Clinical Presentation of TOS

Neural Compression

Because of the various potential anatomic areas of compression and the variety of structures that can be involved, the clinical manifestations can be inconsist­ent in nature. The most common clear presenting symptom of the thoracic outlet syndrome arises from compression of the lower trunk of the brachial plexus. The pain extends from the root of the neck to the shoulder and then down the arm in a diffuse fash­ion. It may be accompanied by paresthesias involving the medial aspect of the hand, particularly the little finger and ring finger, but it may involve the whole of the medial aspect of the arm, particularly from the shoulder to the elbow. Less commonly patients com­plain of weakness of the affected hand, and there may be detectable wasting. Tennis or baseball players may find difficulty gripping the racket or bat. Occasionally there is only painless intrinsic atrophy of the hand. Ultimately the whole of the hand may be involved, but it usually starts on the ulnar side. Some patients complain mainly of neck and shoulder pain, with vague discomfort extending into the trapezius and suboccipital region, which they may describe as a headache-type sensation.

During the history it is important to elicit that the patient or athlete relates the symptoms to upper limb motion in the arc where the nerves are either stretched or compressed. Adopting the pos­ture that either narrows the costoclavicular interval or allows compression of the underlying structures should reproduce the symptoms. Numbness and tingling in the hand with overhead movements must be distinguished from the dead arm syndrome of shoulder instability, where rapid movements are involved. Some patients complain of nocturnal paresthesias, waking to find that they have slept with their arms in an overhead position.

Arterial Compression

Symptoms of arterial compression are usually re­lated to numbness of the whole arm with rapid fatigue during overhead exercises. These symptoms may be an isolated finding or occur in association with some neural symptoms. When there is significant arterial compression, the hand may be obviously cool and pale compared to that on the contralateral side when both are held above the head. In addition, the radial pulse may disappear only to return when the arm is replaced at the side. However, this phenomena is frequently seen in the general population, and so great care should be taken when drawing any conclusions from a weakening or a disappearing pulse with the arms above the level of the shoulder. Rarely there are signs of acute arterial insufficiency with major vascular compromise to the hand or even the entire limb.

Venous Compression

When venous compression in the thoracic outlet is the presenting problem, the patient may arrive with a swollen, discolored limb several hours after a bout of intense exercise. In the general population unaccus­tomed activity such as a building project may cause the problem, but with the patient or athlete it is usually a sudden change in exercise pattern, either different activity or an intense increase in volume of a specific overhead movement. Occasionally, this obvious swelling and color change disappears over several hours so by the time the patient is examined by the physician there is little to see; thus a careful history is important. When Venous compromise is sufficiently severe or there is also occlusion of the subclavian vein, a visible venous collateral pattern may become evident across the patient’s shoulder, chest, and ipsilateral breast.

Diagnostic Tests

 In addition to a detailed history, it is essential to evaluate the cervical spine, shoulder, elbow, and hand for evidence of neural compression. It is mandatory to distinguish the classic ulnar and median nerve compression syndromes and cervical radicular signs. Instability of the shoulder should be ruled out and posture evaluated. Inasmuch as the diagnosis of the thoracic outlet compression is usually one of exclu­sion, this initial screening is mandatory.

Thoracic Outlet Tests

1.         Inspection of posture:

A.     Shoulder asymmetry.

B.     Poorly developed musculature/drooping shoulders.

C.     Unusually large breasts.

2.         Palpation: Reveals tenderness over supra­clavicular fossa, check for increased tone of the scalene muscles.

3.         Listen for bruits: Over supraclavicular fossa while arm is in a provocative position.

4.         Provocative maneuvers: Examiner looks for obliteration of radial pulse and/or exacer­bation of symptoms.

A.     Costoclavicular maneuver. Patient shrugs shoulders with deep in­halation while drawing the shoulders backward in an exaggerated military position.

B.      Scalenus anticus maneuver. Patient turns the head away from the involved side and opens and closes the involved hand 5 times and is then examined for blanching of the hand. This may also be done by turning the head toward the involved side.

C.     Adson’s maneuver. Patient extends and turns head toward involved side with deep inhalation, and the ex­aminer laterally rotates and extends the shoulder.

D.     Wright’s hyperabduction. Patient turns head away from involved side, and with deep inhalation the arm is abducted and externally rotated. The pectoralis minor muscle forces compression against the fulcrum of the coracoid process.

E.     Arm elevation stress test (AEST). With arms overhead, patient rapidly flexes and extends fingers. Reproduction of symptoms or fatigue is a positive sign.

The hyperabduction test is performed by taking the arm into gradual abduction and extension of the shoulder while monitoring the pulse. This test is con­sidered positive only if it reproduces all the clinical signs; it is also helpful if there is confirmatory bruit over the subclavian arterial at the time of pulse diminution and reproduction of the symptoms.

The Arm Elevation Stress Test (a/k/a ROOS' test) is performed by having the patient take the arms into full elevation and then rap­idly flex and extend the fingers. In susceptible indi­viduals a feeling of fatigue or even cramping of the forearm muscles may be experienced within about 20 seconds. The elevated arm may also become pale compared to the normal side, and the obliteration or diminishing of a pulse assists in confirming the diagnosis. A variation of this test is the 3-minute elevated arm exercise test.

Adson’s maneuver is performed with the arm at the side and externally rotated and the examiner monitoring the pulse while the patient rotates the head toward the involved side, elevates the chin, pushes into full rotation, and takes a deep breath to fix the upper rib.  Unfortunately, this test for thoracic outlet compression produces many false-positive findings.

With Wright’s maneuver, the pulse of the abducted and laterally rotated arm is monitored while the neck is rotated to the opposite side. The patient takes a deep breath while adopting the so-called military brace position with the shoulders retracted and pulled down.

Plain cervical spinal roentgenograms (x-rays) may help to rule out certain intrinsic conditions, e.g., cervical spondylosis, narrowed intervertebral discs, and osteophytic impingement (bone spurs). The presence of cervical ribs or long C7 transverse processes may fit in with the findings of thoracic outlet compression. All patients should have adequate studies of the apex of the lung on the affected side.

There is a discrepancy of opinion regarding the value of electrodiagnostic studies. There is considerable difficulty accurately determining the nerve conduc­tion velocity through the thoracic outlet. In many ways, the biggest value of electrodiagnostic studies is to rule out peripheral entrapment, e.g., ulnar neuropathy at the elbow or hand or carpal tunnel syndrome of the median nerve at the wrist.

If there is significant evidence of arterial venous involvement suggesting either thrombosis, aneurysm or compression, it may be prudent to obtain Doppler, Angiographic, or venographic studies.  

Differential Diagnosis

Because there are few definite indicators of the thoracic outlet syndrome, its diagnosis is one of ex­clusion. Thus the differential diagnosis assumes sig­nificance.

Cervical Spine

Cervical spinal pathology is the most common cause of paresthesia in the upper limb, and efforts should be made to distinguish radicular pain in the C8 and T1 distribution. Most disc diseases affect the C5—C6 level and to somewhat lesser extent the C7 level. Thus paresthesias in the ulnar side of the hand are more likely to be of distal origin.

Supraclavicular Fossa

Any space-occupying lesion within the thoracic outlet, particularly the Pancoast’s tumor at the apex of the lungs, may mimic the symptoms of the thoracic outlet syndrome. Although it is believed that the pur­suit of health and fitness is not compatible with smok­ing, a large number of patients and athletes do indeed smoke on a regular basis. The incidence of lung cancer parallels this habit, and so the middle-aged and elderly pateint is not immune from lung tumors.

Peripheral Neuritis

Peripheral entrapment of the ulnar nerve at the elbow and in the cubital tunnel, or in the hand in Guyon’s canal, can produce typical dysesthesia in the ring and little fingers. Similarly, compression of the median nerve and the carpal tunnel may produce paresthesias in the distribution of that nerve, typically in the thumb and index and middle fingers, with wast­ing of the hyperthenar eminence. In previously re­ported series of cervical rib resection for thoracic outlet, there was an uncomfortably large percentage of individuals who subsequently required release of the ulnar or medial nerve peripherally. It is tempting to postulate a double-crush syndrome, with irritation at a subclinical level in both sites, combining to pro­duce a significant clinical entity. One should remain pragmatic, however, and assume that in many of these instances an incorrect diagnosis has been made.

Reflex Sympathetic Dystrophy

Like the thoracic outlet syndrome, reflex sympa­thetic dystrophy presents as a constellation of periph­eral symptoms, including dysesthesias, hypersensitiv­ity, and muscle wasting. The key to diagnosing reflex sympathetic dystrophy is awareness of the possibility of this syndrome. A key feature is the disassociation between the sensations of touch, pressure, and pain. It may be particularly difficult to distinguish the two syndromes if there is appreciable swelling within the

REVIEW OF TOS

CLINICAL MANIFESTATION

It may have a blood vessel (vascular) vascular origin or a nerve (neural) origin.

• Vascular origin

- Dull aching

- Venous distension

- Peripheral edema

- Occasional ulceration

• Nerve Origin

- Intermittent

- Usually ulnar abnormal sensation (dysesthesia) - T1 dermatome usually

- Aggravated by overhead activity

- Generalized upper limb ache

POTENTIAL SITES OF NEUROVASCULAR COMPRESSION      

Supraclavicular— scalene triangle        

Subclavicular—between clavicle and first rib    

Infraclavicular—subcoracoid and costo­coracoid membrane