Neurologic Thoracic Outlet Syndrome Workup

Updated: May 08, 2019
  • Author: Joy Chan, MD; Chief Editor: Robert A Egan, MD  more...
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Laboratory Studies

A thorough history and physical examination are the most important components in establishing the diagnosis of TOS. Use of radiographic and laboratory tests may improve the diagnostic yield. Various screening tests may be appropriate to exclude other causes of upper extremity pain and paresthesia.


Imaging Studies

Radiographs may exhibit bony anomalies.

Chest radiograph may demonstrate cervical or first rib, Pancoast tumor, or other skeletal deformity.

Cervical spine radiograph may be helpful in showing a cervical rib, an elongated transverse process, or scoliosis.

Color flow duplex scanning can identify interruption of blood flow to the affected extremity.

CT angiography can identify stenosis, or blockage of the artery from thrombi or emboli. It also can detect aneurysms that may be compressing the plexus.

Venography (subclavian vein) is confirmatory and remains the criterion standard if intervention is planned. This study can demonstrate the site of obstruction or the presence of thrombus.

CT scan or MRI is useful to exclude cord lesions and radiculopathy, evaluate soft tissue structures and may exhibit plexus distortion.


Other Tests

Electromyography/nerve conduction study (EMG/NCS) may be useful to exclude coexistent abnormalities such as peripheral nerve entrapment or cervical radiculopathy and is more useful in the diagnosis of true neurogenic TOS. In true neurogenic TOS, EMG/NCS of patients will show reduced amplitude in the medial antebrachial and ulnar sensory responses and reduced amplitude in median and ulnar (median more so than ulnar) motor responses, with a normal median sensory response. [8, 9]

Sensory evoked potentials are of limited value in making the diagnosis of neurogenic-type TOS and have no established value in vascular-type TOS.