Neurovascular

Surgical clipping is a tried and tested treatment for brain aneurysms. Benefits for patients who undergo surgical clipping include a durable, immediate cure with little risk for recurrence and little long-term follow-up care required. This procedure involves a skin incision behind the hairline and a craniotomy in which a window of bone is removed from the skull using a special, medical drill. A surgical microscope is used to maneuver in between the bone and brain to pinch off the aneurysm with a surgical clip. Surgical clipping is an excellent treatment option for aneurysms which are easy to access surgically, as well as aneurysms with a wide opening. On rare occasions, bypass surgery is required in addition to clipping.

Another minimally invasive and safe surgical option is endovascular coiling. A long plastic tube, called a microcatheter, is used to travel from an artery in the leg or wrist into the affected artery in the brain and to block off the aneurysm by filling it with platinum wires called coils. Coiling is a very safe and effective treatment for brain aneurysms, particularly for aneurysms with narrow openings or necks and wide waists or domes. This approach is often safer for aneurysms located in the vertebrobasilar system or posterior circulation. Endovascular coiling has a rapid recovery time, but there is a 15% chance of aneurysm recurrence following this procedure, so regular, follow-up monitoring is needed.

For aneurysms with wider openings or necks, there are two approaches that are more complex but still minimally invasive and involve additional support for the coils (in cases where aneurysms cannot be coiled alone). Both balloon assisted coiling and stent assisted coiling have proven benefits and rapid recovery times. A stent is a permanent scaffold to support coils, while a balloon is a temporary one. A stent calls for two additional medications that block platelet function to be taken for three to six months following the procedure. These medications are not required following the balloon procedure.

In cases of fusiform and wide-necked, side-wall aneurysms that cannot be coiled, flow diverter stenting is an extremely effective and minimally invasive treatment. This procedure uses a finely-woven stent which treats brain aneurysms without manipulating the aneurysm at all. The stent works best for aneurysms off of the internal carotid artery and requires patients to take two additional medications to block platelet function for six months.

There are currently four different flow-diverter stents that are FDA-approved in the United States. They differ slightly in size, length, outward force and stiffness. The choice of stent requires expertise and experience using both. These stents have higher cure rates than coiling approaches, with cure rates of 90% at one year, and 95% at three years following the procedure.

There is currently one endovascular flow disruptor device available in the United States, called the WEB device. It was approved in 2019 and is a minimally invasive approach used to treat aneurysms with shapes that cannot be coiled. The WEB is a finely-woven, basket-shaped device that is designed to treat wide opening or necked bifurcation brain aneurysms. The WEB acts like a flow diverter, but it is placed inside the aneurysm. This innovative device is designed to treat aneurysms past the internal carotid artery and does not require dual antiplatelet blood thinner medication.

The surgical treatment option with the highest cure rates is open surgical resection of brain arteriovenous malformations, with success dependent upon the location of the AVM and its proximity to eloquent brain areas (areas of the brain that control important neurologic functions, such as visual perception, language, and movement centers). While this procedure is more invasive, it has immediate results and provides a lasting cure. 

Important factors in determining whether this procedure is the best treatment option include age, the size of the nidus, and whether there is a vein that drains into the deep venous system. Surgery involves a skin incision, a craniotomy (removing a window of bone from the skull using a medical drill), and a surgical microscope that is used to carefully disconnect and remove the AVM nidus.

Another surgical option for AVMs is embolization. This method involves inserting a long plastic tube, called a microcatheter, into either the feeding artery or draining vein and injecting a liquid embolic agent or medical-grade “crazy glue” to disconnect the abnormal connections. While embolization is minimally invasive and can make surgery easier by taking away some of the blood supply, it has the lowest cure rates and is not commonly used as a stand-alone treatment.

In certain situations, embolization can be curative when there is a singular arterial blood supply, and it may be optimal for deep, small AVMs that have bled. The transvenous approach (going through the vein to block the AVM) has not been studied well in comparison to other standard treatments, but it is a promising new technique with potentially high cure rates.

For small, deep-located AVMs, stereotactic radiation surgery (SRS) is a noninvasive procedure that involves delivering focused, high-intensity radiation to the AVM nidus. This treatment is performed in cooperation with a radiation oncologist. The neurosurgeon uses special diagnostic imaging studies to define a target in three-dimensional space. The radiation oncologist and radiation physicist then create a radiation plan to deliver the radiation dose to the specified area. This treatment is specifically highly effective for AVMs with a nidus smaller than 3cm. It typically takes three to five years to achieve a cure.

Sometimes, an AVM requires a combination of therapies to achieve the best possible chance at a cure. The most common combination of procedures is embolization followed by surgery. However, there are times when embolization can be combined with SRS or SRS can be combined with surgery. Often these combinations might be necessary for larger size AVMs. The order in which these treatment combinations are offered requires expert clinical judgment. Embolization and SRS can also be offered in a staged approach, requiring multiple treatments. Again this is more commonly required in larger size AVMs.