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Arterial TOS Diagnosis
DIAGNOSIS CHARACTERISTICS
The diagnosis of ATOS has always been a bit confusing especially for doctors who do not specialize in TOS. It frequently involves a lot of misdiagnoses of ATOS when the correct diagnosis is actually NTOS. This is typically due to the fact that there is some symptom overlap between the two conditions in combination with misinterpretation of the significance of loss of pulse or blood flow with the arm elevated.
KEY POINTS
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ATOS is extremely rare and is almost always associated with a cervical rib or other bony abnormality. The likelihood of ATOS being present is very low when there is no evidence of a cervical rib or bony abnormality.
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Many normal asymptomatic humans will have compression or obliteration of the artery and/or loss of pulse with the arm elevated. Therefore, this finding by itself is NOT considered to be ATOS.
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Patients with symptoms consistent with NTOS including those with hand/finger discoloration and temperature changes who lose their pulse with arm elevation are NOT considered to have ATOS.
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A critical element of ATOS diagnosis is the presence of damage or injury to the wall of the artery resulting in artery dilatation or widening, aneurysm or a clot.
Who Diagnoses & Treats ATOS?
Any doctor who is familiar with ATOS can give a preliminary diagnosis. These most commonly are emergency room physicians or non-TOS specialist vascular surgeons. However, given the large number of NTOS patients who are misdiagnosed as having ATOS, these can also be orthopedic surgeons or neurologists. Once a diagnosis of ATOS is suspected, referral should be made to a TOS specialist to make a definitive diagnosis and treat accordingly. TOS specialists are usually vascular surgeons and occasionally cardiothoracic surgeons. However, most vascular surgeons and cardiothoracic surgeons DO NOT specialize in TOS. In fact, most of them have very little experience with TOS. Therefore, it needs to be a vascular surgeon or cardiothoracic surgeon who specifically specializes in TOS. For help finding a TOS surgeon, click here.
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PHYSICAL EXAM
Physical exam is important in a patient with suspected ATOS as it can help distinguish from NTOS, determine the severity of any ischemia, and help determine the best next step in the diagnostic process. Below is a list of what is typically assessed during a targeted ATOS physical exam:
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Temperature of the arm, hand, or fingers
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Color of the arm, hand, or fingers
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wounds or ulcers on the fingertips
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small spots on the fingers that appear as dark bruising or blood blisters under the skin
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Extremely delayed capillary refill (applying pressure to the skin until it turns white & timing how long it takes for the blood to return and the skin to return to normal color)
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Sensation of the arm and hand
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Symptoms triggered with arm elevation
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Checking the pulse of the arteries in the arm with comparison to the opposite arm either by finger pressure and/or handheld doppler ultrasound
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Exam of the neck and area just above the collarbone for any masses or abnormalities that might be a cervical rib or aneurysm
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Blood pressure measurements in each arm
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Stethoscope exam of the areas just above and just below the collarbone to identify sounds indicating turbulent blood flow
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Identification of any signs of NTOS or VTOS
TESTING
Vascular Testing
Duplex or Doppler Ultrasound this is the least invasive, least expensive, and most readily available test out there to check for blood clots and blood flow abnormalities. Duplex ultrasound involves using high frequency sound waves to look at the speed of blood flow, and structure of the arteries. It involves an instrument called a transducer being placed on the skin in the area of the artery being imaged, and it is moved around on top of the skin to get different views in different areas. It can also be performed with the arm in different positions. However, by itself, compression of the artery or loss of pulse with the arm elevated is not diagnostic of ATOS. This test can visualize an aneurysm. However, more advanced imaging such as angiogram would need to be done to assess the location of the aneurysm and the exact condition of the artery. Along with the ultrasound, something called segmental pressure testing can also be done which uses blood pressure cuffs to measure the blood pressure in different locations on the arm. It compares the blood pressures of two locations on the arm and a difference in blood pressure can indicate where a blockage of blood flow might be.
Photoplethysmography (PPG) This is a non-invasive test which involves clips being put on the ends of the fingers. These clips contain infrared light sensors which can detect blood flow changes via the light traveling through the skin surface and being absorbed by blood. It can detect intermittent blood flow changes particularly with the arm in certain provocative maneuver positions. The finger clips are connected to a machine which converts the blood flow changes into waveforms and displays them on a graph in the report. Again, it is important to note that, by itself, loss of blood flow with the arm elevated in different positions is not diagnostic of ATOS.
CT Angiogram/MR Angiogram of the Chest (CTA or MRA) this is a CT scan or MRI of the chest which can show the vessels particularly the axillary-subclavian vein and axillary-subclavian artery. This is also sometimes referred to as an arteriogram. These tests involve injecting contrast material and taking x-ray images to determine how the blood moves through the artery, the exact location of the artery compression, and to see what physical condition the artery is in as far as damage, clot, or aneurysm. Either test can be performed both with the arm up and with the arm down. Again, by itself, compression of the artery with the arm elevated is not diagnostic of ATOS.
Catheter-Directed Angiogram This is typically only done to assess the smaller arteries lower down in the arm if clots in those arteries are suspected to have traveled down from the axillary-subclavian artery. Thrombolysis can be performed to break up those clots. This procedure is usually performed by a vascular surgeon or an interventional radiologist. Often, the patient is given mild sedation. It involves inserting a needle or sheath into an artery on the affected arm. A catheter will be inserted into the artery, contrast dye will be injected into the artery, and x-ray images will be taken to assess blood flow and condition of the artery. Depending on the findings on the images, during the same procedure, this same catheter can be used to reach and try to break through any clot(s) and/or to administer medication to the area of any clot(s) to help dissolve it.
Radiology (X-Ray Imaging)
There is no plain radiology test that will show ATOS. Therefore, most x-ray imaging is done to look for bony abnormalities that are typically present in patients with ATOS.
Plain Chest X-Ray can be done to look for any anatomical abnormalities such as anomalous first rib, rib fracture, cervical rib, or collarbone fracture.
Plain Cervical Spine (Neck) X-Ray can be done to look for cervical ribs or elongated C7 transverse processes. Most radiologists are not looking for cervical ribs or elongated C7 transverse processes as they are typically incidental findings and most people who have them do not experience symptoms or develop any conditions related to them. Even if a radiologist does see them, they often leave them out of the radiology report for the same reasons. If a patient is having this x-ray specifically to help with diagnosis of ATOS, they should request that the ordering physician state that the purpose of the imaging is to look for cervical ribs. However, the presence of cervical ribs alone is not diagnostic of ATOS. Although most ATOS patients do have a cervical rib or other bony abnormality, it does not mean that everyone with a cervical rib has or will develop ATOS.
Cervical Spine (Neck) CT Scan in rare instances, if plain x-rays are not showing a cervical rib or other bony abnormality but suspicion is high, a CT scan can be done to help identify them.
PROVOCATIVE MANEUVER TESTING
Provocative maneuver testing is tests involving different arm and/or head & neck movements (maneuvers) which are intended to trigger (provoke) certain symptoms. In general, the accuracy of provocative maneuver testing for ATOS is fairly low. The tests have a fairly high false positive rate, which means that they identify a lot of people as having ATOS when they, in fact, do not. Diagnosis of ATOS should not be made based only on a positive provocative maneuver test. Negative provocative maneuver testing cannot rule out ATOS. The provocative maneuver tests done for ATOS are designed to assess positional artery compression where loss of pulse is triggered by certain neck and elevated arm movements. The two most common tests are the Adson’s Test and Wright’s Test but there is also Eden’s Test and the Costoclavicular Maneuver. All of which are considered to be positive if there is loss of radial pulse. As has been noted several times on this page, loss of blood flow with the arm elevated in different positions, by itself, is not diagnostic of ATOS. What these tests can do is assess what symptoms are triggered by the arm being in certain positions which might help support a diagnosis of ATOS.
Adson’s Test this tests the radial pulse with the arm and head/neck in a certain position. The arm is kept low but held out to the side of the body and pulled back a little bit. The patient takes a deep breath and holds it and then elevates the chin and turns the head toward the affected side. A significant decrease or complete loss of pulse is considered positive.
Wright’s Test this tests the radial pulse with the arm in a certain position. The arm is held up in a “surrender” position for 1 minute while the radial pulse is tested. Then the arm is put all the way up next to the head while the radial pulse is tested. A significant decrease or complete loss of pulse is considered positive.
Eden’s Test – aka Military Brace Test this tests the radial pulse with the arm and shoulder in a certain position. It involves sitting straight like in a military position with the chest pushed out and the shoulders pulled back for 1 minute. A significant decrease or complete loss of pulse is considered positive.
Costoclavicular Maneuver – aka Exaggerated Military Brace Test this tests the radial pulse with the arm and shoulder in certain positions. It involves the patient sitting while the examiner assists the patient in performing the following 4 movements: scapula retraction, scapula depression, elevation, and protraction holding each position for up to 30 seconds, while the patient rests his or her forearms on the thighs. A significant decrease or complete loss of pulse is considered positive.
PUBLISHED DIAGNOSTIC CRITERIA
In 2016, the top TOS specialists in the United States collaborated to come up with standardized diagnostic criteria for all 3 types of TOS. It was published in an article in the Journal of the Society for Vascular Surgery. Below are the published standardized criteria for the diagnosis of ATOS.
Illig KA, Donahue D, Duncan A, Freischlag J, Gelabert H, Johansen K, Jordan S, Sanders R, Thompson R. Reporting standards of the Society for Vascular Surgery for thoracic outlet syndrome. J Vasc Surg. 2016 Sep;64(3):e23-35.
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