Stroke is the most common neurological emergency, and, because effective treatment is available that must be started within minutes, most acute neurological presentations should be assumed to be a stroke until proven otherwise by history, exam, or radiographic testing. Unfortunately, there is not a quick and easy laboratory or clinical test to determine for sure that the patient lying in front of you is having a stroke, so an accurate history and exam are essential.

Is this a stroke?

DEFINITION

The term “stroke” usually refers either to a cerebral infarction or to non-traumatic cerebral hemorrhage. Depending on the population you are seeing (ethnicity, age, comorbidities) the ratio of infarcts to hemorrhages is about 4:1.

As will be described in more detail in Chapter 3, cerebral infarcts can be caused by a number of pathological processes, but all end with an occlusion of a cerebral artery or vein. If the arterial occlusion results in a reduction of blood flow insufficient to cause death of tissue (infarction), it is termed “ischemia.”

As will be described in more detail in Chapter 8, non-traumatic cerebral hemorrhages are caused by a number of pathological processes which all lead to bleeding into the brain parenchyma and ventricles. Bleeding into the subarachnoid space (Chapter 9) is usually caused by a ruptured aneurysm or vascular malformation. Other types of brain bleeding, for example into the subdural or epidural space, are usually traumatic and are not considered in this book.