Cooling method to treat brain aneurysms

Jun 21 2004

Patients who undergo brain surgery to treat aneurysms are at risk for permanent brain damage, but a protective cooling system is now being tested at Rush University Medical Center to reduce or eliminate this risk.

The ChillerStrip System, designed by Seacoast Technologies, Inc., works by cooling the brain tissue in the area of the surgery, thereby reducing the metabolism of the brain. The brain consumes 20 percent of the body's oxygen needs and requires 15 percent of the cardiac output of the heart to function properly. But because the brain is contained within the fixed space of the skull, the normal swelling action of tissue during surgery or after an injury can prove irreversible or fatal.

"The idea of cooling is to diminish the metabolic demands of the brain," said Dr. Demetrious Lopes, an endovascular neurosurgeon at Rush and the Chicago Institute of Neurosurgery and Neuroresearch. "By reducing the metabolic demand, you've reduced the need for blood."

The ChillerStrip uses a pumping unit that cools and circulates fluid to disposable silicon "strips" that are attached to the retractors surgeons use to spread brain tissue. Local areas of the brain are cooled to approximately 63 degrees Fahrenheit while the surgery is being performed. After the procedure, the strips are removed and the brain returns to normal temperature, with little or no effect to the tissue, according to Lopes.

Researchers first noticed that patients were able to tolerate brain injury during temporary cerebral artery blockage with body temperatures around 75 degrees Fahrenheit when aneurysm surgeries were done on cardiopulmonary bypass.

Rush is one of five medical centers around the country, and the only one in the Chicago area, to participate in this Phase I safety study.

Rush is seeking patients between the ages 18-65 who have been diagnosed with an aneurysm, which is a dilation, bulging or ballooning out of part of the wall of a vein or artery in the brain. The disorder may result from congenital defects or from other conditions such as high blood pressure, atherosclerosis (the build-up of fatty deposits in the arteries), or head trauma.

Typically, aneurysms are treated by several surgical methods. Many surgeons clip the aneurysm to remove it while other opt to insert coils or glue to fill up the aneurysm so it is rendered harmless. In 2002, Lopes was the first endovascular neurosurgeon to use a magnetic navigation system to treat an aneurysm. This device allows Lopes to treat aneurysms in small, difficult to reach blood vessels that would normally require surgery to access.