Arterial Thoracic Outlet Syndrome

A form of thoracic outlet syndrome that presents as unilateral upper extremity ischemia.

Epidemiology

Determination of incidence is difficult due to the lack of a confirmatory test for TOS. ATOS accounts for less than 1% of all cases of TOS.

Clinical description

ATOS occurs spontaneously in patients of all ages and presents with upper extremity ischemia (pain, pallor, anesthesia, coldness, claudication). Rarely subclavian thrombi embolize retrograde causing stroke.

Etiology

Symptoms of ATOS are caused by subclavian artery compression (often by a cervical rib), or emboli. Subclavian artery compression in the neck results in poststenotic dilation, aneurysm formation, turbulent flow and thrombus formation.

Diagnostic methods

Diagnosis is based on a history of upper extremity ischemia and diminished distal pulses or decreased systolic blood pressure in the affected limb. A cervical rib or long cervical transverse process is identified in over 90% of patients. Subclavian stenosis, occlusion or aneurysm on dynamic ultrasonography, magnetic resonance angiography or arteriography 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's (test is positif if radial pulse disappears while turning the head with extended neck following deep inspiration) tests can also be helpful.

Differential diagnosis

Differential diagnoses include venous and neurogenic TOS (see these terms), peripheral artery disease and other disorders leading to arterial compromise, such as external compression by a tumor. Venous TOS can be ruled out with venous ultrasound or magnetic resonance venography. True neurogenic TOS presents as a lower trunk brachial plexopathy. Patients with PAD have atherosclerotic risk factors. Other external causes of compression can be ruled out with the appropriate cross sectional imaging.

Management and treatment

Acute arterial ischemia is treated with thrombolysis or embolectomy. Surgical decompression is indicated in symptomatic patients. Arterial reconstruction may be necessary. Physical therapy is generally not helpful.

Prognosis

Arterial occlusion is limb threatening, but most patients recover full function when treated appropriately. In 91% of cases, ATOS decompression results in complete resolution of symptoms.