Thoracic outlet syndrome

Ask any three chiropractic neurologists about thoracic outlet syndrome (TOS) and you're likely to get three very different answers about the prevalence-or even the existence-of the condition. That disparity of opinion mirrors the allopathic medical profession's analysis. The National Institute of Neurologic Disorders and Stroke (NINDS) reports that the only type of thoracic outlet syndrome whose definition most scientists agree on is true neurologic TOS-a rare, usually painless disorder caused by congenital anomalies, appearing most commonly in middle-aged women, with symptoms that include weakness and wasting of hand muscles and numbness in the hand.

NINDS also describes several other types of TOS, including arterial TOS, venous TOS, traumatic TOS, and disputed (or common or non-specific) TOS. "For the most part, these disorders have very little in common-except the site of occurrence. The disorders are complex, somewhat confusing, and poorly defined, each with various signs and symptoms of the upper limb," explains the NINDS thoracic outlet syndrome information page.

Chiropractic neurologists who have dealt with this condition would probably agree with much of that description. Indeed, at least one suggests that the name itself poses a problem for chiropractic treatment. Thoracic outlet is not a good term to use because you can get in trouble with billing on that. When you put down 'thoracic outlet syndrome,' gatekeepers automatically see that as a vascular compromise-and that means that decompression has to happen because it's a medical emergency" says Kenneth Tyer, DC, CCCN, associate professor at Texas Chiropractic College. "A more appropriate term is cervico-axillary syndrome, suggested by Rainey in 1996. But don't look for it in the code books because it's not there. It's all under thoracic outlet syndrome." Dr. Tyer suggests that the doctor of chiropractic who is treating a case of TOS should elaborate in the case notes that it is, in fact, cervico-axillary syndrome and neurogenic in nature.

Whether you call it cervico-axillary syndrome or thoracic outlet syndrome, what exactly is it, how might a doctor of chiropractic diagnose it (and differentiate it from conditions that manifest similarly), and how is it treated?

Thoracic outlet syndrome is "kind of an umbrella term that applies to entrapment of the brachial plexus that can occur in a variety of places," says chiropractic neurologist Donald Murphy DC, DACAN, clinical director of the Rhode Island Spine Center and a member of the faculty of Brown University School of Medicine. "When I say brachial plexus, I would include the brachial artery and vein, as well as the nerves. TOS can be venous or arterial, but it is more commonly neural, involving the actual brachial plexus nerves."

This entrapment most commonly occurs at one of three sites, Dr Murphy says. The most common is between the anterior and middle scalene muscles; the second most common is underneath the pectoralis minor muscle; and less common, but still sometimes seen, is between the uppermost rib and the clavicle"

The condition isn't common, but it does happen, according to Dr. Murphy. "In my experience, TOS is probably about as common as is cervical radiculopathy and in my practice, I see both of them quite a lot," he says. "As neck pain problems go, neither of these conditions is extremely common, but certainly when it comes to people with neck and radiating arm pain, both are commonly found."

LaVerne Saboe, DC, DACAN, FICC, DABFC a chiropractic neurologist in Albany Oregon, doesn't see TOS as all that common. In fact, he says, he hasn't diagnosed any new cases in years. "I have two cases I've treated for years, but I can't recall the last new case I've received," he says. "In my experience, much of what was being diagnosed wasn't TOS, but a myriad of other things that can cause symptoms of pain and paresthesia into the arm." As the trend in treating these conditions has moved away from surgery to conservative management, Dr. Saboe believes, overdiagnosis of TOS has ebbed.

When in Doubt, Rule Out

Diagnosis of thoracic oudet syndrome poses a challenge for the doctor of chiropractic. It's also a diagnosis many DCs don't consider as much as they should when dealing with radiating neck and arm pain, Dr Murphy says. "The primary reason is that there are not many objective tests for the presence of TOS. It's difficult to assess through imaging studies and through EMG, so it's hard to determine how common it is and what the causes 7are, because there's no objective test to demonstrate it."

TOS, he explains, is "primarily a diagnosis of exclusion, something you get to once you've ruled out other sources of radiating arm pain." One of the first steps, he suggests, is differentiating TOS from cervical radiculopathy. "Not uncommonly the patient will have neck pain and/or radiating arm pain, and the assumption may be that they have a nerve root problem in the cervical spine-but they may actually have TOS. It's important to be aware of the possibility of TOS as the correct diagnosis," he says.

The easiest way to rule in TOS as a likely diagnosis, Dr. Murphy says, is to rule out radiculopathy. A recent study1 has defined four clinical tests that are most effective in diagnosing radiculopathy: the brachial plexus tension test, the cervical compression test, the cervical distraction test, and the cervical rotation test. "The brachial plexus tension test is very sensitive, but not specific; it will be positive in both radiculopathy and TOS," Dr. Murphy explains. But positive findings on the other three tests are generally only found with radiculopathy and not with TOS.

There are several other tests commonly used in assessing a possible case of thoracic outlet syndrome:

Roos Test - also known as the "hostage maneuver" or "hands-up" test. The patient brings both arms up to shoulder level and slightly behind the head, bent at a 90-degree angle-as if he or she has just been told to "stick 'em up." A patient then opens and closes the hands slowly for three minutes. Pain, heaviness, or arm weakness, numbness, and tingling are positive for TOS; usually a TOS sufferer will not be able to continue the exercise for more than a minute.

Adson's Test - The practitioner locates the patient's radial pulse and holds it. The patient then rotates the head toward the arm being tested, and then lets the head tilt backward by extending the neck while the examiner extends the arm. Disappearance of the pulse can indicate TOS, but the test is not conclusive, as pulse disappearance during this motion can happen in people who do not have TOS, and the pulse does not always disappear in people who do have the condition.

Costoclavicular Maneuver - Again, the practitioner locates the radial pulse. This time, the patient's shoulder is drawn down and back on the affected side as the patient pushes the chest out as if standing at military attention. Again, pulse disappearance is positive for TOS.

Allen Test - The patient extends the arm horizontally and rotates laterally as the practitioner flexes the elbow to 90 degrees. The patient then turns the head away from the affected arm. If the radial pulse disappears during the rotation of the head, the test is positive.

Ruling out radiculopathy and obtaining positive results on one or more of these tests, doesn't definitively indicate TOS. There are more diagnoses to be considered. "If the symptoms are primarily distal to elbow or wrist, it could be ulnar neuropathy radial neuropathy, peripheral polyneuropathy, and so on. These usually can be diagnosed through EMG. One must also consider space-occupying lesions other than the usual herniated disk or lateral canal stenosis such as tumors, subdural hematoma, and epidural abscess. These things must be ruled out," Dr. Murphy says.

Dr. Saboe suggests also looking at the functionality of the shoulder girdle. "Is it really TOS-an impingement of the neurovascular bundle-or is it something else, such as hot, tender trigger points in the scalenus musculature, the infraspinatus, or the subscapularis?"

There are a couple of unusual conditions whose symptoms can mimic TOS. One, says Dr. Saboe, is syringomyelia of the cervical cord. "It's a cavity, a failure of the neural tube to close, which can lead to many of the same symptoms as TOS. It can be ruled out with an MRI," he explains.

Something else to be ruled out: a pancoast tumor, a growth on the upper lobe of the lung that can compress the brachial plexus or the blood vessels in the area and mimic the symptoms of TOS. "It's very uncommon, but obviously important to consider in the diagnostic process," says Dr. Murphy. It, too, can be detected with MRI, and often can be seen on plain film x-ray as well.

In summary, says Dr. Tyer, a patient can be diagnosed as having TOS with three out of the following four conditions: aggravation of symptoms with the arm elevated, a history of paresthesia over the C8-T1 dermatomes, tenderness over the brachial plexus at Erb's point, and a positive Roos test (the latter being the most reliable indicator).

Vascular, Neurogenic, or Both?

Once TOS is diagnosed, it's important to immediately rule out vascular involvement. "If the patient has some coolness, swelling, or loss of pulse in the hand, there may be some vascular compromise, which may require a decompression of the vascular structures," says Dr. Tyer. "If all my tests come up positive for TOS, I may refer that out. I've seen at least one case in which a DC missed TOS with vascular compromise, and the patient ended up losing fingers. If you have a subclavian artery or subclavian vein being compressed, you want that reduced immediately so as not to take the chance of the patient's losing vascular supply to the extremity."

Some positive vascular tests in a TOS patient don't necessarily indicate vascular compromise Dr Tyer adds. "If the patient's hands aren't cold or swelling, but if the pulse goes away when I do an Adson's or a reverse Adson's, that may or may not mean vascular involvement."

More useful both in diagnosing TOS in the first place and in differentiating a case of TOS that is primarily neurogenic in nature from one that has serious vascular involvement, Dr. Tyer believes, is the Roos test-that "hands-up" posture. "You put the patient in the hands-up position and have him or her open and close the fists for three minutes. It's hard for a normal person to do this, and someone with thoracic outlet syndrome-whether it's primarily vascular or neurogenic-will drop the arms within a minute." The telling differences between neurogenic and vacular TOS are coolness, pallor, swelling, and/or loss of pulse in the arm after dropping it. That indicates vascular compromise, Dr. Tyer says, while the patient who drops the arms and experiences weakness and pain probably just has neurogenic TOS.

"As a doctor, you have to decide if the condition is totally neurogenic, or if it also has a vascular component," says Dr. Tyer. "In other words-is it a medical emergency or not? If you suspect a patient has a vascular problem, send the patient to the emergancy room immediately. Let's say you, as a DC, attempt to treat it yourself. If there is a vascular compromise, in your attempt to reduce the stress tightness in that area, you can set off an embolus in the artery that was causing the occlusion. Then you've got a big problem."

Sources of the Syndrome

An arterial embolus is a possible, but less likely cause of thoracic outlet syndrome. There are several others, Dr Saboe says.

"We believe there are three or four primary mechanisms causing thoracic outlet syndrome," he says. "Clearly the first is 'first rib syndrome,' a rudimentary rib with a fibrous band.

"Second, the neurovascular bundle can get pinched as it passes between the first rib and clavicle. When you lose normal joint play in the costovertebral, costoclavicular, and chromioclavicular joints, those structures can't rise and fall and have their normal springiness," Dr. Saboe explains. "When the person breathes in and out and the shoulders move, there's no give there. These joints become rigid, and it sets conditions up for entrapment, similar to Morion's neuroma."

Trauma can also cause TOS. "Lower-neck injuries, upper-thoracic injuries, and whiplash injuries in particular can cause tight scalenus musculature," says Dr. Saboe. "Trigger points that develop, causing the muscles to get tight and clamp down on vascular and neurogenic components." In fact, he says, many of the TOS symptoms, such as pain and paresthesia in the upper extremity are due less to the entrapment of the neurovascular bundle than they are to the trigger points themselves.

"Most thoracic outlet syndrome patients have had a prior accident of some sort/ says Dr. Tyer. "We see many motor vehicle accident patients, and a large percentage of them end up with a cervico-axillary syndrome/thoracic outlet syndrome. When there's an acceleration-deceleration injury fibrotic adhesions can develop in the scalenes. If they're not taken care of, somewhere down the line they can develop into neurogenic TOS."

This may be why TOS affects women far more than it does men. "It's possibly because women's muscle groups are, in general, not as strong," says Dr. Tyer "If women are involved in an auto accident, the muscles may tend to have more contractures and the fibrosis that sets up to produce thoracic outlet syndrome."

Treatment

Until a few years ago, thoracic outlet syndrome was often treated surgically. Even now; in the case of 'first rib syndrome,' surgical resection of the extraneous rib is sometimes done, but it hasn't proven particularly effective, says Dr. Saboe. "It causes drooping of the shoulders, which leads to continued traction on the brachial plexus, and, therefore, continued pain and paresthesia. The outcome really isn't very good, and conservatively treated patients do just as well."

"Thoracic outlet syndrome is best treated by a nonsurgical neuromuscular specialist," agrees Dr. Murphy. "This is almost always a nonsurgical problem, and many chiropractors treat TOS better than any other specialist. I would think that a doctor of chiropractic who is well trained in differential diagnosis and in neural mobilization can treat thoracic outlet syndrome." In some cases, he says, a fibrous band can form between the scalene muscles and another structure that cannot be removed except by surgical excision, but this condition is not very common.

Treatment of thoracic outlet syndrome, says Dr. Murphy depends on where the entrapment is taking place "The DC can find the entrapment through palpation of the muscles involved-primarily the scalene and the pectoralis minor muscle," he says. Once the location of the entrapment is identified, we can use muscle-lengthening techniques to extend these muscles if they're shortened. That will start the process of releasing the entrapment."

Also helpful in TOS cases, Dr. Murphy says, are neural mobilization techniques. "We need to mobilize the peripheral nerves in the brachial plexus and the nerve mots, so that if there are adhesions between the entrapping tissue and the neural tissue, they will be loosened and that segment of the neural complex will be mobilized."

Neural mobilization, he explains, treats "neural tension"-an umbrella term for any kind of adhesion, entrapment, or irritation of a neural structure. "There are specific tests that one can go through to identify neural tension or neural irritation, and the tests allow one to localize which nerves are involved, although not necessarily where the entrapment site is," Dr. Murphy explains. "Then we can use the appropriate mobilization techniques aimed at releasing the entrapment."

Chiropractic adjustment is also well suited to treating TOS, says Dr. Tyer. "Chiropractic neurologists would advise performing a coupled cervical spine manipulation-a contralateral adjustment opposite the side of TOS compromise. In so doing, you're going to activate neuronal input or afferentate through the cerebellum to the contralateral cortex on the involved TOS side," he explains. "Then, you also provide a fast-stretch mechanism on the involved side. That loads the Golgi tendon organs and produces a relaxation of that involved side." With this adjustment, says Dr. Tyer, "You're doing two things at once, "fou're providing an ipsilateral, fast stretch to fire the GTOs to relax the muscle groups on that side, while also activating the contralateral side and firing the cerebellum and the cortex, which ends up on the ipsilateral side Through the descending reticular formation, you're also exciting the pons, which, in turn, inhibits the flexor muscle groups above T6, including the scalenes."

In addition, he suggests, the doctor of chiropractic can do a first-rib adjustment to create space so that the plexus isn't compressed. "You can also do some cross-cord exercises, making the contralateral scalenes contract and the muscles of the other side relax. Myofascial active release is also effective."

Dr. Saboe also recommends deep-tissue work for the trigger points. "I do digital pressure, cross-frictional massage, and origin and insertion work-which means doing friction massage of the origin of the scalenus muscle and the insertion-with hopes of stimulating the tendon apparatus so that the muscle relaxes," he says. "Many times I also use interferential, high and low mode, for 20 minutes after an adjustment and before the soft tissue work, to try to loosen up all the musculature. If there are truly active trigger points in the scalene musculature, the latissimus dorsi and superspinatus, pulse ultrasound in combination with negative galvanic electrical stimulation is very beneficial."

During the course of treatment, patient-performed exercises outside the office can contribute to recovery. "Depending on the particular area that's involved, we have the patients perform a repetitive motion on their own, to gradually move the neural structure back and forth to release the entrapment and relieve the tension," Dr. Murphy says. "For example, if someone had a positive brachial plexus tension test with a median bias, I might suggest a maneuver to do at home in which the patient stands, externally rotates an outstretched arm, opens the fingers fully and then repetitively bends the head away from that side in an oscillating manner to release the brachial plexus from the neural tension."

Dr. Tyer also advocates assigning patients an exercise plan. "Extensor exercises, for example, are good, "You want to strengthen the extensor groups of the neck. When you do that, the flexors have to inhibit, they have to release. If the thoracic outlet syndrome was not caused by trauma, it's often caused by poor posture-certain muscles are starting to contract because their extensor groups are weak," he says. "When someone presents with anterior rotated shoulders and the head carriage is forward, everything's closing up in the anterior group and the extensor groups become weakened. Extensor exercises can help take care of some of these anterior contractures."

Long-Term management

How long does thoracic outlet syndrome take to resolve? It depends on the case, but ""You're probably not going to knock this out the first time," says Dr Tyer. "You have an acute and a subacute phase to go through. Depending on the patient and the history it could take four to eight weeks."

"In my experience, you don't cure thoracic outlet syndrome, you manage it," says Dr. Saboe. "You give symptomatic relief, and the symptoms will slowly return, although in every case I've seen, they never return as intensely as they were before-provided it's managed properly. If the patient comes back in, that patient will respond to palliative and supportive treatment. I haven't had a single case that's progressed or gotten worse. The only cases I've ever heard of that have deteriorated are those in which the first rib was resected."

Once the initial presentation of TOS is resolved, Dr. Murphy recommends that the practitioner look for underlying factors that may serve to perpetuate the problem or promote its return. "These may include cervical or scapular instability residual joint dysfunction in the cervical or thoracic spine, and any residual neural tension that can be detected through the brachial plexus tension tests," he says.

For long-term management of thoracic outlet syndrome patients, Dr. Saboe also recommends supplementing with B complex. "In addition, if patients are really acute, I also use enterically encoded proteolytic enzymes," he says. "They're natural anti-inflammatory agents."

"In my experience, the reason chiropractic gets superior results with conditions like these is the high-velocity short-amplitude manipulative thrust," Dr. Saboe says. "That makes all the difference by re-establishing the normal joint play in all of the articular tissues."

Reference

1. Wainner RS et al. Reliability and diagnostic accuracy of the clinical examination and patient self-report measures for cervical radiculopathy. Spine28(1):52-62.

Copyright American Chiropractic Association Jan 2004
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