Superior vena cava syndrome
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Superior vena cava syndrome (SVCS), is a group of symptoms caused by obstruction of the superior vena cava ("SVC"), a short, wide vessel carrying circulating blood into the heart. The majority of cases are caused by malignant tumors within the mediastinum, most commonly lung cancer and non-Hodgkin's lymphoma, directly compressing or invading the SVC wall. Non-malignant causes are increasing in prevalence due to expanding use of intravascular devices (such as permanent central venous catheters and leads for pacemakers and defibrillators), which can result in thrombosis.<ref>Template:Cite journal</ref> Other non-malignant causes include benign mediastinal tumors, aortic aneurysm, infections, and fibrosing mediastinitis.<ref name=Medscape>Template:Cite journal</ref>
Characteristic features are edema (swelling due to excess fluid) of the face and arms and development of swollen collateral veins on the front of the chest wall. Shortness of breath and coughing are quite common symptoms; difficulty swallowing is reported in 11% of cases, headache in 6% and stridor (a high-pitched wheeze) in 4%. The symptoms are rarely life-threatening, though edema of the epiglottis can make breathing difficult, edema of the brain can cause reduced alertness, and in less than 5% of cases of SVCO, severe neurological symptoms or airway compromise are reported. Resolution of superior vena cava syndrome is directly related to the treatment of the underlying compression.<ref>Template:Cite book</ref>
Signs and symptomsEdit
Shortness of breath is the most common symptom, followed by face or arm swelling.<ref name=emedicine>emedicine > Superior Vena Cava Syndrome. Author: Michael S Beeson, MD, MBA, FACEP, Professor of Emergency Medicine, Northeastern Ohio Universities College of Medicine and Pharmacy; Attending Faculty, Summa Health System. Updated: Dec 3, 2009</ref>
Following are frequent symptoms:
- Difficulty breathing<ref name=oherm/>
- Headache<ref name=oherm/>
- Facial swelling<ref name=oherm/>
- Venous distention in the neck and distended veins in the upper chest and arms<ref name=oherm/>
- Migraines (especially if unusual to normal)
- Large decrease in lung capacity
- Facial swelling after bending/laying down
- Upper limb edema<ref name=oherm/>
- Lightheadedness<ref name=emedicine/>
- Cough<ref name=emedicine/>
- Edema (swelling) of the neck, called the collar of Stokes<ref>define:collar of Stokes at open-resource-project.org. Retrieved Mars 2011</ref>
- Pemberton's sign<ref name=oherm/>
Superior vena cava syndrome usually presents more gradually with an increase in symptoms over time as malignancies increase in size or invasiveness.<ref name=emedicine />
CauseEdit
Over 80% of cases are caused by malignant tumors compressing the superior vena cava. Lung cancer, most commonly squamous cell carcinoma, comprises 75–80% of these cases and non-Hodgkin lymphoma, most commonly diffuse large B-cell lymphoma, comprises 10–15%. Rare malignant causes include Hodgkin's lymphoma, metastatic cancers, leukemia, leiomyosarcoma of the mediastinal vessels, and plasmocytoma.<ref name=Medscape/> Syphilis and tuberculosis have also been known to cause superior vena cava syndrome.<ref name=emedicine/> SVCS can be caused by invasion or compression by a pathological process or by a deep vein thrombosis in the vein itself, although this latter is less common (approximately 35% due to the use of intravascular devices).<ref name=emedicine/>
DiagnosisEdit
The main techniques of diagnosing SVCS are with chest X-rays (CXR), CT scans, transbronchial needle aspiration at bronchoscopy and mediastinoscopy.<ref name=oherm>Template:Cite book</ref> CXRs often provide the ability to show mediastinal widening and may show the presenting primary cause of SVCS.<ref name=oherm/> However, 16% of people with SVC syndrome have a normal chest X-ray. CT scans should be contrast enhanced and be taken on the neck, chest, lower abdomen, and pelvis.<ref name=oherm/> They may also show the underlying cause and the extent to which the disease has progressed.<ref name=oherm/>
TreatmentEdit
Several methods of treatment are available, mainly consisting of careful drug therapy and surgery.<ref name=emedicine/> Glucocorticoids (such as prednisone or methylprednisolone) decrease the inflammatory response to tumor invasion and edema surrounding the tumor.<ref name=emedicine/> Glucocorticoids are most helpful if the tumor is steroid-responsive, such as lymphomas. In addition, diuretics (such as furosemide) are used to reduce venous return to the heart which relieves the increased pressure.<ref name=emedicine/>
In an acute setting, endovascular stenting by an interventional radiologist may provide relief of symptoms in as little as 12–24 hours with minimal risks.Template:Citation needed
Should a patient require assistance with respiration whether it be by bag/valve/mask, bilevel positive airway pressure (BiPAP), continuous positive airway pressure (CPAP) or mechanical ventilation, extreme care should be taken. Increased airway pressure will tend to further compress an already compromised SVC and reduce venous return and in turn cardiac output and cerebral and coronary blood flow. Spontaneous respiration should be allowed during endotracheal intubation until sedation allows placement of an ET tube and reduced airway pressures should be employed when possible.Template:Citation needed
PrognosisEdit
Symptoms are usually relieved with radiation therapy within one month of treatment.<ref name=emedicine/> However, even with treatment, 99% of patients die within two and a half years.<ref name=emedicine/> This relates to the cancerous causes of SVC found in 90% of cases. The average age of disease onset is 54 years.<ref name=emedicine/>