Venous Thoracic Outlet Syndrome

Venous thoracic outlet syndrome (VTOS) is a form of thoracic outlet syndrome (TOS; see this term) that manifests as unilateral (rarely bilateral) arm pain and cyanosis.

Epidemiology

Determination of incidence is difficult due to the lack of a confirmatory test for TOS. VTOS accounts for 2%-3% of all cases of TOS.

Clinical description

VTOS occurs in young adults, usually after excessive arm activity. The characteristic symptoms, caused by venous obstruction, are arm swelling, cyanosis, pain and mild paresthesias. Neck pain and headaches may rarely occur. The forearm fatigues within minutes of use. Visible subcutaneous veins over the shoulder and upper chest are often present.

Etiology

Repetitive arm motion and compression of the subclavian vein in the neck (between the clavicle and the first rib) leads to scar tissue that can predispose one to thrombosis due to narrowing of vessels.

Diagnostic methods

Diagnosis is based on findings of arm swelling, cyanosis and distended superficial veins. Radiographs may identify compressive sources including an elongated C7 transverse process or anomalous first rib. Subclavian vein stenosis or occlusion on dynamic ultrasonography, magnetic resonance or computed tomography venography supports the diagnosis. Provocative physical exam maneuvers such as the Roos (test is positive when patient is unable to maintain the position of opening and closing hands while arms are in an elevated position for 3 minutes) and Adson (test is positive if radial pulse disappears while turning the head with extended neck following deep inspiration) tests can also be helpful.

Differential diagnosis

Differential diagnoses include arterial (ATOS) and neurogenic TOS (NTOS) (see these terms), which are differentiated clinically. ATOS presents as upper extremity ischemia due to subclavian artery compression or thrombosis and can be ruled-out with magnetic resonance angiography. True NTOS usually presents as a lower trunk brachial plexopathy and is diagnosed with electrodiagnostics or MRI. Other causes of venous obstruction including tumors, congenital abnormalities and upper extremity deep venous thromboses must also be considered.

Management and treatment

When acute, treatment is thrombolytic therapy followed by decompressive surgery (first rib resection, pectoralis minor release or scalenectomy) to decrease recurrences. Angioplasty or surgical bypass is performed to repair damaged veins. If chronic, with heaviness and a swollen limb but with a patent subclavian vein, decompressive surgery, angioplasty or vascular reconstruction is recommended. Physical therapy is not generally helpful in treating VTOS, but may be helpful in less severe cases.

Prognosis

Patients undergoing successful thrombolysis followed by decompression have five-year secondary vein patency rates greater than 95% but residual edema may limit function.