Thoracic Outlet Syndrome: Fact or Fiction?

Christopher J. Centeno, M.D.

Thoracic Outlet Syndrome.  The diagnosis inspires fear in the hearts of insurance adjusters and confusion for most medical providers.  Thoracic outlet, or TOS as it’s sometimes known, seems to have gotten this reputation because of its sometimes dubious surgical roots.  The surgeries were expensive, carried significant risk for patients, and rarely seemed to help.  However, TOS has another side, one with no less controversy, but some basis in science and without the baggage of it’s surgical past. 

The diagnosis of TOS first shows up in the medical literature in the 1960’s.    The syndrome gets its name from a constellation of symptoms that all originate from compression of an area where the shoulder meets the rib cage, dubbed the “Thoracic Outlet”.   This area is in the front of the neck, between the shoulder and the chest, under the collarbone and above the ribs.   If you think of this area as a house, the floor would be the upper rib cage, the walls would be the scalene muscles, and the roof would be the collarbone or clavicle.  Since major nerves and vascular structures pass through this space on their way to the upper extremity, any compression can cause weakness, numbness, and vascular changes in the upper extremity.  

The most common sub-type is Myogenic TOS.  This is irritation and or compression of the nerves and vessels that pass through this area.  Since there is no arterial blockage, this is not a surgical emergency, or usually even a surgical problem.  Patients frequently complain of numbness, tingling, burning, or just pain usually in the two small fingers of the hand.  Complaints of weakness are not uncommon.  With proper treatment, Myogenic TOS is relatively easy to treat.  However, due to gaps in the medical education system, the diagnosis is frequently missed and rarely treated promptly.  These patients often spend several years and tens of thousands of dollars getting shuffled from specialist to specialist, with little or no change in their condition.  Finally, frustrated and tired, many are offered a surgical “cure” and frequently end up under the knife.  The results are usually disastrous.

The mechanism of injury can be variable.  Overuse syndromes that involve long-standing poor posture are a common cause.  Shoulder injuries that involve lost range of motion can cause enough nerve irritation to get the syndrome started.  Among some practitioners, a controversial cause of TOS is whiplash.  However, recent research explains why the two seem to go hand in hand.  The connection seems to be a phenomenon known as “Double Crush”.   

In order to understand why TOS can be hard to diagnose and is sometimes confused with Carpal Tunnel Syndrome and Ulnar Entrapment at the Elbow, it helps to know a little about “Double Crush”.  Consider that the nerves in your body are made up of thousands of axons.  Each of these is like a small garden hose that carries nutrients along the course of the axon from the spinal cord to some distal part like the hand.  It also must carry waste materials back from the distal periphery.  This two-way flow is known as axonal transport.  Now consider what would happen if you suddenly stepped on one end of the hose.  Less water, or in this case, fewer nutrients would be transported along the length of the hose.  Let’s say for argument’s sake that you were able to reduce the flow of nutrients by 50% and that the healthy nerve needed at least 40% of the normal flow to maintain it’s needs and to avoid any problems.  Since the nerve needs 40% of the flow and still has 50%, you wouldn't notice a problem.  Now let’s say that you reduced the flow in another area by only 30%.  While either area of pressure alone wouldn’t do enough to the cause the nerve problems, the two combined cause the flow to dip to 35% of normal.  Since the nerve can’t get the nutrients it needs, it gets sick.  This is known as double crush.  Small amounts of irritation and blockage of axonal flow in two or more areas cause the whole nerve to malfunction.  The most common example of this is TOS and Carpal Tunnel and/or ulnar neuropathy or entrapment at the elbow.  The TOS is the cause of the more distal nerve entrapement, and if not treated along with the distal problem, no change in patient symptoms will be noted.  Often, when the more proximal problem is treated (in this example the TOS,  the distal entrapment (in this case the Carpal Tunnel or Ulnar Entrapment) will resolve.  Another commonly seen pair are cervical radiculopathy or radiculitis and Carpal Tunnel Syndrome.  This phenomenon was first observed clinically and later confirmed using animal models.

TOS can take many months to develop.  A good example is a rock in the shoe.  If you place a rock in your shoe and leave it there for a month, you’ll adapt your walking and gait around the pain.  After awhile, you’ll likely develop back pain from walking with a limp.  A similar set of events can occur to produce TOS.  Neck and/or shoulder pain frequently lead to changes in posture that can cause TOS.  It’s because of this phenomenon that there can be several month’s delay between the onset of neck pain and TOS symptoms.

Exam is where most practitioners miss the diagnosis.  The problem seems to be due to a “compartmentalization” of the body by musculoskeletal specialists.  Most MD and DO physicians view the body as disconnected areas.  A common problem is the axial and peripheral mindset.  For example, many doctors without significant soft-tissue training will limit their exam to the areas of complaint.  Since many patients complain of hand symptoms, the exam is often focused from the elbow down.  This poses a problem in rendering a correct diagnosis, since the cause in the shoulder and thorax, not in the hand.  Because of this over focused exam strategy, the diagnoses of carpal tunnel syndrome or ulnar entrapment at the elbow are frequently made in error.  Millions of dollars are paid by insurers each year to doctors treating a shoulder-thorax problem with wrist or elbow surgery.   Each year in my practice, I see a hundred or more patients who have had unnecessary carpal tunnel surgery or ulnar releases who are treated successfully without any additional surgery simply by applying the correct treatment to the problem.

The clinician’s exam will reveal much about whether or not proper care has been taken to rule out this diagnosis.  First, an exam with only elements such as Phalen’s, Tinnels at the wrist and/or elbow, Carpal or Wrist Compression Test, Sensation, Deep Tendon Reflexes or DTR’s is not adequate to detect this diagnosis.  Tests such as the Upper Limb or Brachial Plexus Tension Test (ULTT), Spurling’s Maneuver, Adson’s Maneuver, Scalene Compression Test, First Rib Compression, and/or Shoulder Range of Motion (ROM) should be included.  Again, the focus of the exam in a patient that presents with hand paresthesias must include the neck and shoulder, and not just be limited to the wrist.  Despite this reality and in some part due to the pressures placed on physicians by managed care, many physicians simply don't’ check anything beyond the area of complaint.  This causes massive under-diagnosis of this particular condition.

In general, conservative treatment for TOS is very poor in this country.  This is largely due to an over-emphasis on orthopedic and surgical conditions and a de-emphasis on soft-tissue conditions in American PT schools.  It’s very common for a patient to be placed in an orthopedic based physical therapy program where lifting weights or work hardening are a focus of treatment.  While a few patients respond to this sort of treatment, most are made worse by the increased activity.  This does not usually represent malingering or symptom magnification on the patient’s part, but rather the wrong treatment applied to the condition.  Rehabilitation should only be undertaken by physical therapists with the following educational experiences:

·        A minimum of 16 hours of Education in Muscle Energy or Mobilization of the Thoracic Spine and Rib Cage.

·        A Minimum of 32 hours in Myofasical Release of the shoulder girdle and cervical spine.

·        A minimum of 16 hours of Mobilization of the Nervous System, Nerve Glides, or similar.

Only approximately 10% of physical therapists currently working in the US have this set of minimum educational experiences necessary to treat this condition.  This presents a serious problem for insurers and physicians trying to find a therapist who can help these patients. 

 ·        Providing a good postural base of support for the shoulder girdle.  This may mean treating problems in the low back, thoracic spine, rib-cage, or neck.  While this may seem paradoxical, it must be kept in mind that these structures are the foundation for the shoulder girdle.  Just like building a house, if the foundation isn’t solid, the walls will crack.  In this case, if the low back, thoracic spine, and ribs don’t provide a good base of support for the shoulder girdle, the patient will not get better.

·        Releasing tight muscles in the pectoralis minor, infraspinatus, scalenes, and shoulder girdle.

·        Reducing any friction coming from abnormal rib cage or thoracic spine dynamic motion.  This often requires a very experienced therapist.

·        Restoring normal neuromobility to the upper extremity.  While it’s well known that joints and muscle need to stretch, it’s become apparent that the peripheral nerves also lose their mobility and need to be stretched.

·        Restoring normal shoulder range of motion and dynamic control of the shoulder girdle.

With a well trained PT, about 80% of TOS can be resolved in 4-12 weeks.  Without the proper therapist, most patients worsen instead of improve and quickly move into delayed recovery and disability.  If left untreated, there is some basic science evidence to support that double crush conditions such as carpal tunnel and ulnar neuropathy at the elbow will worsen and may require surgical release.

The second biggest abuse area in TOS is bad or “Shake and Bake” PT.  The clinician, case manager, attorney, or insurer should determine if the PT is qualified to treat TOS based on the criteria listed.  Just because a PT is credentialed through a managed care network does not mean he or she has the additional training needed to treat this often complex disorder.  Millions could be saved annually if the proper rehab care was applied to the proper diagnosis.

In summary, TOS shouldn’t inspire fear in the medical, legal, and insurance communities.  When diagnosed early, treated aggressively by skilled practitioners, it is a minor inconvenience.    However, when left undiagnosed or treated by unskilled therapists, it can be an expensive and frustrating experience for all concerned.

;