Thoracic Outlet Syndrome

What is Thoracic Outlet Syndrome, what causes it, how is it diagnosed, and what are the available treatments?

Thoracic outlet syndrome is a poorly understood syndrome that presents with pain, numbness, and tingling in the upper extremity. The cause has been considered to be a compression of the neurovascular bundle between the first rib, clavicle, and the scalene muscle. This neurovascular bundle consists of the subclavian artery, the vein, and the brachial plexus.

thoracic outlet

The cervical nerve roots of the brachial plexus descend from the cervical spine and merge into trunks and cords and ultimately form the peripheral nerves that goes to the upper extremities. The symptoms of the syndrome have been attributed to vascular and/or neurologic compression.


The symptoms of a person with thoracic outlet syndrome depend on whether the nerve, blood vessels, or both are compressed at the thoracic outlet. Sensory symptoms of nerve compression is the most common, with motor weakness less noted. The sensory symptoms are primarily pain and paresthesia. They are usually insidious in onset and are located in the neck, shoulder, arm, hand, and fingers.

Symptoms attributable to vascular compression include coldness, fatigability, numbness, and some pain. Venous compression is rare and may manifest as edema and bluish discoloration.


The triangle formed by the anterior acalene muscles, the middle scalene, and the first rib through which traverse the subclavian vessels and the brachial plexus remains constant in everyday activites. Symptoms of occlusion can result from various abnormalities such as the following:

  • accessory cervical rib, with or without fibrous extension, marrows the interscalene triangle.
  • the subclavian artery passes through, instead of passing behind, the anterior scalene muscle.
  • thickening of the fibrous band or fascial component of the triangle has occurred because of poor posture [round shoulder posture], hyperextension neck injuries. excessive repititive demands placed on the shoulder [like pitching] or other trauma.


Conservative treatment is the first line of treatment for many musculoskeletal conditions. In the case of thoracic outlet syndrome, physical therapy consult and treatment is mostly effective. Here are some things that a physical therapist would consider:

  • Stress management.
  • Habitual movement and changes in positions as opposed to one static position for long hours.
  • Mobilization and stretching of the cervicodorsal [thoracic] outlet as they may be thickened and contracted, which in turn immobilizes the scalene muscles affecting the excursion of the first rib.
  • Stretches of tightened muscles like the scalenes and pectorals muscles.
  • Strengthening of scapular muscles, particularly the scapular elevators.
  • Treatment program of the cervical spine through manual therapy can also be incorporated.
  • Ulnar nerve and radial nerve glides can be really helpful.