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Cerebral Aneurysm Illustration

Illustration of a cerebral aneurysm
Image: National Institutes of Health

A cerebral aneurysm is like a blister on a blood vessel. As with a blister on the skin, the blister on the blood vessel is made up of thinner and weaker material—bulging and at risk of breaking. A cerebral aneurysm is an “outpouch,” or ballooning, of a weakened blood vessel wall in the brain. The ballooned segment disrupts normal blood flow through the vessel and can lead to blood clots or rupture of the aneurysm. The larger the ballooned section becomes, the greater the risk that it will burst and then cause bleeding into the brain. Many aneurysms are found at the junction of the large arteries at the base of the brain, in an area referred to as the Circle of Willis.

There are three types of cerebral aneurysms: saccular/bifurcation, sidewall and fusiform:

  • A saccular aneurysm (berry aneurysm) is the most common shape for a cerebral aneurysm. It is a small rounded sack of blood that is attached by a neck or stem to an artery or a branch of a blood vessel. It is seen most often in adults.DL_AneurysmTreatmentVideo
  • A sidewall aneurysm is a bulge on one wall of the blood vessel.
  • A fusiform aneurysm is formed by the widening of a segment of an artery along all walls of the vessel.

Dr. Lopes with a patient five years after she was the first patient in Illinois—and one of the first in the U.S.—to receive surgical treatment for a large aneurysm with the Pipeline Device.

Aneurysms are also classified by size:

  • Small aneurysms are less than 10 mm.
  • Larger aneurysms are 10-25 mm.
  • Giant aneurysms are greater than 25 mm.

According to autopsy studies, three to six percent of the adult population in the U.S. has a cerebral aneurysm—many are very small, will not cause symptoms and are not at risk for rupture. Patients at heightened risk for developing a cerebral aneurysm include those with a family history of cerebral aneurysms and patients with connective tissue disorders, polycystic kidney disease or certain circulatory disorders, such as arteriovenous malformations.


Dr. Lopes is helping to develop intravascular imaging with optical coherence tomography, known as OCT, for blood vessels in the brain.

Other risk factors for brain aneurysms include head trauma or injury, high blood pressure, infection, tumors, atherosclerosis, cigarette smoking, and drug abuse. It is sometimes recommended to have screening for cerebral aneurysms using magnetic resonance imaging (MRI), magnetic resonance angiogram (MRA), or computerized tomographic angiography (CTA) in patients who have high-risk factors, including those with a disease called autosomal dominant polycystic kidney disease (ADPKD) or multiple family members with cerebral aneurysm (>2).


CT scan image of a subarachnoid hemorrhage from an aneurysm rupture.


Patients with unruptured aneurysms report symptoms in 40 percent of cases. Symptoms can depend on the size and rate of growth of the aneurysm. A small, slow-growing aneurysm, for example, may cause no symptoms. On the other hand, a larger or giant aneurysm that is rapidly or steadily growing may cause a loss of feeling in the face or problems with eyesight. Additional symptoms for unruptured aneurysms may include:

  • Headaches
  • Visual changes (double vision, peripheral field loss)
  • Drooping eyelid
  • Dilated pupil
  • Weakness, numbness/tingling of one side of the body
  • Seizures
  • Speech disturbances
  • Perception problems
  • Loss of balance and/or coordination
  • Decreased concentration

Unruptured aneurysms should be monitored and/or treated by a cerebrovascular/endovascular neurosurgeon.

Endovascular Approach Illustration

Dr. Lopes treats brain disorders by advancing technologies through the blood vessels of the body. This is an illustration of using a catheter to place coils inside a brain aneurysm.


Patients with ruptured aneurysms report the onset of severe symptoms, including an unusually severe headache (“the worst headache of my life”), nausea, vision changes, vomiting, and loss of consciousness.

Other ruptured cerebral aneurysm symptoms include:

  • Stiff neck or neck pain
  • Pain behind and/or above the eye
  • Dilated pupils
  • Light sensitivity
  • Loss of sensation
  • Seizures

The rupturing of an aneurysm is a medical emergency. Seek emergency medical attention immediately.


This imaging shows treatment using a flow diverter.


Cerebral aneurysms may be treated in a variety of ways. At Rush University Medical Center, Dr. Lopes specializes in minimally invasive endovascular approaches and consults with patients to determine the best course of action, including surgical procedures when necessary.

Pipeline Embolization Device Illustration

Blood vessel remodeling devices, such as the Pipeline Embolization Device, allow Dr. Lopes to redirect the blood flow through the parent vessel.

Determining the best mode of treatment depends on several factors including the aneurysm’s location and size as well as the patient’s preferences and expectations. Generally, patients at high risk for surgery are better suited for endovascular intervention. This includes elderly patients and those in poor health.

Several anatomical characteristics may dictate treatment as well. For example, if an aneurysm is associated with a large hematoma, or if normal blood vessel branches stem from the base or dome of the aneurysm, or if the ballooned segment is pushing on nerves and is causing symptoms, Dr. Lopes may recommend clipping as a preferable treatment.

However, given the lower rate of complications and the proven efficacy of minimally invasive endovascular treatments, many of Dr. Lopes’ patients elect this type of approach, instead of surgical treatment, to treat their aneurysm.

Minimally invasive endovascular options include:


Images of an aneurysm before and after treatment with a Pipeline flow diverter, pictured on the bottom.

Flow Diverter Embolization (Blood Vessel Remodeling) is a breakthrough advancement in the treatment of aneurysms. The Pipeline Embolization Device (PED), approved by the U.S. Food and Drug Administration, is a flexible mesh tube made of platinum and nickel-cobalt chromium alloy that can be used to block off large, giant, or wide-necked aneurysms in the internal carotid artery, a major blood vessel supplying blood to the front of the brain. The device can also reduce the likelihood that an aneurysm will rupture.  Currently there are two new flow diverters available for complex aneurysms and are still a part of clinical trials. Discuss with us your interest in being a part of one of these trials for your aneurysm treatment.

In early 2009, Dr. Lopes was part of a very small group of neurosurgeons and neurointerventionalists selected to participate a clinical trial of the PED.  Dr. Lopes believes these remodeling devices may be the “silver bullet” for treating aneurysms.  One of Dr. Lopes’ patients, Vivian Moore, 67, of Lombard, Illinois, was one of the first patients in the country to be treated with PED.


Dr. Lopes has available to him all possible endovascular treatments approved or under investigation in the U.S. Onyx HD 500 is a liquid embolic that can be used to repair brain aneurysms.

To implant the device, the PED is attached to the end of a catheter, which is inserted into an artery in the leg. The catheter is threaded into the carotid artery and into position at the aneurysm where the Pipeline is expanded against the walls of the artery and across the neck of the aneurysm, cutting off blood flow to the aneurysm. The blood remaining in the blocked-off aneurysm forms a clot which reduces the likelihood the aneurysm will grow bigger or rupture.

Aneurysms successfully treated with the Pipeline will often shrink over time.

Other advantages for this newer device and accompanying procedure include:

  • Ability to treat aneurysms that could not be coiled or treated in the past
  • Ability to treat aneurysms in locations that are difficult to access
  • Minimally invasive procedure resulting in a shorter hospital stay
  • Faster procedure that older types of treatment
  • Less expensive

Some aneurysms are treated with coils.

Coiling is a catheter-assisted procedure where flexible soft-wire coils are threaded through a catheter to the aneurysm via the femoral artery in a patient’s thigh. Very thin coils are advanced to the aneurysm through the catheter and pushed into the aneurismal sac. Additional coils are pushed into the aneurysm until it is tightly packed. Once the procedure is complete, normal blood flow is reestablished in the parent vessel and the risk of rupture of the aneurysm is significantly reduced. Hospitalization after this type of procedure is 1-2 days.

Overall, coiling has been proven to result in lower patient mortality, shorter hospital stays and lower costs.  However, over time coils may compact and allow the aneurysm to reopen and potentially rupture. Because the risk of endovascular intervention is low, undergoing multiple re-coiling procedures, versus craniotomy, may be more palatable for patients. In addition, advancements in coiling materials are allowing coils to more completely fill an aneurysm.

Coiling and Stenting used in combination has been one of the most significant advancements in endovascular surgery. Historically the major factors in determining whether to use coiling were structure of the aneurysm and surrounding vessels, as well as location. Introducing the use of flexible stents to support the vessel and provide a pathway for coiling, opens up more options for patients.


Some aneurysms are treated with a combination of coiling and stenting.

When used in combination with coils, stenting of the parent artery allows for the safe treatment aneurysms with wide-necks using a minimally invasive approach. Also, irregular-shaped, or fusiform, aneurysms that were once considered repairable only with surgery can also be treated with a coil and stent approach.

When used in tandem, coils and stents have been shown to reduce the rate of aneurysm recurrence due to coil compaction. Dr. Lopes has performed more of these combination procedures than most endovascular specialists in the world.

Surgical options include:

Clipping is a highly durable and effective procedure performed via open brain surgery, or craniotomy. This approach has been the traditional way to treat brain aneurysms for more than 25 years. During the procedure, Dr. Lopes places a tiny metal clip at the base of the aneurysm, cutting off the ballooned segment from the circulation. Complication rates associated with open surgery clipping range from eight to 10 percent. Hospitalization after an open craniotomy to occlude an aneurysm can range from 5-10 days.

Clipping Illustration

Some aneurysms are treated with a surgically implanted clip.

For some patients, the proven efficacy of clipping may outweigh the risks associated with the invasive procedure. While the surgical procedure hasn’t changed dramatically in several decades, Dr. Lopes notes that patients have benefited from key refinements, such as better defined and targeted microsurgery techniques. This has simplified the surgeon’s approach to vascular lesions. In addition, Dr. Lopes is experienced using cooling techniques to reduce swelling-induced damage by lowering the brain’s need for blood, which is particularly useful when treating giant aneurysms.

Although clipping surgery has become safer and is a viable treatment option, in many cases, Dr. Lopes discusses a more minimally-invasive approach to treat a patient’s aneurysm.

Clipping and Coiling may be used in combination to treat some aneurysms. Coiling could be implemented after a clipping procedure to fill part of an aneurysm that could not be fully closed during clipping. For example, in the case of an irregular-shaped aneurysm where clipping results in 95 percent occlusion, coiling the remaining five percent, perhaps of a small “dog-ear” segment, is plausible. Dr. Lopes is comfortable using this type of hybrid technique to treat a previously clipped aneurysm.

Videos courtesy of Rush University Medical Center.