Superior Vena Cava Syndrome

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1- Definition & Types

2- Causes (Aetiology)

3- Pathophysiology

4- Clinical Features & Examination

5- Investigations

6- Management

7- Complications

8- Core Concepts

Definition & Types

Superior Vena Cava Syndrome (SVCS) is a clinical condition caused by obstruction of the superior vena cava (SVC), leading to impaired venous drainage from the head, neck, upper limbs, and upper thorax.

The SVC lies within the superior mediastinum, so its compression or invasion usually results from intrathoracic malignancies, particularly lung cancer.

© image from Wikimedia Commons

Causes (Aetiology)

Most common cause:

  • Lung cancer (especially small-cell carcinoma)

Other causes:

  • Lymphoma (e.g. Hodgkin’s, non-Hodgkin’s)

  • Metastatic mediastinal lymphadenopathy

  • Malignant thymic tumors

  • Germ cell tumors

  • Aortic or innominate aneurysms

  • Benign tumours (e.g. dermoid cysts, thymoma) rarely

SVC syndrome in a person with bronchogenic carcinoma© image from Wikimedia Commons

Pathophysiology

  • Obstruction (external compression or internal invasion) → ↑ venous pressure in structures draining into the SVC

  • Causes venous congestion, collateral vein formation, and reduced venous return

  • If severe → cerebral oedema, airway obstruction

Clinical Features & Examination

Classic signs of SVC obstruction (Box 17.67):

  • Non-pulsatile distension of neck veins (jugular venous pressure)

  • Facial swelling and cyanosis

  • Swelling and cyanosis of arms and hands

  • Subconjunctival oedema

  • Dilated superficial veins on the upper chest wall

Other symptoms:

  • Headache, dizziness

  • Visual disturbance

  • Cough or breathlessness (if tracheal compression)

  • Onset may be gradual or sudden, depending on rate of obstruction.

Investigations

  • CXR: may show widened mediastinum, mass, or lymphadenopathy

  • CT or MRI: to identify the site and cause of obstruction

  • Biopsy: (e.g. bronchoscopy or mediastinoscopy) if malignancy suspected

  • Venography: rarely needed but confirms functional obstruction

Management

Urgency depends on severity of symptoms (e.g. risk of airway compromise)

  • Treat underlying cause:

    • Chemotherapy for small-cell lung cancer or lymphoma

    • Radiotherapy for rapidly progressing symptoms

  • Steroids: may reduce tumour-related oedema temporarily

  • Stenting: endovascular SVC stenting for quick relief in severe cases

  • Supportive care: elevation of the head, oxygen therapy if hypoxaemic

Complications

  • Cerebral oedema (headache, confusion, coma)

  • Laryngeal oedema or airway compromise

  • Visual impairment from raised intracranial pressure

  • Deep venous thrombosis in upper extremities

Core Concepts

  • SVCS = emergency when airway or brain are involved

  • Most common cause: lung cancer, especially small-cell type

  • Facial swelling + dilated neck/chest veins = classic clue

  • CT scan is diagnostic; stenting offers rapid relief in emergencies

  • Always assess for signs of respiratory distress or neurological compromise

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