A common theme of the PedEMMorsels is remaining vigilant for the ominous needles in the haystack of benign conditions. There are so many rare entities that we learned about in medical school, thinking that they were just part of the challenge of inundating our brains with minutiae, that are actually important for us to be sensitive to detect. After all, if we do not ponder the problem, it is unlikely the issue will be discovered in a timely fashion (ex, Delayed Diagnosis of Aspirated FB, Delayed Diagnosis of Kawasaki Disease). Recently I had the privilege of caring for a patient who had a chronic cough and “pharyngitis” that ended up not being “just a virus.” Let us take a minute to review what was the real problem – Superior Vena Cava Syndrome:

Superior Vena Cava Syndrome in Children

Basics:

Superior Vena Cava (SVC) Syndrome is due to: [Miler, 2021; Nossair, 2018]
- Obstruction of the SVC leading to…
- Reduced venous return from the head and neck regions.

Approximately 35% of all venous return to the heart is through the SVC.

Peak occurrence in infancy and another smaller peak during adolescence. [Nossair, 2018]

Overal Morbidity and Mortality rates are 30% and 18%, respectively. [Nossair, 2018]

Presentations:

The obstruction of blood flow in the SVC leads to venous congestion in the upper body. [Miler, 2021; Nossair, 2018]

Increased hydrostatic pressure in venous system may lead to: [Miler, 2021; Nossair, 2018]
- Swelling of upper extremities
- Swelling of face and neck
- Dilation of superficial collateral veins in arms, chest, and neck
- Differential appearance of the skin of the upper chest from the abdomen.

With continued increased vascular congestion, more severe symptoms can be seen: [Miler, 2021; Nossair, 2018]
- Dyspnea and shortness of breath (67% of cases had dyspnea) [Nossair, 2018]
- Edema of the oropharyngeal tissues (ex, tongue, posterior pharynx, larynx)
  - May cause sore throat or hoarseness
  - May cause dry cough
  - 9% of SVC syndrome cases found to have oropharyngeal obstruction [Nossair, 2018]
- Edema and compression of the airway
  - Engorgement of the mucous membranes of the airway can lead to overt airway compromise.
  - 10% of SVC syndrome cases had acute airway compression. [Nossair, 2018]

Superior Vena Cava Syndrome in Children: Causes

Masses [Miler, 2021; Nossair, 2018]
- Compression from mediastinal masses / malignancies
- Non-Hodgkin’s Lymphoma is most common in children.

Non-Masses [Miler, 2021; Nossair, 2018]
- Increasing number of cases due to non-malignant, non-compressive causes seen in children.
- Thrombosis of SVC – accounted for 36% of cases of SVC Syndrome in children [Nossair, 2018]
  - Related to central lines or ECMO cannula – accounted for 40% of the thrombosis cases. [Nossair, 2018]
  - Related to medical devices like pacemaker wires.
  - May also be seen with thrombophilias.
  - Thrombosis may also be related to increased thrombosis risk related to oncologic conditions (ex, leukemia).
- Stenosis of SVC
  - Related to vascular and cardiac surgery.
  - Mustard and Senning procedures have been associated with SVC syndrome in children.
  - 47% of pediatric SVC syndrome cases were reported to be associated with congenital heart disease. [Nossair, 2018]

Superior Vena Cava Syndrome: Management

Imaging
- Initial evaluation may include CXR and upper extremity U/S, based on the initial complaint and findings.
- Chest CT with IV contrast will be the modality of choice to determine the extent of the thrombosis and/or the character of the compressive forces.

Treatment
- Therapies should be tailored to the etiology of the SVC syndrome.
- Compressive masses will need therapy directed at them (ex, chemotherapy).
- Thrombosis may benefit from anticoagulation, end-vascular techniques, or surgical excision and correction. [Miler, 2021; Nossair, 2018; Tzifa, 2007]

Moral of the Morsel

Swollen arms? The smaller tissues are also being affected! If you can see the edema on the outside, imagine the potential swelling that is occurring in the delicate tissues around the airway!
Rare, but occurs. Stay vigilant! SVC syndrome fortunately is not common, but the entities that cause it are (and use of central lines becoming more prevalent).