What is the diagnosis?

Thoracic outlet syndrome (TOS). TOS involves compression of one or more of several neurovascular structures between the supraclavicular fossa and the axilla: the brachial plexus, subclavian artery, or subclavian vein. The three areas of compression include the scalene triangle, the costoclavicular junction and the interpectoral space.

• Pearl: There are three types of thoracic outlet syndrome, neurogenic (95%), venous (4%) and arterial (1%) named for the structures they compress. 

What is the mechanism of injury?

Thoracic outlet syndrome can be acute or chronic. Etiologies include:

• Anatomic abnormalities such as cervical ribs and elongated C7 transverse processes, fibrous muscular bands, cysts, tumors, accessory muscles such as the scalenus minimus, and pectoralis minor or scalene muscle hypertrophy. 
• Acute neck trauma such as whiplash 

• Pearl: Paget-Schrötter Syndrome is a variant of venous TOS involving effort induced acute thrombosis of the axillary and subclavian vein at the thoracic outlet seen in younger patients who engage in repeated strenuous activity of the shoulders and the arms [3].

What symptoms are expected?

The clinical presentation is highly variable with the diagnosis being largely based on a history and physical examination. Neurogenic thoracic outlet syndrome can present with pain, numbness, paresthesias, and weakness that often does not correspond to a distribution of a single peripheral nerve or cervical nerve root.. Venous thoracic outlet syndrome presents with symptoms similar to venous thromboembolism including heaviness, swelling, and discoloration while arterial TOS presents similar to claudication with decreased pulses, pallor, or even evidence of digit thrombosis.

• Pearl: Although not reliable on their own, testing with provocative movements such as the Adson test (radial pulse amplitude change and symptom reproduction with the arm hyperextend and head turned ipsilaterally) and Roos test (reproduction of symptoms with opening and closing the hand with the shoulder and elbow in 90˚ of flexion and abduction respectively) can have a specificity of 82% when combined [1,4].

Which imaging modalities can be used?

The preferred imaging depends on the type of TOS that is suspected. Radiographs are helpful to identify cervical ribs, elongated C7 transverse processes, and a low-lying shoulder girdle. If there is a suspicion for congenital anomalies or soft tissue compression, MRI and CT can be helpful to further characterize these lesions while concern for venous or arterial TOS warrants ultrasound or other vascular imaging modalities.

What is the management? When do we need to call Orthopedics?

Treatment of neurogenic TOS normally involves conservative measures including rest from exacerbating activities, physical therapy and medication management with muscle relaxants and anti-inflammatories. These patients generally do not require urgent orthopedics consultation and surgery is usually only considered after 6 months of conservative management. Surgical decompression of the thoracic outlet is warranted in arterial or venous TOS. Those with evidence of venous thromboembolism or signs of arterial occlusion should receive a vascular surgery consult. Treatments include catheter-directed thrombolysis, angioplasty with stenting, surgical decompression of first rib, and scalenectomy and/or subclavius resection [1,2].