The discussant demonstrated the iterative clinical reasoning that experienced clinicians use when they approach a case.
We use the chief complaint to initially generate a list of conditions that we think are most common or that we don't want to miss.
We then use the history of presenting illness in combination with the past medical history to generate diagnostic hypotheses. We test these hypotheses by asking questions that raise or lower the probability of these diagnoses
We then use the physical exam to look for evidence confirming or denying our hypotheses and arrive at several provisional diagnoses. At this point up to 90% of the time a diagnosis is strongly suspected.
At this point the laboratory, radiology and special tests are used to further refine the differential.
Causes
- 65% Malignancy (lung - NSCLC and SCLC ~75%, lymphoma ~ 10%, mets ~ 10%)
- 35% other
- Infections - TB, syphilitic aortitis
- Thrombosis - catheter/pacemaker related, other
- Aortic aneurysm
- Facial and/or arm edema
- Distended neck and/or chest veins
- Facial phethora
- Dyspnea or cough
- Hoarse voice or stridor
- Headache
- Dizziness, confusion, obtundation
Development of facial plethora, distended neck veins, stridor, and elevated JVP when elevating arms above head. This is a sign of SVC obstruction from a mediastinal mass or a thoracic inlet obstruction from a retrosternal goitre or mass.
Diagnosis
Best modality is CT with contrast to evaluate the SVC itself, the lung and mediastinum and the aorta.
Management
- Treat the underlying malignancy or condition (thrombosis, infection)
- Steroids are commonly used in malignancies; however there is little evidence of benefit
- Radiotherapy to radio-sensitive tumors
- Chemotherapy for sensitive tumors in patients who will tolerate
- Angioplasty and stenting of the SVC can be employed in non-chemo/non-radiotherapy cases or when rapid treatment is required
- Venous bypass surgery when above are not an option (mortality of surgery ~5%)
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