Grant: CIHR New Investigator

Stroke is the 3rd leading cause of death in North America and a leading cause of disability in Canada. Most strokes are caused by a blood clot blocking supply of blood to the brain. Collaterals are small connections between arteries in the brain that maintain blood flow to the brain beyond a blocked artery until full flow can be restored by "clot-busting" drugs. The network of brain collaterals is the body's own tool to minimize damage caused by stroke. Patients with poor collaterals do not benefit from acute stroke treatment. Our new brain scan measures collaterals quickly and reliably, immediately identifying patients who will benefit from treatment. This study tests whether this new brain scan is capable of predicting who will benefit from acute stroke treatment. In addition, we can improve our understanding of why some patients have good collaterals and some not. If we can better understand how to keep this natural system (collaterals) strong and healthy we can reduce the effects of stroke. This study involves patients arriving at the Emergency Room with stroke symptoms. Patient information gathered then, such as medical history, blood test results and brain scans, will be analyzed and compared with each other and with information gathered later, such as a follow up CT scan (1 to 7 days later) and the patient's health in 3 months. There has been very little research into understanding collaterals. This study will tell us whether measuring collaterals using our new brain scan helps doctors treat patients faster and better. This study will also tell us why some patients have good collaterals. This knowledge can be used to develop techniques that improve collaterals in patients without them. Supporting blood supply to the brain when it needs it most will help stroke patients significantly. This study will therefore advance our ability to lessen brain damage due to stroke.