Neurogenic Thoracic Outlet Syndrome

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Neurogenic Thoracic Outlet Syndrome

Thoracic outlet syndrome is the term given to a collection of several syndromes involving compression of the neurovascular bundle. The neurovascular bundle passes through the thoracic outlet and is comprised of the brachial plexus, subclavian artery, and subclavian vein.

Three sites of possible compression are reported:

• The interscalene triangle (possibly compromised by the presence of a cervical rib)
• Costoclavicular space (between the clavicle and first rib)
• Subcoracoid space (deep into the tendon of the pectoralis minor)

• Neck, shoulder, chest, arm, and hand pain.
• Pain accompanied by dysesthesia, numbness, and weakness.
• A history of occupational, sporting, or habitual overhead arm activities.

• Sensory abnormalities in the T1 nerve root distribution.
• Provocation of symptoms with neck rotation and lateral flexion as well as shoulder abduction and external rotation.
• Provocation of symptoms during Upper Limb Tension tests.
• The Roos and Adson’s tests may be positive.
• Presence of Gilliatt-Sumner hand (atrophy of the abductor pollicis brevis, interossei, and hypothenar muscles) in chronic and severe cases.

• Plain radiography is used to assess for bony abnormalities.
• CT scanning and MRI are useful for demonstrating the presence of other conditions causing similar symptoms (e.g., space-occupying lesions).
• Doppler ultrasound and MRA (Magnetic Resonance Angiography) may be required to identify venous or arterial forms of Thoracic Outlet Syndrome.

The following are examples of red flags for neck, chest, and upper extremity pain:

• Severe and acute onset or unrelenting pain.
• Associated symptoms indicating cardiac or respiratory disease (e.g., cough, breathlessness).
• Trauma.
• Significant neurological impairment.
• Moderate to severe swelling.
• Deformity.
• Severe tenderness on palpation or severe pain with any examination procedure.

If any red flags are identified during history taking and clinical examination, referral for urgent medical evaluation and further investigation is warranted.

Joint Dysfunction

In our experience, Thoracic Outlet Syndrome is often accompanied by joint dysfunction. When joint dysfunction is present as a contributing factor, we find it most commonly in the clavicle and the first rib. We advocate the management of this dysfunction by using an instrument-assisted procedure or by gentle manual manipulation or mobilization.

Myofascial Pain Syndromes

In patients presenting with symptoms of thoracic outlet syndrome, a complete clinical examination should include an evaluation of the following muscles to check for the presence of myofascial pain syndrome as the concomitant or primary cause of the patient’s pain:

• Pectoralis minor
• Pectoralis major (depending on the location of the trigger point, pain may refer just to the anterior shoulder, or only to the chest and the medial elbow)
• Scalene

The pectoralis minor trigger points primarily refer pain over the front of the shoulder and sometimes down the ulnar side of the arm, forearm, and fingers. The taut fibers of the trigger points in this muscle may entrap the brachial plexus. When they do so, they frequently mimic cervical radiculopathy. The scalene muscle trigger points and their associated thoracic outlet entrapment syndrome are frequently involved. The trigger points refer pain to the shoulder girdle and the upper arm as shown in the images below.