Stroke Diagnosis

According to the National Institution of Health's extensive article on stroke diagnosis, a stroke is diagnosed by observing signs and symptoms, analyzing a patient's medical history, a physical exam, and results from several medical tests.
     Signs and symptoms are one of the predominant methods of stroke diagnosis, because stroke manifests physically in quite significant ways. Examples may include things such as sudden weakness, paralysis (typically on one side of the body), an inability to speak or comprehend speech, vision problems, confusion, respiration difficulty, balance and coordination problems, loss of consciousness, and headache with intense, rapid onset. These symptoms are experienced differently by different individuals, and can vary in intensity and duration. If these symptoms occur, urgent medical attention is needed, in order to limit the damage inflicted by stroke.
     There are several factors that may play into stroke risk, including things such as a family history of stroke incidence, high blood pressure, smoking, and heart disease. In a physical exam, a physician may examine coordination, balance, mental alertness, speech clarity, as well as other factors that could be indicative of stroke occurrence.
     Several diagnostic tests exist for determining stroke occurrence or likelihood, including tests such as brain computed tomography, magnetic resonance imaging, computed tomography arteriogram, magnetic resonance arteriogram, carotid tests, heart diagnostic tests, as well as blood tests. A brain computed tomography (brain CT scan) is an x-ray diagnostic tool that allows a physician to show bleeding in the brain or other damage that could have been caused by stroke. Magnetic resonance imaging (MRI) is used to detect brain tissue changes as well as brain damage that may have occurred in a stroke. A CT arteriogram and MR arteriogram both show large blood vessels in the brain, which can illustrate where a blood clot affected the brain most significantly, and gives blood flow information. Carotid angiography and ultrasound are both utilized by a physician to examine the inside of carotid arteries to determine blood flow success and factors that may have led to stroke. Heart tests illustrate factors of the heart, such as size and shape, valve success, and heartbeat patterns, that may influence the likelihood of stroke incidence. Blood tests may be used to determine blood clotting patterns, blood glucose levels that may mimic stroke symptoms, and thrombotic or bleeding disorders that all can influence the occurrence and severity of stroke.

Video Explanation of Stroke Diagnosis (with pictures of scans and diagnostic tests)

MRI scan of normal brain vs. damaged brain due to stroke
http://www.webmd.com/stroke/stroke-mri

CT scan showing stroke location in brain
http://www.uhnj.org/stroke/images/diagnosis/ct.jpg

References:
NIH Stroke Diagnosis
Mayo Clinic Stroke Diagnosis