By National Institute of Neurological Disorders & Stroke
The National Institute of Neurological Disorders and Stroke sponsors a wide range of research aimed at finding better ways to prevent, diagnose, and treat stroke, and to restore functions lost as a result of stroke.
Currently, scientists are studying the risk factors for stroke and the process of brain damage that results from stroke. Some brain damage may be secondary, occurring after the initial death of brain cells caused by the lack of blood flow to the brain tissue.
This secondary brain damage results from a toxic reaction to the primary damage. Researchers are studying this toxic reaction and ways to prevent secondary injury to the brain. Scientists hope to develop neuroprotective agents, or drugs that protect the brain, to prevent this damage.
"Hibernation" Stroke Research
Scientists are also conducting stroke studies in animals. By studying stroke in animals, researchers hope to get a better picture of what might be happening in human stroke patients. Scientists can also use animal models to test promising therapies for stroke. If a therapy proves helpful for animals, scientists can consider testing the therapy in humans.
One promising area of animal research involves hibernation. The dramatic decrease of blood flow to the brain in hibernating animals is so extensive that it would kill a non-hibernating animal. If scientists can discover how animals hibernate without experiencing brain damage, they may discover ways to stop the brain damage associated with decreased blood flow in stroke patients.
Another study used a vaccine that interferes with inflammation inside blood vessels to reduce the frequency and severity of strokes in animals with high blood pressure and a genetic predisposition to stroke. Researchers hope that the vaccine will work in humans and could be used to prevent many of the strokes that occur each year in people with high risk factors.
Scientists also are working to develop new and better ways to help the brain repair itself to restore important functions to stroke patients. New advances in imaging and rehabilitation have shown that the brain can compensate for functions lost as a result of stroke.
When cells in an area of the brain responsible for a particular function die after a stroke, the patient becomes unable to perform that function. However, the brain's ability to learn and change, called plasticity, and its ability to rewire the connections between its nerve cells means that it can compensate for lost functions. One part of the brain can actually change functions and take up the more important functions of a disabled part.
Clinical trials, another avenue of stroke research, give scientists a way to test new treatments in humans. Clinical trials test surgical devices and procedures, medications, and rehabilitation therapies. They also test methods to improve lifestyles and mental and social skills. The goal of clinical trials is to find safe and effective treatments and to establish the right levels of treatment.
Scientists are using clinical trials to study ways of restoring blood flow to the brain. They hope to find methods that are safer, more effective, and available to more stroke victims. Some of these studies are testing new types of thrombolytic drugs that halt the stroke by dissolving the blood clot that is blocking blood flow to the brain.
Other studies are testing techniques such as combining thrombolytic drugs with other drugs or with ultrasound, delivering clot dissolving drugs directly into the clot, and pulling the clot out with a device unaided by drugs.
Researchers are also testing the use of brain imaging to identify patients who may benefit from treatment even beyond three hours, since many have their strokes in their sleep or are brought to the hospital too late for standard therapy.
In a recent clinical trial, scientists found that aspirin is just as effective as a more expensive medication called warfarin for preventing additional strokes. Before this study, most doctors believed that warfarin was a better blood thinner than aspirin, even though it was more expensive, required monthly blood tests for proper monitoring, and had a greater risk of side effects. The findings from this trial showed that aspirin was not only cheaper and safer than warfarin for preventing stroke, but it was just as effective.
Two other clinical trials are looking at different surgeries for stroke. One trial compares the safety and effectiveness of two types of surgery used to unclog arteries: carotid endarterectomy and stenting.
In another trial scientists are looking at extracranial bypass surgery, a procedure that restores blood flow to a blood-deprived area of brain tissue. The goal of this trial is to determine if extracranial bypass surgery can reduce the risk of recurrent or additional strokes in people who have a blocked carotid artery and whose oxygen extraction fraction, or OEF, has gone up. OEF indicates how hard the brain has to work to pull oxygen out of the blood supply.