INTRODUCTION: Endovascular therapy plays an important role in the treatment of brain arteriovenous malformations (BAVMs). Ethylene vinyl alcohol copolymer (Onyx) Liquid embolization material has been used to treat high grade BAVMs pre-operatively to decrease size and flow. We report a case in which onyx use was complicated by the development of Superior Vena cava syndrome.
CASE PRESENTATION: A 74 year old man presented to our hospital for treatment of a symptomatic dural arteriovenous malformation at the right posterior fossa. He had episodes of altered mental status, headaches, dizziness and seizures which lead to the diagnosis of the AVM. His past medical history was significant for Multiple Myeloma for which he was treated with radiation therapy and chemotherapy. He had a right brachiocephalic and vena cava stent placed for venous stenosis caused by a previous chemoport. The chemoport was no longer in situ. The patient was treated with selective embolization of the AVM through the right middle meningeal artery with onyx liquid embolization. Post procedure the venous flow through the AVM was significantly decreased.Three weeks later the patient was admitted to our hospital for respiratory failure secondary to upper airway obstruction. Stridor and vocal cord edema was noted during intubation. Physical examination was significant for bilateral upper extremity non-pitting edema, plethora of the face and varices on the chest wall. Examination of the heart and lungs were normal.Chest radiography revealed a linear structure extending from the SVC stent into the right atrium. A CT of the chest confirmed the linear structure starting from the stent extending into the right atrium. The patient successfully underwent interventional radiology (IR) guided removal of the material by a femoral vein approach. The material was determined to be onyx. The patient had developed a significant stent stenosis and venous thrombosis. The venous pressure in the right internal jugular vein was 33 mmHg, compared to 15 mmHg in the femoral vein. After anticoagulation and angioplasty of the stent with removal of the onyx material the right internal jugular venous pressure decreased to 22 mmHg. The upper extremity edema and facial swelling improved and the patient was extubated. The patient was discharged with no further complications.
DISCUSSIONS: Onyx is available in three different formulations each with a different viscosity. Onyx 18 and 20 are generally used for embolization of a plexiform nidus and onyx 34 is used for embolization of large arteriovenous shunts. It is less adhesive and polymerizes slowly thus improving ease of use. The complication rate ranges from 6.9 -16.5%.Superior vena cava syndrome (SVCS) is the clinical manifestation of superior vena cava (SVC) obstruction either by obstruction or compression from outside the vessel. Malignancies account for the majority of cases. More recently, the incidence of SVC syndrome due to obstruction has risen due to increased use of intravascular devices.To the best of our knowledge this is the first case of SVC syndrome reported as a complication of embolization with onyx. The onyx material attached to the preexisting venous stent and caused an occlusion of the SVC. The symptoms dramatically improved with removal of the material and restoration of the venous flow.
CONCLUSION: We present a case of a SVC mass caused by embolization liquid from treatment of a brain AVM. This was associated with development of severe acute SVC syndrome. The symptoms promptly resolved with the removal of the onyx material from the superior vena cava.
DISCLOSURE: Kavan Ramachandran, No Financial Disclosure Information; No Product/Research Disclosure Information