People often know of strokes or someone affected by a stroke, but not always what constitutes a stroke. A stroke occurs when blood flow to the brain is interrupted or reduced due to a blockage or rupture of a blood vessel or artery that supplies blood to the brain. The interruption of blood flow deprives the brain of necessary nutrients and oxygen supplies, killing surrounding cells in the brain.
There are three main types of strokes: ischemic stroke, hemorrhagic stroke, and transient ischemic stroke. Ischemic strokes occur due to an obstruction or clotting of a blood vessel or artery. There are two types of ischemic strokes: embolic and thrombotic strokes. An embolic stroke is when a blood clot or other substance forms in the body, travels through the blood stream, and eventually becomes lodged in a small blood vessel or artery supplying blood to the brain. A thrombotic stroke is when a blockage forms in one or more arteries to the brain. The second type of stroke, hemorrhagic stroke, is due to a rupture of a weakened blood vessel. There are two major ways in which blood vessels can weaken: aneurysm, a ballooning of a weak area in a blood vessel, and arteriovenous malformations (AVM), an abnormal connection of arteries to veins. A hemorrhagic stroke can either be an intraccerebral stroke, a bleed caused by a blood vessel within the brain, or a subarachnoid stroke, an aneurysm rupture in a large artery near the membrane surrounding the brain. Lastly, transient ischemic attacks are temporary traveling clots that cause “miniature” or “warning” strokes.
There are many causes of strokes and risk factors that can increase likelihood of stroke. Causes include conditions such as atherosclerosis, also known as plaque buildup. Plaque can harden and break off or rupture a blood vessel causing a stroke. Additional conditions that may cause stroke include: carotid artery disease, atrial fibrillation, brain lesions, brain swelling, hypertension, aneurysm, AVM, and other heart and blood disorders. Lifestyle decisions may also play a part in increasing risk of stroke, such as smoking, lack of exercise, high blood pressure, poor diet, being over weight, and diabetes.
There are many methods used to diagnose strokes. Often doctors will begin with a physical and neurological examination. During the examination, the doctor will ask for patient and family history, listen for atherosclerosis, check blood pressure, look for cholesterol crystals or clots at the back of the eyes, test speech, cognition, muscle strength, nerve sensation, body reflex and coordination, and possibly order blood tests to measure glucose and platelet levels. Medical instruments used to detect stroke include: brain computed tomography (Brain CT), magnetic resonance imaging (MRI), computed tomography arteriogram (CTA), magnetic resonance arteriogram (MRA), carotid ultrasound, carotid angiography, Doppler ultrasound, electrocardiogram (EKG), and echocardiography (Echo). ...