Acute subclavian artery occlusion due to cervical rib

Clinical History

A 43-year-old female patient was admitted to our hospital because of pain, pallor and coldness in her right arm, which began one day ago. Three-dimensional CT and angiographic findings were presented.

Imaging Findings

A 43-year-old female patient was admitted to our hospital because of pain, pallor and coldness in her right arm, which began one day ago. On physical examination, pulse deficit and coldness were detected. Plain radiograph, computed tomographic (CT) images and 3 dimensional (3D) CT images were taken, which demonstrated a right cervical rib articulating with the first rib (Fig. 1). An angiographic examination was also done, which revealed that a subclavian artery was occluded at the side of the cervical rib (Fig. 2).

Discussion

Thoracic outlet syndrome (TOS) refers to clinical manifestations that may exist due to compression on neurovascular structures in the region of the thoracic outlet. Bony abnormalities such as cervical rib, abnormal first rib, first rib exostosis, a large transverse process of the 7th vertebra or soft tissue structures such as ligaments, fibrous bends, scalene muscles, and scars after neck-shoulder trauma are accepted as the etiology of the compression. The cervical ribs can be detected in 3.5 % of the general population, but only less than 10% of these patients have symptoms attributed to extra ribs. Four main varieties of cervical rib are recognized: Type 1: complete rib, articulating with the first rib or the manubrium sternum; Type 2: incomplete rib, with the free end expanding to form a bulbous tip; Type 3: incomplete rib, which is connected by a fibrous band to the scalene tubercle of the first rib; Type 4: a short bar of bone beyond the transverse process of C7 vertebra. The symptoms of TOS are predominantly (98%) neurological. Vascular impingement is reported to be the cause of TOS in as few as 2% of the patients. Repetitive arterial trauma caused by TOS results in focal stenosis, subsequent poststenotic dilatation or aneurysm of the subclavian artery or thrombosis. These arterial changes may cause aching, fatigue, upper limb claudication, pallor, and Raynaud’s phenomenon. Thrombosis may propagate from the subclavian to the vertebral or carotid arteries and can cause different forms of cerebral embolism. Plain radiographs of the cervical spine and the thoracic inlet can be taken when TOS is caused by bone structures such as cervical rib or scar tissue after clavicle or first rib fracture. Angiography can be used to determine both vascular compression and the other vascular abnormalities such as aneurysm, thrombus, and emboli but it is also invasive and requires iodinate contrast media. A Doppler ultrasonography of the arm during normal and provocative position is routinely performed to image the axillary and supraclavicular region. CT or MRI can demonstrate the functional anatomy of the thoracic outlet. In cases caused by bony abnormality, the uses of 3D CT reconstructed images help to produce an image of bony structure of excellent quality. An MRI can be used to determine non-osseous causes of TOS. CT angiography and MRI angiography may reveal the distortion of the subclavian vessels. The vascular TOS requires surgical treatment that always involves decompression and may include vascular procedures. A complete or partial resolution of the symptoms can be seen in up to 90% of the surgical treatment in the early postoperative period.

Differential Diagnosis List

Final Diagnosis

Acute subclavian artery occlusion due to cervical rib.

URL:	https://www.eurorad.org/case/3474
DOI:	10.1594/EURORAD/CASE.3474
ISSN:	1563-4086