount of electrical current to measure the nerves’ ability to send impulses)


Depending on the severity of Thoracic Outlet Syndrome, there are a few recommended treatments:

  • Physical therapy and exercise: Therapy and exercises are prescribed in order to assist in opening up the thoracic outlet that is being compressed. Check out these stretches and exercises  to strengthen the shoulder and improve posture. Most successful for neurogenic Thoracic Outlet Syndrome.
  • Medications: Anti-inflammatory and pain medications are prescribed to reduce swelling and pain.
  • Clot-dissolving medication: Due to an increased risk of blood clots for those with vascular TOS, thrombolytics (clot-dissolving) and anticoagulants (clot-preventing) are used to prevent complications from blood clots.
  • Surgery: Most often used for those with vascular TOS, the primary objective is to identify and correct or remove the source of compression. Surgery is said to be very effective for those with vascular Thoracic Outlet Syndrome according to this Cleveland clinic.
    • Transaxillary: Used to remove a portion of the first rib to release compression
    • Supraclavicular: Repairs compressed blood vessels as well as removing muscles responsible for compression
    • Infraclavicular: Used to treat compressed and damaged veins that need repair