Onyx liquid embolic system (LES): an underestimated tool in the management of peripheral bleedings

Ethylene vinyl alcohol or Onyx copolymer (Medtronic) is an embolization agent increasingly used in peripheral interventional radiology. The Onyx Liquid Embolic System (LES) offers a liquid, non-adhesive, non-absorbable, injectable and permanent embolic agent with an indication for neuro-interventional procedures. Due to its physical properties, Onyx has more embolic predictability than other currently available liquid agents, and seems to have great potential in endovascular bleeding management, especially for non-coagulated patients. The aim of this brief review is to analyze the advantages of Onyx in the emergency setting on the basis of evidence in the current literature.

Endovascular treatment of complex dural arteriovenous fistula using the dual-microcatheter technique

A 71-year-old woman presented with headache and dilated vessels on CTA. Angiography demonstrated a complex dural arteriovenous fistula with retrograde cortical venous hypertension, supplied by branches of internal and external carotids bilaterally into a fistulous pouch paralleling the left transverse and sigmoid sinuses, which was occluded at the jugular bulb. The patient refused treatment and was lost to follow-up, returning with sudden confusion and hemianopsia from left temporo-occipital hemorrhage. Transvenous endovascular embolization was performed using the dual-microcatheter technique with a combination of coiling and Onyx copolymer, completely occluding the sinus and fistula while preserving normal venous drainage.The video can be found here: http://youtu.be/u_4Oc7tSmDM.

Acute Respiratory Distress Syndrome after Onyx Embolization of Arteriovenous Malformation

Purpose. We report a case of a 60-year-old male who underwent sequential Onyx embolizations of a cerebral arteriovenous malformation (AVM) which we implicate as the most likely etiology of subsequent acute respiratory distress syndrome (ARDS).Methods. Case report and literature review.Results. Shortly after the second Onyx embolization procedure, the patient declined from respiratory failure secondary to pulmonary edema. Clinical entities typically responsible for pulmonary edema including cardiac failure, renal failure, iatrogenic volume overload, negative-pressure pulmonary edema, and infectious etiologies were evaluated and excluded. The patient required mechanical ventilatory support for several days, delaying operative resection. The patient met clinical and radiographic criteria for ARDS. After excluding other etiologies of ARDS, we postulate that ARDS developed as a result of Onyx administration. The Onyx copolymer is dissolved in dimethyl sulfoxide (DMSO), a solvent excreted through the lungs and has been implicated in transient pulmonary side effects. Additionally, a direct toxic effect of the Onyx copolymer is postulated.Conclusion. Onyx embolization and DMSO toxicity are implicated as the etiology of ARDS given the lack of other inciting factors and the close temporal relationship. A strong physiologic rationale provides further support. Clinicians should consider this uncommon but important complication.