What exactly are Cerebral Arteriovenous Malformations (AVMs) and what risks do they pose to one's health?

AVMs, or Arteriovenous Malformations, are abnormal tangles of blood vessels that disrupt normal blood flow and oxygen circulation in the brain. This can potentially lead to serious health risks like hemorrhages, seizures, and neurological deficits. AVMs are managed through neurointerventional surgery that may include embolization to block off abnormal vessels and reduce complications.

What is Onyx and how is it transforming the treatment of AVMs?

Onyx, also known as Ethylene Vinyl Alcohol (EVOH) copolymer, is a nonadhesive liquid embolic agent used in AVM embolization. It allows neurointerventionalists to have greater control and precision during the procedure. The precision control and deep penetration ensures complete occlusion, reduced risk, and versatility.

What role does embolization play in managing AVMs, and how does it relate to surgery or radiosurgery?

Embolization is often used with surgery or radiosurgery to block off abnormal vessels, reducing the risk of complications associated with AVMs. The primary goal is to safely occlude the feeding arteries leading to the AVM while preserving normal venous outflow. The Spetzler-Martin grade is a scale used to assess the risk of surgery and help determine treatment strategies.

Can you walk me through the Onyx embolization procedure, detailing how it works to treat AVMs?

During Onyx embolization, a detailed cerebral angiogram is used to map the AVM's network of blood vessels. A microcatheter is then navigated through the feeding arteries to the nidus, where Onyx is slowly injected. This forms a cast within the abnormal vessels, blocking blood flow. Unlike some embolic agents, Onyx is nonadhesive, reducing the risk of the catheter becoming stuck within the vessel.

Besides Onyx embolization, are there alternative embolic agents or future treatment options I should be aware of in treating AVMs?

While Onyx embolization offers significant advantages, it's important to note that N-butyl cyanoacrylate (nBCA) is an alternative embolic agent. nBCA is a synthetic cyanoacrylate-based glue with an Ethiodol carrier, this prevents polymerization when the nBCA comes in contact with ionized solutions. The viscosity of the mixture can be adjusted. Continued research and collaboration will help refine techniques and optimize patient outcomes in AVM treatment.

AVM embolization with Onyx.

Unlocking the Brain: A Guide to AVM Embolization with Onyx

Nico Varela in Health & Wellness November 2025 • 4 min read.

"Discover how cutting-edge techniques like Onyx embolization are revolutionizing the treatment of Arteriovenous Malformations (AVMs), offering hope and improved outcomes for patients."

Cerebral arteriovenous malformations (AVMs) pose significant challenges in the field of neurointerventional surgery. AVMs are abnormal tangles of blood vessels in the brain or on its surface. These tangled vessels disrupt normal blood flow and oxygen circulation, potentially leading to hemorrhages, seizures, or neurological deficits. Managing AVMs requires careful consideration, and while the role of interventional treatments has been debated, embolization has emerged as a valuable tool.

Embolization, often used in conjunction with surgery or radiosurgery, aims to block off the abnormal vessels, reducing the risk of complications and improving overall outcomes. The decision to use embolization depends on the AVM's unique characteristics, such as its size, location, and angioarchitecture – the arrangement of its blood vessels. Factors like the Spetzler-Martin grade, a scale used to assess the risk of surgery, also influence treatment strategies.

While embolization has shown promise, its long-term effectiveness as a standalone treatment is still under investigation. The primary goal of neurointerventional treatment is to safely occlude the feeding arteries that lead to the AVM while preserving the normal venous outflow. By carefully navigating the complex network of blood vessels, specialists aim to minimize complications and maximize the benefits for patients.

Onyx Embolization: A Game-Changer for AVM Treatment

Onyx, also known as Ethylene Vinyl Alcohol (EVOH) copolymer, is a nonadhesive liquid embolic agent transforming how AVMs are treated. Unlike traditional methods, Onyx offers neurointerventionalists greater control and precision during embolization. Its unique properties allow for deliberate injection, penetrating the AVM nidus – the core of the malformation – with remarkable accuracy.

The procedure begins with a detailed cerebral angiogram to map the AVM's intricate network of blood vessels, understanding the AVM’s angioarchitecture. This roadmap guides the neurointerventionalist as they navigate a microcatheter through the feeding arteries, carefully approaching the nidus. Once in position, Onyx is slowly injected, forming a cast within the abnormal vessels and blocking blood flow.

Precision Control: Onyx allows for a slow, controlled injection, enabling the physician to monitor its spread and prevent nontarget embolization.
Deep Penetration: Its liquid form allows Onyx to seep into the smallest recesses of the AVM nidus, ensuring complete occlusion.
Reduced Risk: Unlike some embolic agents, Onyx is nonadhesive, reducing the risk of the catheter becoming stuck within the vessel.
Versatility: Onyx can be used as an adjunct to surgery or radiosurgery, or in some cases, as a definitive treatment for certain AVMs.

Another embolic agent, N-butyl cyanoacrylate (nBCA) is a synthetic cyanoacrylate-based glue with an Ethiodol carrier. The Ethiodol prevents polymerization when the nBCA comes in contact with ionized solutions. Viscosity of the embolizate can be altered by adjusting the amount of Ethiodol in the mixture. Tantalum powder can also be mixed with the solution to increase the radio-opacity of the solution.

Looking Ahead: The Future of AVM Treatment

Onyx embolization represents a significant advancement in treating AVMs. As technology evolves and techniques refine, we can expect even better outcomes for patients. The key lies in continued research, meticulous planning, and a collaborative approach, ensuring that each patient receives the most appropriate and effective treatment tailored to their unique condition.