Thoracic Outlet Syndrome

What is thoracic outlet syndrome (TOS)?

The thoracic outlet is basically two spaces.  The first space is between your collarbone, clavicle, first rib and anterior scalene muscle.  This space contains the vein returning blood flow from your arm to your heart.  The second space is the area between the anterior scalene muscle, middle scalene muscle and first rib.  This space contains the brachial plexus (nerve to your arm) and the artery to your arm.  This narrow passageway is crowded with blood vessels, muscles and nerves.  If the shoulder muscles are not strong enough to hold the shoulder in place, it can ride lower thus putting pressure on the nerves and blood vessels.  This causes a variety of symptoms which together are known as thoracic outlet syndrome.

Most doctors agree that TOS is caused by compression of the brachial plexus or subclavian vessels as they pass through narrow passageways leading from the base of the neck to the armpit and arm.  This can occur from an injury and general postural changes or from repetitive work with your arms too low.

Thoracic outlet problems break down into three categories:

  • The most common thoracic outlet problem is injury to the nerves to your arm. 
  • The second most common is injury to the artery to your arm. 
  • The third most common is injury to the vein taking blood from your arm back to your heart.

To further clarify, the brachial plexus is a network of nerves that come out of the vertebrae in your neck and go together to form bundles of nerves that branch and go to the sides of your neck, your shoulder and your arm.   These nerves begin at the spinal cord in the neck and control the hand, wrist, elbow, and shoulder.  Nerves are our electrical wiring system that carry messages from the brain to the rest of the body.  A nerve is like an electrical cable wrapped in insulation.

Motor nerves carry messages from the brain to muscles to make the body move.  Sensory nerves carry messages to the brain from different parts of the body to signal pain, pressure, and temperature.  The brachial plexus has nerves that are both motor and sensory.

What happens when the brachial plexus is injured?

The network of nerves is fragile and can be damaged by pressure, stretching, or cutting.  Stretching can occur when the head and neck are forced away from the shoulder, such as might happen in a fall off a horse or bicycle or motorcycle.  This can also occur in some types of weightlifting injuries and also with pitching a baseball.

Injury to a nerve

Injury to a nerve can stop the signals going to and from the brain thereby preventing the muscles of the arm and hand from working properly and causing loss of feeling in the area supplied by the injured nerve. When a nerve is cut, both the nerve and the insulation are broken.  Pressure or stretching injuries can cause the fibers that carry the information to break and stop the nerve from working even without damaging the cover.

When nerve fibers are cut, the end of the fiber farthest from the brain dies while the insulation stays healthy.  The end that is closest to the brain does not die and after some time the nerve may begin to heal.  If the insulation was not cut, new fibers may grow down the empty cover of the tissue until reaching a muscle or sensory receptor.

Some brachial plexus injuries are minor and will completely recover in several weeks.  Other injuries are severe enough that some permanent disability involving the arm can occur.

How is a brachial plexus injury treated?

Many brachial plexus injuries can recover with time and therapy.  The time for recovery can be weeks or months.  When an injury is unlikely to improve, several surgical techniques can be used to improve recovery.  To help decide which injuries are likely to recover, your doctor will rely upon multiple examinations of the arm and hand to check the strength of muscles and sensation.  Additional testing, such as an MRI scan or CT scan, may be used to visually evaluate the brachial plexus.  An EMG and nerve conduction study, a test that measures the electrical activity transmitted by nerves and muscles, may also be performed.  In some cases, repair of the nerves or transfer of undamaged nerves from other areas of the body can be performed.  In other cases, transfer of functioning muscles (tendon transfer) to take over areas of lost function can be performed.

What is my role in recovery and what kind of results can I expect?

The patient must do several things to keep up muscle activity and prevent the joints from getting stiff.  Your doctor may recommend therapy to keep joints flexible.  If the joints become stiff, they will not work even after muscles begin to work again.  When a sensory nerve has been injured and feeling is affected, the patient must be extra careful not to burn or cut fingers.  After the nerve has recovered, the brain gets lazy and a procedure called sensory re-education may be needed to improve feeling in the hand or finger.  Your doctor will recommend the appropriate therapy based on the nature of your injury.

Factors that may affect results after brachial plexus injury include age and the type of injury, severity and location of the injury.  Although brachial plexus injuries may result in lasting problems for the patient, care by a physician and proper therapy can maximize function.

Injury to the artery

The artery most commonly injured is the subclavian artery as it goes over the first rib and becomes an axillary artery.  Repetitive injury to this causes degeneration of this artery and it may respond by forming an aneurysm (ballooned out artery) or thrombosing.  The aneurysm is from repetitive injury to the artery in someone with thoracic outlet syndrome.  The aneurysm can thrombose or shower blood clots from within it to the fingers and hand.  The artery can just spontaneously occlude but usually does not happen until there is aneurysm formation.

Another common injury in baseball pitchers occurs at the distal axillary artery, proximal brachial artery or an artery branches off and goes around the proximal humerus bone in your upper arm.  This can cause the artery to thrombose at this level.

Injury to the vein

This most commonly occurs in weighlifters, in someone who exercises aggressively and usually body builders.  It can occur in baseball pitchers.  It can occur after a fracture of the collarbone proximally in which there is a large callus formation or deformity of the collarbone causing pressure on the vein.

The thrombosis related to exercise is known as “effort thrombosis” or Paget Schrötter syndrome.

What are the causes and risk factors?

In general, the cause of thoracic outlet syndrome is compression of the nerves and blood vessels in the thoracic outlet, just under your collarbone (clavicle).  The cause of the compression varies and can include:

  • Anatomical defects.  Inherited defects that are present at birth (congenital) may include a cervical rib—an extra rib located above the first rib—or an abnormally tight fibrous band connecting your spine to your rib or a stubby cervical rib to the front of your first rib.  Also, the anterior middle scalene muscles, which usually have discrete borders, can be fused throughout your brachial plexus.  The anterior scalene muscle can have bands that go around the subclavian artery creating a sling around it.
  • Poor posture.  Drooping your shoulders or holding your head in a forward position can cause compression in the thoracic outlet area.  Sitting on a piano bench that is too high making the piano keyboard too low for your height causes your shoulders to slump and will eventually cause your shoulders to droop.  The same is true for sitting in front of a computer keyboard with it too low or in your lap will cause your shoulders too sag.  A chair in front of your keyboard should have adjustable arms so your arms are held up higher and not drooped at your side.
  • Trauma.  A traumatic event, such as a car accident, can cause internal changes that then compress the nerves in the thoracic outlet.  The onset of symptoms related to a traumatic accident often is delayed and may not become evident sometimes even for years.  A fractured clavicle as noted above that heals improperly can compress the vein as it returns to your heart.
  • Repetitive activity.  Doing the same thing over and over can, with time, wear on your body’s tissue.  Repetitive activity can cause the anterior scalene muscles to hypertrophy or can cause the subclavious muscle along the inferior border of your clavicle to hypertrophy.  You may notice symptoms of thoracic outlet syndrome if your job requires you to repeat a movement continuously, such as typing on a computer for extended periods, working on an assembly line or repeatedly lifting things above your head as you would if you were stocking shelves.  Athletes, such as baseball pitchers, weightlifters and swimmers, also can develop thoracic outlet syndrome from years of repetitive movements.  If you repeatedly carry heavy loads with your arms and low on your body you may cause your shoulders to lower and notice signs and symptoms of thoracic outlet syndrome.
  • Pressure on your joints.  Obesity can put an undue amount of stress on your joints just as can carrying around an oversized bag or backpack.
  • Injury to your shoulder or arm.  If you injure your shoulder or arm and it is painful,  you may quit using it and the normally strong muscles that held it up in place become relaxed and smaller letting your shoulder sag.
  • Pregnancy.  Because joints loosen during pregnancy, signs of thoracic outlet syndrome may first appear while you are pregnant.

What are the signs and symptoms?

Generally, there are three types of thoracic outlet syndrome:

  • Neurogenic (neurological) thoracic outlet syndrome.  This form of thoracic outlet syndrome is characterized by compression of one or all three cords of the brachial plexus—that network of nerves that come from your spinal cord controlling muscle movements and sensation in your shoulder, arm and hand.  In the majority of thoracic outlet syndrome cases, the symptoms are neurogenic.  The most common of these is lower cord brachial plexus injury where there is numbness to the little finger (fifth finger) and half of the ring finger (fourth finger).
  • Vascular thoracic outlet syndrome.  This type of thoracic outlet syndrome occurs when the artery to your arm or the bone under your collarbone is compressed.
  • Nonspecific-type thoracic outlet syndrome.  This is also called disputed thoracic outlet syndrome or common thoracic outlet syndrome.  Some doctors do not believe it exists while others say it is a common disorder.  People with nonspecific-type thoracic outlet syndrome have chronic pain in the area of the thoracic outlet that worsens with activity, but the specific cause of the pain cannot be determined.

Thoracic outlet syndrome is very hard to diagnose in some people and may require visits to your doctor for one to six months before the diagnosis becomes obvious.

Thoracic outlet syndrome symptoms can vary, depending on which structures are compressed.  When nerves are compressed, signs and symptoms of neurological thoracic outlet syndrome often include:

  • Wasting in the fleshy base of your thumb
  • Numbness or tingling in your fingers
  • Pain in your shoulder and neck
  • Aching in your arm or hand
  • Weakening grip

Symptoms may vary depending on which nerves or blood vessels are compressed.  Symptoms from nerve compression are much more common than symptoms from blood vessel compression.

  • Pressure on the nerves (brachial plexus) may cause a vague, aching pain in the neck, shoulder, arm, or hand.  It may also cause pain, numbness, or tingling on the inside of the forearm and the fourth or fifth fingers of the hand or any fingers of the hand.  Weakness may make your hand clumsy causing you to be more inclined to drop things.
  • Pressure on the blood vessels can reduce the flow of blood out of your arm resulting in swelling of the arm and distention of the veins.  More commonly, pressure can reduce the blood flow into your arm and hand making it feel cool and tire easily and particularly when reaching overhead.
  • Overhead activities (reaching in a cabinet, blow drying and combing you air) can be particularly difficult because they worsen with arterial, venous and neurologic thoracic outlet syndrome.
  • There may be a depression in your shoulder or swelling or discoloration in your hand and arm.
  • Your range of motion may be or will become  limited.
  • You may develop a regional pain syndrome, an autonomic nerve system injury, which changes in color and warmth of your hand and occasionally with increased sweating in your palm.

Signs and symptoms of vascular thoracic outlet syndrome—compression of one or more of your veins and arteries—can include:

  • Discoloration of your hand (bluish color)
  • Blood clot under your collarbone (subclavian vein thrombosis)
  • Arm pain and swelling, possibly due to a blood clot
  • Throbbing lump near your collarbone
  • Lack of color (pallor) in one or more of your fingers or your entire hand
  • Weak pulse or no pulse in the affected arm
  • Tiny, usually black spots on your fingers, which are areas of necrosis (dying tissue) due to poor arterial or venous blood supply.

You should see your doctor if you experience any of these symptoms.

How is TOS diagnosed?

Making the diagnosis of TOS even more difficult is that a number of disorders cause symptoms similar to those of TOS including rotator cuff injuries, cervical disc disorders, fibromyalgia, multiple sclerosis, complex regional pain syndrome, and tumors on the spinal cord.  Your doctor’s evaluation will always include a physical exam and detailed medical history and any combination of tests designed to provoke your symptoms (provocation tests) and imaging studies and studies of your nerves. 

Physical exam.  Your doctor will perform a physical examination to look for external signs of thoracic outlet syndrome, such as a depression in your shoulder, a pale discoloration in your arm or limited range of motion.  Other signs are tenderness to palpation over your brachial plexus with movement of your head to the opposite side, and occasionally even to the same side, increased tenderness in your arm with movement.

Medical history.  Your doctor will also ask about your medical history and symptoms, as well as your occupation and physical activities.

Provocation tests.  Provocation tests are designed to reproduce your symptoms.  The tests may help your doctor determine the cause of your condition and also will help rule out other causes that may have similar symptoms.  Some of the more common provocation tests that can suggest the presence of thoracic outlet syndrome include:

  • Adson’s maneuver.  For this test you will be asked to turn your head toward the symptomatic shoulder while you extend your arm, neck and shoulder slightly away from your body.  While you inhale, your doctor will check for a pulse on the wrist of your extended arm.  If your pulse is diminished or if your symptoms are reproduced during the maneuver, your doctor considers this a positive test result which may indicate thoracic outlet syndrome.  Because false-positives often occur, your doctor may repeat the test on the unaffected side.  This test is used much less frequently now than in the past.
  • Wright test.  From a sitting position and with the help of your doctor, you will hold your arm up and back (hyperabduction) rotating it outward while your doctor checks your pulse to see if it is diminished.  Start with your elbow next to your body and go all the way up to 180 degrees while monitoring the arterial flow in your hand.  Your doctor will also want to know if your neurologic symptoms are reproduced during the test.
  • Thoracic outlet exercise testing:  From a sitting position your doctor will ask you to hold both elbows at shoulder height  with your shoulders pulled back.  You will bend your elbows 90 degrees.  If your symptoms are reproduced anytime during the test, you will tell your doctor these symptoms so they can be recorded as they occur.  You will then repeatedly open and close your hands for several (usually 3) minutes.  This test will always cause your shoulders and arms to feel heavy and fatigued and will need to document pain and numbness when and where it occurs and the severity.

Imaging and nerve study.  To confirm the diagnosis of thoracic outlet syndrome, your doctor may also order one or more of the following tests:

  • X-ray.  Your doctor may order an x-ray of the affected area checking to see if you have an extra rib (cervical rib) and also to rule out other conditions in your chest that may cause discomfort in your shoulder such as a tumor.
  • Magnetic resonance imaging (MRI) scan.  These images may help your doctor determine the location and cause of compressions of the brachial plexus nerves or the subclavian artery.  The scans may also reveal any congenital anomalies such as a fibrous band connecting your spine to your rib or a cervical rib to your first rib or any problem with your clavicle that may be the cause of your symptoms.  This test may be of some limited help.
  • Electromyography (EMG). This test enables your doctor to see and hear how your muscles and nerves are working.  To conduct the test, a small electrode needle is inserted through your skin and into the muscles near where you are having symptoms.  The electrical activity detected by this electrode is displayed on a monitor and can be heard through a speaker and can be recorded.  This is a very hard test to perform for thoracic outlet syndrome or carpal tunnel syndrome or cubital tunnel syndrome.  The physician doing this needs much experience and compulsiveness.
  • Nerve conduction study.  Also called nerve conduction velocity, this test measures the speed of conduction of impulses through a nerve.  Doctors use the test to evaluate possible nerve damage.  Small electrodes are placed on your skin over the area being tested and a tiny electrical current is sent to the nerves in your thoracic outlet.  The electrical signals produced by nerves and muscles are picked up by a computer and the information is interpreted by a doctor trained in electrodiagnostic medicine.

What is the treatment for TOS?

If there is an occlusion of the artery to your arm or the vein or a stretch injury with numbness, this is an emergency.  Go to the emergency room.

In most cases, a conservative approach to treatment is effective in mild neurologic TOS as well as mild arterial TOS and mild venous TOS, especially when the condition is diagnosed early.  Treatment for mild problems may include:

Physical Therapy.  You will learn how to do exercises that strengthen your shoulder muscles to open the thoracic outlet, improve your range of motion and improve your posture.  These exercises, done over time (3 to 6 months), will take the pressure off your blood vessels and nerves in the thoracic outlet.  Here are seven that your doctor will work with you on an individual basis to determine how many repetitions you should do, how often you should do them and the amount of weights, if any, you should use as well as when to make any increase in each exercise.

These exercises should all be done while maintaining perfect posture.  These are best done in front of a mirrow.  If you start to get tired, your posture will change and you will start to cheat.

  • Shoulder Shrugs:  Sitting erect with arms and hands hanging down by your sides, begin with shoulders relaxed down and back.  Bring your shoulders up toward your ears, relax and go back down to the starting position.  Repeat
  • Shoulder Retraction.  Begin this just as in shoulder shrugs, but just as you reach highest elevation pull your shoulders back by pulling your shoulder blades together, hold, relax and repeat.
  • Shoulder Rolls:  Sit erect or stand with arms down by your sides.  Roll shoulders forward, lift up, roll back and then down to the starting position.  Perform this motion smoothly like you are tracing a circle with your shoulders.  Relax.  Repeat.
  • Shoulder Abduction (butterfly):  Sitting straight in a chair or standing straight with your arms at your sides with palms up, keep your elbows straight, bring arms up almost to the side of your ear.  Slowly return to starting position.  Relax.  Repeat.  Do both arms at the same time.
  • Chicken Wing:  With hands on your chest between your nipples and collarbone and elbows at your side, lift your elbows as high as possible and hold, relax and repeat.  Do both arms at the same time.
  • Corner Stretch (pectoralis stretch) in Doorway:  Stand in a corner (about 1 foot from the corner) with your hands at shoulder height, one on each wall.  Lean into the corner until you feel a gentle stretch across your chest.  Hold for 5 seconds.  This can also be done leaning through a doorway.
  • Neck Retraction:  Pull your head straight back while keeping your jaw level.  Hold for 5 seconds.

These exercises will be the only exercises you do for the first few months.

We do not want you to try to build up pectoralis muscles on your chest.  We want them to be flabby, soft and flat so they do not pull your shoulders forward.  Sorry!

As with all exercise programs, if any of these movements cause pain, stop that particular exercise and notify your doctor immediately so your routine can be adjusted.

Thanks to Dr. Dan Bartel for this program that he made me do. 

Relaxation.  Techniques that help you relax, such as deep breathing, can keep you from tensing your shoulders and remind you to maintain good posture.

Medications.  Your doctor may prescribe pain medications, muscle relaxants and non-steroidal anti-inflammatory drugs such as ibuprofen, to decrease inflammation and encourage muscle relaxation. 

Only in emergency situations are other medications used that may include a thrombolytic to break up blood clots and an anticoagulant to prevent clots.  There will usually be associated surgery for your thoracic outlet syndrome at this time or at a short interval afterwards.

If conservative treatment appears initially to be all that is needed yet does not relieve the pain, a recommendation may be made for thoracic outlet decompression surgery to release or remove the structures causing compression of the nerve or artery or vein.

Surgical options

We recommend you do everything possible in the way of physical therapy to avoid having surgery, but surgery may be unavoidable.

Surgery is often effective in relieving pain associated with thoracic outlet syndrome. If you have had problems for an extended period of time and your muscles are weak and cannot be built up prior to surgery, the postoperative recuperative period will be longer.

A specialist in thoracic surgery or vascular surgery will perform the procedure.  All surgical options to treat thoracic outlet syndrome pose a significant risk of injury to the brachial plexus.  The most common surgical approaches for thoracic outlet syndrome treatment are:

  • Anterior supraclavicular approach.  This approach repairs compressed blood vessels and nerves. Your surgeon makes an incision just above your clavicle to expose your brachial plexus region.  He or she then is able to look for and may discover fibrous bands contributing to compression of nerves through your upper most rib.  It may then be possible to remove the first rib so there is nothing for your brachial plexus to sag on.  He or she can remove muscle slings around the artery and can remove the subclavious muscle from under the clavicle to decrease compression on the vein.  Sometimes this subclavious is hard to remove in an anterior supraclavicular approach.
  • Transaxillary approach.  In this surgery your surgeon makes an incision under your armpit and dissects up to access the first or upper most rib and then removes a portion of the first rib to relieve compression.  Slings around the artery and the anterior middle scalene muscle can also be divided in this approach.  The subclavious muscle can also be removed in this approach.  The advantage of this approach is that it gives the surgeon easy access to the first rib, artery and vein and lower brachial plexus without disturbing the rest of the brachial plexus.  It also means the surgeon has limited access to the areas upper nerves and muscles to take out any vessels.  Most fibrous bands and cervical ribs that may be contributing to compression can be removed.

Weight loss

If you are overweight, your doctor may recommend that you begin a weight loss program.  Being overweight can stress the shoulder muscles that support your collarbone.  Being significantly overweight may make surgical exposure harder.

If you are body building, stop immediately.  Heavy muscles make surgical exposure more difficult.

Thoracic outlet syndrome that goes untreated for years can cause permanent neurological damage and permanent damage to the artery and permanent damage to the vein that empties your arm, so it is important to deal with the symptoms early.


Thoracic outlet syndrome that goes untreated for years can cause permanent neurological injury, injury to the artery or vein so it is important to deal with the symptoms early.  Whether or not you are susceptible to thoracic outlet compression, be aware of your posture and work environment and do the following:

  • Maintain good posture
  • Take frequent breaks at work
  • Practice relaxation techniques
  • If you are overweight, lose weight
  • Do not do repetitive motion work in your job unless your work station is elevated to match your height

Even if you don’t have symptoms of thoracic outlet syndrome, observe the following:

  • Avoid prolonged carrying of heavy bags over your shoulder with your arms
  • Stretch daily and perform exercises that keep your shoulder muscles strong
  • Avoid repetitive movements and lifting heavy objects
  • Keep keyboards and work stations elevated appropriately
  • If you are overweight, begin a weight-loss program
  • Be careful with body building and weightlifting.  Maintain good posture through all of your lifts and breathe through all of your lifts.  Avoid Valsalva maneuvers through all of your iifts (this will also destroy the veins in your legs).  Again we emphasize the need to seek medical attention immediately if you experience any symptoms of decreased flow to y our hand or arms or any symptoms of venous thrombosis (sudden swelling of your arm) often assoicated with increased size of veins in your arms or

Again we emphasize the need to seek medical consultation right away if you experience any symptoms of a thoracic outlet syndrome of decreased flow to your hand or arms or any symptoms of venous thrombosis (sudden swelling of your arm) often associated with increased size of veins in your arms or shoulder.  Delay can result in permanent damage.


We hope the information on these pages is both informative and helpful, but it is intended for education only.  Please do note that no web site, no matter how much information is shared, can replace a consultation with your doctor and a vascular specialist.  Medical technology and treatment are continually improving and evolving so before making any decision on treatment, it is always advisable to see your doctor first for a comprehensive evaluation of your vascular disease and other medical conditions.

At the Vascular Center of Wichita Falls, we work closely with your other physicians.  If you have concerns about your arteries or veins, contact us.  A referral is not necessary to make an appointment.