SVC syndrome is an oncological emergency. There is obstruction of the superior vena cava resulting in stagnating blood and a high risk of thrombosis. Due to this obstruction, collaterals develop to drain the head, neck & upper extremities which dilate over several weeks. Cardiac output is usually not severely diminished as the quick rise in venous pressures opens up these collaterals which reestablishes blood flow.

The most common cause is non-small cell lung cancer followed by Non-Hodgkin’s Lymphoma. Other malignancies (such as breast, colon, oesophageal & testicular cancer) are also able to cause SVC syndrome. Often this malignancy has not yet been identified at the time of presentation. There are other benign causes of SVC syndrome such as mediastinal fibrosis and secondary to a central venous catheter.

Signs and Symptoms

The common features are SOB & facial/neck swelling (with dilated collateral veins over chest/forehead & arms). Often the facial & neck swelling is worsened by bending forward or lying down. The swelling can be very visually striking and the concern is of larygneal oedema which can result in compression of the airways. Associated cyanosis, mild dysphagia, cough or impairment of head/eye/neck movements with mild visual changes are all fairly common.

One can look for Pemberton’s Sign: on raising both arms above their head, there is congestion of the face due to engorgement of neck and facial veins

Features of cerebral oedema (headache, dizziness, drowsiness), larygenal oedema (hoarse voice, stridor), diminished cardiac return (syncope after bending, haemodynamic instability) are very concerning features requiring emergency help.

Investigations

• CXR will often show a widened mediastinum but contrast enhanced CT imaging will be needed to confirm the diagnosis. CT imaging is both very sensitive & specific.
• Duplex USS can be considered to exclude a thrombus. Indirect features can also help identify whether there is likely SVC obstruction.

Management

• If there is suspected larygneal oedema or airway compromise, urgent stablisation and intubation is usually required followed by urgent endovascular recanalisation with stent placement as needed.
• If a thrombus is present, systemic anticoagulation is usually started.
• If a central venous catheter is present, it may need repositioning or removing if there is an associated thrombus
• If mild to moderate symptoms, elevating the head can provide symptomatic relief whilst awaiting decisions on more definitive treatment from specialist teams such as oncology who may recommend dexamethasone, diuretics, radiotherapy, chemotherapy or a combination of the above. Steroids & radiotherapy may impact subsequent histopathological diagnosis.
• Surgical management (e.g. stent or bypass) needs to be carefully balanced against prognosis and risk of harm

References

1. BMJ Best Practice – SVC Syndrome
2. UpToDate – Malignancy related SVC Syndrome
3. Patient.info – SVC obstruction

Written by Dr Myra Amer (FY2) & Dr Katie Newton (FY1) & Dr Akash Doshi (ST4)