Research Compares Two Diagnostic Methods for Subarachnoid Hemorrhage

• Stroke • Apr 24, 06

Cerebrovascular disease is a leading cause of serious long-term disability, affecting as many as 700,000 people every year. The interruption of blood flow to the brain can be caused by a blockage, leading to the far more common ischemic stroke, or by bleeding in the brain, leading to the more deadly subarachnoid hemorrhage (SAH). The latter condition affects approximately 30,000 Americans every year. Of those, about one half will not survive beyond 30 days, and an additional 25 percent will have some form of neurological deficit.

About 90 percent of all cases of SAH are caused by cerebral aneurysms. A cerebral aneurysm is a weakened part of an artery in the brain that results in a bulging or ballooning out of part of the vessel wall. Identifying the exact location, size and configuration of the aneurysm is critical to prevent rehemorrhage, which occurs in about 20 percent of cases within the first 14 days after the initial rupture. The current “gold standard” for identification is the diagnostic cerebral angiogram, which involves temporarily inserting a tube (catheter) into the artery of the leg (the femoral artery) and navigating it to the vessels of the brain (the two carotid arteries and the two vertebral arteries). Though very sensitive and very specific in identifying these potentially lethal aneurysms, the procedure is invasive and carries a small risk of causing ischemic stroke.

Neurosurgeons recently studied a relatively new method of testing, called computed tomographic angiography (CTA). This is performed by injecting a volume of contrast agent, similar to that used in the conventional angiogram, through a vein in the patient’s arm. The results of this study, Three-Dimensional Computed Tomographic Angiography (3D CTA) vs. Digital Subtraction Angiography (DSA) in the Detection of Intracranial Aneurysms in Spontaneous Subarachnoid Hemorrhage, will be presented by Charles J. Prestigiacomo, MD, senior author of the study, 2:45 to 3:00 p.m. on Monday, April 24, 2006, during the 74th Annual Meeting of the American Association of Neurological Surgeons in San Francisco. Co-authors are Aria Sabit, MD, Pinakin Jethwa, BS, and Jonathan Russin, BS.

This study evaluated how sensitive CTA is compared to the conventional angiogram. It analyzed whether CTA can detect aneurysms that cause SAH as accurately as the conventional angiogram, but with less risk and within a quicker timeframe. The 179 patients in this study were all initially evaluated by CT scan to confirm if they sustained SAH. If SAH was detected, patients immediately underwent CTA, and the results were processed. The following results were noted:

•Of the 179 patients evaluated in this study, 166 patients were found to have one or more aneurysms on CTA, a result which was confirmed at surgery or by conventional angiogram.

•Thirteen patients had no detectable lesions on CTA; conventional angiogram did not reveal any vessel lesions in these same patients.

•One small incidental aneurysm (NOT responsible for the hemorrhage) was detected on conventional angiogram, but not initially detected on CTA. Further review of the CT angiogram images, however, clearly demonstrated this lesion.

The benefits of CTA are multiple:

Patients do not need to be transferred to an angiographic suite
No additional personnel are required
The imaging is completed within one minute
There is no risk of ischemic stroke

The only risks in this procedure are also associated with conventional angiography: an allergic reaction to the dye and potential damage to the kidneys caused by the dye. “This method enables an accurate identification of the exact size, location and configuration of the lesion within 10 minutes of diagnosing a patient with SAH, as opposed to the hours that it can take to transport the patient to the angiographic suite, prepare the patient, and then perform a full four-vessel angiogram that may itself take 30 to 60 minutes, or even longer,” remarked Dr. Prestigiacomo.

“This study suggests that CTA is as sensitive in detecting aneurysms in patients with SAH as conventional angiography, but with less overall risk to the patient,” added Dr. Prestigiacomo. Further studies are ongoing to determine the cost-effectiveness of this technique, which may eventually replace diagnostic angiography as the standard in detecting aneurysms in patients with SAH.

Founded in 1931 as the Harvey Cushing Society, the American Association of Neurological Surgeons (AANS) is a scientific and educational association with more than 6,800 members worldwide. The AANS is dedicated to advancing the specialty of neurological surgery in order to provide the highest quality of neurosurgical care to the public. All active members of the AANS are certified by the American Board of Neurological Surgery, the Royal College of Physicians and Surgeons (Neurosurgery) of Canada or the Mexican Council of Neurological Surgery, AC. Neurological surgery is the medical specialty concerned with the prevention, diagnosis, treatment and rehabilitation of disorders that affect the entire nervous system, including the spinal column, spinal cord, brain and peripheral nerves.