Superior vena cava syndrome

Definition

Superior vena cava syndrome comprises the symptoms and findings resulting from narrowing or occlusion of the thin-walled superior vena cava. Venous pressure in the head, neck, arms, and upper trunk rises; collateral veins can form an alternative venous pathway.

Causes: About 70 % are tumor-related, due to external compression, ingrowth of tumor cells into the vessel, or thrombosis. Lung carcinoma and non-Hodgkin lymphoma together cause about 85 % of tumor-related cases (non-small cell lung carcinoma about 50 %, non-Hodgkin lymphoma about 10 %); the rest is mainly due to mediastinal metastases, e.g., of breast cancer, and rarely germ cell tumors, thymomas, or mesotheliomas. Superior vena cava syndrome may be the first sign of a previously unknown tumor in up to 60 %. Non-tumor causes (up to about 30 %) are mainly thromboses on central venous catheters and pacemaker leads, as well as mediastinal fibrosis, retrosternal goiter, and Behçet disease.

Clinical features

Symptoms usually develop over weeks to months. Severity and pace depend on the location, speed, and degree of obstruction and on the collaterals.

• Common: swelling of the face and neck, breathlessness (often worse when supine), a sensation of head fullness, cough, distended neck and chest wall veins, arm edema, facial flushing (plethora), dizziness on bending forward
• Less common and signs of severe disease: cyanosis of the upper body, hoarseness, stridor due to laryngeal edema, headache, visual disturbances, confusion, and syncope due to cerebral edema

Severity grades

The grading by Yu and colleagues describes severity:

• Grade 0: radiographic occlusion without symptoms
• Grade 1 (mild): edema of the head or neck, cyanosis, plethora
• Grade 2 (moderate): additional functional impairment, e.g., mild dysphagia, cough, visual disturbances due to eyelid edema
• Grade 3 (severe): mild to moderate cerebral or laryngeal edema or diminished cardiac capacity (syncope after bending forward)
• Grade 4 (life-threatening): significant cerebral edema (confusion, obtundation), laryngeal edema with stridor, or hemodynamic compromise (syncope without precipitating factors, hypotension, renal insufficiency)
• Grade 5: fatal

Diagnosis

• History and examination focusing on the typical signs; confirmation requires imaging.
• Chest x-ray: indirect signs such as mediastinal widening, pleural effusion, lung mass, or right hilar lymphadenopathy.
• Contrast-enhanced CT: the most helpful study; shows the extent of obstruction, collateral veins, and the cause (external compression or thrombosis) as well as mediastinal masses and lymph nodes. Collaterals on CT strongly indicate obstruction (sensitivity 92 %, specificity 96 %).
• Duplex ultrasound of the arm veins: thrombi in the subclavian, axillary, and brachiocephalic veins, especially with catheter thrombosis; the superior vena cava itself cannot be visualized directly by ultrasound.
• Conventional venography: gold standard for depicting obstruction, collaterals, and extent of thrombus; MR venography as an alternative.
• Clarification of the cause: histologic confirmation when a tumor is suspected.

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Further reading (open access)

1. MSD Manual Professional: Lung Carcinoma (Abschnitt Superior Vena Cava Syndrome)
2. MSD Manual Professional: Non-Hodgkin Lymphomas

Cross-references