What is thoracic outlet syndrome?

Thoracic outlet syndrome (TOS) occurs when the vessels and/or nerves running from the upper body to the arm become compressed, leading to swelling, reduced blood flow, tingling, weakness, pain and/or numbness in the neck, shoulder, arms or hands. It is caused by trauma, repetitive movements, exertion, anatomic narrowing of the muscles or congenital conditions. If left untreated, the pain can worsen and upper-extremity function may decrease. Certain forms of the disease can lead to limb- and life-threatening blood clots.

Basic Anatomy of thoracic outlet syndrome

There are three types of TOS:

  1. Arterial, which involves compression of the subclavian artery as it exits the chest and travels to the arm.
  2. Venous, which involves occlusion of the subclavian vein as it enters the chest cavity from the shoulder.
  3. Neurogenic, which involves compression of one or more brachial plexus nerves running from the neck to the hands.

Symptoms of thoracic outlet syndrome

TOS may cause:

  • Neck, shoulder or arm pain
  • Numbness in the arm, hand or fingers
  • Impaired circulation to the extremities (causing discoloration)
  • Weakness in the shoulders, arm, and hands
  • Swelling of the entire arm and shoulder

Risks of thoracic outlet syndrome

Musicians, athletes (especially those who train their upper bodies with weights), and employees who continuously use their lower neck and upper chest muscles are particularly at risk of TOS. The disorder is also linked with extra cervical ribs or abnormal ribs that are present from birth, as well as poorly healed whiplash, collarbone or first-rib injuries.

Thoracic oulet syndrome diagnosis

TOS can mimic other disorders and is difficult to diagnose by health providers who aren’t familiar with its specific symptom profile. Expert vascular specialists can identify TOS through:

  • A comprehensive medical history and physical exam
  • Stress tests to determine how long the arms and hands can be held above the head and complete certain movements
  • Examination of the anterior scalene muscle in the neck, which might be tender
  • An ultrasound scan to determine arterial compression or venous occlusion
  • Imaging studies such as X-rays and CT (computed tomography)

Treatment for thoracic outlet syndrome

Treatment plans are tailored based on the type of TOS and length of symptoms and can encompass conservative therapies and surgery. Nonsurgical approaches include:

  • Physical, massage and exercise therapy to strengthen and align the back and shoulders
  • Ergonomic evaluations to assure that patients are sitting at desks and using computers in correct positions
  • Pain management with nerve-blocking agents, Botox and/or acupuncture 

In cases involving blood clots or when non-surgical treatments fail, surgery is the best option. A unique procedure championed by a UC Davis vascular surgeon involves making an incision in the armpit and removing the anterior scalene muscle in the neck and first rib, immediately reducing nerve or vessel compression and improving arm symptoms. The hospital stay is typically overnight.

Follow-up care is dependent on the type of TOS. Venous TOS patients undergo a venogram — an X-ray using contrast dye — to make sure vessels are not narrowed two weeks after surgery with ultrasound exams for up to one year. These patients also require a short course of blood thinners. Patients with arterial TOS require ultrasound evaluations following surgery at regular intervals. All TOS patients require at least two months (sometimes up to a year) of physical therapy to build up the shoulder muscles.