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Therapeutic Management of Unruptured Brain Aneurysms

When a brain aneurysm is detected, the next step is to determine a treatment plan and the need for any potential therapeutic intervention. Current treatment options for unruptured brain aneurysms range from non-invasive observation to more invasive surgical interventions. 

The overseeing physician or medical team may take into consideration multiple factors when determining the most appropriate treatment option. These factors include: 

  • Aneurysm size and location in the brain
  • Patient’s overall health status, age, and co-morbidities
  • Overall risk of rupture, including family history of rupture or subarachnoid hemorrhage 
  • Risk of potential complications from treatment compared to benefits of intervention

The need for intervention and treatment recommendations are determined based on clinical decision making and an overall risk analysis. The three main treatment categories are observation, endovascular therapy, and open surgery.
Observation

Many unruptured brain aneurysms are small and do not cause any symptoms. These tend to be found incidentally while imaging for other medical conditions. In this case, immediate intervention may not be needed and the brain aneurysm will instead be closely observed. This may include repeated imaging over time to monitor for any growth or changes that would increase risk for rupture. 

An individual with an unruptured brain aneurysm will be encouraged to adopt healthy lifestyle habits, including smoking cessation or changes in diet or exercise to manage weight and blood pressure.

Endovascular Therapy

Endovascular therapy is a minimally-invasive technique most often performed by an interventional neuroradiologist. It involves the insertion of a catheter into an artery, typically in the groin (similar to a cerebral angiogram). The catheter is then passed through the blood vessels to ultimately reach the location of the brain aneurysm. This allows therapeutic devices to be passed through the catheter to the site of the brain aneurysm. These are most often coils or flow diversion devices. The goal of endovascular treatment is to cut off blood supply to the aneurysm in order to decrease risk for rupture or bleed.
  • Coiling

This endovascular technique involves the placement of very thin pieces of pliable coiling wire (often made of platinum) directly into the brain aneurysm sac. 

After the catheter is placed and passed to the site of the brain aneurysm, a guide wire is inserted. Using X-rays to visualize the blood vessels in real time, the guide wire pushes the small platinum coiling wire through the catheter to the site of the brain aneurysm. Once there, the platinum wire is released into the brain aneurysm sac. The coiling wire takes on the shape of the aneurysm which prevents blood from entering. This ultimately cuts off the blood supply to the aneurysm and causes any remaining blood inside to clot (a process known as embolization). 

Multiple coils may be required for larger aneurysms. A stent or balloon may also be inserted into the parent artery (the artery a brain aneurysm branches off of) as a way to keep the coils in place.

Coiling is a less invasive option than open surgery, however there is a higher potential risk for recurrence and need for a repeat procedure.

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  • Flow Diversion Devices

Flow diversion devices are wire mesh stents that are implanted utilizing a similar technique as endovascular coiling. Unlike coiling, placement of the device does not require putting any material directly into the brain aneurysm sac. A flow diversion device is threaded through the catheter and placed in the parent artery at the site of the aneurysm. This allows blood flow to continue as normal through the artery while bypassing the aneurysm neck and limiting its blood supply. The end goal is to promote remodeling and healing of the parent artery. This technique may also result in elimination of the brain aneurysm over time, minimizing the risk of future rupture.

Flow diversion devices are often used to treat larger aneurysms that cannot be successfully managed with coiling or surgical intervention. They may also be used to treat high risk ruptures, as the technique avoids the most risky part of placing a device directly into the aneurysm sac.
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Open Surgery: Clipping

Surgical clipping is an invasive procedure performed by a neurovascular surgeon. The goal is to cut off blood flow to a brain aneurysm. This open surgery technique involves a craniotomy, which means that a small portion of the skull is removed. This allows direct access to the brain and blood vessels where the aneurysm is located. The surgeon uses a microscope to locate the vessel bringing blood to the aneurysm, then places a small clip on the neck of the aneurysm. This seals off the aneurysm and eliminates its blood supply.

Surgical clipping is a more invasive technique than the endovascular approaches. However, it is an effective and proven treatment option with a very low risk of rupture or recurrence. 
Clinical Decision Making: Endovascular versus Open Surgery Approach

When intervention is deemed medically necessary and the patient is in agreement, how does the medical team determine which treatment strategy to use? 

Debates over safety and efficacy of the different treatment strategies have been going on for years. Research has focused on the possible implementation of clinical prediction guidelines to help medical teams determine the most appropriate intervention and to help facilitate optimal results. The Unruptured Intracranial Aneurysm Treatment Score (UIATS) is an example of a model that can help guide clinical decision making in determining the appropriate treatment. 

Endovascular and surgical interventions are both approved as effective treatments for unruptured brain aneurysm. The multidisciplinary medical team must work together to determine the most appropriate intervention based on evaluation and interpretation of the testing/diagnostic results, clinical prediction guidelines, the patient’s overall health status, and specific details of the aneurysm including size, type, and location. Each decision is made on a case-by-case basis, with active participation from multiple specialties. The personal skill and expertise of the medical team and technology available onsite may also play a role in decision making. The end goal of any intervention is complete obliteration of the aneurysm and any risk for future rupture with minimal complications or risk for mortality. 
Resources: 
  • Brain Aneurysm Foundation
  • Cerebral Aneurysm Fact Sheet
  • Current treatment strategies for intracranial aneurysms: An overview
  • Interdisciplinary decision-making and treatment of intracranial aneurysms in the era of complementary microsurgical and endovascular techniques
  • Mayo Clinic
  • The unruptured intracranial aneurysm treatment score