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Diagnosing TOS 
Diagnosing Thoracic Outlet Syndrome can be difficult as signs and symptoms are often confused with other conditions and symptoms can often times be vague.  This is especially true with predominant Neurogenic Thoracic Outlet Syndrome as pain and tingling are often times the only complaints. Predominant vascular Thoracic Outlet Syndrome often has signs and symptoms relating to arterial or venous compression.  A patient can present with signs and symptoms of both neurogenic and vascular Thoracic Outlet Syndrome.

Many times patients are told they have TOS based on a simple arm elevation test but these test do NOT completely rule in or out Thoracic Outlet Syndrome. Most TOS experienced physicians use these arm tests only has a very small part of their clinical exam. These arm tests are usually followed by more advanced diagnostic testing such as: scalene blocks; chest xray, cervical spine xray, Cat Scan (CT), MRI/MRA and electrophysiology studies.

One of the most important first steps in diagnosing Thoracic Outlet Syndrome is giving a comprehensive history of your symptoms to your TOS experienced physician. Some patients keep a list of their symptoms and bring it to their first exam. This list usually includes:

List of symptoms
When did you first notice these symptoms?
Was it a gradual onset or after an acute injury or accident?
What makes your symptoms appear or are they constant?
What (if anything) relieves or reduces your symptoms?
What treatment(s) have you had? How effective were they? Including medications.

Each physician has their own method of history taking but you can be assured these questions will be included. Expect for your TOS examination to last for some time. Some patients report that their TOS physician spent over an hour for their exam so be prepared for this.

Most TOS experienced physicians rely heavily on a long standing hands-on clinical examination and each physician has his or her own way in proceeding with the exam. Additionally, each TOS physician has their own opinion about many of the TOS diagnostic procedures currently available today. It is a good idea to discuss with your TOS physician, in detail, each procedure he or she has ordered and any alternatives to these treatments.

If your physician suspects that you may have vascular involvement, he or she may order additional invasive and non invasive diagnostic tests such as ultrasound, CT, MRI, venogram and arteriogram. You should discuss the risk and benefits of each procedure with your physician.

Your physician may order an EMG and/or MAC test. These are nerve conduction studies commonly performed to help rule out other compression neuropathies of the upper extremity. The reliability of EMG studies is of great debate in diagnosing TOS as often times EMG studies are inconclusive. Currently, the Medial Antebrachial Cutaneous (MAC) nerve conduction test is being studied as an alternative or addition to EMG studies in diagnosising TOS.  Many patients report that although EMG studies are tolerable, there is some intermittent pain so make sure you ask your physician.  

Arm elevation tests for diagnosing TOS have been the subject of much controversy and still are today. The Adson's Maneuver has proven to have fairly high false positive rates among the general population and is not a sole predictor of TOS. The Adson's test is still used in practice today but is given little weight without further more accurate arm elevation testing and more advanced diagnostic testing. Arm tests such as the EAST test and the White Hand sign are now the more accepted of the arm elevation tests. These tests can be correlated with TOS but further diagnostic work up is almost always necessary, especially if your physician suspects vascular involvement.

Scalene blocks using a numbing agent or Botox are currently being used and studied by some physicians as a predictor of treatment outcome, to determine if the Scalenes muscles are causing compression with the Thoracic Outlet and to reduce pain. These procedures are usually done with the patient sedated and are usally done with the help of a visual aide such as ultrasound or fluoroscopy. Some physicians place a high predictive value on scalene injections.  Some patients have reported a total relief of pain temporarily while others report no or minimal short acting pain relief. In any event, scalene injections are now being evaluated in diagnosing and treating Thoracic Outlet Syndrome. As with any medical procedure, there are risks with this procedure, especially if the injections are unguided. It is very important for you discuss these risk with your physician.

Cat scans or "CTs" are done to assess the structures within the thoracic outlet. Many times a CT is ordered "with contrast". This means that dye will be injected into your veins through an IV (intravenous line) to determine the condition of your blood vessels and to determine if you have a DVT (blood clot) or aneurysm. There are risks with this procedure and you should discuss these risks with your physician and also the CT staff.

MRIs are quickly becoming a very valuable tool in detecting anatomical compression within the thoracic outlet. An MRI can also be ordered "with contrast" to enhance the visualization of structures within the thoracic outlet. MRI does have advantage over CT in that radiation exposure is avoided and the pictures are more detailed but as with any medical procedure there are risks. Discuss the risk and benefits with your physician and MRI staff. For more TOS MRI informaion please visit, , and

Ultrasounds are generally painless. Your physician may order an ultrasound of your brachial plexus and/or blood vessels to determine compression within the thoracic outlet and to also determine the presence of blood clots, narrowing of a vessel and aneurysms. Discuss the risk and benefits with your physician and ultrasound staff.

As previously stated, diagnosing TOS can be difficult even for the most experienced TOS clinicians but your odds do improve if you seek out a physician with an active, current and documented history of treating Thoracic Outlet Syndrome patients. It is not uncommon for patients to seek several opinions from TOS experienced physicians.



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