Endovascular Neurosurgery

• What is the difference between open vascular and endovascular neurosurgery?

• What makes a neurosurgeon an endovascular neurosurgeon?

• What interventional techniques are endovascular neurosurgeons trained to perform?

• What disorders do endovascular neurosurgeons typically treat?

• Where do endovascular neurosurgeons practice?

• With what other specialists do endovascular neurosurgeons interact?

Using cutting-edge technologies, endovascular neurosurgeons treat conditions affecting the blood vessels in the brain and spinal cord. They do this by accessing these vessels from the inside of the vascular system, which is why it's called "endovascular" (endo meaning inside).

Endovascular approaches are minimally invasive, typically done through major blood vessels in the wrist or groin. They are used to address problems that disrupt normal blood flow to the brain and spinal cord.

This field is rapidly advancing within neurosurgery and offers innovative techniques to treat a range of disorders. Neurovascular surgery has particularly transformed stroke care, much like interventional cardiology has improved outcomes for heart attacks.

In the following sections, we'll explain the current practices of endovascular interventions, what they involve, and answer common questions asked by patients and their caregivers.

Open vascular neurosurgery involves traditional surgical techniques, like craniotomy, to address vascular issues in the brain and spinal cord. On the other hand, endovascular neurosurgery is a minimally invasive approach that uses specialized catheters (thin flexible tubes) inserted into blood vessels in the wrist or groin.

These catheters travel through major vessels connected to the heart and eventually reach the arteries supplying blood to the brain. Endovascular techniques allow for advanced diagnostic imaging using contrast dyes (catheter angiography) to visualize the network of blood vessels that supply the brain and spinal cord.

These catheters can also be used to treat conditions such as strokes and aneurysms and even to block blood supply to brain and spinal tumors, a process known as "embolization."

In summary, open vascular neurosurgery involves traditional surgical methods, while endovascular neurosurgery is minimally invasive and utilizes specialized catheters to access and treat vascular issues in the brain and spinal cord. Each approach has its own benefits and shortcomings, and the treatment has to be tailored to the needs of the patient.

There is no single path to becoming an endovascular neurosurgeon, but there are two main paths to acquiring the neurointerventional skills required to perform the same procedures that an endovascular neurosurgeon can perform.

Endovascular neurosurgeons begin with a 7-year neurosurgery residency during which they may complete an “enfolded” (extra case experience during residency) or post-residency endovascular neurosurgical fellowship.

These fellowships typically last one year in duration and can be combined with a second year of open cerebrovascular training if the neurosurgeon desires dual board certification in open and endovascular neurosurgery.

Even with specialized fellowship training, many vascular neurosurgeons continue treating many different brain and spine issues. Vascular disorders are commonly intertwined with other types of diseases, and the use of specialized techniques can assist with diagnosis and treatment.

• Embolization: After a catheter is passed through an artery (for example, the femoral artery in the groin region), it is guided to the location of the vascular pathology, such as a tumor. Embolization involves injecting an occlusive material, such as a special glue, that blocks off normal blood flow to the lesion.
• Coiling: Technique for treating cerebral aneurysms in which a thin flexible catheter is inserted into an artery, typically in the groin, and guided through the blood vessels to reach the aneurysm in the brain.

Once the catheter reaches the aneurysm, tiny platinum coils are delivered through the catheter and into the aneurysm sac. These coils promote clotting within the aneurysm, effectively sealing it off from the surrounding blood vessels and preventing it from causing a brain hemorrhage.

Over time, the body's natural healing process further reinforces the coil mass, preventing the aneurysm from rupturing.

Endovascular coiling is often preferred over traditional surgical methods for treating certain types of aneurysms because it is less invasive and generally associated with shorter recovery times and lower risks of complications.

However, not all aneurysms are suitable for coiling, and the decision to pursue this treatment option is made based on factors such as the size, location, and shape of the aneurysm and the patient's overall health and medical history.

Most commonly, endovascular neurosurgeons focus on disorders of the blood vessels (arteries and veins), such as:

• Stroke: Acute ischemic stroke is one of the most time-sensitive and common indications for emergent intervention in endovascular neurosurgery. Ischemic strokes occur when a portion of the brain loses blood flow.
  • Ischemic Stroke: Blockages in brain arteries leading to reduced blood flow and oxygen supply to brain tissue. This typically occurs when a clot or other debris blocks the passage of blood flow through a major vessel in the brain. Endovascular neurosurgeons can retrieve the clot and restore flow.
  • Hemorrhagic Stroke: Bleeding into the brain due to ruptured blood vessels. Neurovascular surgeons can use endovascular techniques to divert flow away from the damaged vessel (among other techniques), effectively stopping the source of the bleeding.
• Intracranial aneurysms: Weak spots in blood vessel walls that can balloon and potentially rupture, leading to hemorrhagic strokes.
• Arteriovenous malformations (AVMs): AVMs are often congenital (present at birth) abnormalities involving tangles of blood vessels in the brain or spinal cord that disrupt normal blood flow and increase the risk of bleeding. Endovascular intervention can block these abnormal arteries, and surgery can remove the AVM. Surgery remains the most definitive way to cure an AVM, but multimodality techniques involving endovascular embolization (to block arterial feeder vessels) are often incorporated into comprehensive management strategies.
• Dural arteriovenous fistulas (dAVFs): Abnormal connections between arteries and veins, often in the brain or spinal cord, which can lead to increased pressure in blood vessels and neurological symptoms.
• Brain tumors: Endovascular embolization of a tumor's blood supply, particularly for vascular tumors such as meningiomas, can be advantageous prior to surgery. This procedure helps reduce blood loss during the surgical tumor removal and may lead to better patient outcomes. It is normally performed at least 1-2 days prior to surgery.
• Cerebral Vasospasm: Narrowing of brain arteries following a subarachnoid hemorrhage, leading to reduced blood flow and potential complications.
• Carotid Stenosis: Narrowing of the carotid arteries in the neck, which can lead to ischemic strokes

These are just a few examples of the disorders that endovascular neurosurgeons are trained to diagnose and treat using minimally invasive techniques.

There are roughly 3,500 neurosurgeons in the United States, yet endovascular neurosurgeons constitute a minority within this profession. The advanced technology needed for endovascular imaging and treatment means that endovascular neurosurgeons are mainly located in academic university hospitals or urban centers, where they are more likely to encounter the highest volume of cerebrovascular emergencies.

Unfortunately, because the demand for their expertise is lower in less populated areas simply by nature of case volume, these experts are rarely found in rural areas. Instead, they are typically based in teaching hospitals accessible to the broader community. This arrangement proves advantageous as they can promptly assist patients transported by ambulance or helicopter from smaller or rural hospitals to the emergency department.

Endovascular neurosurgeons collaborate with various specialists to provide comprehensive care for patients with cerebrovascular disease. In the emergency department, patients presenting with acute stroke symptoms or brain hemorrhage are typically evaluated by endovascular neurosurgeons.

Additionally, other healthcare professionals such as radiologists, neurologists, family practitioners, and internists may identify endovascular diseases “incidentally” (meaning “unintentionally”) while investigating separate, potentially unrelated conditions.

At large cancer centers, endovascular neurosurgeons may be consulted for cases involving brain tumors. More specifically, they might be called upon by their neurosurgery and neuro-oncology colleagues to perform embolization of a vascular tumor that carries an unusually high risk for intraoperative bleeding.

By cutting off the blood supply to the tumor via embolization prior to surgery, endovascular neurosurgeons contribute to reducing the overall risk associated with undergoing surgery involving an open craniotomy approach for the removal of a brain tumor. As one of the fastest-growing subspecialties in neurosurgery, vascular neurosurgery offers significant advantages in managing various patients and pathologies.

• Endovascular neurosurgery is a critical sub-specialty with true promise and major contributions to the future of neurosurgery.
• Endovascular neurosurgery belongs to the general field of vascular neurosurgery, including “open cerebrovascular” neurosurgery.
• Endovascular techniques are minimally invasive and gaining further traction with the neurosurgical community for various treatment scenarios.
• Open vascular techniques, while more invasive, are necessary for certain complex and difficult-to-access vascular diseases.

• American Association of Neurological Surgeons Cerebrovascular Section
• Brain Aneurysm Foundation
• The Aneurysm and AVM Foundation 
• American Stroke Association