Am I Having a Stroke?
We go about day-to-day activities and take for granted the normal function of our bodies. We do not think about our hearts beating, our lungs breathing, or our brains functioning. Therefore, when we suddenly lose one of those functions, or somehow become focused on them, the resulting situation can be quite frightening. One of the hallmarks of a stroke, implied in the very word, is the sudden onset of symptoms. One second a person is normal, and the next is marked by some part of the body simply not responding to the usual commands being sent out from the brain. Recall that the three elements of a stroke have to do with (1) abrupt onset, (2) symptoms attributable to loss of blood flow in a single arterial territory, and (3) the duration of symptoms last at least twenty-four hours. Let’s focus on each of these elements separately.
ABRUPT ONSET
The sudden onset of symptoms helps to distinguish stroke from other neurological problems that can be confused with stroke. The weakness from a brain tumor could be the same as the weakness caused by a stroke, but the former usually begins slowly and progresses over time whereas the weakness from a stroke begins suddenly. The visual losses from a cataract, or an infection in the eye, also manifest themselves gradually, whereas the decreased vision from a stroke (or a TIA) begins abruptly. Therefore, this type of onset is very helpful to doctors in distinguishing the cause of one kind of neurological dysfunction from another. It is important to recognize, however, that some patients with stroke, especially the ischemic kind, may go to sleep normal and wake up with their neurological deficit. In this setting, although the precise time of onset cannot be firmly established, we presume that the neurological deficit began at some specific point in time during the night.
NEUROLOGICAL DYSFUNCTION IN A SINGLE ARTERIAL
TERRITORY
This component of the definition of stroke is also important in helping to define the condition. This is especially true in an ischemic stroke. If one artery has lost blood flow, the brain tissue that is supplied by that artery either ceases to function or functions poorly. The patient will have particular symptoms. We will
explore this concept further later in this chapter, but a patient with a left middle cerebral artery clot will have different symptoms than a patient with a right anterior cerebral artery clot. That is to say, the particular symptoms that an individual patient has are attributable to which part of the brain is not working correctly.
In a hemorrhage, some of the symptoms can be a result of pressure on more remote areas of the brain the nonspecific irritation caused by blood in the CSF. However, when there is a hematoma that has leaked into the brain tissue itself, the symptoms will be more or less focal based on which part of the brain is involved.
DURATION OF SYMPTOMS LASTS GREATER THAN TWENTYFOUR
HOURS
The final factor relates to how long the symptoms last. The classic distinction between a TIA and a stroke has to do with this factor of duration. However, this distinction has become less important over the past decade for several reasons. First, because there are treatments for acute ischemic stroke that have to be given within a very short period of time, in fact within three hours of onset, having a twenty-four-hour time distinction simply doesn’t make sense any more. Second, as doctors do magnetic resonance imaging (MRI) scans on more patients whose symptoms do not last twenty-four hours, they are finding that some of the patients whose symptoms have gone away have actually had a stroke (more about this in the next chapter). For both of these reasons, for patients who see their doctors in the first hours after symptom onset, the time duration is a less important part of the definition than the first two components.
