Four major syndromes have specific characteristics and diagnostic tests

by Elaine Wallace, DO

A 28-year-old weight lifter presents to your office for assistance due to a complaint of progressive numbness in the lateral aspects of his forearms accompanied with a recent inability to bench press his usual weight routine. He increased his upper body workout (pectoralis and neck muscles) six weeks ago, but has no other life changes. He has a friend in a similar situation who received great relief after seeing her osteopathic physician and wants to know if you can help him. Where do you begin?

There are few syndromes seen by the busy family practitioner that better demonstrate the osteopathic interrelationship of structure and function than does Thoracic Outlet Syndrome (TOS).

Thoracic Outlet Syndrome is actually a group of upper extremity impingement syndromes involving the neurovascular bundle of the arm that are logical in progression, easy to diagnose and easy to help.

The thoracic outlet is the upper lid (operculum) of the chest cage, so named because it is the site from which the arterial flow of the thorax flows out. Actually, more things flow into the thorax at the operculum than out, including venous flow, ascending and descending terminal ducts of the lymphatic system, the vagus nerve, the phrenic nerve and parts of the brachial plexus, the esophagus and the trachea.

This fact has given rise to its newer alternative nomenclature of the superior thoracic inlet. The thoracic outlet is approximately a four-centimeter area boundaried anteriorly by the manubrium of the sternum, laterally by rib one and its costal cartilage, and posteriorly by the body of T1.

This tightly confined area, covered by Sibson’s fascia and surrounded by the scalene muscles, the sternocleidomastoid muscle and the trapezius muscle serves as the exit site of the subclavian artery, the subclavian vein and the brachial plexus (i.e. the neurovascular bundle). These rigid osseous boundaries, strong muscles, and superficial vital structures are prime conditions associated with syndromes of impingement or compression.

TOS Classifications
The syndromes of the Thoracic Outlet are easily subclassified according to the symptoms of the structures compressed – artery, nerve, vein, or lymphatic.

The first structure compromised in these compression syndromes is the subclavian artery (five percent of all cases).
This great vessel leaves the thorax by arching over the first rib from behind the scalenus anticus muscle and in front of the scalenus medius muscle.

This egress of the artery through the interscalene triangle places it at high risk for compression by the scalenes whenever there is muscular hypertrophy. Compression of the subclavian artery gives rise to ischemia, decreased peripheral pulses, coolness, pallor, and possible cyanosis of the upper extremity.

Running directly beside the subclavian artery, with the exception of passage anterior to the scalenus anticus muscle, is the subclavian vein. Due to the vein’s escape from inter-muscular passage, venous compression syndromes are much less common (one percent), but involve swelling in the hands whenever the vein is involved.

The third component of the neurovascular bundle, the brachial plexus, also follows the same course as the subclavian artery through the interscalene triangle, only slightly more posterior and lateral. It is the most frequently involved structure in TOS (95 percent of all cases) and produces paresthesias, anesthesias, pain, weakness, and atrophy in the upper extremity as a result of its compression.

Finally, the great lymph channels also pass through Sibson’s fascia, following the course of the neurovascular bundle, but are rarely compressed.

Causes of TOS
Thoracic Outlet Syndromes are caused by a narrowing of one of the boundaries of the outlet. Aberrant muscles or muscle hypertrophy cause such a narrowing. Osseous pathologies such as anomalous thoracic ribs, improperly healed rib or clavicular fractures, or cervical ribs are also culprits.

More likely, however, somatic dysfunctions of C7, T1, the clavicle, and ribs 1 or 2 will be the etiology in the normal patient who is subjected to traumatic injury or compromised posturing.

Thoracic Outlet Syndromes are also divided into four major syndromes, each dependent on the site and structure involved in the impingement. Each has specific characteristics and diagnostic tests.

Scalenus Anticus Syndrome
The Scalenus Anticus Syndrome involves a compression on the brachial plexus and/or the subclavian artery as these structures pass through the interscalene triangle. Pressure is usually imposed by muscle hypertrophy.

Usually, it is the posterior portion of the brachial plexus (i.e. the ulnar nerve) that is involved in this syndrome so symptoms of neuropathy most often involve numbness in the fourth and fifth fingers, the lateral side of the hand and possibly the forearm, and decreased sensory appreciation of light touch or pinprick in the 5th digit.

Symptoms of arterial compression are also appreciated (e.g. coolness, pallor, decreased pulses). Additionally, auscultation of the anterior cervical triangle will often reveal a bruit, especially when the arm is held in abduction and extension.

Clinically, Scalenus Anticus Syndrome is diagnosed by utilizing Adson’s maneuver. This test is designed to increase tension in the anterior and middle scalene muscles, narrow the interscalene space, compress the first rib against the C8 and T1 nerve roots and reproduce the compression on the structures being tested, specifically the subclavian artery.

To perform the test, evaluate the vascular flow in the radial artery with your patient in the seated position. Then have your patient extend the neck fully. Rotate the chin towards the side being evaluated, while producing a downward traction on the shoulder. Then recheck the radial pulse. A diminution or obliteration of the radial pulse is a sign of compression and a positive test (figure 1).

Cervical Rib Syndrome
A variation of the Scalenus Anticus Syndrome is the Cervical Rib Syndrome. In this syndrome, it is an osseous anomaly, not muscular hypertrophy, that is responsible for the compression. Cervical ribs are hereditary elongations of the transverse processes of the C7 vertebrae. They may be unilateral or bilateral.

These anomalous structures increase compression of the subclavian artery and the lower components of the brachial plexus against the first rib, causing both parasthesias and decreased distal pulses. It, too, is diagnosed utilizing Adson’s test, but in this case, pulse changes may be better appreciated by turning the head away rather than towards before assessment.

Costoclavicular Syndrome
The Costoclavicular Syndrome is caused by a narrowing of the space between the clavicle and the first rib. This narrowing places undue pressure upon the subclavian artery and vein, and sometimes on the brachial plexus.

Costoclavicular Syndrome may be appreciated in the normal athletic male with massive shoulders or may be seen in any individual who typically has a backwards, downwards thrust of the shoulders such as in a military posture.

Costoclavicular symptoms include coolness, pallor, diminished distal pulses and edema in the fingers and dorsum of the hand. It may be diagnosed by utilizing a modification of Adson’s maneuver known as the Costoclavicular maneuver, where the radial pulse is assessed, then the patient is placed in the military posture, then the radial pulse is evaluated again. A decreased or absent pulse is again the sign of a positive test.

Hyperabduction Syndrome
Hyperabduction Syndrome is the last of the commonly seen thoracic outlet syndromes and the only one where the impingement may not take place in the thoracic outlet itself.

Hyperabduction syndrome is caused by impingement of the neurovascular bundle as it passes either beneath the pectoralis minor tendon and the coracoid process of the scapula or as it passes through the retroclavicular space, between the clavicle and the first rib.

Those individuals who experience repeated and prolonged hyperabduction of the upper extremities such as mechanics, painters, volleyball players, and tennis players are particularly prone to development of this syndrome. Hyperabduction Syndrome can clinically be diagnosed utilizing the hyperabduction test.

Evaluate the patient’s radial pulse, then place the patient in hyperabduction (i.e. arms above the head, elbows fully flexed). A diminution or obliteration of the radial pulse again suggests a thoracic outlet problem.

In addition the specific provocative tests listed above, the EAST test (Elevated Arm Stress Test) may be a good screening test for all categories of thoracic outlet. To perform the EAST test, have the patient sit with his/her arms abducted at 90 degrees from the thorax and the elbows flexed 90 degrees. The patient then opens and closes the hands for three minutes. Patients with TOS cannot perform this test without a reproduction of symptoms.

A variety of somatic clues also elevate the index of suspicion for TOS. In some cases, infraclavicular parasternal asymmetry (i.e. a drop off from the medial clavicle to the cartilage of the first rib) may be noted.

TOS is usually accompanied by tenderness at the angle of rib1 cartilage and a lack of resilience in the cartilaginous joints. Often the angle of Louis is prominent. Muscular contraction in the scalenes and the sternocleidomastoid muscle must be closely evaluated and somatic dysfunctions of rib1, the manubrium or the gladiolous of the sternum, ribs 1 or 2, T1 or 2, or in the clavicle must be carefully considered.

Differential Diagnoses
The differential diagnoses for Thoracic Outlet Syndromes are multiple and sometimes serious.

Most commonly misdiagnosed for TOS is Carpal Tunnel Syndrome. In contrast to TOS, which most commonly involves the lower two nerve roots (C8and T1) with paresthesias into the ulnar nerve, and second most commonly involves the upper three nerve roots (C5,6 and 7) with paresthesias into the radial nerve, Carpal Tunnel Syndrome involves a compression of the median nerve in the distal wrist.

It is important to separate these two syndromes as the sites of pathology and treatment are at opposite ends of the extremity. Additionally, when performing the differential diagnosis, the astute clinician must rule out angina, multiple sclerosis, rotator cuff injuries, spinal cord radiculopathies, superficial thrombophlebites, spinal cord neoplasms, Raynaud’s disease, cervical spondylitis, ulnar nerve compression at the elbow, vasculitis, trauma, and pancoast tumor.

Imaging studies will help the clinician pinpoint the diagnosis of TOS. Chest radiograph will identify clavicular deformity, and cervical ribs. Color flow duplex scanning, as well as arteriogram and venography, highlight etiologies of a vascular nature. Nerve conduction evaluation via root stimulation and F wave is the best diagnostic evaluation for neurologic symptoms of the syndrome. EMG is unreliable and does not provide objective evidence for diagnosis.

Treatment of Thoracic Outlet Syndromes is truly a demonstration of dynamic osteopathic philosophy and practice. Identify the cause of the compression, treat all somatic dysfunctions, optimize normal function, and allow the body to heal itself. This approach will ameliorate most of the syndromes seen by the busy practitioner.

Attention to relaxation of Sibson’s fascia with indirect or direct myofascial release, in and of itself, will greatly affect the spatial proximity of structures in the thoracic outlet. Relaxation of all tight muscles must be attended to. Spray and stretch techniques, with or without the use of ethyl chloride, are particularly useful, as are trigger point injections of muscle spasms.

Stretching oaf the trapezius, rhomboids, and scalenes must be accomplished. Clavicular, cervical spine, thoracic spine, shoulder, and elbow somatic dysfunctions must be corrected. There is no specific benefit to utilization of direct versus indirect methods; both are effective.

In addition to osteopathic manipulation, muscle relaxants, NSAIDS, antidepressants and BOTOX have all been used in the pharmocologic approach to treatment. Biofeedback has also proven to be helpful.

However first and foremost, patients must have an evaluation of the ergonomics of their work site and activities of daily living. Remove the etiology of the compression.

Conclusion
Thoracic Outlet Syndrome is truly an osteopathic presentation. We, as osteopathic physicians, can set the body back on course with the use of appropriate manual medicine and often prevent undue suffering, chronic pharmacologic intervention and even surgery.

Fix the problem. Trust that the body will do the rest.

Elaine Wallace, DO, is Chair of the Osteopathic Principles and Practices Department and Liaison for International Osteopathic Medicine at Nova Southeastern University in Ft. Lauderdale, Florida.