Thoracic outlet syndrome is a rare condition caused by compression of blood vessels and nerves in the area of the clavicle (collar bone). This compression is caused by the presence of an extra cervical rib (above the first rib) or an abnormal tight fibrous band connecting the spinal vertebra to the rib.

People with long necks and droopy shoulders may be predisposed to develop this condition because of extra pressure on their nerves and blood vessels.

The following symptoms may indicate thoracic outlet syndrome:

• Discomfort in the last 3 fingers and inner forearm
  • Numbness
  • Pain
  • Tingling
• Pain and tingling in the neck and shoulders (may be worsened by carrying something heavy, such as a suitcase)
• Weakness and wasting of the muscles of the hand

Upon lifting, the arm may appear pale due to compression of the blood vessels. The arm may be smaller on the side of the symptoms, as this is a congenital anomaly (present since birth).

Tests to confirm the diagnosis include the following:

• X-ray (may reveal the extra rib)
• MRI (may reveal fibrous band)
• Nerve conduction velocity study
• Electromyography (EMG)

The syndrome is treated with physical therapy to strengthen the shoulder muscles.

Surgery to remove the rib or cut the band has also been tried. There is no good evidence that this is effective, and there have been reports of some patients' sympoms becoming worse after surgery. However, some carefully selected patients with demonstrated nerve conduction disorders may benefit from surgery.