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Physicians Update

 
Summer 2006: Neuroscience

Neurosurgical Advances Applied to Brain Aneurysms

Brain-saving treatments for intracranial aneurysms—the most common cause of subarachnoid hemorrhage, a devastating form of stroke—require skills possessed by experts in neurosurgery, neuroradiology, interventional neuroradiology and neurocritical care. Advances in all of these fields working in concert have improved the outlook for many stroke— and potential stroke— patients.

“It is rare that we find an untreatable aneurysm,” observes Neil Martin, M.D., FAANS, chief of UCLA’s Department of Neurosurgery. When an intracranial aneurysm bursts and bleeds into the space around the brain, the consequences are devastating, with approximately 70 percent of people either dying or suffering a severe stroke. When a patient makes it to the hospital alive, the aneurysm has bled for less than 30 seconds and then sealed itself off.

“The initial hemorrhage will cause irreversible damage, but a second rupture will likely be fatal,” Dr. Martin explains. Therefore, treatment for a ruptured aneurysm aims to prevent a second hemorrhage. “Based on what the aneurysm looks like, we decide what the absolute best treatment is for that patient,” Dr. Martin notes. Quick diagnosis is key. Patients who arrive in UCLA’s emergency room with “the worst headache of their lives”— indicating the possibility of a ruptured aneurysm—now undergo one noninvasive diagnostic study to locate the intracranial aneurysm. “This is a revolutionary change,” Dr. Martin suggests.

At most centers, the diagnosis requires two tests, one a computed tomography (CT) scan and the other an invasive transfemoral angiogram. “At UCLA, if the CT scan detects a hemorrhage, then we do a CT angiogram contrast study to see what the aneurysm looks like,” notes Pablo Villablanca, M.D., UCLA diagnostic neuroradiologist, and director of UCLA’s Clinical Image Processing Service. Three-dimensional images from a CT angiogram, which visualize blood flow in the arteries of the neck and brain, provide detailed information on the location, size, geometry and particular characteristics of the aneurysm so that the patient can be triaged to the appropriate therapy, Dr. Villablanca explains. “It takes 45 seconds to acquire the images, and then about three minutes to process the images for immediate information. So within five minutes you know with what you are dealing,” Dr. Villablanca notes.

 

“In some cases, we can avoid the angiogram altogether and go directly into surgery,” Dr. Martin adds. Recommended treatments may include endovascular therapy, microsurgical clipping of the aneurysm or brain bypass surgery. These options, plus a few more, are also available to treat high-risk unruptured aneurysms that are often discovered during tests a patient is undergoing for an unrelated problem.

Endovascular Therapy
Aneurysms—weak, balloon-like defects that protrude from arterial walls—with a narrowed neck may be ideal for endovascular coiling. A device called the Guglielmi Detachable Coil (GDC), which was developed at UCLA by Guido Guglielmi, M.D., is released via microcatheter so that it fills the aneurysm and isolates it from circulation. This technology is the gold standard for endovascular treatment of aneurysms; more than 300,000 patients have undergone the procedure worldwide. An improvement on the GDC coil, also developed at UCLA, is one made of a combination of platinum wire and a bio-absorbable biopolymer (matrix coil) that accelerates aneurysmal clot maturation and transformation into collagen treatment. The new tissue anchors the platinum coil and causes the aneurysm to heal across its neck, closing the connection between the aneurysm and the parent artery, says Fernando Vinuela, M.D., co-director of UCLA’s Stroke Center. Another new development in endovascular treatment for wide-neck or large aneurysms is endovascular employment of small stents that can be used intracranially. These stents are deployed across the neck of the aneurysm and create an artificial boundary between the aneurysm and the parent artery, allowing for a safe coil deployment. These stents—specially developed for intracranial utilization—can be safely deployed in anterior cerebral, middle cerebral and basilar arteries.

Neurosurgery
Not all aneurysms are appropriately shaped for endovascular coiling or stenting. In those cases, neurosurgeons perform microneurosurgical clipping techniques via craniotomy to prevent bleeding. Brain bypass surgery presents another option for certain inoperable or uncoilable aneurysms, allowing the aneurysm and blood vessel upon which it lies to be blocked off completely. “The extracranial-intracranial bypass is accomplished by using a scalp artery to connect to a brain artery,” explains Dr. Martin, who, along with UCLA colleague John Frazee, M.D., specializes in this technically challenging procedure, of which 10 to 15 are performed each year at UCLA. For small aneurysms, judged to be relatively low risk, experts may prefer instead to follow patients with a periodic CT angiogram. “We’ve found that about 10 percent of aneurysms in these patients will grow, and we assume that those are the few high-risk aneurysms destined to rupture at some point, so we will opt to treat those,” Dr. Martin says.

Neurocritical Care
Following a hemorrhagic stroke or surgery, patients need the same careful management that those with severe head injuries receive. At UCLA, the patient care in the 20-bed neurocritical care unit is melded and fused with the clinical research programs of neurology and neurosurgery, observes Paul Vespa, M.D., UCLA neurosurgeon and director of the unit. UCLA has pioneered many brain monitoring innovations, including electroencephalogram (EEG), positron emission tomography (PET), magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS), all of which indicate how the brain is metabolizing nutrients and whether the brain is getting enough oxygen. Further, patients are monitored daily with a transcranial Doppler to detect early signs of vasospasm—a constriction of the brain’s arteries caused by the initial bleed that can produce an ischemic stroke. “We’ve completely reinvented the paradigm of how brain injury patients are treated,” Dr. Vespa notes. “In most ICUs, these patients have been treated based on monitoring their heart, lungs and blood. We have made convincing arguments over the past 10 years that one should monitor the brain when treating brain injury.” Based in large part on information gathered from monitoring, new treatments have developed. “Stereotactic hemorrhage evacuation is, in large part, based on EEG observations that if you leave blood inside the brain, seizures can develop and the patient can deteriorate,” Dr. Vespa explains.

Telemedicine allows doctors remote access to patients from anywhere there is access to the Internet. Expanding on that concept, UCLA was the first to introduce the robotic telepresent system to the ICU. The patient sees, hears and interacts with the doctor through a nearly 5-foot-6-inch tall robot, which displays a live video image of the physician’s face on its monitor/head. The physician, seated at a computer console, also sees and hears the patient through a live video image projected on a monitor. Using a joystick, the physician can drive the robot to the patient’s bedside, control movements of the robot’s head and even zoom in to take a closer look at the patient or bedside monitors. “We are using the robot clinically and also conducting a research study to assess its effectiveness in such factors as preventing medical errors and decreasing the amount of time it takes to get to a patient during an emergency,” notes Dr. Vespa.

Research
According to Dr. Martin, current stroke research efforts at UCLA in neurosurgery, interventional neuroradiology and neurology are focusing on:

  • Improving endovascular coils
  • Refining microsurgical techniques for bypass surgery for aneurysms
  • Studying brain injury associated with ruptured aneurysm
  • Studying brain monitoring techniques to identify problems at an earlier stage
  • Improving telemedicine
  • Developing noninvasive, four-dimensional imaging tools




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