The study is led by Patrick D. Lyden, M.D., professor and chairman of the Department of Neurology at Cedars-Sinai Medical Center. Co-principal investigators are James C. Grotta, M.D., the Roy M. and Phyllis Gough Huffington Distinguished Chair in Neurology at The University of Texas Medical School at Houston, part of UTHealth; and Thomas Hemmen M.D. at the University of California, San Diego School of Medicine (UCSD).
Grotta, chief of Neurology Services and co-director of the Mischer Neuroscience Institute at Memorial Hermann-Texas Medical Center, is principal investigator for eight of the trial’s 18 total sites.
This study, which includes the use of intravenous tissue plasminogen activator (IV tPA) – a clot-buster that is the only FDA-approved treatment for acute stroke – is the latest in a series of clinical trials on brain cooling (controlled hypothermia) to reduce neurological damage after stroke. Brain cooling has been shown to decrease brain swelling and reduce loss of neurological function after acute stroke. It also has proved highly effective in saving lives and preventing neurological damage after heart attack and after oxygen deprivation in newborns.
Researchers employ a state-of-the-art system to provide rapid heat exchange and fast cooling by inserting a special catheter into the inferior vena cava – the body’s largest vein. No fluid enters the patient; an internal circulation within the catheter absorbs the body’s heat and transfers it out to slow metabolism, keep tissue swelling in check and give the brain time to rest.
Study participants are covered with a warming blanket to trick the body into feeling warm, and temperature sensors in the skin and a mild sedative help suppress shivering. Body temperature is cooled to 33 degrees Celsius (about 91 degrees Fahrenheit) for 24 hours before the patient is gradually warmed.
TPA, which must be given to a patient as quickly as possible after stroke onset, sometimes can dissolve a clot and prevent or reduce serious brain injury. But only one third of stroke patients recover completely after receiving tPA and studies of intra-arterial catheter-based treatments that dissolve more clots that tPA did not show benefit, so researchers continue to seek better treatments, Grotta said.
“Hypothermia takes a completely different approach that complements the effect of tPA and other methods to open arteries; it ameliorates the damaging biochemical changes that occur in brain cells as a result of the stroke,” Grotta said. “Hypothermia is the most potent of these so called ‘neuroprotective’ approaches in animal models, and data from our pilot study in humans, and in the first 50 patients in the first phase of this randomized study, are so encouraging that the FDA has given us the green light to proceed to the next stage of enrolling 400 patients. Hopefully, at that point we will be allowed to complete the study, which will require more than 1,200 patients to determine if cooling is truly effective.”
The brain cooling clinical trials (ICTuS, Intravascular Cooling for Acute Stroke) are funded by two grants from the National Institute of Neurological Disorders and Stroke, part of the National Institutes of Health (Grant numbers NIH/NINDS 3P50NS044227-08S1 and 5P50NS044148-06S1).
Stroke occurs when blood flow to the brain is interrupted by a blockage or a rupture in an artery, depriving brain tissue of oxygen. It is the third-leading cause of death behind heart disease and cancer. According to the American Stroke Association, nearly 800,000 Americans suffer a stroke each year – one every 40 seconds. On average, someone dies of stroke every three to four minutes.
Deborah Mann Lake
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