Neurovascular Cases

What’s the diagnosis?

A massive, contrast-enhancing sinus and nasal mass in an adolescent male is most likely a juvenile angiofibroma. Bilateral carotid arteriography shows the vascular supply of the tumor, predominating from the right external carotid artery, with extensive radiographic tumor blush. In contrast, the left external carotid artery does not appear to robustly supply the tumor.

Background

  • Juvenile angiofibroma is a tumor seen almost exclusively in teenage boys between 10 and 20 years old. Classic presentation symptoms include recurrent, unprovoked epistaxis and nasal obstruction.
  • Technically, this tumor is “benign,” but its anatomic location in the posterior nasal cavity and its expansive and destructive growth pattern → morbidity.
  • It is typically diagnosed based on imaging alone. The tumor is very bloody and incisional biopsies, such as those routinely performed in the otolaryngology clinic for other nasal pathology, are not performed because of the risk of massive hemorrhage.

What's your treatment plan?

  • Surgical gross total resection is curative. Endoscopic endonasal approaches and also skull base and otolaryngology approaches are used for tumor resection.
  • Because this tumor is so bloody, preoperative embolization of the tumor is routinely performed. Embolization can be performed using coils, micro-particles, or liquid embolic agents such as Onyx. Effective preoperative embolization → ↓ intraoperative blood loss, improved intraoperative visibility, and a more controlled resection.
  • Onyx is a liquid embolic agent made of ethylene vinyl alcohol dissolved in dimethyl sulfoxide. This liquid is suspended in tantalum powder (which is visible on fluoroscopy). Onyx is available in two different formulations, Onyx 18 (6% ethylene vinyl alcohol) and Onyx 34 (8%), with Onyx 18 theoretically traveling more distally and penetrating feeders more deeply than Onyx 34 because it is less viscous. It takes about five minutes for the Onyx to completely solidify.
  • To deliver Onyx, dimethyl sulfoxide (DMSO) is first injected through the delivery micro-catheter. Distal to the catheter tip, the DMSO dissipates into the blood within the tumor. Next the Onyx is injected through the delivery micro-catheter. It will not harden when it is in contact with the DMSO, which is coating the inner wall of the micro-catheter. However, once it exits the catheter tip and contacts blood, it immediately precipitates into a hardened embolic material, casting the walls of the vessel lumen. As additional Onyx is delivered, the cast hardens from outside to inside, and gradually spreads more distally into the lesion.
  • As with any embolization procedure, it is critical to prevent any embolic material from refluxing back along the delivery tract such that it could result in embolization of an unintended vessel. For example, during an external carotid artery embolization, reflux that caused embolic material to enter the internal carotid artery circulation would be a dreaded complication because it could cause a stroke.

In this case, preoperative embolization of this sinonasal tumor was performed. The right external carotid artery was catheterized and the right internal maxillary artery feeders were embolized with Onyx. The patient was subsequently taken to the operating room for resection of the mass.

It is important to image the contralateral external carotid artery again, after the embolization has been completed, to determine whether or not the tumor has recruited significant supply from a new feeder, since it has lost its right-sided feeder. In this case, the tumor did not recruit significant left external carotid artery contribution.