Figura 1. Limits of thoracic outlet syndrome and its association with the subclavian vein: 1) Subcl...

Tabla 1. Different diagnostic maneuvers.

Tabla 2. Diagnostic imaging modalities.

Figura 2. A: The compression of the vein can be seen with the arm stretched out and hyperabduction w...

Introduction

The axillary vein is a continuation of the brachial vein that ascends towards the thorax. Then, it turns into the subclavian vein as it passes above the first rib underneath the clavicle. Then, it meets with the internal jugular vein to become the brachiocephalic vein. The term axillosubclavian is used to refer to the axillary and subclavian segments of the vein. To reach the internal jugular vein, the subclavian vein needs to run through the thoracic outlet. Tunnel roof is the clavicle, the floor is the first rib. Medially, the sides are made up by the subclavian and costoclavicular ligaments; laterally, by the anterior scalene muscle. Both the clavicle and the first rib meet in a support site that allows exerting maximum strength between the two in the region where the vein resides. The subclavian muscle is another significant structure of the thoracic outlet. This muscle, as its name indicates, is found underneath the clavicle, and can compress the subclavian vein (Figure 1).1 Thoracic outlet syndrome (TOS) is a rare disease that mostly affects young patients. It is due to the compression of neurovascular structures. Depending on what structure is compromised it can be categorized into neurogenic (due to brachial plexus compromise), venous, and arterial (due to subclavian compromise). Although the main cornerstones of diagnosis are the past medical history and physical examination (Table 1),1-3 imaging modalities are useful to confirm diagnosis or the site of the lesion, outline abnormal anatomies, assess other possible causes for the symptoms, and categorize the situation of the patient properly (Table 2).1,3-6 This is the case of a female patient treated with phlebography with an image suggestive of recanalized thrombus. Dynamic angiography confirmed the diagnosis of venous thoracic outlet syndrome (VTOS) with compressed subclavian vein in the proximal third. The objective of this case is to know the pathophysiology and most convenient hemodynamic study to achieve diagnosis.

Case report

This is the case of a 28-year-old woman with a past medical history of 2 episodes of deep venous thrombosis (DVP) of right upper limb at right subclavian vein level confirmed on the venous Doppler echocardiography with favorable response to anticoagulant therapy. Due to suspected VTOS, the patient was referred to our unit to confirm the diagnosis. At the questioning, she complains of right upper limb pain, swelling, functional disability, and color changes during movement. Angiography of central veins is performed with hyperabduction maneuver and right upper limb stretch. It reveals the presence of a dynamic obstruction at right subclavian vein level with abundant collateral circulation with flow and caliber recovery during adduction and flexion (Figure 2). The patient is then referred to the vascular surgery unit for treatment.

Discussion

TOS describes the possible compression of neurovascular structures: by order of frequency, brachial plexus (90% to 95%), subclavian vein (5%) and artery (1%). Patients show specific signs and symptoms of the compromised anatomic structure. VTOS or the Paget-Schroetter syndrome is a rare entity with an incidence rate of 1/100 000 inhabitants/year. The population with more chances of being affected are active young men in their thirties with a 2:1 ratio compared to women being right arm the most commonly affected limb. Overall, the cause is associated with an intense physical activity or anomalous position of the arms (elevation) that causes the compression of the subclavian vein. Other structures like cervical ribs and anomalous ligament bands also promote compression. It has been suggested that the continuous compression of the vein would generate an inflammatory reaction at endothelial level that, added to venous stasis, would promote thrombosis.7 Clinically, it presents with edema, cyanosis, and color in the damaged upper limb. In chronic disease progressions, dilated superficial veins on the upper side of the arm, neck, and thorax are visible. Diagnosis is achieved through non-invasive images like the ultrasound. One limited acoustic window can complicate the acquisition of direct images of the costoclavicular interval. Also, it is operator-dependent and can be a technical challenge in muscular patients or with large adipose tissue. Magnetic resonance imaging is the non-invasive imaging modality of choice since assessing position narrowing requires image acquisition in multiple positions. This gives an inherent advantage over the computed tomography scan due to its lack of ionizing radiation being particularly beneficial in the population of often young patients. Last but not least, computed tomography scan is performed when magnetic resonance imaging is not a possibility due to dialysis-dependent chronic kidney disease, claustrophobia or incompatibility with the device implanted. However, venous angiography is still the key to diagnose vascular lesions. In case of DVP, treatment is based on the administration of thrombolytic drugs depending on the severity of the patient’s symptoms with further surgical decompression. In certain cases, anticoagulation for 2 up to 4 weeks followed by surgical decompression would be enough. The latter is recommended even if the vein remains occluded after thrombolysis since, over time, more than 90% of these patients will recanalize properly. The use of stents is ill-advised as first-line therapy due to the risk of fracture with the corresponding vascular occlusion and difficulty involved in the reconstruction of surgical anatomy.1-4

Conclusion

Our case emphasizes the importance of knowing pathophysiology, provocation maneuvers, and the performance of a dynamic angiographic study to achieve diagnostic certainty. The development of new devices with properties that appeal to flexuosity and compression can be future effective alternatives for endovascular treatment.

1. Robert Moore, Yin Wei Lum. Venous thoracic outlet syndrome. Vascular Medicine 2015, Vol. 20(2) 182-9.

2. Mark R. Jones, Amit Prabhakar, Omar Viswanath, et al. Thoracic Outlet Syndrome: A Comprehensive Review of Pathophysiology, Diagnosis, and Treatment. Pain Ther 2019, 8:5-18.

3. Jérôme Gillard, Maryse Pérez-Cousin, Éric Hachulla, et al. Diagnosing thoracic outlet syndrome: contribution of provocative tests, ultrasonography, electrophysiology, and helical computed tomography in 48 patients. Joint Bone Spine 2001;68:416-24.

4. Constantine A. Raptis, Sreevathsan Sridhar, Robert W. Thompson, Kathryn J. Fowler, Sanjeev Bhalla. Imaging of the Patient with Thoracic Outlet Syndrome.Radiographics 2016, Vol. 36, Issue 4.

5. Xavier Demondion, Pascal Herbinet, Serge Van Sint Jan, Nathalie Boutry, Christophe Chantelot, Anne Cotten. Imaging Assessment of Thoracic Outlet Syndrome. Radio Graphics 2006; 26:1735-50.

6. Leonard T. Buller, Jean Jose, Michael Baraga, Bryson Lesniak, MD. Thoracic Outlet Syndrome:Current Concepts, Imaging Features,and Therapeutic Strategies. The American Journal of Orthopedics.August 2015.

7. Smith DE. Síndrome del opérculo torácico. Hematología 2016;20:50-58.

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