Thoracic Outlet Syndrome

Pain, numbness, tingling, and weakness in your upper extremities may be a result of thoracic outlet syndrome (TOS). This condition stems from impingement on a network of nerves called the brachial plexus or impingement of the large blood vessels that accompany this bundle of nerves.

The brachial plexus is formed by nerve roots that branch off the spinal cord in the lower cervical spine and upper thoracic spine (C5-T1). The purpose of the brachial plexus is nervous system communication between the spinal cord and the upper extremities (eg, arms). Various nerves are formed in the brachial plexus and several nerves branch off this intricate structure. Nerves created from the brachial plexus supply almost all of the sensory and motor nerve flow to and from the shoulders, arms, hands, and fingers.

The brachial plexus is located in the anterior (front) neck, shoulder, and chest, leaving it susceptible to compression in several locations. This impingement may be placed on the nerves, their accompanying blood vessels, or both. The locations of impingement in thoracic outlet syndrome include:

• between the anterior and medial scalene muscles on the side of the neck
• beneath the collar bone
• beneath the pectoralis minor muscle in the upper lateral chest
• less commonly, an extra rib, known as a cervical rib, may be the source of impingement

Symptoms of Thoracic Outlet Syndrome
Symptoms of thoracic outlet syndrome may include:

• dull achy pain
• sharp shooting shock-like pain
• numbness
• tingling
• weakness
• burning
• fatigue
• lack of motion in the fingers, thumb, hand, wrist, elbow, and shoulder
• muscle atrophy
• a weak pulse throughout the arm
• paleness in the hand and fingers
• arm heaviness
• coldness in the limb
• lack of grip strength

These symptoms may have an insidious (gradual) onset or can begin abruptly. The location of your symptoms will vary with the location of the nerve and/or blood vessel compression.