Thoracic Outlet Syndrome Workup

Updated: Jan 10, 2019
  • Author: Daryl A Rosenbaum, MD; Chief Editor: Sherwin SW Ho, MD  more...
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Workup

Approach Considerations

In thoracic outlet syndrome with vascular compromise or nerve compression, with resultant atrophy of the intrinsic hand muscles, the diagnosis is not controversial and specific tests can confirm the diagnosis. However, no infallible clinical tests, laboratory tests, radiographic tests, or electrical studies establish the diagnosis of thoracic outlet syndrome syndrome in patients with disputed or nonspecific-type thoracic outlet syndrome. [25] Many tests are available to refine the differential diagnosis and confirm or exclude other potential conditions (see Differentials and Other Problems to Be Considered).

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Laboratory Studies

To exclude systemic disease and inflammation, a few simple blood tests may refine the differential diagnosis for thoracic outlet syndrome, including a blood glucose level, complete blood cell (CBC) count, erythrocyte sedimentation rate (ESR), basic metabolic panel, thyrotropin level, and rheumatologic workup, if indicated.

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Imaging Studies

Radiography

Cervical spine and upper thoracic spine radiographs may demonstrate bony abnormalities. Chest, shoulder, and clavicle radiographs may also identify bony abnormalities.

Computed tomography (CT) scanning and magnetic resonance imaging (MRI)

CT scanning and MRI are more useful for identifying other conditions that might cause similar symptoms, rather than for establishing the diagnosis of thoracic outlet syndrome. [26]

Magnetic resonance angiography (MRA)

MRA can be useful for the diagnosis of arterial vascular thoracic outlet syndrome. [27, 28]

Venography and duplex scanning

Venography and duplex scanning (ie, ultrasonography combined with Doppler velocity waveforms) are used to assist in the diagnosis of subclavian vein compression (thrombosis). These tests can be performed dynamically with positions that recreate the tension placed on the thoracic outlet during certain motions such as abduction and external rotation.

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Other Tests

Electrodiagnostic studies can be helpful for classic cases of neurogenic thoracic outlet syndrome and therefore can be useful when the results are positive. However, many symptoms are intermittent in neurogenic thoracic outlet syndrome; therefore, negative test results do not rule out this diagnosis. Electrodiagnostic testing can also be helpful in diagnosing other neuromuscular disorders.

Nerve conduction velocity has been used for the diagnosis of thoracic outlet syndrome as defined by a reduction to less than 85 m/s of either the ulnar or median nerves across the thoracic outlet and was found to corroborate the clinical diagnosis. A nerve conduction velocity of less than 60 m/s was considered an indication for surgery. [24] However, as with many aspects of thoracic outlet syndrome, this remains controversial and has not been universally accepted.

Somatosensory evoked potentials are equally controversial, with some studies favoring their use [29] and others not. [30]

Electromyography may be helpful in confirming the presence or absence of a specific alternative diagnosis.

A study reported that intravascular ultrasound detected greater levels of stenosis than venography in the treatment of 14 venous thoracic outlet syndrome patients. [54]

 

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